地聚物净浆、砂浆和混凝土高温后力学性能比较

Mechanical Performance Comparison of Geopolymer Paste,Mortar and Concrete after Exposure to High Temperature

以钾水玻璃为激发剂、偏高岭土和粉煤灰为主要硅铝原料制备地聚物,测试了地聚物净浆、砂浆和混凝土的常温和高温后抗折及抗压强度,并与矿渣硅酸盐水泥净浆、砂浆和混凝土的试验结果进行了比较。通过地聚物热重分析以及高温后地聚物试样的收缩变形量测,对试验结果进行了分析及解释。结果表明,配制出的地聚物净浆、砂浆和混凝土的抗压及抗折强度均随温度升高而降低,但无论是常温还是高温后,其强度都基本能达到或超过水泥净浆、砂浆和混凝土的相应强度;高温下地聚物收缩而骨料膨胀,两者变形的不一致将导致地聚物混凝土高温开裂。

Geopolymer was prepared by using potassium silicate as activator solution, metaKaolin and fly ash blend as main silicoaluminate materials. The bending and compressive strength before and after exposure to high temperature was tested on geopolymer paste, mortar and concrete specimens, and the results were compared with that of cement paste, mortar and concrete speci- mens. The trends of test results and phenomena were explained by thermogravity analysis and thermal contraction measurement of geopolymer. The test results show that the bending and compressive strength of geopolymer paste, mortar and concrete decrease with increase of temper- atures, but either at ambient temperature or after exposure to high temperature the strength of geopolymer paste, mortar and concrete prepared in this study can almost reach or exceed that of cement paste, mortar and concrete. The incompatibility between thermal contraction of geopoly- mer and thermal expansion of aggregates induces cracking of geopolymer concrete at elevated temperatures.