摘要
以硼砂和硫酸铝为主要成分研制成新型硫铝酸盐水泥缓凝剂 .实验结果表明 ,只要合理控制缓凝剂中硼砂与硫酸铝的比例 ,在一定的加入量范围内可保证水泥适度缓凝 ,对强度也无不利影响 .通过对水泥水化初期浆体中钙矾石生成量的测定、水泥浆体液相组成的分析及XRD ,DTA ,SEM分析 ,对这种新型缓凝剂的作用机理进行了系统研究 .由于熟料颗粒形状的极度不规则和表面凹凸不平 ,只有加入足够的硼砂量才能保证熟料颗粒周围迅速形成严密的硼酸钙包裹层 ,有效抑制水化 .适量硫酸铝的同时引入 ,可以促使包裹层外部液相中析出钙矾石 ,相当于在包裹层外部液相中设置了一个降低液相浓度的机构 ,迫使水较快向包裹层内渗透 ,从而达到促使包裹层破裂。
A new type of retarder, of which main ingredients are borax and aluminum sulphate, was developed for sulphoaluminate cement (SAC). Experimental results show that as long as the ratio of borax and aluminum sulphate in the retarder and the amount of the retarder added are controlled appropriately, a moderate retardation of the hydration of sulphoaluminate cement can be achieved without any negative effect on its strength. The action mechanism of the retarder was studied by XRD, SEM, DTA with the measurements of ettringite formed and the analysis of the liquid composition of cement pastes at the initial hydration stage. The study results indicate that it is the dense calcium borate wrapping layer around the clinker particles which is formed when an enough amount of borax is added that efficiently retards the hydration. Adding a proper amount of aluminum sulphate can promote the crystallization of ettringite in the liquid phase outside the wrapping layer. As a result, the concentration of the liquid outside the wrapping layer is decreased and the water is forced to permeate into the inside of the layer more quickly. And the breaking of the wrapping layer is accelerated and the over retardation can be avoided.
出处
《硅酸盐学报》
EI
CAS
CSCD
北大核心
2002年第2期155-160,共6页
Journal of The Chinese Ceramic Society
基金
河北省自然科学基金资助项目 (5 992 91)
关键词
硫铝酸盐水泥
钙矾石
缓凝剂
硼砂
硫酸铝
Aluminum compounds
Cement additives
Crystallization
Hydration
Sulfur compounds
