改性温轮胶微丸对水泥浆体性能的影响及其作用机理研究

Modified Welan Gum's Effects on the Performance of Cement Paste and the Function Mechanism

研制开发出了一种新型的改性温轮胶微丸,旨在改善温轮胶与聚羧酸减水剂之间的竞争吸附问题,即解决原状温轮胶和聚羧酸减水剂共同使用时,原状温轮胶虽然改善浆体的离析泌水,但会大幅降低浆体流动性的问题。对掺入该类型温轮胶微丸后水泥浆体的1h静置泌水率、流变性能、水泥砂浆流动性和胶砂强度的变化进行了研究。结果表明:改性温轮胶微丸能够有效地降低水泥浆体的触变性,当改性温轮胶微丸掺入水泥浆体中时,水泥浆体1h静置泌水率和原状温轮胶一样,能很好地解决浆体的离析泌水问题,同时能够改善水泥砂浆的工作性能并能在一定程度上增进水泥胶砂的强度。其原因是改性温轮胶一方面会形成三维空间网状结构,具有与原状温轮胶相同的增稠、抗离析泌水和剪切稀化的特性;另一方面,衣膜材料与聚羧酸减水剂不存在竞争吸附问题,当其溶解后温轮胶才得到释放,而后释放的温轮胶在浆体中起到增进稳定性的作用,对流动性影响小。

A new kind of modified welan gum （MWG） was developed in order to improve the competitive adsorption between the welan gum （WG） and the polycarboxylate superplasticizer （PCE）,in order to solve the big decrease in the fluidity of the cement paste with the addition of WG and PCE. The 1 h stand bleeding rate and rbeologieaI property of ce ment paste,and workability and mechanical property of mortar,were studied with the addition of the MWG. The experi- mental results show that the thixotropy of the paste can be reduced significantly with the addition of MWG. At the same time,the I h stand bleeding rate of the paste is the same with that with the addition of WG or MWG. In another word,the MWG can effectively solve the segregation and bleeding and improve the workability and strength of the mortar. The rea- sons are that the three dimensional network structure will come out when MWG is dissolved in cement paste, and that there is no competitive adsorption Between the clothing membrane material of MWG and PCE. The dissolved welan gum promotes the stability and has little effect on the fluidity. Therefore, the cement paste has good rheologieal property, and the mortar has fine workability and mechanical property.