滇东北地区河砂碱活性及工程适用性研究  

Study on River Sand Alkali Activity and Engineering Applicability in Northeastern Yunnan

作　　者：李安强 王世涛 徐东 LI Anqiang;WANG Shitao;XU Dong(Zhaotong Qiaoshan Expressway Investment and Development Corporation,Zhaotong Yunnan 657000;Yunnan Provincial Institute of Highway Science and Technology,Kunming 650000;Yunnan Yinfan Construction Engineering Consulting Co.,Ltd.,Kunming 650000)

机构地区：[1]昭通市巧善沿线高速公路投资开发有限公司,云南昭通657000 [2]云南省公路科学技术研究院,昆明650000 [3]云南尹帆建设工程咨询有限公司,昆明650000

出　　处：《公路交通技术》2024年第2期57-65,81,共10页Technology of Highway and Transport

摘　　要：滇东北地区机制砂开采受限、资源较为匮乏,河砂虽丰富,但多为活性骨料,直接应用会对混凝土结构耐久性产生严重的不利影响。为解决滇东北地区活性河砂在公路工程中的直接应用不利问题,采用砂浆棒快速试验与混凝土棱柱体试验相结合的试验检测方法研究曲靖市会泽县、昭通市巧家县河砂的碱活性,提出3种抑制活性骨料碱-硅酸反应的措施并验证其有效性;根据碱-硅酸反应机理,分析工程所在区域的气候条件和结构物所处环境,并提出活性河砂的工程应用对策。结果表明:1)采用砂浆棒快速试验与混凝土棱柱体试验相结合的综合检测方法能更加客观评定河砂碱活性和抑制措施的有效性;2)外掺不低于20%的Ⅰ级或不低于25%的Ⅱ级粉煤灰可有效抑制碱-硅酸反应;3)活性河砂在应用时可根据工程环境采取适宜的应用策略,对于直接处于水中、空气相对湿度不低于80%或处于干湿交替环境的结构混凝土,应采取有效的抑制措施,其他环境使用时可不采取抑制措施直接使用。The exploitation of mechanism sand resources in the northeastern region of Yunnan is limited.There is abundant river sand,but most of them are siliceous active aggregates.Direct application will have serious adverse effects on the durability of concrete structures.In order to solve the adverse problem of the direct application of active river sand in highway engineering in northeast Yunnan,the alkali activity of river sand in Huize county of Qujing city and Qiaojia county of Zhaotong city was studied by the combination of mortar bar rapid test and small concrete prism test.Three measures to suppress the alkali silica reaction of active silica aggregates was proposed and their effectiveness was verified.Based on the mechanism of alkali silica reaction,the climatic conditions and environment of the structure in the project area were analyzed,and engineering application strategies for active river sand were proposed.The results show that:The comprehensive detection method combining rapid testing with small concrete prism testing using mortar bars can more objectively evaluate the alkaline activity of river sand and the effectiveness of suppression measures;2)The addition of no less than 20%GradeⅠor no less than 25%GradeⅡfly ash can effectively inhibit the alkali silica reaction;3)When using activated aggregates,appropriate application strategies can be adopted according to the engineering environment.For structural concrete that is directly in water,relative humidity of no less than 80%in the air phase,or has been in a dry wet alternating environment,effective suppression measures should be taken,when using in other environments,it can be used directly without taking any suppression measures.

关 键 词：活性骨料 砂浆棒 混凝土小棱柱体 抑制措施 应用对策 

分 类 号：U414[交通运输工程—道路与铁道工程]