【摘要】 用测量膨胀值、强度和XRD以及液相分析等方法研究了不同浓度的NaOH溶液拌和的硫铝酸盐水泥的膨胀性能。结果表明,NaOH的存在使早期强度提高而后期强度降低;NaOH浓度增加,钙矾石生成量也增加,膨胀值增大;即使在pH=13.28的液相环境中,生成的仍然是晶体而不是非晶体钙矾石;随NaOH浓度增大,液相中CaO浓度降低,而Al₂O₃浓度提高;钙矾石的膨胀值的大小不一定取决于液相中CaO饱和程度,而与液相的pH值有关,pH值越大,膨胀值越大;在CaO浓度低而pH值高的情况下,钙矾石的膨胀值比在CaO浓度高而pH值低的情况下大。更多还原

【Abstract】 The effect of alkali （NaOH） on expansion of sulfoaluminate cement was studied by means of expansion test, compressive strength test and XRD as well as liquid phase analysis.The presence of NaOH increases compressive strength of hydrated pastes in early ages but decreases compressive strength in later ages.NaOH promotes the formation of ettringite in the pastes. The expansion value and ettringite content in the cement pastes increase with the increase of NaOH concentration. Even in the high concentrated NaOH solution （0.7mol/L） with pH=13.28, the ettringite formed is not amorphous but crystalline. With the increase of NaOH concentration, concentration of CaO in the liquid phase contacted with the pastes decreases while eoncentration of Al₂O₃ increases. The expansion caused by ettringite does not always depend upon the saturation degree with respect to CaO but depends on the pH value of liquid phase in which ettringite is formed. The expansion caused by ettringite formed in a liquid phase with lower CaO concentration but higher pH value is higher than that in liquid phase with higher CaO concentration but lower pH value. The higher the pH value of liquid phase, the greater expansion will be caused by ettringite.更多还原