论文部分内容阅读
耐久裂缝 (D裂缝 )是普通水泥混凝土 (PCC)损坏产生的 ,而且通常引起的原因是冬季的冻融循环。为了较好地研究D裂缝 ,PCC配合比设计应采用良好级配的粗骨料。对PCC路面上D裂缝维修的方法 ,大多是在PCC上用沥青混凝土 (AC)罩面 ,这样可使路表的使用功能重新恢复。但是有关AC罩面对开裂路面的长期作用的效果 ,人们却很少了解。对裂缝影响最主要的气候因素反映在湿度和温度方面。采用计算机模拟的有限差分瞬间流动的温度变化模型与在野外采用仪器测试效果完全相同 ,而且室内测试表明 ,AC罩面对PCC路面湿度影响可以忽略不计。对PCC路面温度影响确定 ,则是通过有限差分热传导计算机模型。另外还发现 ,AC罩面可将PCC路面冻融循环次数减少及冷却速率降低。室内冻融疲劳试验可模拟野外的环境条件 ,即伊利诺斯和Vandlia州际公路 70附近 ,制备的PCC试件 ,AC罩面厚度为 0～ 6in ,所有的PCC试件反复经过相当 5年冬季的野外暴露 ,强度折减情况由劈裂拉伸试验确定。具有 4in厚罩面试件的实验表明大部分强度已损失 ,可断定AC罩面没有阻止PCC的裂缝扩展反而促进发展 ,当PCC路面裂缝上设计AC罩面层时 ,使PCC强度降低的影响应给予考虑
Durable cracks (D-cracks) are caused by damage to normal cement concrete (PCC), and are usually caused by freeze-thaw cycles in winter. In order to better study D cracks, PCC mix design should be used with a good graded coarse aggregate. On the PCC pavement D cracks repair methods, mostly in the PCC with asphalt concrete (AC) cover, so that the use of road functions to resume. However, people are rarely aware of the long-term effects of AC masks on cracked pavements. The main climatic factors that affect the cracks are reflected in humidity and temperature. The finite-difference transient simulation of temperature variation using computer simulation is identical to the field-instrumented test, and laboratory tests show that the effect of AC overlay on PCC pavement humidity is negligible. PCC pavement temperature to determine the impact, then through the finite difference heat conduction computer model. In addition, it was also found that the AC cover can reduce the freeze-thaw cycles and the cooling rate of PCC pavement. Indoor freeze-thaw fatigue tests simulate field environmental conditions, PCC specimens prepared near Illinois and Vandlia Interstate 70, with AC cover thicknesses of 0-6in, and all PCC specimens repeated over a period of five years of winter The field exposure, strength reduction by the splitting tensile test to determine. Experiments with 4 in. Thick overlay specimens show that most of the strength has been lost, confirming that the AC overlay did not prevent the PCC from propagating but instead promoted the development of the PCC. When the AC overlay was designed on the PCC pavement crack, the effect of reducing the PCC strength should be given consider