| dc.description.abstract | This study aims at the fresh property and microscopic composition of alkali-activated mixed slag. We mix ladle slag and blast furnace slag according to a certain proportion, and activate mixed slag by alkali-activated technology. The fresh property and microstructure of the cementing material are analyzed experimentally, and we discuss the rheological behavior, setting time, setting condition and microscopic composition of alkali-activated mixed slag cementing material.
This study shows that the fresh property of alkali-activated mixed slag cements is sensitive to workability and setting condition due to external disturbances, and has obvious viscosity at one hour after mixing. According to the analysis of the fresh property, when the paste is mixed by w/b ratio 0.5, the initial setting time is nearly 160 minutes and the final setting time is nearly 540 minutes. To determine the setting time should be divided into paste and mortar two systems for testing, especially the setting condition of paste should be flowability of less than 80% as a reference point. The compressive strength of alkali-activated mixed slag paste achieves 350 kgf / cm2 at 3 days, and it achieves 430 kgf / cm2 at 7 days. but the compressive strength at 28 days develop slowly, only 450 kgf / cm2. In terms of microscopic composition, the alkali-activated mixed slag cement will has a slight difference due to the different proportion, but the main microstructure is still based on the C-A-S-H gel. Alkali-activated mixed slag cement incorporates the Al ion with Si ion and Ca ion to form a long chain-like product. In contrast to ordinary Portland cement that expel Al out of the hydration products to form a more crystalline phase, alkali-activated mixed slag cement has better resistance to chemical attack, especially for the chemical attack of Al.
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