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C4A3$-CaSO4-CaO体系在硅酸盐水泥浆体中的膨胀能力
作者:韩建国1 阎培渝1 侯维红2 
单位:1. 清华大学土木工程系 北京 100084 2. 三源特种建材有限责任公司 武汉 430000 
关键词:硫铝酸钙 氧化钙 膨胀剂 自收缩 干燥收缩 
分类号:TU528
出版年,卷(期):页码:2016,44(8):1120-1125
DOI:10.14062/j.issn.0454-5648.2016.08.07
摘要:

对掺入硅酸盐水泥中的C4A3$-CaSO4-CaO体系(CCC膨胀剂,C4A3$为4CaO·3Al2O3·SO3)的膨胀能力进行了研究。CaO、CaSO4和CCC膨胀剂掺入到硅酸盐水泥浆体中均会产生膨胀。相同掺量下,CaO使得浆体在水化初期表现出剧烈而短暂的膨胀;CaSO4使得浆体表现出轻微的膨胀;CCC膨胀剂使得浆体表现出适中而持续的膨胀。因此,掺入CCC膨胀剂的混凝土若长时间缓凝或延迟浇注会导致补偿收缩能力的损失。CCC膨胀剂可补偿混凝土的自收缩和干燥收缩,补偿能力随着膨胀剂掺量的增加而增大。相同掺量下,膨胀剂补偿收缩的能力,在早龄期随着水胶比的降低而减小,在后期随着水胶比的降低而增大,前者与自干燥导致的自收缩有关,后者与失水速率、毛细孔隙率和孔径分布有关。低水胶比混凝土中,当CCC膨胀剂的掺量较高时,在非饱和环境(失水过程)中也可表现出膨胀现象,这一点在工程应用时需要重视。
 

Expansion character of C4A3$-CaSO4-CaO system (CCC expansive agent, C4A3$ is 4CaO·3Al2O3·SO3) was discussed. Introducing CaO, CaSO4 and CCC expansive agent to cement paste can promote expansion. Under the same dosage, CaO results in intensive and transient expansion during early hydration period; CaSO4 results in ignorable expansion; CCC expansive agent results in moderate and sustainable expansion. So, postponed casting should be avoided for guaranteeing the expansive ability of shrinkage compensating concrete made with CCC expansive agent. CCC expansive agent can compensate both autogenous and drying shrinkage of concrete, and the compensating ability increases with the enhancement of its dosage. Under the same dosage, the shrinkage compensating ability of CCC expansive agent decreased with the decrease of water-binder ratio during early hydration period, due to the enhancement of autogenous shrinkage. However, the shrinkage compensating ability increased with the decrease of water-binder ratio during later hydration age, due to the decrease of water losing rate, capillary pore size and volume ratio. Meanwhile, high strength concrete can show unexpected expansion even under drying condition, when the dosage of CCC expansive agent exceeds some limitation, this should be avoided in engineering application.
 

基金项目:
国家自然科学基金(No. 51278277)资助项目。
作者简介:
韩建国(1974—),男,博士,高级工程师。
参考文献:

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