玄武岩纤维耐碱性能及其网格布对混凝土的增强效应

对玄武岩纤维进行了碱蚀试验,通过比较碱蚀前后纤维的微观形貌、元素组成和分子结构,分析了其碱蚀机理,并探究了纤维在NaOH溶液中的碱蚀模型.在此基础上,对玄武岩纤维网格布增强混凝土板(BFTRC)进行了加速老化试验和弯曲试验,采用老化系数(Ac)和增强系数(Ec)评价了玄武岩纤维网格布对混凝土的增强效应.结果表明:玄武岩纤维的耐碱性能与耐碱玻璃纤维相当;碱蚀后的玄武岩纤维直径减小,其典型结构包括核心层、凝胶层和沉淀层,碱蚀过程可采用零级模型和收缩圆柱体模型来表征;玄武岩纤维网格布增强混凝土板抗弯强度和能量吸收值的老化系数和增强系数均随老化时间增加而减小,但增强系数始终大于1,尤其对于能量吸收值,其增强系数在老化14d后仍达29.00.在进行网格布增强混凝土构件设计时,需考虑因纤维网格布在混凝土基体中碱蚀引起的承载力降低系数.

Alkali Resistance of Basalt Fiber and Strengthening Effect of Its Textile on Concrete

An alkali corrosion test on basalt fiber was carried out to analyze alkali corrosion mechanism by comparing micro-morphology,elemental composition and molecular structure of basalt fiber before and after alkali corrosion.And the alkali corrosion model of basalt fiber in NaOH solution was explored.Then the accelerated aging test and bending test regarding basalt fiber textile reinforced concrete(BFTRC)slabs were conducted to evaluate the strengthening effect of the textile on concrete via aging coefficient(Ac)and enhancement coefficient(Ec).The results show that the alkali resistance of basalt fiber is comparable to that of alkali resistant-glass fiber.For basalt fiber after alkali corrosion,the diameter becomes smaller,the typical structure is composed of fiber core,gel layer and deposition layer,and the dissolution kinetics can be expressed by zero-order model and contracting cylinder model.The Ac and Ec of flexural strength and energy absorption for BFTRC slabs are decreased with time,and the Ec is greater than 1.In particular,the Ec for energy absorption still amounts to 29.00 after aging treatment for 14d.The reduction coefficient of bearing capacity should be considered for the design of BFTRC members because of alkali corrosion of fiber textile in the concrete matrix.