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采用超滤法将脂肪族高效减水剂(SAF)切割为相对分子质量(以下简称分子量)范围依次为<2 500、2 500~10 000、10 000~50 000和>50 000的4个级分,测试结果表明,随级分分子量的增大,重均分子量、特性黏度依次增加,磺化度依次降低。对不同级分减水剂的应用性能研究表明,级分分子量增大,对水泥的减水分散性能显著提高,但对流动度的保持能力降低,同时磺酸根与羟基对Ca2+的络合作用逐渐减弱,使缓凝作用减小。与空白砂浆比较,掺4种级分的7 d和28 d硬化砂浆抗压强度均增大,增幅在30%~60%,并随分子量的增大而增加;掺量(减水剂相对水泥的质量分数)大于0.3%时,由于分子量较大的两个级分对掺量及用水量较敏感,使砂浆泌水严重,抗压强度比低掺量时略低。
The ultrafiltration method was used to cut the superplasticizer (SAF) into 4 grades with relative molecular mass (hereinafter referred to as molecular weight) in the order of <2 500, 2500 500, 000 000, 000 000 000 and> 500 000 The test results show that with the increase of molecular weight, the weight average molecular weight and intrinsic viscosity increase in turn and the degree of sulfonation decreases. The research on the application properties of different water-reducing agents showed that the increase of the molecular weight of the components significantly enhanced the water-reducing and dispersing properties of cement, but decreased the retention of fluidity, and the complexation of sulfonate and hydroxyl gradually increased Weakened, so that retarding effect is reduced. Compared with the blank mortar, the compressive strength of the hardened mortar doped with four kinds of blends for 7d and 28d increased from 30% to 60%, and increased with the increase of molecular weight. Of the mass fraction) is greater than 0.3%, due to the larger molecular weight of the two components of the volume and water content is more sensitive to serious bleeding sand, compressive strength slightly lower than the dosage.