علي طالب جاسم البوزويده

Abstract From several points of view, disposal of waste materials in an environment is respected to be a significant problem because of its very low biodegradability and existence in huge quantities. Waste of plastic and metal bottles caps, cans of juices and soft drink, and tires rubber being among the most pronounced. This study was conducted to evaluate the efficiency of reusing these waste materials in concrete production and solve the segregation problem. As segregation increases in concrete involving these waste materials due to lighter weight of them relative to nature aggregate, therefore, attention was intensive on using natural product (Gum Arabic) that is an environmentally friendly chemical material for improving concrete properties. The conducted tests include; compressive strength, flexural strength, splitting tensile strength, density, water absorption, and ultrasonic pulse velocity. The results showed that replacing the volume of coarse aggregate by 25% compacted bottles caps and pull-tab of cans, 20% the plastic bottle caps, and 25% tires rubber shreds used decreased the mechanical properties of concrete to some extent less than reference mix and they were enhanced by employing Gum Arabic. In addition, the employment of Gum Arabic as liquid in concrete mixes developed the mechanical properties of concrete, reduced segregation, however raised the water absorption percent and declined the density of concrete.

effect of hydrostatic pressure on the properties of underwater self compacting concrete. In this research, 30 mixes of self compacting concrete have been prepared with six groups. The first three groups contain AWA, while the second groups made without AWA. The main parameters explored in this research were: silica fume, limestone powder and rice husk ash as a cement replacement content with 0% and 1% anti washout admixture and different water depth (10 ,20 , 30 ,40 and 50 m). Washout loss was determined using either the CRD C61 test method or a newly developed device for simulation of increased hydrostatic pressure on the concrete/water interface. Good correlations were obtained between the standard washout loss determined according to CRD C61 and simulated threshold water head and corresponding maximum washout loss . Increasing AWA from 0% to 1%, decreasing slump flow by 28.6% /, 31.3% and 24.24% ,decreasing washout loss by 58% , 64.35% and 69.28% and increasing compressive strength by 52.6% , 68.4% and 71.5% for concrete mix contain silica fume , lime stone powder and rice husk ash respectively .

The main objective of this study is to investigate the effect of anti washout admixture with various concentrations on fresh and hardened properties of self compacting concrete cast underwater. In this study, 16 mixtures was placed under water. The main parameters investigated in this study were: various concentrations of anti washout admixture, two dosages of superplasticizers, silica fume as replacement of cement content, limestone powder as replacement of cement content. The results obtained from this study indicates that the increasing AWA dosage from (0 to 1)%, for concrete mixes contain silica fume and limestone powder, reduced the slump flow by (25 - 33)% and (27-34)% respectively, decreases the standard washout mass loss by (69- 68)% and (75-78)% respectively, increased the compressive strength of concrete cast in standing water by (202 - 203)% and (266 -385)% respectively and increased the splitting tensile strength of concrete cast underwater by (169 - 191)% and (229 - 285

In this research effect of rice husk ash (RHA) on Fresh and Hardened Properties of concrete which used to reduction the seepage in the canal lining was studied. To establish the suitable proportion of RHA for the partial replacement of cement, Concrete specimens was molded with 10%, 20%, and 30% of (RHA) replacing the cement, and measured it to workability, compressive strength, splitting tensile strength, dryings shrinkage, The results were compared with the concrete mix that does not contain RHA. The obtained results indicated that it was a significant reduction of workability in fresh concrete with the increase amount of RHA content in concrete, and it was an increase in the compressive strength and splitting tensile strength by increased of RHA% until 20% , The maximum increment is around 10.5%and 11% for the compressive strength and splitting tensile strength respectively then it were decrease with the increase of RHA to 30%, the decrease was around 17 % and 10.5% for compressive strength and tensile splitting strength respectively. The test of drying shrinkage indicated that it was decreased with increased of RHA%, the maximum decreased given by 30% RHA it was about 28% of normal concrete shrinkage after 90 days age.

Control of water losses by lining canals is one of the important aspect to solve problem of Seepage from irrigation canals. In this research work was experimentally carried out to study the performance of concrete containing Rice Husk Ash (RHA) in lining canals, due to its great availability and low cost. In the presented research concrete specimens was molded with 10%, 20%, and 30% of (RHA) replacing the cement. Tests of water absorption, sorptivity and coefficient of water absorption indicate that it were decrease with the increase of RHA% until 20%. from the result of ponding test it can be concluding that it was a clearly reduction in the rate of seepage losses with the increase of RHA% replacement concrete until 20% where the reduction was recorded to be 34% and 67% for 10% and 20% RHA respectively, while when the %RHA increased to 30 the rate of seepage losses was more than it was in the control mix, where it was increased to 26% than that in the control mix for the older age thus, it can be concluded that used of rice husk ash (RHA) as partial replacement to 20% of ordinary Portland cement in concrete lining canals will reduce the rate of seepage losses from canals and improvement the properties of concrete which u

Control of water losses by lining canals is one of the important aspect to solve problem of Seepage from irrigation canals. In this research work was experimentally carried out to study the performance of concrete containing Rice Husk Ash (RHA) in lining canals, due to its great availability and low cost. In the presented research concrete specimens was molded with 10%, 20%, and 30% of (RHA) replacing the cement. Tests of water absorption, sorptivity and coefficient of water absorption indicate that it were decrease with the increase of RHA% until 20%. from the result of ponding test it can be concluding that it was a clearly reduction in the rate of seepage losses with the increase of RHA% replacement concrete until 20% where the reduction was recorded to be 34% and 67% for 10% and 20% RHA respectively, while when the %RHA increased to 30 the rate of seepage losses was more than it was in the control mix, where it was increased to 26% than that in the control mix for the older age thus, it can be concluded that used of rice husk ash (RHA) as partial replacement to 20% of ordinary Portland cement in concrete lining canals will reduce the rate of seepage losses from canals and improvement the properties of concrete which u

The main objective of this study was to investigate the performance of no-fine concrete made with lightweight aggregate (porcilinite) and modify with Styrene Butadiene Rubber (SBR) and to suggest possible applications of this type of concrete.

The main objective of this investigation is to study the effect of oil (kerosene, gas oil and crude oil) on the compressive and tensile strengths of high performance concrete and to compare the behavior with that of normal strength concrete. Four exposure periods were used for each specimen and for each liquid, 30, 60, 90 and 120 days after 28 days water curing. To provide a basis for comparison, reference specimens were cast and exposed to water for a respective time of test. The test results showed that the loss in mechanical properties (compressive and splitting tensile strengths) resulting from exposure to oil was relatively smaller for high performance concrete (HPC) compared with normal strength concrete (NSC). The difference was about 10 percent. Furthermore, the reduction in compressive and splitting tensile strengths of NSC and HPC increased with decrease in viscosity of oil in the entire period of exposure.

Self-compacting concrete (SCC) is a very important advance in the concrete technology in recent time. It is a new type of high performance concrete with the ability of flowing under its own weight and without the need of vibrations. Due to its specific properties, SCC may contribute to a significant improvement of the quality of concrete structures and open up new field for the application of concrete. This study aims to check whether the fresh properties of self compacting concrete mixed by the Nan Su et al., [1] method and using limestone filler comply with the requirements specified by the ACI Committee 237. In this study, four values of cement content 200, 250, 300 350 kg/m3 are used. The maximum aggregate size of 20 mm was used. The contents of limestone powder for each cement content were 165, 139, 116, and 96 kg/m3 respectively. Fresh performance of self compacting concrete was determined by slump flow, Jring and column segregation. The results showed that the workability of all studied mixes is good, with slump flow diameter range between 570 to 630 mm. The difference between slump flow diameter and J-ring diameter is not exceed 50 mm, while the segregation resistance range between 10 and 15%. These results showed that the self compacting concrete used was complied with the requirements specified by the ACI Committee 237. The results also showed that the volume of coarse aggregate, paste fraction, mortar fraction and powder content were 0.294 m3/m3, 0.32 m3/m3, 0.69 m3/m3 and 446 kg/m3 respectively, which meet the lower limits requirements of ACI Committee 237. Further, to obtain self compacting concrete with 15 to 30 MPa compressive strength, the content of cement required is only 200 to 350 kg/m

Data on the high performance concrete behavior at elevated temperature is of concern in predicting the safety of building and constructions in response to certain accidents or particular service conditions. This investigation was carried out on the behavior of three types of concrete (two high performance concrete (HPC) with and without polypropylene fibers and one normal strength concrete (NSC)). The concrete specimens heated to target temperatures of 100, 200, 400, 600 and 800 o C, at a rate of 10 o C per minute. When the target temperature was reached, the specimens were kept at that temperature for 2 hours and then allowed to cool to room temperature by natural cooling. For each type of concrete, compressive strength and splitting tensile strength were determined before and after exposing the concrete to the target elevated temperatures. Experimental results indicated that the plain HPC suffered more reduction in its compressive and splitting tensile strength compared to NSC. These differences are more pronounced at exposure temperature of 400 and 600 o C. Average difference of about 55 percent was observed in compressive and tensile strength for specimens heated up to 400 o C. The test results also showed that the presence of polypropylene fibers in HPC would improve its residual compressive and tensile strengths at temperature of 400 and 600 o C.

Most studies on self-compacting concrete (SCC) reported in the literature deal with mixture proportioning and characterization of fresh and hardened concrete properties with limited information on the change of workability characteristic of SCC with time. The fundamental objective of this study is to evaluate the effect of time and environmental temperatures on fresh properties (filling ability, passing ability and segregation resistance) and compressive strength of self compacting concrete. In this study, one SCC mix designed according to ACI Committee 237 and mixed under two different environmental temperatures (22 and 43 oC). Fresh properties of self compacting concrete were determined by slump flow, J-ring, column segregation and visual stability index and repeated at intervals of 15 minutes after brief remixing. The results showed that the slump flow and passing ability of SCC mixtures were significantly lost within 30 minutes and beyond after mixing. Except the segregation resistance of SCC increased as the elapsed time was increased. The results also showed that the addition of 0.5% by weight of powders superplasticizer after 30 minutes, from the end of mixing, brought the SCC mix back to its initial fresh properties and maintaining a further workability period of about 15 minutes. Furthermore, the compressive strength of SCC decreased when the slump flow less than 550 mm.

Abstract: The durability of concrete is an important factor in assessment of concrete elements that require long service lives, particularly elements used in infrastructure systems such as roads and bridges which have high construction costs. The purpose of this research is to investigate the potential for enhancement of the properties of high performance concrete (HPC) girders in terms of both their structural behaviours and mechanical properties using the internal curing method. In this research, crushed brick was implemented as a partial replacement for fine aggregate as an internal curing material. Three different mixes were made, and each mix was tested in the structural field within reinforced concrete beams (1700*150*100 mm), concrete cubes, and cylinders to examine the mechanical properties of the high performance concrete. The first reference mix had no crushed brick replacement, but the two others were brick mixes with 5 and 10% partial replacement of fine aggregate. Tests were carried out at three different ages (28, 90, and 150 days) to examine the effects of age on the enhancement of properties. A high improvement in ultimate load capacity was recorded at later ages with the 10% brick mix, which increased the load capacity by 18.5% at 90 days. Improvement of the compressive and tensile properties of 12.5% was seen for both mixes, despite the fact that the use of crushed brick decreased the ductility of the beams when compared with the reference mix. In general, the obtained results showed that using crushed bricks as an internal curing material can improve the structural and mechanical properties of high performance concrete and improve its durability by showing enhancement with respect to the age of the piece