Non-Portland Cement-Based Engineered Cementitious Composites

Calcium aluminate cement (CAC) is known as the most important class of non-Portland cement, which contains high alumina and lime. Different than ordinary Portland cement (OPC) which is made of 95% clinker, the manufacturing of CAC involves bauxite as a source of alumina in addition to limestone, which makes it more appropriate for applications requiring high-early strengths and chemical resistance. Although the use of CAC in engineered cementitious composites (ECCs) can enhance their mechanical characteristics in terms of compressive and flexural strengths, it may also cause higher shrinkage and risk of cracking than OPC-ECCs. In this study, the fresh, mechanical, and shrinkage properties of ECC compositions incorporating CAC as an alternative to OPC were considered. Furthermore, the effect of using fly ash with CAC at various FA/CAC ratios of 0, 0.8, 1.2, and 1.5 was investigated in an attempt to control the shrinkage of CAC-based ECCs, while targeting equivalent or better mechanical strengths and deflections. The performances of five ECC mixtures were studied by measuring their flowability, compressive and flexural strengths, mid-span deflection capacity, and cracking and shrinkage behavior at different curing ages. Also, the microstructural change related to the high alumina content of CAC was analyzed by SEM–EDS. The results confirmed the possible development of high-early strength ECC with the use of CAC cement instead of OPC. Interestingly, the higher calcium amounts with the use of FA in CAC-ECC mixtures allowed to optimize the shrinkage results to reach values two times lower than the control OPC-ECC.