偏高岭土-粉煤灰地聚物混凝土高温后的力学性能研究

Experimental Study on Mechanical Properties of Metakaolin-fly Ash-based Geopolymer Concrete after Exposure to Elevated Temperatures

采用钾水玻璃激发偏高岭土和粉煤灰的混合物制备地聚物。对不同水胶比（0.45、0.40、0.35）、砂率（0.25、0.30、0.35）和骨胶比（3.0、3.5、4.0）的地聚物混凝土进行常温下的抗压及劈拉强度试验,并据此优选地聚物混凝土配方,而后进行地聚物混凝土高温后的抗压及劈拉强度试验。结果表明：随温度升高,地聚物混凝土的抗压及劈拉强度逐渐降低,且在300-500℃间,强度下降尤为明显;相比于抗压强度,地聚物混凝土的高温后劈拉强度降低得更快。对比文献发现,本文的地聚物混凝土高温后相对残余抗压强度要明显高于普通混凝土。根据试验结果,建立了地聚物混凝土高温后抗压强度与劈拉强度的关系式,公式计算结果与试验结果吻合较好。

Geopolymer was prepared through potassium silicate solution activating metakaolin and fly ash blend. Compressive and splitting tensile strength tests were carried out on geopolymer concrete specimens with different water-cement ratios （0.45, 0.40, 0.35）, sand ratios （0.25, 0.30,0.35） and aggregate-binders （3.0,3.5,4.0） at room temperature. Based on these test results, the optimal formula of geopolymer concrete was determined, and compressive and splitting tensile strength tests were conducted after exposure to elevated temperatures on geopolymer concrete prepared with the optimal formula. The test results show that compressive and splitting tensile strength of geopolymer concrete decrease with an increase in temperature, especially a great decrease of strength occurs in 300-500 ℃ range. In comparison to compressive strength, the splitting tensile strength of geopolymer concrete after exposure to elevated temperatures decreases with temperatures at a higher rate. The test results on compressive strength of geopolymer concrete after exposure to elevated temperatures were compared with that of ordinary concrete from literatures. And it shows that geopolymer concrete exhibits higher compressive strength. A formula describing the relationship between the compressive and splitting strength of geopolymer concrete were built through regression analysis, and the calculation results from the formula agree well with test results.