基于孔体积分形维数的稻壳灰混凝土冻融损伤劣化机制  

Freeze-thaw damage deterioration mechanism of rice husk ash concrete based on pore volume fractal dimension

作　　者：张韦 刘超[1] 刘化威 林鑫 张治宁 ZHANG Wei;LIU Chao;LIU Huawei;LIN Xin;ZHANG Zhining(School of Civil Engineering,Xi'an University of Architecture and Technology,Xi'an 710055,China;Far East Façade(Xi'an)Limited,Xi'an 710018,China;School of Science,Xi'an University of Architecture and Technology,Xi'an 710055,China)

机构地区：[1]西安建筑科技大学土木工程学院,西安710055 [2]远东幕墙(西安)有限公司,西安710018 [3]西安建筑科技大学理学院,西安710055

出　　处：《复合材料学报》2023年第8期4733-4744,共12页Acta Materiae Compositae Sinica

基　　金：国家自然科学基金项目(51878546,52178251);陕西省杰出青年科学基金项目(2020 JC-46);陕西省重点研究发展项目(2020 SF-367)。

摘　　要：在日益严峻的环境压力下,稻壳灰(RHA)等农业副产品在混凝土中的应用引起了广泛关注。为研究稻壳灰等质量部分取代(0%、10%、20%、30%)硅酸盐水泥对混凝土抗冻性能的影响,对冻融循环作用下的稻壳灰混凝土进行表观形貌、质量损失、动弹性模量和抗压强度试验,并通过建立孔体积分形维数模型来探究水泥浆体孔空间分布形态,揭示了稻壳灰混凝土冻融损伤劣化机制。结果表明:随着冻融循环次数增加,混凝土表面剥落损伤逐渐加剧,质量损失率呈现先减小后增加的趋势,相对动弹性模量和相对抗压强度呈现下降趋势。此外,由于冻融循环前后的硬化水泥浆体表现出明显的多重分形特征,可将其孔结构分为大孔和小孔两类。冻融循环作用下,稻壳灰介孔结构改善了小孔的孔径分布,其分形维数增加。而大孔对冻融循环更敏感,其孔隙结构会由于膨胀压的逐渐累积而发生冻融破坏。Under the increasingly severe environmental pressure,the application of agricultural by-products such as rice husk ash(RHA)in concrete has attracted widespread attention.In order to study the effect of rice husk ash partial replacement(0%,10%,20%,30%)of Portland cement by equal mass on the frost resistance of concrete,the apparent morphology,mass loss,dynamic elastic modulus and compressive strength of rice husk ash concrete under the action of freeze-thaw cycles were conducted,while the spatial distribution pattern of cement paste pores was explored by establishing the pore volume fractal dimension model,and the freeze-thaw damage deterioration mechanism of rice husk ash concrete was revealed.The results show that with the increase of the number of freezethaw cycles,the surface spalling damage of concrete gradually intensifies,the mass loss rate tends to decrease and then increase,while the relative dynamic elastic modulus and relative compressive strength show a decreasing trend.In addition,since the hardened cement paste before and after freeze-thaw cycles shows obvious multifractal characteristics,its pore structure can be divided into two categories:Small pores and great pores.Under the action of freeze-thaw cycles,the existence of the mesoporous structure of rice husk ash will improve the pore size distribution of concrete,resulting in an increase in the fractal dimension of the small pores.The great pores are more sensitive to freeze-thaw cycles,and their pore structures will be subject to freeze-thaw damage due to the gradual accumulation of swelling pressure.

关 键 词：混凝土 稻壳灰 冻融循环 分形维数 介孔结构 

分 类 号：TU528[建筑科学—建筑技术科学] TB333[一般工业技术—材料科学与工程]