纤维素醚结构对CSA水泥砂浆拉伸黏结强度的影响

Effect of Cellulose Ether Structure on Tensile Bond Strength of CSA Cement Mortar

研究了固定水灰比条件下具有不同取代度和取代基团的5种纤维素醚在0.3%和0.6%掺量时对硫铝酸盐(CSA)水泥砂浆拉伸黏结强度的影响,并结合保水率测试及压汞法对砂浆孔结构进行分析,探讨了纤维素醚结构对其拉伸黏结强度的影响机制.结果表明:对于同类纤维素醚,高取代度的引气多,改性砂浆孔隙率大、拉伸黏结强度低;对于不同类纤维素醚,羟乙基甲基纤维素醚改性砂浆的孔隙率较羟丙基甲基纤维素醚改性砂浆的要小,拉伸黏结强度更高.基于测试结果提出了CSA水泥砂浆拉伸黏结强度影响因子模型.

Effect of five types of cellulose ethers with different substitution degrees and groups at 0.3%and 0.6%dosage on the tensile bond strength of calcium sulphoaluminate(CSA)cement mortar at fixed water to cement ratio was studied.Based on the water retention rate and porosity measured by mercury intrusion porosimeter,the influence and the mechanism of cellulose ether structure on the tensile bond strength of CSA cement mortar were discussed.The results show that for the same cellulose ether,higher substitution degree makes more air entrainment which in turn leads to larger porosity and lower tensile bond strength.For different cellulose ethers,hydroxyethyl methyl cellulose has smaller porosity and higher tensile bond strength than hydroxypropyl methyl cellulose.A model to interpretate the influencing factors on the tensile bond strength of CSA cement mortar is proposed based on the experimental results.