考虑裂缝存在的水泥混凝土性能劣化试验

Degeneration Test of Cement Concrete Properties with Cracks

为研究车辆荷载、冻融循环和干湿循环作用下水泥混凝土性能劣化机理,并分析裂缝的存在对混凝土性能劣化的影响,对带有裂缝和不带裂缝的混凝土进行加速加载、干湿循环和冻融循环试验,得到试件的相对动弹模量、质量损失及强度的变化,对混凝土性能劣化机理进行研究。试验结果表明:车辆荷载反复作用下水泥混凝土性能劣化不明显,但裂缝的存在使混凝土抗压强度明显降低;干湿循环作用下混凝土性能劣化明显,56次干湿循环作用下混凝土抗压强度降低20%,裂缝的存在对混凝土性能劣化影响不大;冻融循环作用下混凝土性能劣化尤为突出,150次冻融循环作用下不带裂缝和带有裂缝的混凝土弯拉强度分别降低48.3%和52.3%。可见,冻融循环和干湿循环作用是水泥混凝土性能劣化的主要原因,裂缝的存在并未加速混凝土性能的劣化,但裂缝的存在使水分更易进入路面结构内部,并使路面全深范围内的混凝土经受干湿循环和冻融循环作用,车辆荷载的疲劳作用使劣化的路面混凝土加速开裂。

In order to study the degeneration mechanism of cement concrete under vehicle load, freezing and thawing cycle and drying and watering cycle, and study the effects of cracks, acceleration loading test, freezing and thawing cycles test and drying and watering cycles test are carried out, relative dynamic elastic modulus, losses of quality and changes of strength are obtained. The results indicate that repeated vehicle load has small influence on the degeneration of cement concrete, but cracks make the compressive strength lower than before; drying and watering cycle has big influence on degeneration of cement concrete, the compressive strength is reduced by 20% after 56 drying and watering cycles and cracks have small influence; freezing and thawing cycle has great influence on the degeneration of cement concrete, the flexural-tensile strength is reduced by 48.3% and 52.3% for cement concrete without cracks and with cracks after 150 freezing and thawing cycles. It is thus clear that freezing and thawing cycles and drying and watering cycles are main reasons for the degeneration of cement concrete; cracks cannot accelerate the degeneration of cement concrete, but can make the water easier into the pavement structure and the whole depth of pavement endure freezing and thawing cycles and drying and watering cycles, and the repeated vehicle load can accelerate pavement fracture.