激发剂对碱矿渣水泥砂浆中碱-硅酸反应的影响

采用硅酸钠溶液为激发剂制备碱矿渣(AAS)水泥砂浆,在80 ℃的1 mol/L氢氧化钠溶液中养护以加速碱-硅酸反应(ASR)进程,研究了激发剂碱含量和硅酸盐模数对ASR膨胀破坏的影响。结果表明,AAS砂浆中出现了危险性ASR膨胀破坏。激发剂中Na₂O掺量大于4%(质量分数)时,砂浆在14 d龄期的ASR膨胀率超过0.1%,且当激发剂硅酸盐模数在1.2~2.0范围内时膨胀率更大。ASR产物主要分布在集料颗粒表面与AAS凝胶相接触的界面区,附近可观测到明显的裂缝扩展。ASR膨胀破坏同时引发了砂浆抗压强度损失。

Effects of Activators on Alkali-Silica Reaction in Alkali-Activated Slag Cement Mortars

The sodium silicate solution was used as activator to prepare the alkali-activated slag (AAS) cement mortars. The AAS mortars were cured in 1 mol/L NaOH solution at 80 ℃ for purpose of accelerating the alkali-silica reaction (ASR). Effects of alkali content and silicate modulus in activator on ASR expansion failure of AAS mortars were investigated. The results show that the mortars exhibit ASR hazardous expansion failure. When the Na₂O content is higher than 4% (mass fraction), the ASR expansion rates of mortars are higher than 0.1%. When the silicate modulus is in the range of 1.2 to 2.0, the ASR expansion rate is further increased. The ASR products are mainly formed in the aggregate-binder interface zone, where microcracks development is also observed. The ASR expansion occurrs in the mortars results in compressive strength loss.