Enhancement of hydraulic activity of Portland cement-slag paste by non-chlorine chemical activators and quality improvers

This work investigates the effects of both soluble and insoluble chemical activators and quality improvers on hydraulic activity of Portland cement-Blast furnace slag paste. An optimum mix consisting of 48% Portland cement, 43% slag and 9% compound insoluble activator was firstly selected based on 28- and 60-day compressive strengths. A number of different soluble chemical activators and two different quality improvers including Triisopropanolamine and Triethanolamine were then utilized for enhancing the hydraulic activity of the mix. Experimental results show that addition of 0.04% Triethanolamine result in 60-day compressive strengths up to 102.5 MPa. Nonchlorine soluble chemical activators, however, alone or in combination with quality improver do not result in higher compressive strengths. Application of Fourier transform infrared spectroscopy has confirmed the presence of calcium-silicate hydrates as the main binding compound of the material. Studies by scanning electron microscopy and X-ray diffractometry on 60-day cured hardened paste of the material shows that the microstructure is composed of an amorphous matrix in which non- or partially reacted slag particles are embedded.