Enhancement of cementing properties of fly ash-Portland cement blend with chemical activators and quality improvers

This study has investigated the activation of fly ash and Portland cement mixture with a compound additive using different chemical activators and quality improvers. The compound additive is mainly composed of a sulfate-containing compound, e.g. gypsum and anhydrite, with little amount of suitable calcium aluminate. A number of different chemical activators of different groups including chlorides, sulphates, nitrates, and phosphates with two different quality improvers including Triethanolamine and Triisopropanolamine were used individually. The obtained experimental results confirm the effectiveness of activators and quality improvers on enhancement of the cementing properties of fly ash-Portland cement binary blends. Paste specimens from optimum proportion including 55 wt% fly ash, 40 wt% Portland cement, and 5 wt% compound additive chemically activated with suitable soluble salts exhibit 28- and 60-day compressive strengths up to almost 65.0 and 98.5 MPa. Also 28- and 60 day compressive strength of optimum proportion with 0.08 wt% of TEA increases to 70 and 90 MPa, respectively. Also attempts were made to characterize the binding compound of the material using the laboratory techniques of xray diffractometry.