减水剂对高掺量粉煤灰砂浆性能的影响

研究了萘系高效减水剂（FDN）和木质素磺酸钙（LS）对高掺量粉煤灰砂浆性能的影响，测定了减水剂在胶凝颗粒表面的吸附、对水泥颗粒表面zeta电位等方面的影响。结果表明，和FDN相比，LS对砂浆的减水率较低，而对砂浆流动度保持能力较优；当掺量为0.4 wt%时，两者对砂浆稳定性的影响几乎一样。当掺量低于0.4 %时，LS的减水率和FDN接近是因为其具有较强的引气作用和FDN在胶凝颗粒表面吸附不完全；LS保持砂浆流动性能力较好是由于它的缓凝作用以及吸附LS的水泥颗粒表面zeta电位较稳定导致的。为了更好地将LS应用在高掺量粉煤灰砂浆中，可以从提高其减水率方面对其进行改性。

Effects of Water Reducer on the Properties of High-volume Fly Ash Cement Mortar

Effects of FDN and Calcium lignosulfonate (LS) on the properties of high-volume fly ash cement mortar were studied. It was found that compared with FDN, the water-reducing ratio of LS was lower and the ability of retaining the fluidity of the cement mortar was better; for the stability of the cement mortar, the effect of LS was almost the same as that of FDN at the dosage of 0.4 %. The adsorption on the cementitious surface, the effect on the zeta potential of cement particle surface and the foaming capacity of FDN and LS were measured. The results showed that, for the reasons of stronger air-entraining capacity of LS and the incomplete adsorption of FDN on the surface of cementitious particles, the water-reducing ratio of LS was close to FDN when the dosage was lower than 0.4 %. The better fluidity retention capacity of LS was attributed to the more stable zeta potential of the cement surface and the retarding effect of mortar setting. The experimental results suggested that for the purpose of utilizing LS better in the high-volume fly ash cement mortar in the grouting, some modification should be conducted to increase its water-reducing ratio.