An investigation on micro pore structures and the vapor pressure mechanism of explosive spalling of RPC exposed to high temperature  

作　　者：JU Yang LIU HongBin TIAN KaiPei LIU JinHui WANG Li GE ZhiShun 

机构地区：[1]State Key Laboratory of Coal Resources and Safe Mining,China University of Mining and Technology [2]Beijing Key Laboratory of Fracture and Damage Mechanics of Rocks and Concrete,China University of Mining and Technology [3]School of Mechanics and Civil Engineering,China University of Mining and Technology

出　　处：《Science China(Technological Sciences)》2013年第2期458-470,共13页中国科学（技术科学英文版）

基　　金：supported by the National Science Foundation for Distin-guished Young Scholars of China (Grant No. 51125017);the National Natural Science Foundation of China (Grant No. 50974125);the ResearchFund for Doctoral Programs of Chinese Ministry of Education (Grant No.20110023110015);the National Basic Research Program of China("973" Project)(Grant Nos. 2010CB226804,2011CB201201)

摘　　要：Reactive powder concrete （RPC） is vulnerable to explosive spalling when exposed to high temperature. The characteristics of micro pore structure and vapor pressure of RPC are closely related to the thermal spalling. Applying mercury intrusion po- rosimetry （MIP） and scanning electron microscopy （SEM） techniques, the authors probed the characteristics of micro pore structures of plain RPC200 when heated from 20-350~C. The pore characteristics such as specific pore volume, threshold pore size and most probable pore size varying with temperatures were investigated. A vapor pressure kit was developed to measure the vapor pressure and its variation inside RPC200 at various temperatures. A thin-wall spherical pore model was proposed to ana- lyze the thermo-mechanical mechanism of spalling, by which the stresses varying with the vapor pressure q（T） and the character- istic size of wall （K） at any point of interest were determined. It is shown that the pore characteristics including specific pore volume, average pore size, threshold pore size and most probable pore size rise significantly with the increasing temperature. 200~C appears to be the threshold temperature above which the threshold pore size and the most probable pore size climb up dramatically. The increase in the specific pore volume results from the growth both in quantity and in volume of the transition pores and the capillary pores. The appearance of the explosive spalling in RPC200 is mainly attributed to being unable to form pathways in favor of releasing water steam in RPC and to thin-wall sphere domain where the vapor pressure governs the the rapid accumulation of high vapor pressures as well. The spalling is bounded through the pore model.

关 键 词：reactive powder concrete （RPC） high temperature SPALLING pore structure vapor pressure MICROSTRUCTURES mercuryintrusion porosimetry （MIP） 

分 类 号：TU528[建筑科学—建筑技术科学]