聚羧酸系减水剂的合成及其在再生混凝土中的应用研究
发布时间：2018-11-07 15:32
【摘要】：聚羧酸系减水剂是近三十年发展起来的新型高性能减水剂,具有掺量低、减水率高、保坍性好、收缩率低、增强效果好及不污染环境等优良性能,被认为是未来混凝土外加剂发展的方向。本文采用活性单体共聚法合成聚羧酸系减水剂,首先制备具有聚合活性的聚乙二醇单甲醚甲基丙烯酸酯大分子单体,再在过硫酸铵的引发作用下将其与甲基丙烯酸和甲基丙烯磺酸钠共聚,得到目标产物。通过正交试验和单因素试验,采用较为准确的酯化率计算方法,得到大单体的最佳酯化工艺参数：甲基丙烯酸和聚乙二醇单甲醚(分子量1000)的摩尔比为2.5：1,催化剂对甲苯磺酸的用量为甲基丙烯酸和聚乙二醇单甲醚总质量的3%,阻聚剂吩噻嗪用量为甲基丙烯酸质量的2%,酯化温度120℃,酯化时间6h,酯化率达95.37%。表征了大单体的分子结构,讨论了大单体的储存条件。 聚羧酸系减水剂的合成工艺为：甲基丙烯酸和酯化大单体的摩尔比为3：1,甲基丙烯磺酸钠用量为单体总质量的12%,引发剂用量为单体总质量的5%,聚合温度85℃,单体混合溶液和引发剂水溶液分别均匀滴加,滴加时间1-2h,保温时间3h。聚羧酸系减水剂的匀质性和混凝土应用性能测试结果表明：掺量为0.5%,水灰比为0.29时,聚羧酸系减水剂表现出良好的分散性和分散保持性,混凝土和易性较好,后期增强效果显著。 相比于天然骨料,再生骨料具有表观密度低、吸水率高、压碎指标高等特点。采用再生骨料配制的再生混凝土用水量大,硬化后强度低、弹性模量低,只能应用于一些非承重构件和普通承重构件。为扩大再生混凝土的应用范围,须对再生骨料进行强化改性。 本文采用纯水泥浆、水泥外掺硅粉浆液、水泥外掺Ⅰ级粉煤灰浆液、水泥外掺聚羧酸系减水剂浆液四种矿物浆液对再生粗骨料进行强化试验,结果表明：经过强化后的再生粗骨料的表观密度较强化前有所提高,压缩指标降低,相比于其他三种化学浆液,水泥外掺聚羧酸系减水剂浆液的强化效果更好。聚羧酸系减水剂强化改性后的再生粗骨料配制的再生混凝土较原生再生粗骨料配制的同强度等级、同取代率的再生混凝土,具有坍落度控制更好,抗压强度和弹性模量更高的特点,满足再生混凝土的施工和应用要求。这表明将聚羧酸系减水剂运用在再生混凝土中,对于拓宽再生混凝土的应用范围,缓解资源环境难题,实现混凝土行业的可持续发展具有积极意义。
[Abstract]:Polycarboxylic acid superplasticizer is a new type of high performance water reducing agent developed in recent 30 years. It has good properties such as low dosage, high water reducing rate, good collapse retention, low shrinkage, good enhancement effect and no pollution to the environment. It is regarded as the development direction of concrete admixture in the future. In this paper, poly (carboxylic acid) series water reducer was synthesized by copolymerization of active monomer. The macromolecular monomer of poly (ethylene glycol monomethyl ether) methacrylate with polymerization activity was first prepared. The target product was obtained by copolymerization of ammonium persulfate with methacrylic acid and sodium methacrylate sulfonate. By orthogonal test and single factor test, the optimum esterification parameters of macromonomer were obtained by using more accurate method of esterification. The molar ratio of methacrylic acid and polyethylene glycol monomethyl ether (molecular weight 1000) was 2.5: 1. The amount of catalyst p-toluenesulfonic acid is 3% of the total mass of methacrylic acid and polyethylene glycol monomethyl ether, the amount of the inhibitor phenothiazine is 2% of the mass of methacrylic acid, the esterification temperature is 120 鈩，
本文编号：2316788
[Abstract]:Polycarboxylic acid superplasticizer is a new type of high performance water reducing agent developed in recent 30 years. It has good properties such as low dosage, high water reducing rate, good collapse retention, low shrinkage, good enhancement effect and no pollution to the environment. It is regarded as the development direction of concrete admixture in the future. In this paper, poly (carboxylic acid) series water reducer was synthesized by copolymerization of active monomer. The macromolecular monomer of poly (ethylene glycol monomethyl ether) methacrylate with polymerization activity was first prepared. The target product was obtained by copolymerization of ammonium persulfate with methacrylic acid and sodium methacrylate sulfonate. By orthogonal test and single factor test, the optimum esterification parameters of macromonomer were obtained by using more accurate method of esterification. The molar ratio of methacrylic acid and polyethylene glycol monomethyl ether (molecular weight 1000) was 2.5: 1. The amount of catalyst p-toluenesulfonic acid is 3% of the total mass of methacrylic acid and polyethylene glycol monomethyl ether, the amount of the inhibitor phenothiazine is 2% of the mass of methacrylic acid, the esterification temperature is 120 鈩，
本文编号：2316788
本文链接：https://www.wllwen.com/kejilunwen/sgjslw/2316788.html
