| 摘要: |
| 养护条件对混凝土的硬化过程和微观孔隙结构的形成具有重要影响，而混凝土的毛细吸水性能与材料自身的孔隙结构及分布密切相关。开展了养护条件（标准、自然、浸水和密封养护）对混凝土毛细吸水性能影响的试验研究。对从混凝土方形板试件取出的圆柱体进行了抗压强度试验，并对沿圆柱体高度方向上等厚度切割成的3个“圆饼”试件，分别进行了超声波速和孔隙率两种指标的测试。为了实现吸水观测的连续性，利用改进的混凝土吸水测重法试验装置，开展了不同养护条件下“圆饼”试件的毛细吸水试验。试验结果发现，养护条件对混凝土的抗压强度、超声波速和孔隙率具有较大影响，是决定养护过程中强度发展和内部孔隙结构及密实性的关键因素。标准养护下强度和超声波速最大，孔隙率最小；密封养护下强度和超声波速最小，孔隙率最大；自然和浸水养护试验结果接近，介于标准和密封养护两者之间。相同养护条件下，混凝土由上到下不同位置的累积吸水量、初始吸水率和孔隙率逐渐降低，超声波速则逐渐增大，说明混凝土由上到下不同位置的密实度逐渐增大。 |
| 关键词: 养护条件 毛细吸水 累积吸水量 吸水率 超声波速 孔隙率 |
| DOI： |
| 分类号:TU528 |
| 基金项目:国家自然科学基金面上项目（51378090）；国家重点基础研究发展计划（973计划）资助项目（2015CB057701） |
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| Experimental studies on influences of curing conditions on capillary absorption of concrete |
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CHENG Bao-juan, WANG Li-cheng, BAO Jiu-wen, MA Hai-jun
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State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology, Dalian
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| Abstract: |
| The curing conditions of concrete have significant influences on both the hardening of concrete and the formation of its micro-pore structure, and the capillary absorption is closely related to the structures and distributions of the pores within the material so that the curing conditions can influence the water absorption process of concrete. The objective of this paper is to carry out experimental studies of the influences of four curing conditions (i.e. standard curing, natural curing, water curing and sealed curing) on the capillary absorption of a normal strength concrete. The compressive strength of the cylinder specimens core-drilled from concrete slabs is tested. The measurement of ultrasonic pulse velocity (UPV) and porosity is then implemented with “pie” specimens cut along three different elevations of the cylinder specimens. A series of water absorption experiments are conducted on the “pie” specimens by an improved gravimetrical test apparatus to measure the cumulative water absorption variation, realizing the continuity of water absorption testing. The test results indicate that the curing conditions of the concrete have a great influence on its compressive strength, UPV and porosity, which is the key factor to determine its strength development, internal pore structures and compactness during the curing process. The compressive strength and UPV of the specimens are the largest and the porosity is the smallest under the standard curing conditions, whereas the compressive strength and UPV of the specimens are the smallest and the porosity is the largest under the sealed conditions, the case is exactly the opposite, and the results in the natural curing and water curing conditions are close to each other, lying between the standard and sealed curing conditions. For the same curing conditions, the cumulative water content, absorptivity and porosity of concrete gradually decrease with the increase of the surface distance, but the UPV gradually increases, which implies the gradual increase of the concrete compactness from top to bottom. |
| Key words: curing condition capillary absorption cumulative water absorption absorptivity ultrasonic pulse velocity (UPV) porosity |
