Understanding nanoscale mechanism of compression casting on rubber-cement interface: A molecular dynamics study

Abstract

Using rubber particles as concrete aggregate can effectively address the issue of “black pollution” caused by waste tires. Although the inclusion of rubber particles reduces concrete strength, a compression casting method can enhance its mechanical properties, offering a novel approach to expanding the application range of rubber-concrete. Further development of the compression casting method requires an in-depth understanding of the mechanism behind the novel technique. This study focuses on the nanoscale mechanism of the compression casting, via all-atom molecular dynamics simulations of a C-S-H/rubber interface. Surface roughness is introduced to the employed C-S-H model, providing a more realistic representation of the cement surface compared to existing studies. Models subjected to various levels of compression casting are prepared and tested. Interface integrity is found to be significantly improved with sufficient pre-compression. When the pre-compression force increases from 100 atm to 4000 atm, the peak pullout force of the C-S-H/rubber interface transition zone increases by 90.26%, and the interfacial bond energy increase by 56.65% to 2.27 J/m². Lastly, a novel pre-compression method for rubber-concrete aggregate is proposed to enhance its economic and engineering applicability. This study reports an in-depth investigation on compression casting mechanisms and contributes to advancement of compression casting methods.