Model of coherent interface formation in cement-based composites containing polyblend of polyvinyl alcohol and methylcellulose

Abstract

The texture of interfacial zone between cement paste and quartz in the cement-based composites containing polyvinyl alcohol (PVA), methylcellulose (MC) and their polyblend in an amount of 10 wt % with respect to cement, as well as the texture of dehydrated bodies of PVA, MC, and the polyblend solutions, were investigated with SEM. The network texture of the dehydrated polyblend is confirmed by comparing the texture of dehydrated bodies of PVA and MC. The network texture has restrained the movement of polyblend molecules in the cement mortar but is helpful to forming a coherent interface between cement paste and quartz. The key factor of forming the coherent interface is not the neutralization reaction between H⁺ from hydrolysis of quartz and OH⁻ from hydration of cement, but the electrostatic attraction and the chemical reaction between polar groups on the polyblend molecule and cations and anions from hydrolysis of quartz and hydration of cement, respectively. The model of the coherent interface formation is that excessive [HSiO₃]⁻ and [SiO₃]²⁻ anions are bonded with the hydrated cations such as Ca²⁺ and Al³⁺, which is confirmed by the gel containing Ca and Si on the quartz surface.

Keywords

cement-based composite / coherent interface / cement paste / quartz / polyblend of PVA and MC

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