变形钢筋与机制砂混凝土黏结性能试验研究

Experimental Study of Bond Properties between Deformed Steel Bar and Concrete with Machine-Made Sand

通过混凝土试块中心的钢筋拉拔试验,研究了机制砂原料形态、石粉含量和混凝土强度对变形钢筋与机制砂混凝土黏结性能的影响规律.机制砂原料形态为碎石和卵石,石粉含量(质量分数)为5%,9%和13%,混凝土强度等级为C30,C40,C50和C60,月牙肋变形钢筋直径为12mm.结果表明:所有试件均因钢筋肋前的混凝土齿发生剪切破坏而使钢筋拔出,其黏结-滑移关系曲线可以通过特征点的黏结应力和滑移值表达为四阶段变化关系;变形钢筋与混凝土的黏结性能随着混凝土强度的提高而增加,钢筋与碎石破碎机制砂混凝土的黏结性能优于钢筋与卵石破碎机制砂混凝土;石粉含量的增加会降低黏结强度并使得黏结-滑移关系曲线的内劈裂段延长和下降段变陡.根据试验统计分析,建立了变形钢筋与机制砂混凝土的黏结-滑移本构关系.

Pullout tests of steel bar positioned in central of concrete specimen were conducted to investiga tion of the source rock state of sand, the content of stone powder and the concrete strength on the bond properties between deformed steel bar and concrete with machinemade sand. The source rocks of sand were crushed stone and gravel, the contents of stone powder（by mass） were 5%, 9M and 13%, the strength grades of concrete were C30, C40, C50 and C60, the diameter of deformed steel bar was 12 mm. The results show that all specimens damaged from shear broken of concrete dentals in front of bar ribs and pullout of deformed bar, the bondslip curve can be represented as four phases by the characteristic values of bond stress and slip; the bond properties between deformed bar and concrete increase with the increas ing concrete strength, which is better while the concrete mixed with sand made of crushed stone. The bond strength between deformed bar and concrete decreases with the increasing content of stone powder in＇ machinemade sand while the internal splitting phase of bondslip curve is prolonged and the decreasing phase becomes steeply. Based on the statistical analyses of test data, the constitutive relationships of bond slip between tensile deformed bar and concrete with machinemade sand are proposed.