再生混凝土超声-回弹测强曲线的建立及应用

Establishment and Application of Ultrasonic-rebound Strength Curves for Recycled Aggregate Concrete

为了获得再生混凝土的超声．回弹测强曲线，针对G20-C40共5种强度等级再生混凝土，进行了系统的超声回弹综合法检测抗压强度试验研究。试验中，再生骨料的取代率分别为0，25％，50％和100％。试验结果表明，随着再生骨料取代率的增加，混凝土的超声声速和回弹值均有所降低；再生混凝土的抗压强度和超声声速及回弹值之间存在一定的相关关系；再生骨料取代率对混凝土抗压强度与超声声速的关系影响显著，但是对抗压强度与回弹值的关系影响很小。基于本文获得的再生混凝土的超声声速和回弹值试验结果，建立了再生混凝土的测强曲线。并进一步将本文得到的测强曲线应用于某再生混凝土刚性路面混凝土抗压强度检测，发现再生混凝土抗压强度的实测值与推定值吻合良好。

In order to develop the ultrasonic-rebound strength curves for recycled aggregate concrete, experimental work was performed on the inspection of compressive strength using ultrasonic rebound combined method for recycled aggregate concrete. The involved strength grades ranged from C20 to C40. Four recycled concrete aggregate replacement ratios including 0, 25%, 50% and 100% were used. The test results indicate that the ultrasonic velocity and rebound strength of concrete reduce with the increase of recycled concrete aggregate. The recycled concrete aggregate has a remarkable influence on the relationship between compressive strength and ultrasonic velocity, while nearly no influence on the strength-rebound relation. Based on the test results, the ultrasonic-rebound compressive strength curves for recycled aggregate concrete were proposed. The curve was further applied into the inspection of compressive strength of recycled aggregate concrete in a pavement. It was found that the inferable compressive strength coincides well with the measured values for recycled aggregate concrete.