The Influence of Organic and Mineral Additives on Hydration of Cement

Abstract

This paper describes the inhibitory impact of water soluble extractives in wood sawdust on Portland cement setting. It was determined that pozzolanic mineral additives (e.g. opoca) eliminate this harmful influence of extractives. Fresh sawdust extracts of Lithuanian wood’s species (the fir, the alder, the asp, the hornbeam and the birch) have been analyzed in the article. Alkali medium dissolves much more wood’s extractives, than water. The influence of extractives’ additive on binding material (pure cement and cement with opoca additive) was estimated according to the setting time of binding material paste, chemically combined water changes, cement stone strength and X-ray diffraction of hardened cement stone.
The efficiency of mineral additives depends on its pozzolanic activity. The influence of specific surface (grinding degree) of opoca on CaO binding rate and pozzolanic activity was determined, and relation between adsorption power of opoca and its specific surface was investigated.