天然沸石对碱-硅酸反应的抑制及其机理

EFFECT OF NATURAL ZEOLITE ON ALKALI - SILICA REACTION

用高碱水泥和天然沸石制备了含沸石水泥,测定了其砂浆棒的膨胀率、可溶性碱量和有效碱量。用能谱分析(EDXA)测定了c-s-H凝胶的化学组成。讨论了总碱量、可溶性碱量和有效碱量与膨胀率的关系。结果显示,由碱硅酸反应(ASR)引起的膨胀与可溶性碱量和有效碱量之间有很好的关系。沸石主要通过离子交换和提高C-s-H凝胶对Na+和K+的吸收,使可溶性碱量和有效碱量降低,从而起到抑制ASR的作用。

High alkali cements containing natural zeolite were prepared. The water soluble alkali content and the available alkali content of the cements were measured. The chemical composition of C-S-H gel was analyzed by the energy-dispersive X-ray analysis (EDXA). The relationships between the total alkali content, water soluble alkali content, effective alkali content and the expansion of mortar bars were examined. The results show that there is a good relation between the expansion caused by the alkali-silica reaction (ASR) and the water soluble alkali content, or the effective alkali content. The ASR was suppressed by natural zeolite through reducing the water soluble alkali content and the effective alkali content in the samples due to the natural zeolite's ability of ion exchange and reaction with Ca(OH)2 to produce the C-S-H gel with a lower molar ratio of CaO/SiO2, which makes the C-S-H gel bind more Na+ and K+ ions.