不同强度等级的机制砂和天然砂混凝土的高温后性能响应  

Performance response of concrete with different strength grades of machine-made sand and natural sand after high temperature

作　　者：吉龙华 李卫文 樊亚男[2] 王宇杰 柴松华 JI Longhua;LI Weiwen;FAN Yanan;WANG Yujie;CHAI Songhua(Shanxi Engineering Vocational College,Taiyuan 030009,China;College of Civil Engineering,Taiyuan University of Technology,Taiyuan 030024,China)

机构地区：[1]山西工程职业学院,山西太原030009 [2]太原理工大学土木工程学院,山西太原030024

出　　处：《混凝土》2023年第7期108-112,共5页Concrete

基　　金：山西省重点研发项目(201903D321113)。

摘　　要：混凝土原材料及强度等级不同其火灾高温响应不同,根据目前大量使用机制砂拌制混凝土的现状,研究不同强度等级的机制砂和天然砂混凝土遭遇火灾高温后产生的损伤破坏及差异,对高温作用后的混凝土测试其抗压、劈拉强度及孔隙结构,分析不同混凝土不同温度作用后力学性能、孔隙率和孔径分布的变化。结果表明,不同温度作用后混凝土性能的响应及变化规律基本相同。不同强度等级、不同种类砂子,混凝土强度损失变化规律基本相似,但强度等级越高,下降速率越大;抗压强度400℃之前下降较慢,之后强度下降迅速,尤其500~600℃抗压强度陡降,800℃后强度基本丧失;劈裂抗拉强度随温度升高急剧下降,但仍在500~600℃内强度下架速率最快,800℃后强度基本丧失;相同强度等级下机制砂混凝土抗压强度下降速率略高于天然砂混凝土。各种混凝土孔隙率及不同孔径所占比例随温度变化相似,均呈现出总孔隙率增加、无害孔及少害孔数量降低,有害孔及多害孔数量增加的趋势。不同强度等级、不同种类砂子,混凝土内部孔隙结构变化规律与抗压强度变化规律一致。Different raw materials and strength grades of concrete have different responses to fire and high temperature.According to the current situation that a large number of machine-made sand is used to mix concrete,it studies the damage and damage of machine-made sand and natural sand concrete with different strength grades after encountering fire,tests the compressive strength,splitting tensile strength and pore structure of concrete after high temperature test,and analyzes the mechanical properties of different concrete after different temperatures changes in porosity and pore size distribution.The results show that the response and variation rules of concrete properties under different temperatures are basically the same.The change law of concrete strength loss is basically similar for different strength grades and different types of sand,but the higher the strength grade,the greater the decline rate.The compressive strength decreases slowly before 400℃,and then decreases rapidly.Especially,the compressive strength drops sharply between 500℃and 600℃,and basically loses strength after 800℃.The splitting tensile strength decreases sharply with the increase of temperature,but the unloading rate is the fastest in the range of 500~600℃,and the strength basically loses after 800℃.Under the same strength grade,the reduction rate of compressive strength of machine-made sand concrete is slightly higher than that of natural sand concrete.The analysis of concrete pore structure shows that the porosity of different concrete and the proportion of different pore sizes change similarly with temperature after the high temperature test,showing a trend of increasing the total porosity,decreasing the number of harmless and less harmful pores,and increasing the number of harmful and multi harmful pores.The pore structure of concrete with different strength grades and different types of sand is consistent with the compressive strength.

关 键 词：机制砂 天然砂 高温试验 力学性能 孔隙率 

分 类 号：TU528.041[建筑科学—建筑技术科学]