Abstract:
The test on uniaxial compression, split tension, freeze-thaw cycle, air-void and SEM analysis were carried out on basalt fiber-slag powder-fly ash concrete (BF-SP-FAC). The changes of damage amount, compressive strength and tensile strength of BF-SP-FAC were studied under different freeze-thaw cycles. The relationships of air-void structure parameters (air content, specific surface area, spacing factor and average chord length) with compressive strength, tensile strength of BF-SP-FAC were analyzed. The effects of the air-void structure parameters on the compressive strength, tensile strength and damage amount were investigated by grey correlation entropy analysis. The results show that under the same freezing and thawing times, compared with other fiber dosage, BF-SP-FAC mixed with basalt fiber of 0.18vol% has the best frost resistance and the highest compressive strength and tensile strength. Under the same fiber content, the compressive and tensile strength of BF-SP-FAC decrease with the increase of air content, spacing factor, and average chord length, while the damage amount increases. The compressive strength and tensile strength of BF-SP-FAC increase with the increase of specific surface area, while the damage amount decreases. The most important factor to the compressive strength and tensile strength of BF-SP-FAC is specific surface area, the main factor to the damage amount of BF-SP-FAC is the average chord length. The minimum grey entropy correlations are 0.998 and 0.993, respectively. The establishment of relationships among air-void structure parameters, strength and freeze-thaw damage can predict the strength and freeze-thaw damage of concrete.