Study on producing ultra - rapid hardening high-strength concret with adđitions of amorphous calcium aluminate

Abstract

This paper presents the test results of using an amorphous calcium aluminate (ACA) binder to produce ultrarapid hardening high-strength concrete with a high flowability. The results show that the combined use of mineral admixtures, i.e., silica fume and ground granulated blast furnace slag (GBFS), and ACA can produce concrete with a flow value above 500 mm and compressive strength of over 10 MPa after 4 hours and 55 MPa after 28 days. Besides, it was demonstrated that the addition of GBFS with a content of up to 30 % by weight of binder did not influence the rate of hardening and strength development of concrete. The compressive strength of the sample using 15 % ACA can reach 23 MPa after 4 hours and over 71 MPa after 28 days. Although the concrete strength after 4 h was lower than that of the sample using 20 % ACA, the 28-day compressive strength of the concrete was similar. In addition, the concrete sample using ACA had no difference in chloride permeability compared with the control sample (without ACA).