Effects of an Organotitanate Cross-linking Additive on the Processing and Properties of Macro-Defect-Free Cement

Abstract

We have investigated the effects of an organotitanate cross-linking additive on the processing and moisture sensitivity of macro-defect-free (MDF) cements. The modified samples were formed by a two-part process: first, the as-received calcium aluminate cement powder was coated with the organotitanate compound, followed by the standard MDF cement fabrication procedure. It was estimated that 6 wt% (by weight of the cement powder) of the additive was adsorbed. Rheological measurements showed that cross-linking reactions between the organotitanate additive and the polymer (polyvinyl alcohol-acetate) used to form MDF cement occurred during the high shear mixing process. This led to a 65% reduction in the processing window for the modified pastes as compared to the standard MDF cement pastes. However, the organotitanate-modified MDF cement samples exhibited improved moisture resistance as compared to the standard samples when exposed to 100% relative humidity at 22°C. The most significant result was that the modified samples retained nearly 100% of their initial strength after 200 days of exposure to these conditions, whereas the strength of the standard MDF samples was decreased by approximately 45%.