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针对不同磷酸盐缓凝机理的不确定性问题,通过ICP测定六偏磷酸钠、三聚磷酸钠、焦磷酸钠、磷酸钠和磷酸二氢钠的吸附量及钙离子浓度,同时结合水化热、XRD及水泥浆体流动性的经时变化,揭示了不同磷酸盐对普通硅酸盐水泥的缓凝调控机理。结果表明:不同磷酸盐在水泥颗粒表面的吸附速度如下:六偏磷酸钠>三聚磷酸钠>焦磷酸钠>磷酸钠>磷酸二氢钠,即聚磷酸钠的吸附速度大于单磷酸钠;聚磷酸钠与钙离子生成的络合物吸附在水泥颗粒表面抑制水泥水化产物生成、延缓水泥水化的能力强于单磷酸钠与钙离子生成的磷酸钙;聚磷酸钠提高水泥净浆流动度的能力大于单磷酸钠,其中六偏磷酸钠的效果最好,初始流动度最大。
According to the uncertainty of retarding mechanism of different phosphates, the adsorption capacity and calcium ion concentration of sodium hexametaphosphate, sodium tripolyphosphate, sodium pyrophosphate, sodium phosphate and sodium dihydrogen phosphate were determined by ICP, , XRD and cement slurry fluidity changes over time, revealing different phosphate on the ordinary Portland cement retarding regulation mechanism. The results showed that the adsorption rates of different phosphates on the surface of cement particles were as follows: sodium hexametaphosphate> sodium tripolyphosphate> sodium pyrophosphate> sodium phosphate> sodium dihydrogen phosphate, ie sodium polyphosphate adsorbed faster than sodium monophosphate; poly The complex formed by sodium phosphate and calcium ion adsorbed on the surface of cement particles to inhibit the generation of cement hydration products and retard the hydration of cement more than the calcium phosphates generated by sodium monophosphate and calcium ions. Sodium polyphosphate increased the fluidity of cement paste Of the capacity of sodium monophosphate, sodium hexametaphosphate, the best effect, the maximum initial mobility.