The present investigation considers the effect of steel fibers content and the combined effect of rice husk ash (RHA) and high range water reducing agent (HRWRA) on the mechanical properties of the produced matrix. The experimental results showed the using steel fibers in High-performance concrete led to a considerable improvement in mechanical properties of concrete. The results exhibited that the addition of steel fibers to high performance concrete up to 1% with 6% (HRWRA) and 8% (RHA) as a partial replacement by weight of cement, increases the compressive strength significantly. Also, the results showed that the addition of 1.5% steel fibers with 6% (HRWRA) and 8% (RHA) increases the splitting and flexural strengths significant. At 28 days, the compressive, splitting and flexural strengths were increased to 11.57%, 63.86%, and 32.93% more than High performance concrete without steel fibers, respectively.
Self-compacting concrete (SCC) is a special type of concrete that can flow through intricate geometrical configurations under its own mass without external or internal vibration or segregation. The objectives of the research work were to evaluate the effects of filler types (silica fume and limestone dust) and high-range waterreducing agent, (HRWRA, superplastizier-type Sikament-163) on the workability and splitting tensile strength of SCC. The experimental results showed the using silica fume and limestone dust in Self-compacting concrete led to a considerable improvement in splitting tensile strength. As the percentage of limestone powder and silica fume increases, the workability properties of SCC slightly decreased with increases in splitting tensile strength. The workability properties of SCC for all the replacements satisfy the recommended values given by specifications.
The effects of limestone dust and superplasticizer upon the permeability, mechanical properties and durability of concrete exposed to sulfuric acid have been investigated. The properties of admixtured concrete and conventional concrete are compared. The coefficient of permeability of admixtured concrete was lower than that of normal concrete by 91.44%. The results indicated that the mechanical properties (compressive, splitting and flexural) strengths of superplasticized limestone dust concrete were higher than of normal reference concrete at all ages of concrete. The compressive strength of superplasticized concrete containing limestone dust were 46.94%, 49.48% and 47.59% more than that of reference concrete at ages 28, 60 and 90 days, respectively. The decreasing ratios in compressive strength of normal and superplasticized limestone dust concrete were (21.41%, 55.73% and 65.80%) and (20.46%, 43.81% and 54.20%) at 28,60 and 90 days of exposure to sulfuric acid, respectively.
In this study, high strength concrete of 75 MPa compressive strength was investigated. Theexperimental program was designed to study the effect of fibers and hybrid fibers (steel andpolypropylene fibers) on the fresh (workability and wet density) and hardened properties(compressive strength, splitting strength, flexural strength and dry density) of high strengthconcrete. Results show that decreases in slump flow of all concrete mixtures containing steel,polypropylene and hybrid fibers compared with control mix (0% fiber). Hybrid high strengthconcrete with steel and polypropylene fibers showed superior compressive, splitting, flexuralstrengths over the others concrete without or with single fibers content. The test resultsindicate that the maximum increase in compressive and flexural strengths are obtains with thehybridization ratio (70%steel + 30% polypropylene) and were equal to 14.54% and 23.34%respectively, compared with the control mix. While, the maximum increase in splitting tensilestrength with (100% steel fiber + 0 polypropylene) is 21.19%.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.