Analysis On Mechanical Properties And Crack Resistance Of Basalt Fiber Reinforced Steel Slag Powder Concrete

Steel slag powder concrete with low heat of hydration, good adhesiveness, low exudation rate, and other advantages, was usually used for concrete pumping project and mass concrete. But, steel slag powder concrete also had some flaw, such as slow development strength, low early strength, concrete cracking because of more free oxide hydration. Research showed that fibers can reinforce mechanical properties of concrete, prevent cracks expansion of concrete. The experiments of compressive strength, splitting tensile strength, flexural strength and crack resistance were conducted and the effects of basalt fiber and steel slag powder on the mechanical properties and anti-cracking abilities were studied.The basic mechanical properties were obtained through tests which regarded basalt fiber content (Okg/m3,2kg/m3,3kg/m3,4kg/m3 and 5kg/m3) and steel slag powder content (0%,10%,20%,25%,30% and 35%) as variables. Tests showed that with the basalt fiber content increasing, the strength of concrete only adding basalt fiber first increased and then declined. When the content was 3kg/m3, the strength was better. Compressive strength of this concrete was 3.7% more than that of standard concrete, splitting tensile strength was 8.7% and flexural strength was 7.8%. With the steel slag powder content increasing, the strength of concrete only adding steel slag powder reduced after improved. When the content was more than 20%, the decline was faster. For the concrete adding both basalt fiber and steel slag powder, the strength was better and compressive strength was 6.5% more than that of standard concrete, splitting tensile strength was 11.9% and flexural strength was 10.3% when the basalt fiber content was 3kg/m3 and the steel slag powder was 10～20%. When the steel slag powder was more than 20%, the strength decreased obviously. So the suitable content of basalt fiber and steel slag powder was 3kg/m3 and 10%～20% respectively. In terms of saving resources, protecting environment and satisfying strength, concrete adding 3kg/m3 basalt fiber and 20% steel slag powder had better engineering significance.The early age mechanical properties tests under the suitable content showed that the 7d compressive strength of steel slag powder concrete, basalt fiber reinforced concrete, steel slag powder concrete with basalt fiber were -12.4%,8.0% and 3.1% respectively more than that of standard concrete, the 7d splitting tensile strength were -13.9%,14.9% and 8.8% respectively and the 7d flexural strength were-9.0%,12.3% and 7.5%. Basalt fiber could improve the early strength of steel slag powder obviously.Early crack resistence tests under four types of concrete showed that the coefficient of crack decreased of steel slag powder concrete, basalt fiber reinforced concrete and steel slag powder concrete with basalt fiber were 68.0%,85.2% and 95.7%, early anti-crack grade were second-grade, first grade, first grade, and the best effect of anti-crack was steel slag powder concrete with basalt fiber.