Enhanced Flexural Strength and Crack Resistance of Concrete by Constructing a Polymer-Cement Network

Abstract

Concrete is a kind of building material with high compressive strength but eases to crack. Herein, we disperse acrylamide (AM) in the concrete to construct a polymer-cement work via in situ polymerization to improve flexural strength and crack resistance. Incorporating 10% AM leads to concrete with 28-day flexural strength (19.38 MPa) 65.5% higher than normal concrete. The initial cracking fracture toughness is increased by 47.5% with the incorporation of 7% AM. In situ polymerization of AM is more efficient and effective than directly adding PAM in enhancing flexural strength. The polymer network is formed by in situ polymerization of AM crosslinks with cement hydrates to construct the polymer-cement network, which is responsible for the improvement of flexural strength and crack resistance. As the polymerization reaction finishes, the aggregate and the cement matrix are bridged by polymer concomitant with the densification of the interfacial transition zone (ITZ), increasing the bonding strength between the aggregate and cement matrix. Refinement of the pore structure is also observed with the addition of AM by in situ polymerization. Our work offers a convenient and efficient approach to fabricating high performance concrete.

Keywords: concrete, acrylamide, in situ polymerization, flexural strength, crack resistance, polymer-cement network