电阻率法研究减水剂与水泥的作用

測定了摻β-萘磺酸甲醛聚合物減水劑(β-naphthalene sulfonate-formaldehyde condensate superplasticizer,FDN)和木質素磺酸鈣減水劑(lignosulphonate superplasticizer,LS)水泥漿體的電阻率和流動度,以其第5min的電阻率為初始電阻率,并測定了其凝結時間。研究發現:FDN和LS對漿體電阻率影響不同,可用減水劑的吸附、溶解機理來解釋漿體初始電阻率隨FDN和LS摻量的變化。摻FDN水泥漿體的初始電阻率–摻量曲線可分為4個區:選擇吸附區、有效吸附區、溶解電離區、電離飽和區,各區很好地反映了FDN的吸附與溶解特性。研究還發現摻LS漿體的最大初始電阻率與最大流動度對應的LS摻量相同,因此,電阻率法有望用于測定LS的最佳摻量。 Electrical behavior of cement pastes with β-naphthalene sulfonate-formaldehyde condensate superplasticizer (FDN) and lignosulphonate superplasticizer (LS) as well as their relation to the fluidity of the pastes were investigated. The setting time tests of the pastes were also carried out. The resistivity at 5 min is regarded as initial resistivity. Results show that the FDN and the LS have different effects on the resistivity of cement pastes. The initial resistivity of the pastes changing with the amount of superplasticizer can be explained by the adsorption and the dissolution of superplasticizer. The curve of initial resistivity as a function of FDN dosage can be divided into 4 zones, which are the selective adsorption zone, the effective adsorption zone, the dissolution and ionization zone, and the saturated ionization zone, respectively. Each zone reflects the properties of FDN as a superplasticizer of cement paste. The LS dosage of the paste with the highest fluidity is the same as that of the highest initial resistivity. Electrical resistivity method will potentially be used to test the optimal dosage of LS.