稻壳灰粒径对水泥砂浆的碱硅酸反应风险影响  

Effect of rice husk ash particle size on alkali silica reaction risk of cement mortar

作　　者：刘文丰 李碧雄[1,2] 王熠泽[1,2] 汪知文 陈权 高攀越 LIU Wenfeng;LI Bixiong;WANG Yize;WANG Zhiwen;CHEN Quan;GAO Panyue(College of Architecture and Environment,Sichuan University,Chengdu 610065,China;Key Laboratory of Deep Earth Science and Engineering,Ministry of Education,Chengdu 610065,China;Huashi Green Homeland Building Materials Co.,Ltd.,Chengdu 610000,China)

机构地区：[1]四川大学建筑与环境学院,四川成都610065 [2]深地科学与工程教育部重点实验室,四川成都610065 [3]华西绿舍建材有限公司,四川成都610000

出　　处：《西安建筑科技大学学报（自然科学版）》2024年第1期30-37,共8页Journal of Xi'an University of Architecture & Technology(Natural Science Edition)

基　　金：四川省重点研发计划项目(2023YFQ0047)。

摘　　要：固废资源化是实现可持续发展的重要内容.稻壳灰的火山灰活性高,有望作为辅助性胶凝材料用于水泥砂浆或混凝土,但其中K 2O和Na 2O含量较大,需探明不同粒径稻壳灰的掺入可能带来的碱硅酸反应风险.现有研究表明,粉煤灰的火山灰活性能抑制碱硅酸反应,已得到广泛应用.对比起见,设置了基准组、掺4种粒径粉煤灰组和稻壳灰组,在分别测试其抗压、抗折强度的基础上,测试膨胀率,通过SEM和EDS测试了掺粒径为5μm的稻壳灰试件和未掺稻壳灰试件的微观形貌和元素组成.试验结果表明:稻壳灰或粉煤灰的掺入均可以提高砂浆的力学性能,稻壳灰粒径越小提高的程度越大,中值粒径为5μm的稻壳灰可以使砂浆28 d抗压强度提高50.6%,抗压强度提高64.7%,效果均好于粉煤灰;稻壳灰的粒径不超15μm时,对砂浆的膨胀率可起到显著的抑制作用,且抑制效果优于粉煤灰,5μm的稻壳灰能使14 d膨胀率减小90%,并使骨料表现为无害,而8~20μm粉煤灰均仅减小60%左右的14 d膨胀率,骨料仍表现为有害;稻壳灰的火山灰活性不仅能生成低Ca/Si比的C-S-H凝胶,降低碱含量,还能使砂浆致密性提高,抑制碱离子和水的渗透,从而表现为对碱硅酸反应的抑制效果.Solid waste recycling is an important part of achieving sustainable development.Rice husk ash has high pozzolanic activity and is expected to be used as an auxiliary cementitious material for cement mortar or concrete.However,the content of K 2O and Na 2O in RHA is high,so it is necessary to find out the risk of alkali silica reaction that may be caused by the mixing of RHA with different particle sizes.The existing research shows that the pozzolanic activity of fly ash inhibits alkali silica reaction and has been widely used.For comparison,a benchmark group,a group with 4 different particle sizes of fly ash,and a group with rice husk ash are set up.On the basis of testing the compressive strength and flexural strength respectively,the expansion rate is tested,and the microstructure and elemental composition of the rice husk ash specimens with a particle size of 5μm and the specimens without rice husk ash are tested by SEM and EDS.The test results show that the mechanical properties of mortar can be improved by adding rice husk ash or fly ash.The smaller the particle size of rice husk ash,the greater the degree of improvement.The RHA with a median particle size of 5μm can increase the 28 d compressive strength of mortar by 50.6%and 64.7%,both of which are better than fly ash.When the particle size of RHA is not more than 15μm,it can significantly inhibit the expansion rate of mortar,and the inhibition effect is better than that of fly ash.5μm rice husk ash can reduce the 14 d expansion rate by 90%,and make the aggregate harmless,while 8-20μm fly ash only reduces the 14 d expansion rate by 60%,and the aggregate is still harmful.The pozzolastic activity of RHA can not only generate C-S-H gel with low Ca/Si ratio and reduce alkali content,but also improve the compactness of mortar and inhibit the penetration of alkali ions and water,thus showing an inhibitory effect on alkali silicate reaction.

关 键 词：碱硅酸反应 稻壳灰 粒径 粉煤灰 微观分析 

分 类 号：TU528.041[建筑科学—建筑技术科学]