Journal
CONSTRUCTION AND BUILDING MATERIALS
Volume 247, Issue -, Pages -Publisher
ELSEVIER SCI LTD
DOI: 10.1016/j.conbuildmat.2020.118600
Keywords
Recycled aggregate concrete (RAC); Pore structure; Relative humidity; Old mortar
Categories
Funding
- National Natural Science Foundation of China [51878546]
- Innovative Talent Promotion Plan of Shaanxi Province [2018KJXX-056]
- Science and Technology Coordination Innovation Project of Shaanxi Province [2016KTZDSF04-02-01]
- Key Research and Development Program of Shaanxi Province [2018ZDCXL-SF-03-03-02]
- Science and Technology Innovation Base of Shaanxi Province Technology Innovation Service Platform for Solid Waste Resources and Energy Saving Wall Materials [2017KTPT-19]
- Key Technology Innovation Team Plan of Shaanxi Province [2016KCT-31]
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In this paper, based on the pore structure characteristics of old mortar attached to recycled concrete aggregate (RCA) surface, recycled aggregate concrete (RAC) internal relative humidity (RH) response process and mechanism were investigated, considering different temperatures, RCA replacement ratios and load condition. The RH was determined by the embedded probe, pore structure was measured by mercury intrusion porosimetry (MIP), and micro-cracks of the old and new mortar were observed through scan electron microscope (SEM). The experimental results indicated that: (1) The range of critical pore size distribution and the proportion of large capillary pores volume in the old mortar was larger than in new mortar, resulting in RH response rate in RAC being faster than natural aggregate concrete (NAC). The obstruction of saturated small pores (pore neck) on the diffusion of gaseous water in the connected large pores causes the RH response hysteresis. (2) The RH response rate in the pores increases with the increasing temperature, especially in RAC. (3) Under the bending load, the pore network of old mortar creates more micro-cracks than the new mortar which provided additional channels for the diffusion of gaseous water. These conclusions will be helpful for further understanding to the durability of RAC. (C) 2020 Elsevier Ltd. All rights reserved.
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