THE BINDING OF CHLORIDE-IONS BY SULFATE RESISTANT PORTLAND-CEMENT

The relative tendency of different portland cements to remove chloride ions from the mix water by forming chloro-complexes is an important f actor in the study of the corrosion of the embedded steel. The tri-cal cium aluminate(C(3)A) phase of the ordinary portland cement(OPC) plays a dominant role in binding the chloride ions, but little quantitative information is available in the literature concerning the relative in fluence of the tetra-calcium aluminoferrite (C(4)AF) phase of the ceme nt. The present investigation is an attempt to elucidate the role of C (4)AF in the sulphate resistant portland cement with respect to chlori de binding. It is concluded that the chlorides in SRPC are bound in th e form of the chloro- complex C3F.CaCl2.10H(2)O which is derived from the C(4)AF phase of the cement.