超声回弹综合法研究碱式硫酸镁混凝土抗压强度

Study on the Compressive Strength of Basic Magnesium Sulfate Cement Concrete by the Combined Method of Ultrasonic and Rebound

碱式硫酸镁混凝土(BMSC)的主要水化产物为5·1·7相,该相具有自形成、自分散、自增强和自增韧作用,故BMSC具有较高的抗拉强度。同时,BMSC具有不碳化、早强、内部致密、早期水化完成后内部结构变化小等特点,如使用普通混凝土无损检测的测强曲线,检测结果误差较大。本工作采用超声-回弹综合法测试了BMSC试块(100 mm×100 mm×100 mm,标准养护28 d)的抗压强度,与单参数法及超声-回弹两参数相比,综合法得到的测强曲线误差最小(平均相对误差δ=12.3%,相对标准差e_(r)=16.9%)。根据BMSC试块的超声波传播速度与表面回弹值,建立了推定BMSC强度的超声波-回弹综合法的专用测强计算公式,推定了在沈阳室外自然暴露2年后的BMSC构件的混凝土抗压强度。该法可以用于BMSC材料检测和耐久性评估。

The main hydration product 5·1·7 phase of basic magnesium sulfate cement concrete(BMSC)plays the role of self forming,self dispersing,self reinforcing and self toughening.So BMSC has high tensile strength.BMSC has the characteristics of non⁃carbonization,early strength,internal densification and small internal structure change after early hydration,which makes the error of strength measurement curve of non⁃destructive test of Portland cement concrete larger than that of BMSC.In this work,ultrasonic⁃rebound combined method was used to study BMSC block with the dimension of 100 mm×100 mm×100 mm.The data of the ultrasonic⁃rebound combined method was more accurate than that of the method of single parameter.The data of the combined method is that the average relative error is 12.3%and the relative standard deviation is 16.9%.According to the ultrasonic propagation velocity and surface rebound value of the BMSC specimen,a formula of special strength measurement for the comprehensive ultrasonic rebound method to estimate the compressive strength of BMSC is established.The compressive strength of BMSC members can be estimated after natural exposure in Shenyang for two years of.This method is expected to be used for BMSC material testing and evaluation of durability.