| 摘要: |
| 应用立式比长仪测试了玻化微珠保温砂浆长期（2a）干燥收缩，研究了引气剂掺量(质量分数，下同)对保温砂浆干燥收缩的影响；用称重法测试了保温砂浆的质量损失，以反映其失水程度；采用氮吸附法测试了保温砂浆的孔结构，探讨了其干燥收缩、失水程度与孔结构之间的关系.结果表明，保温砂浆的干燥收缩随龄期增长呈快速期(7d前)慢速期(7～365d)亚稳定期(365d后)三阶段发展特征，引气剂的加入没有从根本上改变这种三阶段式的发展趋势，但显著抑制了后两个阶段的干燥收缩幅度；第一阶段干燥收缩的快速发展主要是由保温砂浆快速失水造成的，而第二、三阶段的干燥收缩主要归结于硬化浆体中小于500nm，尤其是73～123nm的孔体积分数明显增加；引气剂的作用与其掺量成正比，但掺量过大时因其不再增加引气作用而不能对保温砂浆的干燥收缩产生更大影响. |
| 关键词: 引气剂 玻化微珠保温砂浆 长期干燥收缩 质量损失 失水；孔结构 |
| DOI：103969/j.issn1007 9629201601001 |
| 分类号: |
| 基金项目:“十二五”国家科技支撑计划项目(2012BA20B02)；中央高校基本科研业务费专项资金资助项目(05000219164)；同济大学开放测试基金资助项目(0002013009) |
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| Effect of Air Entraining Agents on the Long Term Drying Shrinkage of Glazed Hollow Beads Thermal Insulation Mortar |
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FAN Shujing, WANG Peiming
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School of Materials Science and Engineering, Tongji University, Shanghai 201804, China
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| Abstract: |
| The drying shrinkage of glazed hollow beads thermal insulation mortar after two years was measured by vertical length comparator, and influences of air entraining agents of different contents (0%, 006%, 012%, 018%, 024%, by mass) on the long term drying shrinkage were investigated, water loss was measured by weighting method and pore structure was characterized by nitrogen adsorption/desorption method, the correlation among them was researched. The results show that drying shrinkage process includes three steps according to curing time extension: the acceleration period (before 7d), the deceleration period (7365d) and the metastable period (after 365d). There is no change in the development trend of drying shrinkage of mortar with addition of air entraining agents. In three steps in the curing time, the drying shrinkage at the last two stage is greatly restrained. The drying shrinkage of mortar in the first stage increases quickly owing to the fast dehydration, but its development in the last two stages is due to pore volume of mortar with radius less than 500nm, especially the increase of pore volume fraction of the pore radius within the size range of 73nm to 123nm. Effect of air entraining agents is proportional to its use level, there is no more effect with too large content of air entraining agents on drying shrinkage owing to lack of air entraining effect. |
| Key words: air entraining agent glazed hollow beads thermal insulation mortar long term drying shrinkage mass loss dehydration pore structure |
