True Self-Healing Polymer-Modified Cement for Ambient-Temperature Applications

Abstract A polymer-modified cement formulation with self-healing capability at ambient temperature is reported. The polymer used is a copolymerization product from the crosslinking reaction between N, N-methylene-bis-acrylamide (MBA) and 1,4-butanediamine (BDA) (MBA-BDA). Results show that the added polymer homogeneously distribute in the cement matrix without phase separation or water segregation. The polymer-modified cement has better workability than conventional cement and self-healing capability as demonstrated by the recovery of compressive strength after multiple damage/healing events. From 13C NMR data a mechanism for self-healing of MBA-BDA-modified cement is proposed based on multiple hydrogen bonding interactions between the oxygen of the carbonyl in the polymer and the hydrogen of the calcium silicate hydrates of cement. Unlike any other polymer-cement technologies reported in the open literature, such as cement modified with superabsorbent polymers or encapsulated polymers where fractures are filled without any apparent chemical bond formation, this self-healing polymer-modified cement represents a true self-healing cement formulation since chemical bonds are formed between the polymer and the surface of a crack restoring the structural integrity of cement as demonstrated by its multiple self-healing capability. To the best of our knowledge, this is the first polymer-modified cement technology with true self-healing capability at ambient temperature.