| 王来贵*,丁盛鹏,何慧娟,刘向峰.不同粒径砂粒水泥砂浆冻融破坏实验研究[J].实验力学,2019,34(1):138~148 |
| 不同粒径砂粒水泥砂浆冻融破坏实验研究 |
| Experimental investigation on the influence of sand grain size in cement mortar on freeze-thaw failure |
| 投稿时间：2017-11-01 修订日期：2018-01-10 |
| DOI：10.7520/1001-4888-17-227 |
| 中文关键词: 水泥砂浆 砂粒 粒径 冻融循环 力学性质 |
| 英文关键词:cement mortar sand grain diameter freeze-thaw cycles mechanical properties |
| 基金项目:国家自然科学基金(51474121, 51274110)资助 |
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| 中文摘要: |
| 为研究颗粒粒径差异对水泥砂浆冻融破坏的影响，对不同粒径砂粒水泥砂浆试件进行冻融循环实验，测试不同冻融循环周期后水泥砂浆立方体抗压强度，并利用扫描电子显微镜(SEM)对不同粒径砂粒试件破坏面进行观察，分析冻融循环条件对不同粒径砂粒试件破坏形态及其物理力学性质变化规律的影响。结果表明：随冻融周期增加，粒径≥30目试件表面以颗粒脱落为主，粒径≤40目试件表面以片状剥落为主。纵波波速以及单次冻融前后质量差值均随冻融周期增加而降低。在冻融循环前期，水化反应对试件力学性能影响占主导地位，造成试件抗压强度、弹性模量增加，冻融循环后期，冻融损伤加剧，微裂纹、微孔洞扩展造成抗压强度、弹性模量降低。相同冻融周期后，纵波波速、抗压强度和弹性模量随粒径减小而降低。提出改进的微观颗粒胶结物理模型，解释了不同粒径水泥砂浆冻融破坏机制。 |
| 英文摘要: |
| In order to study the effect of grain size difference on the freeze-thaw damage of cement mortar, freezing-thawing cycle experiment was carried out for cement mortar specimens with different sand grain sizes, and the compressive strength of cement mortar cube was measured after different freezing-thawing cycles. The failure surface of samples with different grain sizes was observed by scanning electron microscope (SEM), and the influence of freezing-thawing cycle conditions on the failure patterns and physical and mechanical properties of cement mortar with different grain sizes was analyzed. Results indicate that with the increase of freezing-thawing cycles, when sand grain size ≥30 mesh, grains on specimen surface fall off mainly. When sand grain size ≤40 mesh, grains mainly flake off from specimen surface. The difference of quality before and after single freezing-thawing and P wave velocity decreases with the increase of freezing and thawing cycles. In the early stage of freeze-thaw cycle, the hydration reaction has a dominant effect on the mechanical properties of the specimen, resulting in the increase of compressive strength and elastic modulus. In the later stage of freeze-thaw cycle, the effect of freeze-thaw damage is enhanced, and micro-cracks and micro-hole expanded causing the decrease of compressive strength and elastic modulus. The compressive strength and elastic modulus decreased with the decrease of particle size after the same freezing and thawing cycle. The improved micro-particle cementing model is proposed to explain the freeze-thaw damage characteristics of cement mortar with different particle size. |
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