الفهرس 
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Abstract
Compared to conventional concrete, self-consolidating concrete (SCC) has a higher cost due to the large content of cement, use of mineral fillers, and use of various chemical admixtures, resulting in a relatively high material cost. Up to date, there is no theoretical approach that can be utilized to design self-consolidating concrete with minimum content of supplementary cementitious and filler materials to obtain optimum properties. The traditional method of designing SCC is to use pre-determined proportions of supplementary cementitious materials (SCM) in trial batches. If it gives acceptable results, that proportion is used for SCC. Economical SCC cannot be produced without optimizing constituent materials. The proper selection of material and mixture proportioning can enable reduction in cement and additives contents, leading to savings in cost.Research scope:- The application of an optimization technique in the field of concrete manufacture by optimizing properties and cost of SCC incorporating fly ash, silica fume, and limestone powder.Research objective:- The aims of this investigation project are to study the characteristics of fresh and hardened self-consolidating concrete, and to proposed statistical models to design and optimize SCC mixes incorporating fly ash, limestone powder, and silica fume. Compared with vibrated concrete, mixture proportioning of SCC is found to be relatively difficult as high deformability and stability of concrete are desired in the case of SCC, and many trial mixes are needed to generate optimum flow without segregation and bleeding of concrete. The influence of total powder content, fly ash, limestone powder, silica fume, w/p ratio, and superplasticizer dosage on various characteristics of fresh and hardened SCC is studied. Statistical models are established for important properties of SCC such as slump flow, L-box (H2/H1) ratio, segregation index, compressive strength at different ages, flexural strength, and elastic modulus. With the help of these models, SCC mixes can be developed with optimum total powder content, percentage of FA, percentage of LP, percentage of SF, w/p ratio, SP dosage leading to optimum properties with minimum cost, time and effort.Steps of the study:- In this investigation an introduction to SCC followed by a literature review on the fresh and hardened properties, testing methods, criteria, constituent materials, mix designs, and statistical models for proportioning and optimizing of self-consolidating concrete. The constituent materials used in the investigation were selected due to their locality, convenience, availability, and consistent supply. The methodology of experimental program along with the tests on fresh and hardened properties are discussed. The analysis and discussion of the whole set of test results, and the statistical models are presented. This follows by conclusions for the whole project and suggestions for further work.Summary of the study:- The results indicated that using Central Composite Design (CCD) reduces the number of experiments need to be performed to obtain significative data, high relations between the responses and the constituent materials of self-consolidating concrete can be developed using Response Surface Methodology (RSM), analyses of variance to test the effects of the variables and their interactions on responses can be performed, and the possibility to evaluate the optimum values of variables to achieve the responses target. The increase in partial replacement of PC by FA resulted in higher slump flow diameter and L-box (H2/H1) ratio with enhancement in segregation resistance. Using limestone powder as a replacement of cement content resulted in negative effect on L-box test and insignificant impact on slump flow while the resistance to segregation enhanced. Lower slump flow observed at higher levels of silica fume content. Also, L-box (H2/H1) ratio decreased with the increase in silica fume percentage. SP dosages can be estimating and optimizing to resist the risk of bleeding and segregation by using the established models. The increase in total powder content and w/p ratio increased the slump flow diameter and L-box (H2/H1) ratio while the resistance to segregation decrease.The increase in partial replacement of PC by FA decreased the compressive strength of the mixtures at 7 and 28 days while at 56 days the compressive strength increased. Also, 28 days flexural strength decreased, and 56 days modulus of elasticity increased with the increase in FA content. Using limestone powder as a replacement of PC resulted in negative impact on the compressive strength, flexural strength, and modulus of elasticity. The higher values of compressive strength were observed when SF was incorporated at a dosage of 10% SF. The main contribution of SF to concrete strength development takes place from about 7 to 28 days, and after 28 days it is minimal. Also, the flexural strength and elastic modulus enhanced with the increase in SF content. The compressive strength, flexural strength, and elastic modulus increased with the increase in total powder content and decrease in w/p ratio. While the increase in SP dosage decrease 56 days compressive strength and modulus of elasticity.The incorporation of SF and LP decreased the water penetration depths. Fly ash can decrease the water penetration depth until 20%, but the increase in FA from 20% to 30% resulted in a slight increase in water penetration depth. The dry shrinkage decreased with the increase in FA and LP, and decrease in SF, total powder content, and w/p ratio.