Research on the effect of carbon nanotubes on cracking and impact properties of rubber aggregate mortar

Abstract

Carbon nanotubes (CNTs) were added into rubber aggregate mortar (RM) as fillers. Three CNT gradients of 0.05%, 0.1%, and 0.2% were set to study the effects of different CNT contents on the fluidity, mechanical strength, cracking resistance , and impact performance of RM. The strain and displacement of the specimen's critical path during the impact process were analyzed by data simulation. As a result, CNT can reduce the fluidity of RM to a certain extent. The effect on mechanical strength, cracking property, and impact property of RM increases first and then decreases. When the content of CNT was 0.1%, the performance of RM was optimal, the flexural strength and compressive strength of 3d, 7d, and 28d are 6.3 MPa, 7.5 MPa, 8.7 MPa, and 30.3 MPa, 43.8 MPa, 52.1 MPa, respectively, increased by 46.5%, 38.9%, 29.9% and 43.6%, 53.7%, 40.1%, according to the control group. And the cracking time was 52.33 h, 16.1% longer than the control group. The first crack and failure impact times were 61 and 66, respectively, were greatly improved. Numerical simulation of impact tests found that the displacement of the specimen reached its peak value at 30°, 90°, and 150° along the circumference, which is consistent with the location of tensile damage. • The strength loss caused by rubber particles was compensated by the addition of CNT. • Carbon nanotubes can effectively slow down the cracking of rubber aggregate mortar and improve its impact resistance. • The stress state of U-shaped specimen under impact load is analyzed in detail by calculation.