Wood-Cement Composites: Effect of Model Compounds on Hydration Characteristics and Tensile Strength
Keywords:Composites, tensile strength, hydration, exotherm, cellulose, lignin, hemicellulose, extractives
The development of wood-cement composite products is limited by cement's incompatibility with numerous wood species that inhibit cement setting and hardening. This study investigated the relative effects of specific model compounds commonly found in wood on the tensile splitting strength and hydration characteristics of Type I portland cement.
Model compounds representing classes of wood components were added to cement at concentrations of 0.01, 0.10, and 1.00%. Glucose decreased cement tensile strength by nearly 50%. Quercetin, xylan, and acetic acid lowered tensile strength by a lesser amount. Wood components added to cement in 0.10% concentrations had a greater effect on strength than on exothermic behavior. Little correlation was found between tensile splitting strength and exothermic hydration characteristics (maximum hydration temperature, time to maximum hydration temperature, and relative heat generation). The relative difference in heat generation between an additive-cement sample and a cement standard was best able to distinguish differences among wood component effects.
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