木聚糖酶预处理麦秸对麦秸/水泥体系水化的影响

Influence of Xylanase Pretreatment of Wheat Straw on the Hydration Process of Wheat Straw-Cement Mixture

研究了木聚糖酶预处理麦秸对改善麦秸与水泥之间相适性及提高麦秸水泥板性能的作用.结果表明:麦秸对水泥水化有阻碍作用,体现在水泥与其混合后水化热峰值温度T由42.5℃降低到23.5℃,适合系数C_A降低到30.49%,水泥浆体的水化结合水量也明显降低;用木聚糖酶处理麦秸后可将麦秸中的部分木聚糖溶出,减少麦秸在水泥碱性环境中低聚糖的溶出量,进而减弱麦秸对水泥水化的阻碍作用,表现为木聚糖酶处理后该混合体系的T升高到28.5℃,C_A升高到50.04%,水泥浆体的水化结合水量也相应提高;XRD分析结果表明,木聚糖酶处理后混合体系中水泥熟料组分峰强较弱,生成物组分(Ca(OH)_2)的峰强较强,用木聚糖酶处理后麦秸制得的麦秸水泥板各项性能也均强于由未处理麦秸制得的麦秸水泥板.

The improvement of wheat straw-cement compatibility and wheat straw-cement board property by xylanase pretreating wheat straw were studied.Results show that wheat straw may hinder cement hydration, when cement mixed with wheat straw(untreated),the peak temperature T reduce from 42.5℃to 23.5℃,the compatibility factor C_A reduce to 30.49%and the bonding water content of cement is reduced. During the pretreatment process,xylanase dissolves part of xylan from wheat straw with the result that the oligosaccharides dissolution of wheat straw in the alkaline cement environment is reduced,furthermore, hinderance of cement hydration by wheat straw is also reduced.When xylanase pretreated wheat straw and cement are mixed,compared with untreated wheat straw,its peak temperature T improves to 28.5℃,its compatibility factor C_A improves to 50.04%,its bonding water content of cement is also increased. The result of XRD analysis shows that after xylanase pretreatment the cement of its mixture has lower peak intensity of clinker and stronger peak intensity of hydration products(Ca(OH)_2).The properties of wheat straw(xylanase pretreated)-cement board are better than wheat straw(untreated)-cement board.