| At present,with higher requirements on environmental protection,steel slag concrete,in which steel slag powder as a partial replacement of cement,has been widely concerned because of good workability and low hydration heat.However,there are some imperfections such as the slow growth strength,low early strength,low crack resistance and strength decreasing greatly when the replacement percentage is too high.The temperature of nearly half of the land is below zero in winter,for construction,low temperature should be an essential factor within consideration.As a admixture,steel slag powder can improve the frost resistance of concrete and it is a new idea that the application of the basalt fiber which has low temperature resistance and good crack resistance.The first part of this paper studied the basalt fiber content for different steel slag under 3kg/m~3 influence on the splitting tensile strength and performance of steel slag concrete compressive strength of basalt fiber,find the suitable dosage of steel slag.In the second part,the effect of different amount of basalt fiber on the compressive strength and splitting tensile strength of steel slag concrete was studied under the condition of suitable steel slag powder.First of all,the effect of steel slag powder on compressive strength and splitting tensile strength of concrete at different ages was studied.The curing ages were 7d,14d,28d,and the content of steel slag powder was 0%,12%,15%,20%,respectively.The test results compared with no steel slag powder concrete,the 28d compressive strength and splitting tensile strength of concrete mixed with steel slag is flat or slightly improved,reached 15%in the optimal dosage of steel slag,the compressive strength increased to 2.6%,the splitting tensile strength is 9.2%.When the curing age is 14d,the compressive strength of the steel slag powder reaches 12%,the strength is improved by 7.5%,and the splitting tensile strength is the best at the time of 20%,which is increased by up to 4.4%.The compressive strength and splitting tensile strength of concrete decreased with the increase of the content of steel slag when the curing age was 7d.Comparing with the results of different groups of the steel slag concrete with different replacement percentage in the development rule of strength at different ages,the early strength development of basalt fiber reinforced slag powder concrete is slower,and the latter strength is faster,and the 28d intensity is higher than that of the no steel slag powder concrete.Based on the above results,the orthogonal experiment was carried out with the basalt fiber content of 0kg/m~3,2kg/m~3,3kg/m~3,4kg/m~3,5kg/m~3,curing temperature as standard curing,-5?,-10?,-15?,-20?,respectively,with a total of 25 groups.Compared with different curing temperatures without fibers in group,curing temperature for standard curing and-5?,when the basalt fiber content is 3kg/m~3,concrete strength reached the maximum compressive strength and were increased by 3.9%and 7.4%,the splitting tensile strength were increased by 11.5%and 7.8%.In the curing temperature of-10?,-15?,-20? when the basalt fiber content is 4kg/m~3,the strength of concrete is maximum.The compressive strength was increased by 8.9%,8.9%and 17.9%,the splitting tensile strength increased by 8.9%,10.5%and 23.1%,respectively.The concrete strength of steel slag powder without adding fiber under standard curing is 38.8MPa.Compared with the incorporation of basalt fiber in concrete at the curing temperature of-5?,-10?,-15?,-20?,the maximum compressive strength of up to 100.7%,98.9%,98.2%,98.2%,the maximum splitting tensile strength can reach 96.9%,94.1%,92.3%,91.3%.The experimental results show that the strength of the steel slag powder concrete in the low temperature condition is improved effectively when the basalt fiber is added into the concrete.It can be concluded that basalt fiber can improve the frost resistance of steel slag powder concrete at low temperature. |
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