减水剂不同掺加方式对其适应性影响

Study on the superplasticizer compatibility of different addtion ways

通过水泥净浆、砂浆、TOC吸附及混凝土等试验,减水剂采用同时掺加、滞水掺加法(滞水60 s)与分次掺加法(2 min后补加、10 min后补加及30 min后补加)等方式,研究了不同掺加方式下聚羧酸减水剂和萘系减水剂的应用效果。结果表明:在一般情况下,萘系减水剂的滞水法明显优于同掺法,分次掺加法总体也优于同掺法;聚羧酸减水剂的同掺法优于滞水法,一般也优于分次掺加法;从对流动性大幅降低混凝土工作性调整的角度,萘系减水剂在更长时间跨度内具有更好的易调性;聚羧酸系减水剂易调整的时间跨度较窄,错过适宜时间,为再次获取较好混凝土的流动性,需再次掺加减水剂的比例明显高于萘系产品;现行通常方法的TOC分析数据有时不能可靠代表有效减水剂残余量或实际吸附率。

Based experiments by different methods, The difference of effectiveness which associated with addition ways in usage of superplasticizer between polycarboxylate and naphthalene sulfonate were studied. The test data shows that application performance of dif- ferent superplasticizer types is associated with addition ways. Though delayed addition is an accepted way for naphthalene sulfonate, it isn＇t efficient for polycarboxylate. With polycarboxylate superplasticizer, adding at the beginning of the mixing sequence when cement and water contacts can usually be more beneficial from the compatible point of view ,both of fractional addition and delayed addition are suboptimal. To achieve good fluidity of concrete with naphthalene sulfonate again, a longer period of time is permissible. By contrast, when miss the best time,more superplasticizer is needed for Polycarboxylate.Tbe TOC analysis sometimes cannot give reliable data a- bout residual volume of superplasticizer after adsorbtion.