Abstract
Production of calcium sulfoaluminate (CSA) cement from solid industrial wastes consumes enormous amounts of wastes and provides an environmentally friendly binder for the construction sector. However, carbonation of CSA cement is much faster than that of portland cement. Silane was used to reduce water absorption of portland cement concrete and thus promote its carbonation resistance. To clarify the effect of silane on carbonation resistance of CSA cement prepared from solid industrial wastes, three silanes, including glycidoxypropyltrimethoxysilane (GOPTS), vinyltrimethoxysilane (VTMS), and dodecyltrimethoxysilane (DTMS), were employed in this research. Their influence on early-age hydration and water absorption of CSA cement mortar was investigated. Accelerated carbonation was performed. The results show that GOPTS and VTMS retarded early-age hydration of CSA cement and slightly decreased 28-day compressive strength, whereas DTMS had less influence. All three silanes decreased water absorption of mortar. However, they bring about more pores larger than 200 nm, which would facilitate the spread of CO2 in mortar. Nevertheless, other than silane’s effect on water absorption and the pore structure of mortar, carbon chain length of silane determines the carbonation resistance of CSA cement mortar. DTMS accelerates carbonation due to its long chain, but, GOPTS and VTMS, with shorter chains, promote resistance of mortar.
Published Version
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