湿喷混凝土支护强度影响规律探究及改进*

为探究普朗铜矿湿喷混凝土技术应用中出现的喷层强度低、易开裂等问题原因，针对水灰比、养护温度2个因素对湿喷混凝土强度发展规律展开研究，采用扫描电子显微镜（SEM）观察湿喷混凝土的微观形貌、EDS和XRD进行物相分析。结果表明:温度是影响湿喷混凝土强度增长关键因素；水灰比越大，硬化水泥石浆体内孔隙越多，混凝土强度越低；温度和水灰比通过影响水化反应造成界面过渡区不同程度微缺陷，是影响混凝土强度根本原因。通过提高养护温度、优化配比及改进施工工艺，改进后喷层28 d强度提高约30%，生产效率提高约8%。

Research on influence laws for support strength of wet shotcrete and improvement

In order to explore the reasons for the low strength and easy cracking of the sprayed layer in the application of wet shotcrete technology in Pulang copper mine,the strength development of wet shotcrete was studied based on the two factors of water-cement ratio and curing temperature,and the scanning electron microscope ( SEM) was used to observe the micro morphology of wet shotcrete,as well as the EDS and XRD for the phase analysis.The results showed that the temperature was the key factor affecting the strength growth of wet shotcrete.The larger the water-cement ratio,the more pores in the hardened cement paste,and the lower the strength of concrete.The temperature and water-cement ratio were the fundamental factors affecting the strength of concrete by affecting the hydration reaction,resulting in different degrees of micro-defect in the interface transition zone.Through increasing the curing temperature,optimizing the proportion and improving the construction technology,the strength of improved spray layer was increased by about 40% after 28 days,and the production efficiency was increased by about 8%.