One of the most popular non- destructive techniques is ultrasonic pulse velocity (UPV) which used in assessment of concrete properties. A statistical experimental program was carried out in the present study to establish an accurate relation between the UPV and the concrete compressive strength. The program involved testing of concrete cubes cast with specified test variables. The variables are the age and density of concrete. In this research, all the samples were tested by direct ultrasonic pulse velocity (DUPV) and surface ultrasonic pulse velocity (SUPV) to measure the wave velocity in concrete and the compressive strength for each sample. An experimental study was conducted to compare between the velocities of ultrasonic waves that transmitted along the two paths; direct and indirect. A total of more than 150 cubes having dimensions of 150 mm side were prepared to conduct both non-destructive and the compressive strength (destructive testing). The results from experimental program were used as input data in a statistical program (SPSS) to predict the best equation, which can represent the relation between the UPV (direct, indirect), and compressive strength, a linear equation is proposed for this purpose. The UPV measurement and compressive strength tests were carried out at the concrete age of 7, 28, 56 days. A relationship curves were drawn between DUPV, SUPV, compressive strength and density. The mixes composition in this study consists of ordinary Portland cement, fine sand, gravel, super-plasticizer, and water. All the specimens were under (20) Cº. The statistical analysis revealed that the possibility in evaluating the properties of the concrete by using direct and indirect wave velocities
The Impact of silica fume existence and its content with the duration of curing on concrete compressive strength (ordinary and high) has investigated experimentally. Two mixture sets were done in this work to examine the concrete ordinary and high strength. Every set involved four mixtures with varied silica fume proportions as a substitution of cement with (0, 5, 10 and 15 percent). Ninety-six cubes of concrete were prepared and cured by immersion in water to the required age (7, 28, 90 and 150 days). In ordinary concrete and high strength concrete, the results demonstrate that when silica fume used as a substitution with 15 %, the compressive strength of concrete gave the highest value. As compared with concrete having nil content of silica fume, the earned strength for high compressive concrete consisting of silica fume was relatively less than the corresponding ordinary concrete strength. However, continuously curing with water after 28 days produced a considerable increase in the compressive strength of concrete; such an increase in compressive strength was greater in the existence of silica fume
This research includes the study of improving impact resistance of concrete using styrene butadiene rubber (SBR) with different weight ratios of polymer to cement 3%, 5% and 10%. Two series of polymer modified concrete (PMC) were produced the first level I with moderate compressive strength and the other level II with higher compressive strength. Cubes, prisms and panels were made as follows: Results showed an improvement in impact resistance of polymer modified concrete (PMC) over reference concrete in low-velocity and high-velocity impact properties. In conducting low-velocity impact tests, method of repeated falling mass was used: 1300gm steel ball falling freely from three heights 2400mm, 1200mm and 830mm. In high-velocity impact tests, shooting of 7.62mm bullets was applied to slab specimens from distance of 15m. The improvements were significant in low velocity impact resistance. The maximum increases were (33.33%, 75% and 83.33%) at ultimate failure for falling mass heights 2400mm, 1200mm and 830mm respectively. In high-velocity impact strength tests, maximum reductions recorded in spalling area were (18.5% and 27%) for polymer modified concrete (level I) with moderate compressive strength and polymer modified concrete (level II) with higher compressive strength.Maximum reductions recorded in scabbing area were (11.42% and 35.6%) for polymer modified concrete (level I) with moderate compressive strength and polymer modified concrete (level II) with higher compressive strength, respectively.
This work study the effect of partial replacement of cement by hydrated cement on some properties of cement paste and cement mortar such as normal consistency, initial and final setting time, compressive strength, and length change. The results show that pastes containing hydrated cement require more water than reference paste to give normal consistency. The results also show that the replacement by hydrated cement delay the initial and final setting time of cement paste. The delay in setting time increased with increasing the partial replacement by hydrated cement. Compressive strength test was carried out on (54) cubes of (50) mm side dimensions of mortars containing (5, 10, 15, 20, and 25%) of hydrated cement at (3, 7, and 28) days. They were then compared with reference mortar. The compressive strength results show that the compressive strength decreases with increasing the replacement percentage by hydrated cement at all ages. The decreases in compressive strength reached (23.05 %) when (25%) of cement was replaced by hydrated cement in (28) days. The results also show that the replacement of cement by hydrated cement increases the length change of mortars compared with reference mortar.
This study concern with a new technology to modified the compressive strength of the thermo brick which have a main role in construction field. This research using a new local cheap additives called (tar) which is available in Iraq (Kirkuk area). The experimental program have include three type of thermo brick available in local market (Iraqi, KSA, and Kuwaiti) and these type are common used in south area of Iraq especially Basrah City. The sample has exposed to the steam of tar in different temperature. Four affecting factor are studied carefully on compressive strength of brick including, tar , brick manufacture type, number of exposing faces of brick, and the age of brick after finishing expose of brick to the tar steam. The result shows maximum compressive strength conducted are 4.4 MPa when two faces expose to tar and two hours’ time of exposing ( one hour for each face) and the modified percentage was 62% compared with reference sample (KSA type). The improvement in compressive strength of Iraqi type and Kuwaiti were 27% and 45% respectively. Furthermore the improvement of compressive strength with same condition aforementioned but for one hour exposing time (half hour on each face) are 37.5%. The chemical properties also has conducted in this study.
Abstract:This research studies the effect of high temperature which is reached to 600 °C onstructural lightweight and normal weight concrete. Lightweight concrete mix designedaccording to ACI committee 211-2-82 with mix proportion 1:1.12 :3.35 by volume .Thewc ratio equal to 0.5 by weight and cement content 550 kgm3. Mix proportions ofnormal weight concrete were 1:2:3 by weight with cement content 400 kgm3 and samewc. The design compressive strength at 28 days of normal weight concrete (NWC) andlightweight concrete (LWC) were 34.7 MPa and 22.62 MPa respectively. Compressivestrength tests were performed on 100 mm cubes exposed to high temperature 100,200,400and 600 °C. The normal weight concrete and light weight concrete test specimens wereexposed to high temperature for 10 minute suddenly at the required degree. Moreover,light weight concrete test specimens tested after graduate exposure to high temperaturereaching to the required degree with and without drying to examine the effect of moisturecontent.The results indicated that the structural lightweight concrete exhibits approximatelysimilar compressive strength loss compared to normal weight concrete up to 600 °C at 28days in graduate exposure .The percentage of reduction on compressive strength was30% in lightweight concrete compared to 28% in normal weight concrete at 600 °C .Insudden exposure to high temperature ,the opposite behavior was noticed .The percentageof reduction on compressive strength was 64.4% in lightweight concrete at 600°C .Drying of lightweight concrete specimens before graduate exposure to high temperaturessignificantly reduce the loss of compressive strength.
This study program has been conducted to investigate the influence of adding waste plastic fibers (WPF) resulting from manual cutting for bottles used in the conservation gassy beverage on different characteristics of ordinary concrete. Cutting plastic waste by volumetric rates ranging between (0.5%) to (2%) was approved. Reference mix was produced for comparison. Tests were conducted on the models produced from waste plastic fiber concrete like compressive strength, flexural strength and splitting tensile strength. The analysis of the results showed that the use of plastic waste fibers (1%) has led to improve the properties of flexural strength and splitting tensile strength compared with reference concrete .When the( 0.75%)WPF ratio improved the compressive strength as compared with the control specimen . Compressive strength in (28 days) with fiber ratio (0.75%) WPF is higher than equal (5.1%) from compressive strength in (28 days) of reference concrete. Volumetric ratio (1%) WPF can be also observed that each of the flexural strength and splitting tensile strength increases equal (12.5 and 12.5%) respectively, from flexural strength and splitting tensile strength for the reference mix at(28day).
This research includes producing compacted concrete by rolling method and the possibility for using in highway construction field with studying the influence of adding waste plastic fiber resulting from manual cutting for bottles used in the conservation gassy beverage on different characteristics of this type of concrete. For the purpose of selecting mix proportions appropriate for rolling compacted concrete (RCC). Approved design method for ACI-committee (5R-207 .1980) was selected for this research. Destroying plastic waste by volumetric rates ranging between (0.5%) to (2%) was approved. Reference mix was produced for comparison. Tests were conducted on the models produced from rolling compacted concrete like compressive strength, flexural strength and split tensile strength. The analysis of the results showed that the use of plastic waste fibers (1%) has led to improve the properties of each of the compressive strength and flexural strength and split tensile strength compared with reference concrete. Compressive strength in 28 days with fiber ratio (1%) is higher than (52.15%) from compressive strength in 28 days of reference concrete. It can be also observed that each of the flexural strength and split tensile strength increases by (17.86, 25.61)%, respectively, from flexural strength and split tensile strength for the reference mix
The purpose of this paper is to investigate the relationship between the Ultrasonic Pulse Velocity (UPV) and the compressive strength and the flexural strength of hardened concrete when subjected to different concentrations of sulfate attacks. The specimens used in the studies were made of concrete with different water-cement ratios (w/c). The UPV measurement and compressive and flexural strengths tests were carried out for concrete specimens of ages (4-40) days. The experimental results show that the relationship between UPV and the compressive and the flexural strengths of concrete is significantly influenced by age and the concentration of sulfate attack. The UPV and the compressive strength of concrete grow with age, but the growth rate varies with w/c ratio. It is found that with the same concentration of sulfate attack, a clear relationship curve can be drawn to describe the UPV and compressive and flexural strengths of hardened concrete. This paper presents the UPV-strength relationship curves for concrete having different (w/c) ratios subjected to different concentrations of sulfate attack. These curves are thought to be suitable for prediction of hardened concrete strength with a measured UPV value when sulfate attack is considered. It is concluded that the UPV increases with the increase of the compressive and flexural strength. The observed range for UPV was (3.5 to 4.75 km/sec) corresponds to (24 to 28.5 N/mm2) for compressive strength and to (4.6 to 6.5 N/mm2) for flexural strength. The UPV decreases with the increase of the concentration of sulfate exposure. The obtained maximum reduction in UPV was 31.6% with respect to the control spacemen at age of 40 days.
This research investigates the impact resistance of concrete slabs with different volume perecentage replacement ratios of waste plastic fibers (originaly made from soft drink bottles) as follows : 0.5%, 1% and 1.5%. Reference mix produced in order to compare the result. For the selected mixes, cubes with (100×100×100mm) were made to test compressive strength at age of (90) days. Flexural strength (Modulus of Rupture) test was also conducted using prisms sample of (500*100*100 mm) dimensions. The low-velocity impact test was conducted by the method of repeated falling mass where 1400gm steel ball was used. The ball falling freely from height of 2400mm on concrete panels of (500×500×50 mm) having a mesh of waste plastic fiber.The number of blows that caused first crack and final crack (failure) were determined, according to the former obtained results , the total energy was calculated. Results showed an improvement in mechanical properties for mixes containing plastic fibers compared with reference mix. For compressive strength the maximum increase in compressive strength was equal to (3.2%) at age of (90) days. Flexural strengths for mixes containing plastic fiber at ages 28, and 90 days are higher than that of these of reference mix. The maximum value of increaseing was (18%) for 28 days age of test and it was equal to (26%) for 90 days age of test for the mixture with plastic fiber content by volume equal to (1%) . Results showed a significant improvement in low-velocity impact resistance of all mixes contining waste plastic fibers when comparing with reference mix. Results illustrated that mix with (1.5%) waste plastic fibers by volume give the higher impact resistance at failure than the others. The magnitude of an increase over reference mix was equal to (340%).
The influence of concrete mixing water quality on the compressive strength of concretes was investigated in this study. During the study, the compressive strength (CS) of the concretes was determined at 7, 14, and 28 days age. This study used 8 types of water of varying qualities as concrete mixing water (water with 71 UTN impurity level, water with 250 UTN impurity level, water with 1000 UTN impurity level, well-sourced water, acidified water, and alkaline water). Potable water was used as reference water. The results indicated that the lowest CS has been obtained by using alkaline water at a concrete age of 7 days while the usage of water with 250 UTN impurity level as a concrete mixing water yielded the highest CS. in addition, the lowest CS has been obtained when using a mixing water of alkaline at a concrete age of 14 days while the highest CS resulted from using water with 71 and 250 UTN impurities levels. Furthermore, the usage of water with 71 UTN impurities level and an acidic water as a concrete water mixing gave the lowest CS at twenty eight days concrete age, while using magnetic water and water with 250 UTN impurities as concrete mixing water resulted in the highest CS. The use of water with 250 UTN impurities as concrete mixing water favored CS development at all concrete ages. These obtained results have shown a various effects of different impurities which significantly indicate that only a few water impurities affect the concrete’s CS seriously..
This paper is dedicated for studying the effect of curing methods on the compressive strength of concrete by using five methods of curing which are: the British method which is carried out by immersing the specimens in water starting after 24 hours of casting, then putting them in polyethylene bags- which are closed tightly- till the date of testing .The second method is carried out by covering specimens with burlap and sprinkling the specimens twice a day. The third method is carried out by immersing the specimens with water. The fourth method is carried out by sprinkling the specimens twice a day. And the last method is to paint the specimens with flint coating to prohibit the water from escaping by evaporation. The results showed that the British method is the best one for compressive strength values (36.66,31.26,25.83 MPa(, also the method of immersion in water has a close values to this method especially after 28 days. It has been noticed that the results of the fifth method have the smallest values and for all ages of curing (19.65,19.18,18.24 MPa).
The researches in Iraq has expanded in the field of material technology involving the properties of the light weight concrete using natural aggregate aviable in westran of Iraq. Researches work on porcelinite concrete has been carried out in several Iraqi Universities. The study is deals with mechanical properties of porcelinite aggregate concrete by casting (273) different specimens. These properties are, compressive strength, flexurale strength, splitting strength, static modulus of elasticity and absorption. The results indicated that the structural light weight aggregate concrete produced from local porcelinite aggregate is suitable to used as a structural concrete, it can produce structural light weight concrete of compressive strength varies from (23.0 to 29.8) MPa with the density ranges from (1745 to 1855) kg/m3, by using cement content about (550 and 650) kg/m3.Such concrete exhibited good mechanical properties. It gave the values of splitting tensile strength, modulus of rupture and modulus of elasticity, 75%, 90% and 60% from those of normal weight concrete respectively owning the same compressive strength and meeting the requirement of ACI-213
Presently development length of tension bars in reinforced concrete beams, in both codes and researches has a very wide range on the influence of major parameters. Namely, the influence of concrete compressive strength f́c affects the development length of beams by varying power values: 1/2, and 1/3. It is well known that the development length of beams is essentially based on empirical or semi empirical formulae. A total of 254 NSC and HSC tested beams available from the literature are studied in this work. These includes 154 beams without transverse reinforcement and 100 with transverse reinforcement and having a different compressive strength ranged from (16.4 – 98) MPa. The best available design method obtained from the literature leads to 43.31% increase in the coefficients of variation COV compared to the proposed design method in this work, which is essentially whose COV of 14.06%.
The problem of discarded tires has received a lot of attention from many authors. Incorporation of rubber aggregate recycled from waste tires is one of the solutions to this issue. This research is based on evaluating fresh and hardened properties such as slump flow, T500, segregation resistance, and L-box tests, compressive strength, impact resistance, and flexural toughness. Rubber aggregate replacements in the self-compact concrete mixes was 10% by volume of fine aggregate. Additionally, both PET and steel fibers are utilized at a volume rate of 0.25%.The outcomes indicate that introducing rubber declines rheological and hardened properties, whereas incorporating hybrid fibers enhances hardened properties such as compressive strength, impact energy, and flexural toughness. The best increase impact energy was obtained at roughly 166.6% when 0.25% hybrid fibers and 10% rubber were used. 74.21 was the greatest increase in flexural toughness when 0.25% hybrid fibers (SCCH3) were used. As for the compressive strength, it was the highest by about 11%.
The present study, concern about an experimental work to study the stress-strain relationship of steel-fiber reinforced polymer modified concrete under compression. Four different mixes with weight proportions of (1:2:4) were used as; normal weight concrete (NC), polymer modified concrete (PMC) with (10%) of cement weight and two mixes of steel-fiber polymer modified concrete with (1%) and (2%) volume fraction of steel fiber, (SMPC). The influences of polymer and fiber addition on peak stress, strain at peak stress and the stress-strain curve were investigated for concrete mixes used. For all selected mixes, cubes (150×150×150mm) were made for compressive strength test at (28) days while stress-strain test was caried out on cylinders (150 mm 300 mm) at the same age. Results showed an improvement in compressive strength of polymer modified concrete (PMC) over reference mix, the maximum increase of it was (13.2 %) at age of (28) days. There is also an increase in compressive strength with increasing of steel fibers content with comparison to normal concrete, the maximum increases of it were (19.6% and 25.2%) of mixes with 1% and 2% fiber content by volume respectively. In terms of modulus of elasticity, the addition of polymer and the presence of fibers cause a significant increase in it. The peak of stress- strain curve for normal strength concrete (Mix No.1) was linear whereas it was more sharp for the other mixes. The behaviour of normal strength concrete (Mix No.1) was linear up to 20 % of ultimate strength, while for the mixes with the higher strength i.e. polymer modified concrete and fibers reinforced concrete (Mixes No.2, 3 and 4) the linear portion increases up to about 50 % of ultimate strength
Composite columns are frequently used in constructing high-rise structures because they can minimize the size of the building's columns while increasing the floor plan's usable space. This study aims to create a nonlinear 3D finite element model for square composite columns designed for solid and hollow columns with various multi-skin tubes subjected to loads at eccentricities of (30 and 60) mm, compressive strength, and mesh size using the ABAQUS software. The comparison was based on the experimental data of six references of composite columns. While the compressive strength of concrete increases, the stiffness of the composite column rise. The ratio of concrete compressive strength values for composite column increased by (0, 12.3, 17.8, and 26.7 percent) for (fc'=25, 31.96, 35, and 40) MPa, respectively. The results of the different mesh sizes (20, 40, and 60) mm are showing; The experimental results and the finite element solution developed using the (20 X20) mm element correspond well. The nonlinear finite element analysis method was used, and the finite element outputs results were confirmed to be in favorable agreement with the experimental data
AbstractThis research includes the study of the effect of adding steel fibres resulting from cutting chicken wire (which is available in Iraqi markets now) as fibres added to the polymer concrete. These fibres were added with percentages of concrete volumes. These percentages were (0.5%) and (1%). Reference concrete mix was also made for comparative reasons. From the results, it can be noted that the increasing of compressive strength of SFPC1 comparing with RPC at 28 days equal to 9.90%, whereas the increasing of compressive strength of SFPC2 comparing with RPC at 28 days is equal to 15.48%. The increasing of splitting strength of SFPC1 comparing with RPC at 28 days equal to 15.50%, whereas the increasing of SFPC2 comparing with RPC at 28 days is equal to 21.40%. The increasing of flexural strength of SFPC1 comparing with RPC at 28 days equal to 10.80%, whereas the increasing of SFPC2 comparing with RPC at 28 days is equal to 20.63%.Results proved that adding of steel fibres with these percentages lead to improvements in compressive strength, splitting strength and flexural strength of concretes containing steel fibres, but the improvement in flexural strength appeared more clearly. Results proved also an increasing in densities of fibre concrete samples according to these made of reference mix.
Concrete is by far the most widely used construction material now today. Foamed concrete is light building material with good strength as well as low thermal conductivity and easy workability; it is produced by either Mix Foam Method or Preformed Foam Method. Ultrasonic Pulse Velocity(UPV) is a non destructive technique involve measuring the speed of sound through concrete in order to predict concrete strength and to detect the presence of cracking, voids, decay and other damages. This research includes three main experimental stages:- The first stage includes the production of foamed concrete and it was divided into two parts, the first part, mixing design(determination the proportions of the raw materials) was presented in the second part, the mixing procedure has been illustrated. The second stage includes preparation of samples,(i.e. molding, finishing surface, removal from molds, and curing). The third stage includes several teste to estimate properties the final product and factors influencing them, these properties include density, compressive strength, and the ultrasonic pulse velocity. From the experimental work and at the same test's age, the compressive strength and the ultrasonic pulse velocity for foamed concrete with 800 kg/m3 density were respectively (2.38 MPa,1.56 km/s)and the compressive strength and the ultrasonic pulse velocity for foamed concrete with 1200 kg/m3 density were respectively (3.7 MPa,1.96 km/s) while it were (7.8 MPa and 2.12 km/s) for foamed concrete with 1600 kg/m3 density
AbstractThere is no doubt that the type and properties of cement extremely affect the general properties of produced concrete .Cement is one of the main ingredients of cement past phase in concrete. In present study chemical and physical properties of four types of Portland cement available in Iraqi local market were studied ,these types as follow : two types of ordinary Portland cement Kubaisa (Iraqi cement) and Ismnta (Jordanian cement) and the others of sulfate resisting cement Torab alsabia (Lebanese cement ) and Al-qaim (Iraqi cement).Chemical analysis of the four types of cement were conducted in Baghdad central laboratory in National Center for Constructional Laboratories and Researches (NCCLR) and Al-qaim factory laboratory .The physical tests were conducted in the concrete laboratory of Al_anbar university-college of engineering including standard cement paste ,initial and final setting and compressive strength of cement mortars.The results indicate that the local cement (Kubaisa and Al-qaim) showed better performance than imported cement (Ismnta and Torab alsabia) in most tested chemical and physical properties .Kubaisa cement showed 34.1 % , 35.5 % higher compressive strength compared with Ismnta cement at 3 and 7 day respectively and lower loss on ignition and insoluble residue . The major compounds of Kubaisa cement were nearest to those in typical cement. For sulfate resisting cement , Al-qaim cement showed 13.3 % higher compressive strength at 7 day and lower percentage of C3A (1.95%) . Torab alsabia cement exceed the limits of Iraqi standard I.O.S No.5 1984.
The problem of solid waste is being emerged increasingly due to the increased quantity of solid waste as a result of population’s increase .From the point of view of environmental and energy concerns, it is preferable to reuse the organic and inorganic components of solid waste in order to minimize the cost. In this investigation, the possibility of using solid waste ash (SWA) as a partial replacement of cement and its effect on the mechanical properties of concrete was studied. Samples of municipal solid wastes were collected were burring and changed to ash. A total of 50 cubes, 15 small cubes, and 30 cylinders, as well as 5 prisms were prepared .Various properties of solid waste ash are added to the cement mistures with percent's of 5, 10, 15 and 20 percent by weight of solid waste ash. A concrete mix with a percent solid waste ash was used as reference. Pozzolanic activities of all mortars, and setting times of all pastes, and workability of all mixes were investigated .Compressive strength, splitting tensile strength, absorption, and drying shrinkage for reference for reference and solid waste concrete specimens were investigated at various ages. Results demonstrate that the pozzolanic activity was within ASTM requirements for the cases of 5% and 10% ash replacement. For 15 and 20 percent replacement this activity was only slightly less than the ASTM value. The 90-day compressive strength rose, in comparison with control specimens, with 5 percent replacement and was only slightly lower at 10 percent replacement. In splitting tensile strength was at least equal to reference specimens for all replacement ratios. The rise in these values, over the reference specimens, ranged between 0 to 21 percent for the case of 20 and 5 percent replacement, respectively.
Abstract This research studies the effect of adding steel fiber in two percentage 0.5% and 1% by volume on plain structural lightweight concrete (SLWC) produced by using crushed bricks as coarse lightweight aggregates (LWA) in a lightweight concrete mix designed according to ACI committee 211-2-82 with mix proportion 1:1.12 :3.35 by volume .The wc equal to 0.5 and cement content 550 kgm3. Different tests where performed for fresh and hardened SLWC such slump test ,fresh and hardened unit weight ,compressive strength and two indirect tests of tensile strength (splitting tensile and flexural strength). The results demonstrated that the effect of addition of steel fiber was more pronounced on the tensile strength of SLWC than the compressive strength of such concrete .The maximum increase of compressive ,splitting tensile and flexural strengths at 28-days were 38.8,77.12 and 111.2 % in the SLWC containing 1% fiber. On the other hand the rate of strength gain between 3 and 28 days was constant on compressive strength of plain concrete and that containing steel fiber while this rate was clearly increase on tensile strength especially flexural strength.
Concrete is produced from millions of tons of Cement, which emits a significant amount of carbon dioxide from cement mills and contributes to global warming. Therefore, it is important to seek out less expensive and more environmentally friendly substitutes for OPC. While various substitutes are available, such as recycled glass, marble, silica fume fly ash, or agricultural waste like rice husks or wheat straw, the performance of concrete is significantly affected when bentonite is used as a replacement for Cement. This study aims to evaluate Jhelum bentonite, which is located at 32°56′ north and 73°44′ east longitude, as a replacement for Cement in different ratios (0:100, 10:90, 20:80, 30:70, and 40:60) to improve the durability of the system as more bentonite is used to replace conventional Portland cement, the workability, density, and water absorption of the new concrete all decrease. Compressive Strength, Tensile Strength, and flexural Strength of blocks and cylinders were tested after being cured for 7 and 28 days. Analysis of these strength tests revealed that the mixes containing bentonite were weaker after 7 days compared to 28 days, and the Strength of blocks was reasonable compared to cylinders.Keywords: Bentonite, Concrete, Compressive Strength, Tensile Strength.
This research includes studying the possibility of producing a new kind of No-fines concrete by replacing granules of coarse aggregates with grains results from the fragmentation of industrial waste of polystyrene. This replacing were with different volumetric proportions of coarse aggregate, and theses volumetric ratios were equal to (5%, 10%, 15% and 25%). Waste plastic fibers (WPFs) resulting from cutting of soft drinks bottles were added for strengthening this new kind of concrete. Mixing ratio was equal to (1:5) (cement: coarse aggregate) by weight. One reference mix was produced for comparative purpose. Compressive strength, flexural strength and density tests were conducted, it was examined three samples of each examination and taking the average. Compressive strength values of the new sustainable concrete were ranged from 10 MPa to 12.4 MPa at age of test equal to 28 days, while the average value of the density of this concrete at the same age reaches 1930 kg/m3. This average value of modulus of rupture was equal to 2.36 MPa at 28-day age test.
Adding fibers to the shotcrete concrete mixes is very important to increase the load carrying capacity, toughness, and reducing crack propagations by bridging the cracks. On the other hand, this fiber has an effect on the fresh and hardened properties of shotcrete. In this study, fresh properties evaluated by using slump flow, , and segregation resistance tests. Hardened properties included testing of air voids, dry density, water absorption, ultrasonic pulse velocity (UPV), compressive strength, and flexural strength. This works including two types of fibers in three forms (waste plastic (PET)fibers only, polypropylene fibers (PP) only, and hybrid fiber (PET and PP)), each form added by three percentages (0.35%, 0.7%, and 1%) by volume.The results showed that the addition of 1% of all types of fiber has a negative impact on fresh properties. Especially in shotcrete containing waste plastic fiber. Also, all specimens containing fibers showed a decrease in the ultrasonic pulse velocity (UPV) and an increase in air voids and water absorption compared to the reference specimens. Also, the results clarify that the addition of waste plastic fiber to shotcrete led to a slight decrease in dry density. The highest increasing in compressive strength of shotcrete recorded by about 8.2% with using 0.35% PP fiber and highest decreasing was 20.9% with using 1% waste plastic fiber. the highest increasing in flexural strength was 62 with using 1% PP fibers.
The accumulation of wastes, especially plastic and car tires, has become a major problem facing society today. Therefore, through this research, these wastes were recycled and used to improve some properties of concrete. Recycled crumb rubber from car tires was used instead of sand as a partial replacement of 10%. The substitution was done by two methods: random and equivalent size substitution. As well, 1%polyethylene terephthalate (PET) fiber was added by the volume of concrete to improve some properties of rubberized concrete. Compressive strength, ultrasonic pulse velocity test (UPV) were conducted in this study to investigate the efficiency of PET rubberized concrete, as well the impact resistance test was also conducted to investigated the ability of PET rubberized concrete in term of energy absorption. Slabs of size (50cm×50cm×5cm) were utilized for low velocity impact test. The results indicated there were a reduction in compressive strength and UPV results were observed in PET fiber rubberized concrete the reduction were (37.47% and 5.4%) respectively as compared with PETC mixture and the result of dynamic modulus of elasticity show the same pattern of UPV result , in contrast there was an improvement in the impact resistance when PET fiber and crumb rubber were used it increased by(117.63% and 52.9% ) for random and equivalent replacement respectively as compared with PETC.
This study is conducted to investigate the strength and stiffness of clayey soil stabilized with fly ash-based geopolymer for unpaved roads. Two sodium hydroxide concentrations of 6 and 8M and two alkali solution ratios of NaOH:Na2SiO3= 1 and 1.5 were considered. Other factors such as fly ash replacement ratio (by mass), curing period, and curing temperature were held constant at 15%, 48 hours, and 65 C, respectively. The unconfined compressive strength (UCS) and ultrasonic pulse velocity (UPV) tests were performed to evaluate the mixtures. Outcomes of this study revealed that the strength of the clayey soil could be increased by up to 94%. Additionally, increasing sodium silicate content in the alkali solution increased the solution's activity and yielded higher strength and stiffness. This study confirms the effectiveness of the geopolymer binder for the improvement of soil strength and stiffness.
Abstract:-This investigation studies the mechanical characteristics of carbon fiber reinforcedlight weight aggregate concrete, containing different percentages of fiber. The effect ofusing high range water reducing agent (SP) with 8% silica fume (SF) and 8% highreactivity Metakaolin (HRM), as a partial replacement by weight of cement, on thebehavior of (LWA) concrete is also studied.This investigation was carried out using several tests. These tests were workability freshand hardened density, compressive strength, splitting tensile strength and modulus ofrupture. Tests were performed for specimens at ages of (7,28,60,90 and 180) days . Thetest results indicated that the inclusion of carbon fiber to the light weight concrete mix didnot affect the compressive strength significantly, while the splitting tensile strength andthe modulus of rupture were improved significantly. The addition of silica fume andmetakaolin improves the compressive, splitting tensile , and modulus of rupture strengthsof carbon fiber light weight concrete. The average improvement was about (26.5%, 71%and 73 %) respectively for carbon fiber LWA concrete containing silica fume and (28%,72% and 75%) respectively for carbon fiber LWA concrete containing high reactivitymetakaolin.
Abstract: This work investigates some properties of chopped worn-out tires concrete (Ch.W.T.conc.). It is a type of concrete characterized by the incorporating of Ch.W.T into the mixes as a partial replacement of volume of aggregate (sand and gravel of equal proportion). Three mixes of Ch.W.T conc. In addition to the reference mixes were selected, using Partial Replacement Ratio (PRR)of 30%, 40%, and 50%.The tests which were used in this study were: compressive strength, modulus of elasticity (static and dynamic), and impact resistance (low and high velocity). It was found that incorporating Ch.W.T in concrete effect on the properties of concrete, for example the percentage decreases in compressive strength were 41%, 46.7%, and 52.4% for concrete with 30, 40, and 50% Ch.W.T. PRR by volume of aggregate (50% sand, 50% gravel) respectively. However, it gave good indicator to be utilized as a new construction material in many applications.
SIFCON is a relatively new material and consists of slurry (cement or cement and sand), water, super plasticizers (water reducers) and fibers. In all previous research, steel fibers and other types of fibers were used, but in this study, waste plastic fibers Polyethylene Terephthalate (PET) created by cutting carbonated beverage bottles were used for the first time in the production of SIFCON. Three volume ratios (3%, 6% and 10%) of the total volume of the concrete mixture were used to add fibers in different volume ratios, and a reference concrete mixture was created for comparison. Tests of compressive strength, impact resistance, ultrasound transmission velocity check and other tests were performed on the constructed models. Compared with the reference concrete, according to the analysis of the results. The results showed an improvement in the compressive strength it increased by (18.5%), an increase in the impact resistance by (416.67%), and a decrease in the velocity of ultrasound by (19.42%).
ABSTRACT:The resistance of concrete to sulfate attack is considered as one of the important factors for concrete durability.The effect of SBR polymer on sulfate resistance of concrete is investigated. Both internal and external sulfate attack are considered.Internal sulfate attack was made by adding gypsum to raise the sulfate content of sand to that of Ramadi city soil (2.17%), while the external sulfate attack was made by adding chemical materials (MgSO4.7H2O, Na2SO4, CaCl2.2H2O, NaCl) to tap water to convert it into water similar to groundwater of Ramadi city.The laboratory tests were compressive and flexural strength, modulus of elasticity, slump, ultra-sound velocity and total percentage of sulfate after exposing to attack for different ages. It was found that the compressive strength of reinforced normal concrete (RNC) for ages (7,28,90,180) days respectively were (20,28,11.166,7) MPa, the compressive strength of polymer Portland cement concrete( PPCC) with polymer/cement ratio( P/C)=5% (PPCC5) were (21.83,32.666,12.766,8.733) MPa and for PPCC with (P/C)=10% were (24.166,35.866,15.533,11.366)MPa.While the flexural strength of RNC for different ages (7,28,90,180) respectively were (3.953,3.7,1.68,11.305) MPa, the flexural strength of PPCC5 were (4.05,5.025,2.13,1.605) MPa and for PPCC10 were (4.43,6.375,2.43,1.92) MPa.The static modulus of elasticity at age (28) days for (RNC) was (37.4) GPa , for PPCC5 was (9.7) GPa and for PPCC10 was (13.63) GPa.Slump for (RNC) was (155) mm, for PPCC5 was (142) mm and for PPCC10 was (75) mm.T he ultra-sound velocity of RNC for ages (7,28,90,180) respectively were (4.2,4.445,4.203,4.53) Km/sec , for PPCC5 were (4.36,4.646,4.53,4.176) Km/sec and for PPCC10 were (4.437,4.837,4.656,4.52) Km/sec.It was found that (PPCC10) has higher resistance to sulfate attack than (PPCC5) and (NRC). The thesis refers to necessity of polymer to improve the resistance of concrete to sulfate attack although if the sulfate percentage raise to more than (0.5) % which represents the maximum limit of sulfate percentage in I.O.S No. 45-1970.
There are various means of recycling agricultural wastes to maximize economic benefit from it. According to environmental statistics, agricultural wastes is one of the most dangerous types of wastes, especially in villages, because it is disposed of by burning. In this study, production of natural ash from agro wastes was carried out. Two types of agro waste ash were produced through burning and grinding process. waste date tree and waste reeds ash. The waste date ash (WDA) and waste reeds ash (WRA) were included in concrete by replacement of a specific portion of cement weight (5%, and 10%). Moreover, a blend of the two types of ashes were also considered. Furthermore, the natural ash was utilized in production of green concrete. Hardened density and compressive strengths at various ages (7, 28 and 56 days) were evaluated. The results in this research showed an excellent increase in compressive strength at ages (7,28 and 56) days. When measuring the compressive strength at the late age (56 days), DPA + WRA it was the best model used if it recorded the highest increase in it. Also, the use of WRA10% gave a good result, increasing its strength of the reference mixture and the rest of the mixtures also gave good and remarkable results in increasing the resistance, as the use of ash in these mixtures protects the environment from pollution and gives mixtures of higher resistance and can be used as a partial substitute for cement, except for DPA10%, so the usual mixture was better than it.
SUMMARY This research work includes three main experimental stages. The first stage includes the production of foamed concrete. It is divided into two parts; in the first, mixing design (determination of the proportions of the raw materials) according to the required density was presented and in the second part, the mixing procedure has been illustrated. The second stage includes preparation of samples,(i.e. molding, finishing surface, removal from molds and curing). The third stage includes several tests to estimate properties of the final product and factors influencing them . These properties include density , compressive strength , splitting tensile strength and flexural strength. For foamed concrete with 800 kg/m3 density, the 28-day compressive strength is from (1.334 MPa) to (2.323 MPa), while with 1600 kg/m3 density, the strength is from (7.015 MPa) to (9.591 MPa). For 1600 kg/m3 density foamed concrete, the 28-day flexural strength range is from (1.08 MPa) to (2.205 MPa).
ABSTRACT: Many of researchers study the uses of chopped worn-out tires as a replacement material to production special types of concrete. In presented work, the worn-out tires were used as fibers which have dimensions of 1×1×3 cm. The fibers used as a partial replacement from volume of coarse aggregate. Two mixes of fiber worn-out tires (F.W.T.) concrete in addition to reference mix were selected, using Partial Replacement Ratio (PRR) of 20% and 30%. The tests which were used in this study were: compressive strength, splitting tensile strength and flexural strength. It was found that incorporating of F.W.T. in concrete effected negatively on most properties of concrete, for example the percentage decreases in compressive strength relative to reference mix at 28 day were 20% and 27.3% for concrete with 20% and 30% F.W.T. by volume of coarse aggregate respectively. However, it gave good indicator to be utilized as a new construction material in many applications.
Abstract:Many of researchers study the uses of chopped worn-out tires as a replacementmaterial to production special types of concrete. In presented work, the worn-out tireswere used as fibers which have dimensions of 1×1×3 cm. The fibers used as a partialreplacement from volume of coarse aggregate. Two mixes of fiber worn-out tires(F.W.T.) concrete in addition to reference mix were selected, using PartialReplacement Ratio (PRR) of 20% and 30%. The tests which were used in this studywere: compressive strength, splitting tensile strength and flexural strength. It wasfound that incorporating of F.W.T. in concrete effected negatively on most propertiesof concrete, for example the percentage decreases in compressive strength relative toreference mix at 28 day were 20% and 27.3% for concrete with 20% and 30% F.W.T.by volume of coarse aggregate respectively. However, it gave good indicator to beutilized as a new construction material in many applications.
1-AbstractThis research includes the variation effect of (W/C) water: cement ratio on the properties as compressive strength , flxural strength , density and workability of concrete contains low Polymer SBR ratio.1:2:4 (cement: sand :gravel) by weight mixes were used . The polymer was added as percentages of cement weight and it was 2%. Reference mix was made. Water cement ratio (w/c) were used are 0.2 , 0.3 , 0.4 , 0.5 and 0.6 respectively and 0.35 (w/c) was used for reference mix . The density of concrete varied between 2030 kg/m3 and 2360 kg/m3.
This main aim of this study is evaluate wide range of fresh and hardened properties of sustainable self-compacting concrete containing various types of Cement Replacement Materials with optimum contents of Polyethylene Terephthalate PET waste plastic as fibers and fine aggregate replacement. This is to evaluate effect of the two forms of PET and to determine the best CRMs could be used with sustainable SCC. such as limestone, glass powder and fly ash with high replacement rate of 70% by weight of cement were used while fourth one (kaolin) was used with replacement rate of 20%. PET fibers were added to SCC with an aspect ratio of 24.4 and 0.7% volume fraction whereas fine aggregate partially replaced by 4% of waste plastic. Four reference mixtures contained FA, LP, GP and KA only, same four mixtures contained 0.7% PET fibers by volume, and the other same four mixtures contained 4% PET fine aggregate by volume. The obtained results all tested fresh properties, which include slump flow, T500, L-Box and segregation resistance were within the limits of the specification reported in EFNERC guidelines. Further, the forms PET have an adverse effect fresh properties of SCC. As for hardened properties (compressive strength, splitting tensile strength, flexural strength and impact strength). Further, this produced type of SCC showed an range of compressive strength (15.2-31.64 MPa) at 28 days. It can be from the current study the best CRMs to be used in SCC containing PET wastes was FA in terms of most tested properties.
Composite beams, made up of a concrete slab and steel in the IPE steel section, are commonly used in bridges and buildings. Their main function is to enhance structural efficiency by merging the compressive strength of concrete with the tensile resistance of steel, thereby improving overall stiffness, ductility, and load-bearing capacity. This study offers an extensive review of the flexural behavior of steel-concrete composite beams, focusing on the interplay of concrete strength, shear connector types, and interaction levels in determining structural performance. It integrates experimental and numerical research to analyze critical parameters, including load-deflection behavior, shear transfer efficiency, and crack propagation at the steel-concrete interface. The study emphasizes the effect of concrete compressive strength, particularly in ultra-high-performance concrete (UHPC) and lightweight concrete, on stiffness, ductility, and load-bearing capacity while reducing self-weight and enhancing sustainability. The study revealed that fully bonded shear connectors, using CFRP sheets and welded plates, enhance flexural capacity and stiffness. In contrast, partial bonding or pre-debonding reduces performance due to crack propagation. Indented and hot-rolled U-section connectors enhance interaction and minimize slip, while uniform distribution of shear connectors optimizes load capacity and stiffness. Lightweight concrete decreases slab weight without compromising performance, and high-performance materials such as ECC, SFRC, and UHPFRC improve strength and ductility. Numerical modeling, particularly finite element methods, and higher-order beam theories validate experimental results, providing accurate tools for predicting structural behavior under various loading and environmental conditions.
This research includes study the effect of fineness upon physical properties of cement mortar where use ordinary Portland cement with fineness (300 m2/kg) as reference mixture which denoted by symbol (M1), and then produce with flowing fineness (350,400,450 and 500 m2/kg) which denoted by ( M2, M3, M4, M5 ) respectively . The results of study show that increasing in fineness makes an increase in water quantity that requires for consistence of standard paste and the ratio of above mixes with reference mixture (2%,5%,7%,11%)respectively, although the increasing in density for all ages and increasing in compressive strength in early age, the increasing ratio in 3 days age was ( 45% , 50% , 60% , 70%)respectively .this increasing in fineness makes increasing in ratio of flow as compared with reference mix(16%, 25%, 50%, 66%) respectively
The performance of the structural materials (concrete and steel reinforcement) and the behavior of the structural members after they were exposed to high temperatures have been considered the main topics of the current literature review. All varieties of concrete mixtures lost their compressive strength after 300˚C, even though there was no discernible strength loss between 150 and 300˚C. It was also discovered that the heating time had no appreciable impact on the strength loss when the exposed to heat less than 300 ˚C. Above 300 ˚C. Concrete begins to lose strength after being exposed for longer than one hour; the greatest loss of strength occurs during the first and second hours of exposure. Both the cured cement paste and the aggregates undergo chemical and physical changes at temperatures ranging from 600 °C to 900 °C. The 5% weighted rice husk ash (RHA) blended concrete still had an advantage in compressive strength, over the concrete when subjected to temperatures up to 700 C for two hours. Adding more recycled glass and ceramic particles to regular concrete increases its overall compressive and tensile strengths. Concrete becomes more durable and has fewer cracks when there is a higher replacement rate for ceramic and glass particles. The splitting tensile strength decreased with increasing temperature, changing from 60% to 70% of its initial strength after 600 °C. In this review, the better performance of concrete than the other concrete in terms of mechanical, physical, and durability properties at both room temperature and high temperature were concrete with 10% waste glass powder (WGP) substitution as a partial of cement and 10%–20% crushed glass (CG) substitution as a partial of aggregate .
Polyethylene terephthalate (PET) fiber is a green-friendly fiber that is capable of enhancing the mechanical properties of wet-mixing shotcrete. The main purpose of this study is to see how varied volumes of waste plastic fibers (WPF) affect the flowability and mechanical properties of wet-mix shotcrete. For this aim, a variety of experimental tests based on WPF content were chosen. Fresh and mechanical tests included slump, T500, density, compressive strength, and splitting strength were applied. The results shown a improved in shotcrete performance as the WPF content increased. Among all fitting correlations, density and compressive strength revealed the strongest linear ship association. Due to greater interlocking between WPF and concrete matrix, WPF was a major use in enhancing splitting tensile strength. WPF had the most influence on splitting strength, with 23–31 percent, 7–23 percent, and 6–38 percent for 7, 14, and 28-day, respectively.
This research includes study of the of effect of adding sulphur, which is obtained from Samrraa factory on the properties of concrete like compressive strength, flexural strength and splitting tensile strength. The concrete mixes were: (1:8.5:8.5:7), (1:8.5:8.5:9), (1:8.5:8.5:12) and (1:1.5:3:0) (cement: sand: gravel: sulphur) respectively. The results refer to increasing of compressive strength , flexural strength and splitting tensile strength with increasing of sulphur ratio but increasing decreased at age (28)day with respect to ordinary concrete (sulphur ratio=0%).
This paper presents and discuses some properties of self-compacting concrete SCC containing optimum contents of different types of cement replacement materials CRMs like fly ah, silica fume and limestone powder. The purpose is to evaluate the performance of SCC mixtures to choose the best one for strengthening purposes of corroded reinforcement concrete beams. In a preliminary work, the theoretical optimum contents of the above materials were specified using statistical program (Minitab) and they were verified experimentally. This verification based on checking fresh properties such as slump flow, T500, L-box and segregation resistance as well as compressive strength. The optimum contents of CRMs: 14% fly ash, 19% limestone, 18% silica fume plus fly ash and 11% silica fume were selected and studied. Compressive, tensile, and flexural strengths were examined, as well as the modulus of elasticity, water absorption and porosity (which reflect the related durability properties) were examined. Test results show that the optimum verified theoretical percentage of a combination of fly ash and silica fume, at 18% by weight of cement with a fixed water-binder ratio of 0.33 showed the best overall performance. It was deduced that this SCC mix gave the highest mechanical properties and the lowest porosity and water absorption. For example, the compressive strength increased by 36.25% as compared to SCC mix containing limestone powder. Further, the porosity and water absorption decreased by 120.8% and 164% respectively as compared to the above same SCC mix. Thus, it could be used for strengthening purpose of corroded RC beams.
This paper deals with the nonlinear finite element analysis of two shear-critical concrete dapped-end beams. Reinforced concrete dapped-end beams having nominal shear span to depth ratio values of 0.56 and 0.59, concrete strength 32MPa and 34MPa, and reinforcement ratio via yield strength 2.83MPa and 7.39MPa, that failed in shear have been analyzed using the ‘ANSYS’ program. The ‘ANSYS’ model accounts for the nonlinearity, such as, post cracking tensile stiffness of the concrete, stress transfer across the cracked blocks of concrete. The concrete is modeled using ‘SOLID65’- eight-node brick element, which is capable of simulating the cracking and crushing behavior of brittle materials. The internal reinforcements have been modeled discretely using ‘LINK8’ – 3D spar element. A parametric study is also made to explain the effects of variation of some main parameters such as shear span to depth ratio, concrete compressive strength, and the parameter of main dapped-end reinforcement on the behavior of the beams. From the present modality the capability of the model to capture the critical crack regions, loads and deflections for various types of shear failures in reinforced concrete dapped-end beams have been illustrated. The parametric study shows that the beams shear strength is affected by the shear span to depth ratio, concrete compressive strength and the amount of main reinforcement.
In this paper, the laboratory experiments works were conducted to study the effect of adding recycle waste plastic as polyethene terephthalate PET fibers on the fresh properties as the slump test and hardened properties as a compressive strength, splitting strength, elastic modulus, ultrasonic pulse velocity (UPV), density, absorption, voids, flexural toughness and flexural rupture for the normal concrete. The parameter of this paper included percentage of fibers content (0%, 0.5%, 1%, and 1.5%). The geometric design of the PET fibers was a strip with dimensions 4mm width, 70mm length, and 0.035mm thickness. The aspect ratio of the PET fibers in this work was about 50. The results showed that the PET fibers improving the most properties of the normal concrete and on the other hand there is negative effect on some properties of concrete. There is a significant increase in flexural toughness, about 21.2%, while the compressive strength and splitting were increased by 5% and 18.8%, respectively. Besides this improving, using PET fibers conform to the principle of sustainability, which is reducing the pollution and the cost of waste plastic disposal. It’s observed that properties of concrete as a static modulus of Elasticity and density were decreased with the fiber percentage increased
Abstract: The presented investigation studies the effect of steel fiber content on the dynamic properties of High Performance Steel Fiber Concrete by using non-destructive testes; Vibration tests (Electrodynamics tests) were used to obtain the dynamic modulus of elasticity, dynamic shear modulus (modulus of rigidity), damping capacity, and dynamic Poisson‘s ratio. The results demonstrated in general an improvement in dynamic properties, which were tested for example, the percentage increasing in compressive strength relative to the reference concrete were 2.5%, 6.6%, 5.8% for High Performance Concrete (HPC) with 0.5%, 1%, and 1.5% steel fiber by volume of concrete respectively.
The earth-fill dams are simple structures which are able to prevent the sliding and overturning because of their self-weight. Due to lack of suitable clay materials, the dams may be designed as zoned core which is composed of three vertical zones contains central impermeable core and two permeable shells on their two sides of the core. Impervious core is used in zoned earth dam to reduce the quantity of seepage through the body of the dam and to relief part of risk of piping and erosion in the downstream side. This study aims to study the soil properties that is used as a core of earth dam through a series of laboratory experiments that were carried out a several soil samples mixed with both lime and silica fume, in order to stabilize the soil. The process of stabilization aims to increase the soil strength and reducing its permeability and compressibility. Test results show that adding lime and silica fume to the soil decreases the permeability of soil with different cases of study, the percentage of decreases in case of standard compaction about (21%-90%) while in modified compaction test the permeability decreases in range (41.7%-91.3%). Also the unconfined compressive strength of the soil increasing significantly in both cases of compaction which were standard and modified. When add the materials, these values were increased in range (76%-90%) for samples from standard compaction test, while it being (0.21%-42%) in modified compaction test.
This study presents an experimental research of Self-Compacting Concrete (SCC) properties containing waste plastic fibers (WPF). Adding waste plastics which resulting from cutting PET bottles as fibers to SCC with aspect ratio (l/d) equal to (28). To illustrate the effects of WPFs on the SCC, the current study was divided into two parts, the first part shows the effect of adding plastic fibers on the properties of fresh SCC, which include the ability flow, spread, passing and resistance to segregation, and the second part to evaluate the properties of hardened (mechanical) destructive and non-destructive, which include compression strength, flexural strength and ultrasonic pulse velocity test. One reference concrete mix was conducted and eight mixes contain WPF has been producing self-compacting concrete mixers containing a different volumetric ratio of plastic fibers (Vf) % percentages (0.25, 0.5, 0.75, 1, 1.25, 1.5, 1.75, 2) %. Three cubes samples were prepared for testing the compressive strength, three prisms were prepared for the test modules of rupture, one cylinder were prepared testing the modulus of elasticity. The experiments show that adding plastic fibers to SCC leads to an increase in the compression strength and modulus of rupture at 28-day as follows (42.30)% and (73.12)% respectively for mix ratio (1.5)% in comparison with the reference mix, which represent the best ratio of fibers, as such the results of testing the fresh concrete containing waste fibers showed that adding these fibers led a reduction in workability for SCC.
The main rule of this search is determining the effect adding various types of fiber to normal concrete mixes on performance normal strength concrete ,it has been used three types of fibers (glass, short steel fibers& long steel fibers)with different contents in mixes(0.5,1.0&1.5%) respectively. It had been cast (210) cubes with dimensions (100×100×100m) mm,(160) cylinders with dimensions (100×200) mm , All concrete specimens heated under different temperatures (100,200,300,400,500 &600 C°) at age 28 days, so that it had been stayed under specified temperatures about two hours then , cooled in naturally in room temperatures and tested in compressive for cubes &splitting strength for cylinders. The results stated that the fiber improve the compressive strength under fire temperatures about (87%) compare with reference mixes, and the fiber glass take little differences than steel fiber in splitting strength when its content reach (1.0,1.5%) respectively and using this types of fibers improved the properties of concrete against the fire.
To preserve the natural materials, applying the principles of sustainable engineering, to approach the principle of zero waste and to contribute the solution of the negative environmental impact of two decades, which is caused by excessive use of bottles of polyethylene terephthalate (PET) in packaging, has led to the approach of alternative, clean and innovative technologies aimed at recycling and reuse to address this environmental problem. Proposed re-use empty bottles as a way to get rid of them and benefit from them at the same time the way, this method through which the empty bottles cutting into fibres using these fibres made of PET to improve the properties of concrete. Percentage of fiber that has been used are 1%, 1.5%, 2%, 3%, 4%, and 5%. Suitable tests were performed to measure properties of concrete reinforcement by recycle PET fibre such as compressive strength, splitting tensile strength, four-point bending strength, modulus of elasticity and toughness index. Flexural toughness tests were performed to measure the ductility capacities of reinforced concrete members with recycled PET fibre reinforced concrete. The results obtained indicate Toughness index was enhanced by using PET fibre reinforced concrete specimens, compared to no ductility performance of concrete specimens without fibre reinforcement. A significant change in ductility was when observed PET used fibre with 3%.
This research work includes production of new type of light weight concrete and studies the mechanical and thermal properties. Several proportions of raw materials were used to produce this type of concrete. This study is intended to produce light weight concrete with low thermal conductivity so that it can be used for concrete masonry units. Polystyrene aggregate was added as percentages by weight of cement to improve the thermal properties of this type of concrete .Mechanical , and thermal tests with difference ages were made in this work .For polystyrene concrete with polystyrene cement ratio (p/c) of (2.67 – 6 )% , the28-day compressive strength range is from (4.31 – 2.67)MPa, flexural strength range is from (3.05-1.719 ) MPa , density range is from ( 1493-1213 ) kg/m 3 ,and thermal conductivity range is from ( 0.91-0.782)% as a percentage by that of reference mix. The study show suitability of this type of concrete to be used in concrete masonry units of non-bearing walls.
The aim of this research is to produce lightweight cement mortar with properties better than reference ordinary cement mortar. Porcelanite stone were utilized as lightweight aggregate with a volumetric partial substitution of fine aggregate. The process includes using different percentages (5, 10, 15 and 20 %) of pre-wetted (24hr.) porcelanite to produce lightweight mortar with internal curing. Water curing was used for reference mortar mixture and air curing for the other mixtures of porcelanite substitution. Compressive strength, flexural strength, density and ultrasonic pulse velocity for different ages (7, 14 and 28 days) have been tested. The results show an improvement in the properties of cement mortar especially in replacement percentage of 10 %.
The aim of this study is to investigate the effect of adding recycled materials such as CKD and RAP to weak cohesive soils, in addition to evaluate the change in the strength of these soils. This study was conducted on soil type MH, and only RAP particles finer than 10 mm were used in preparing the mixtures. 7, 14, and 28 days were selected as curing periods for soil- CKD and soil- CKD- RAP mixtures to obtain the effect of curing periods on soil improvement. The results showed that adding 20% of CKD to the natural soil increased the unconfined compression strength UCS from 0.43 MPa to 2.6 MPa at a 28-day curing period. Also, the results showed that adding 25% of RAP to the soil- 20% CKD mixture increased the UCS value to 5.3 MPa after 28 days of the curing period. The final results showed that the optimum contents of CKD and RAP added to the cohesive soil were 20% and 25%, respectively, while the optimum curing period was 28 days
The paper shows the final findings of the effect of metakaolin on the strengths properties of concrete exposed to crude oil. Sulfate resistance Portland cement of V type was used and specimens of concrete were adjusted and subjected to a solution of concentrated crude oil. However, the samples are cured in a control media at immersion ages of (28, 56 & 120 days) with ambient temperature, then samples have been kept in curing water for comparisons purpose as well. The results explain that the use of metakaolin reinforces compressive, flexural and splitting resistance of concrete which is exposed to crude oil. The compressive strength reduction increased from 8.0% at (28 days) to 37.7% at (120 days) curing for normal weight concrete (NW) whereas the concrete incorporating metakaolin (MC) has a reduction of 6.0% at (28 days) & 29.3% at (120 days). .
Housing represents a major world wide problem, especially for developing countries. It is essential to construct suitable housing units that are appropriate for the continuing population increase. Many countries have applied construction (policies) that depended on the available material and human resources. These schemes aim at producing the greatest number of dwelling units that are suitable for the people who do not own units. The aim of this research is the scope of low cost dwelling units in general, and through the reduction of roofing cost. The objective of the research, Economical feasibility study for production precast units (ferro cement units) for roofs of low cost dwelling and compare the cost of the proposed system With other conventional roofing systems: roofing by (jack arching) and reinforced concrete. Fifteen units of Ferrocement with square shape and three different dimensions were cast and tested for load test, tensile strength, compressive strength and bending. The optimized dimensions were (750*750*20)mm and the capacity ranges from (13 to 17.7)KNM2.The cost of (1m2 ) of these units was (38292.4)I.DM2 while the cost of (1m2 ) reinforced concrete (58534.94(I.D and (51062.7) I.DM2 for (jack arching)
The concept of sustainability was developed in the last years and included the construction industry to solve the issues that pertaining by high consumption of natural sources, environmental pollution and high amount production of solid wastes. On the other hand, the plastics generation is growing exponentially every year, especially, types of Polyethylene Terephthalate (PET) that are used to produce soft drinks bottles, this study attempts to apply the concept of sustainability and reduce the environmental pollution by cutting the plastic bottles (PET) as small fibers added to the ordinary concrete to improve the shear and tensile strength of reinforced concrete beams. For this purpose, the experimental work was carried out to study the effect of waste plastic fibers (PET) on the shear behavior of seven reinforced concrete beams with dimensions of (100×150×1200) mm that were designed to fail in shear, the fibers percentages that were used in this study are (0.25, 0.5, 0.75, 1, 1.25 and 1.5%). Also, the influence of Polyethylene Terephthalate (PET) fibers on the mechanical properties of concrete was studied such as: workability, compressive strength, splitting tensile strength, static modulus of elasticity and ultrasonic pulse velocity.
This study addressed some important tests for concrete including thermal, acoustic insulation and some mechanical behaviour of concrete containing granular Polyvinyl Chloride (PVC) waste as a sand replacement. The PVC waste was collected from a plant of manufacturing PVC doors and windows, was used to replace some of fine aggregate at ratios of 2.5%, 5%, 7.5%, 10%, 12.5% and 15% by weight Properties that studied are thermal conductivity, acoustic insulation slump, fresh density, dry density, compressive strength, flexural strength, and splitting tensile strength. Curing ages of 7, 28, and 56 days for the concrete mixtures were applied in this work. From the results of this study, it is suggested that using of 12.5% fine PVC as a sand replacement by weight can improve thermal insulation to about 82.48% more than concrete without plastic waste Acoustic insulation is about 43.09% more than reference mix and it satisfies the requirement of ACI 213R 2014 for structural lightweight concrete.
AbstractThis study deals with establishing high-velocity impact properties of polymer –modified concrete (PMC) including Styrene-Butadiene rubber (SBR), with different weight ratios of polymer to cement: 4%, 8% and 12%. Steel fibers were also included. Sixteen (500mm) diameter, (50mm) thick discs for high-velocity impact tests were used. In addition compressive strength, splitting tensile strength, and flexural strength (modulus of rupture) were companionly recorded. In all the tests, concrete was with and without crimped steel fibers of ratio 1% by volume.In investigating high-velocity impact strength, the decrease in projectile penetration depth was (5-17%) and the scabbing area reduced (15-35%) over reference concrete.In studying PMC including 1% by volume steel fibers, an additional increase was observed in all properties. The increases were quite significant in high-velocity impact strengths. Further reduction was recorded in scabbing area of (64-95%) and penetration depth reduced (28-39%) over control specimens. The fragmentations were reduced also. The range of corresponding compressive was (48-64)MPa ,of splitting tensile strength (4.2-7.8) MPa, and of flexural strength (5-8) MP
The current research’s purpose is to examine how Ultra-High Performance Fiber Concrete (UHPFC) holds up in terms of strength and durability for strengthening purposes. For this reason, the experimental and the theoretical studies in this research attempted to assess different fresh and hardened properties of a variety of ultra-high performance combinations. Steel fibers were utilized to differentiate all of the program's combinations at percentages of 0.25 %, 0.5 %, 0.75 %, 1%, and 1.25 % by volume. Mini flow slump, compressive and flexural strength, ultrasonic pulse velocity, water absorption, and porosity tests were all used to examine the performance of the strength and durability of the material. The findings of this study's trials showed that steel fibers increased the strength of UHPFC. The steel fiber ratio of 1% gave the maximum compressive strength, whereas 1.25 percent yielded the highest flexural strength. Because the fibers function as a bridge, preventing internal breaking, the tensile test results were improved as the proportion of steel fiber rises. Through the use of the multi-objective optimization approach, the optimal ratio of fibers was chosen at the end of the laboratory work since it has the best durability and strength characteristics. Statistical software (Minitab 2018) was used to find the optimal combination of UHPFC that meets all of the requirements. The theoretical selected optimum ratio of 0.77% of fibers obtained from the optimization was evaluated and validated experimentally. The optimized mix provided 90.28 MPa, 14.6 MPa, and 20.2 MPa for compressive, splitting tensile and flexural tests respectively with better durability performance compared to other mixes prepared in this investigation.
The use of textile reinforcement made from non-corrosive materials, such as carbon and glass can reduce the required concrete material; this is known as Textile Reinforced Concrete (TRC). This study deals with plate specimens having dimension of 500×500×40mm tested under impact load at 28 and 90 days age under two conditions of ends, simply supported and fixed. Cement mortar with about 60 MPa, 7cm cube compressive strength at 28 days was designed for casting the plates. Plate specimens were divided into four groups, they consist of reference plates (no reinforcement) and plates reinforced with 3D glass fabric having three different thicknesses 6, 10 and 15mm. The results indicate that using 3D textile glass fabric cause an increase in number of blows, reduce in final stage deflection, an improvement in toughness and energy absorption under impact loads. Using 3D textile glass fiber with 10mm thickness gave higher number of blows for 28 and 90 days as compared with 6 and 15 mm. Plates with slice 6mm 3D textile glass fiber in two way reinforced has significantly enhancement in number of blows, the improvement was about (80 - 125%) and (128.5- 114. 3%) for 28 and 90 days respectively. The specimens showed increase in the energy absorption, besides the number and width of cracks was reduced and only few cracks are propagated up to the edge of the plates.
This research includes a study of the behavior of beams made from No-fine concrete using 10 maximum size of aggregate and improved by SBR polymer. From test results, the effect of addition of polymer to concrete leads to improved compressive and flexural strengths, The beams improved by polymer failed under loads more than the beams which were made from reference concrete. The percentage increases in compressive strength for No-fines polymer concrete compared with reference concrete were (41%, 58, 38%) for ages (3,7,28) days respectively
This study presents an investigation of the mechanical properties of normal concrete reinforced with discarded steel fibers (DSFs) resulting from tire manufacturing. DSFs were added to concrete in two different volume fractions of (0.25 %, and 0.5 %), and these fibers have dimensions of (40 mm length×0.92 mm diameter). The results showed that the compressive strength of the concrete was enhanced by (8.8%, and 3.3%) by adding of DSFs. However, the workability of concrete decreased at all added ratios. While the density is slightly changed. Also, the results indicate that the modulus of elasticity shows slight increases by (3.06%, and 2.25%). Additionally, the incorporation of DSFs improves the splitting tensile strength and modulus of rupture significantly. For concrete mixes having volume fractions of 0.25% and 0.5%, the splitting tensile increased by (7.89%, and 23.68%), and the modulus of rupture increased by (6.67% and 25.58%), respectively. It was concluded that using this type of discarded fibers can improve the mechanical properties of concrete as an alternative type for other types of industrial fibers.
This paper presents the numerical study to simulate the flexural behavior of normal strength, high strength and hybrid reinforced concrete beams, under two points load with two different reinforcement ratio. The hybrid beam consists of two layers: the compressive layer is made of high strength concrete, and the tension layer is made of normal strength concrete. The simulation was done with a finite element model using the commercial finite element code, ANSYS (v.9.0). The concrete component material is modeled, the internal steel reinforcement modeled using ''LINK'' elements. The modeled behavior shown a good agreement with the experimental data. The maximum percentage difference in ultimate load-carrying capacity is 8% at the ultimate load level.Analytical study also included the effect of increasing the depth of the normal strength concrete for the hybrid reinforced concrete beam and the effect of increasing the compressive strength for high strength concrete and normal strength concrete respectively on the behavior and the load carrying capacity of the hybrid reinforced concrete beams.
Fresh and hardened properties of self-compacting concrete was experimentally examined by replacing different percentages of cement by soft clay powder, which resulting from crushing the wastes of clay bricks. Three percentages (5%, 10%, and 15%) of cement were replaced with clay powder to study their effect on the properties of cement mortar and concrete of Grade (C35) in both fresh and hardened states. It was found that development rates of the compressive and tensile strengths for the mortar between ages of 7 to 28 days, decreased with increasing the percentage of the clay powder. Compared to the mix without clay powder, it was found that replacing (5%) from the cement causes a significant increase in the workability of the self-compacting concrete and the properties of the resulting hardened concrete such as compressive strength, tensile strength, and modulus of elasticity. While using (10%) and (15%) of the clay powder causes a significant decrease in the workability of the fresh concrete and the properties of the hardened concrete compared to mix without clay powder.
Research in Iraq has expanded in the field of material technology involving the properties of the light-weight concrete using natural aggregate. Research work on porcelinite concrete has been carried out in several Iraqi Universities. However , despite the great practical importance of such concrete in construction fields ,very limited amount of work has been carried out to investigate the (shear strength) of structural light-weight aggregate concrete , therefore it is important to study the properties and their structural behavior. In this work an attempt is made to study shear strength of porcelinite reinforced concrete beams without (stirrups). The results have been compared with the results predicted by the equations of International codes, such as ACI 318M-02, BS-8110 codes and with some authors' equations as for, Hanson. The experimental results also have been compared with results obtained from normal weight concrete specimens that had been prepared for this purpose. The study mainly deals with the structural behavior of porcelinite reinforced concrete beams without stirrups, especially the shear strength, besides, the short-term deflection, strain and cracks. The variables are, compressive strength ranging between (23.0-29.8) MPa and reinforcement percentages ranging between (0.0174-0.0307). A total of 12 beams are tested; (9) are light weight concrete beams without stirrups and (3) are normal weight concrete beams, also without stirrups. The dimensions of all those beams are 135 * 260 * 1800 mm. The structural results more often, give values 2.9 times more than that of (ACI-02)