Research on crystalline admixtures for low carbon buildings based on the self-healing properties of concrete

Abstract

The increasing fascination surrounding low carbon construction materials has propelled self-healing concrete into the realm of vital technologies for attaining low carbon objectives. This investigation through artificial cracking and precompression experiments demonstrates the efficacy of two specific crystalline admixtures (CAs), namely L-aspartic acid (LAA) and Ethylenediaminetetraacetic acid (EDTA), in augmenting the self-healing characteristics of concrete. The flexural and compressive strength as well as chloride ion diffusion coefficient tests, were used to evaluate the mechanical properties and durability, and the microstructures was analyzed by X-ray diffraction (XRD), differential thermogravimetric analysis (TG-DTG), scanning electron microscopy (SEM), Bruno-Emmett-Teller (BET) and mercury intrusion pore size measurement (MIP). The findings indicate that the optimum dosage for both LAA and EDTA is determined to be 0.5%. At this dosage level, these admixtures effectively fill the pores by stimulating the production of hydrated calcium silicate gel (CSH) and calcium carbonate, leading to a reduction in porosity, enhanced concrete compactness, and successful activation of the self-healing mechanism. Moreover, the incorporation of these admixtures results in improved strength grade and enhanced resistance against chloride ion penetration.