不同养护条件下含石英玻璃地质聚合物砂浆的变形行为

为阐明典型活性组分（无定型SiO2）在地质聚合物中的作用行为和效应,探索地质聚合物体系中碱-集料反应评价方法,研究常温（23℃）和38℃湿气养护（相对湿度〉95%）、80℃在1 mol/L NaOH溶液浸泡及150℃在10%（质量分数）的KOH溶液压蒸下,含石英玻璃集料地质聚合物砂浆的变形行为,采用扫描电镜、电子散射能谱研究产物的组成和微观结构。结果表明：4种养护条件下,特别是在传统普通硅酸盐水泥（OPC）体系所规定的养护条件和龄期内,含石英玻璃集料地质聚合物砂浆没有发生有害膨胀;但是随养护条件不同,地质聚合物基体和石英玻璃可能经历不同的化学反应过程,进而导致不同的变形行为,特别是在高温且有外碱介入时,地质聚合物基体在后期会产生膨胀效应。不宜采用单一的适于OPC体系的高温、高碱快速检测混凝土碱-集料反应的检测方法来评价地质聚合物体系中的碱-集料反应行为。

Deformation Behaviour of Geopolymer Mortars with Silica Glass under Different Curing Conditions

In order to explore the alkali–silica reactivity (ASR) of armorphous silica and the method for assessing the alkali–aggregate reaction in geopolymeric materials, the expansion behavior of fly ash based geopolymer mortars with silica glass cured under various conditions (i.e., 23 and 38 ℃ with relative humidity over 95%, immersed in 1mol/L NaOH solution at 80 ℃and autoclaved in 10% KOH solution at 150 ℃) was investigated via linear defromation test and scanning electron microscopy. The results show that there is little harmful expansion in geopolymer mortars with silica glass with the criteria specified for OPC system under the curing conditions. However, the geopolymer binder and armorphous silica could experience different reaction processes under the different curing con- ditions, leading to a different deformation behavior, especially with additional alkalis and at elevated temperatures. It was suggested that a high temperature with the additional alkali for accelerating AAR in the traditional OPC system could not be appropriate for the assessment of the alkali–aggregate reactivity behavior in geopolymers designed under normal conditions.