硫酸盐和干湿循环作用下玄武岩纤维混凝土劣化规律

盐湖、盐渍土地区水位变幅区的混凝土材料劣化问题突出。该文开展不同质量浓度硫酸盐溶液干湿循环侵蚀作用下玄武岩纤维混凝土侵蚀试验、材料力学试验和微观测试,测试分析混凝土试件抗压强度、劈裂抗拉强度、质量变化、相对动弹性模量等参数的演变规律,揭示不同浸泡浓度及龄期下玄武岩纤维混凝土的劣化机制;结合混凝土试件侵蚀后的表观形态和细观结构特征,研究不同侵蚀周期下掺玄武岩纤维混凝土的细观结构演变机理。结果表明:掺入长度6mm玄武岩纤维的混凝土抗压及劈裂抗拉强度增强效果优于长度12mm纤维;硫酸盐和干湿循环侵蚀作用下玄武岩纤维混凝土劣化规律受硫酸盐溶液浓度、干湿循环次数和纤维掺量3个因素协同作用影响,干湿循环作用下硫酸盐侵蚀产物主要为石膏型侵蚀和钙矾石型侵蚀。掺玄武岩纤维混凝土抗硫酸盐侵蚀能力明显优于于素混凝土。

Deterioration law of basalt fiber reinforced concrete under sulfate attack and dry-wet cycle

The deterioration of concrete materials in salt lake and saline soil area with water level fluctuation is a key problem. In this work, the erosion tests, mechanical tests of material and microscopic tests of basalt fiber reinforced concrete under the action of dry-wet cyclic erosion of sulfate solution with different mass concentrations were carried out to analyze and explore the evolution law of those affected parameters such as compressive strength, splitting tensile strength, mass change and relative dynamic elastic modulus of concrete specimens. The degradation mechanism of basalt fiber reinforced concrete under different immersion concentrations and with different ages was revealed. Based on the apparent morphology and meso-structure characteristics of concrete specimens after erosion, the evolution mechanism of meso-structure of concrete mixed with basalt fiber under different erosion cycles was studied. The results show that the compressive strength and splitting tensile strength of concrete reinforced with 6 mm long basalt fiber are better than those with a length of 12 mm. The deterioration law of basalt fiber reinforced concrete under sulfate and dry-wet cycle erosion is influenced by synergistic actions of sulfate solution concentration, dry-wet cycles and fiber content. The main sulfate erosion products under the action of dry-wet cycle are gypsum erosion and ettringite erosion. The sulfate-resistance of basalt fiber reinforced concrete is obviously superior to that of plain concrete.