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本文主要介绍了日本化学外加剂发展历史及其最新的发展趋势。聚羧酸系减水剂是目前日本超塑化剂市场上的主要产品。而最近他们又在传统聚羧酸系超塑化剂研究的基础上,开发出了一种新型的低粘度型聚羧酸系超塑化剂。掺有这种低粘度聚羧酸系超塑化剂的混凝土的流动速度比掺有传统聚羧酸系超塑化剂的混凝土的流动速度快。而加入一种同时含有阴离子和阳离子表面活性剂的新型增稠剂后,在新拌混凝土中会形成三维网状结构,水泥浆体的粘度增加并且可以避免离析。通过加入缓凝剂可以控制浆体中水泥的水化,因为在水泥浆中存在着许多的未反应的阿利特相,所以水泥的比表面积并没有增加。当在水泥浆中加入缓凝剂葡萄糖酸钠时,不会对混凝土的性能产生不利的影响,因此有利于搅拌站延长混凝土的浇注时间。目前在喷射混凝土工艺中,液体和粉状铝酸钙系(CA)速凝剂以及硫铝酸钙系(CSA)速凝剂已经得到了广泛的应用。对于CA速凝剂而言,随着其加入量的增加砂浆的终凝时间会加快,而在掺有CSA速凝剂的砂浆中,随着其加入量的增加砂浆的初凝时间和终凝时间均会缩短。
This article mainly introduces the history of Japanese chemical admixture and its latest development trend. Polycarboxylate superplasticizer is currently Japan's main superplasticizer products on the market. Recently, they have developed a new type of low viscosity polycarboxylate based superplasticizer on the basis of the research on the traditional polycarboxylate superplasticizer. Concrete mixed with such a low viscosity polycarboxylate type superplasticizer has a higher flow rate than that of a concrete incorporating a conventional polycarboxylic acid type superplasticizer. With the addition of a novel thickener containing both anionic and cationic surfactants, a three-dimensional network is formed in the fresh concrete and the viscosity of the cement paste increases and segregation can be avoided. By adding retarders, the hydration of the cement in the slurry can be controlled. Because of the large amount of unreacted alite phase present in the cement slurry, the specific surface area of the cement does not increase. When added to the cement slurry sodium gluconate retarder will not adversely affect the performance of concrete, it is conducive to the mixing station to extend the pouring time of concrete. Currently in the shotcrete technology, liquid and powdered calcium aluminate (CA) quick-setting agent and calcium sulphoaluminate (CSA) quick-setting agent has been widely used. For the CA quick-setting agent, the final setting time of the mortar accelerated with the addition amount of the quick-setting mortar. However, the initial setting time and the final setting of the mortar increased with the addition of the CSA quick-setting mortar Time will be shortened.