温度、粗糙度对混凝土桥面沥青铺装层层间拉拔强度的耦合作用

Coupling effect of temperature and roughness on the pull-out strength of concrete bridge deck inter-layer

为研究温度与粗糙度对混凝土桥面沥青铺装层层间拉拔强度的耦合作用,首先制备了不同粗糙度的混凝土试件,测定其摩擦因数、构造深度与灰度值;然后在混凝土试件表面涂刷SBS改性沥青作为黏结层,同沥青混合料制成车辙板,并进行钻芯取样,将车辙板芯样在不同温度下进行保温后,进行拉拔试验得到其拉拔强度;最后利用主成分分析法将摩擦因数、构造深度、灰度值转化为粗糙度综合指数,对层间拉拔强度与粗糙度综合指数进行线性拟合。研究结果表明:当温度为[20℃,28℃]时,温度每升高1℃引起的层间拉拔强度变化,相当于温度保持不变,下降一个粗糙度当量值引起的拉拔强度变化;同时在这一温度范围内,温度对层间拉拔强度的影响程度明显大于粗糙度,当温度为20℃、23℃、25℃、28℃时,层间拉拔强度与粗糙度之间的相关系数以及粗糙度对层间拉拔强度的影响程度总体高于其他试验温度;当温度升高至30℃时,层间拉拔强度与粗糙度的相关系数比28℃时下降了62.2%,拟合方程的斜率比28℃时下降了58.2%,二者线性相关性明显减弱,粗糙度对拉拔强度的影响程度显著降低;当温度超过30℃时,层间拉拔强度与粗糙度之间的线性相关性极弱,拟合方程斜率接近于0,粗糙度的改变几乎不影响层间拉拔强度。

To study the coupling effect of roughness and temperature on the inter-layer pull-out strength of concrete bridge deck, concrete specimens with different roughness were prepared at first, and their friction coefficients, structural depth and gray values were measured. SBS modified asphalt was coated on the surface of concrete specimens as bonding layer, and rutting board was made with asphalt mixture and core drilling was taken. The core samples of rutting plate were insulated at different temperatures, and then the pull-out strength was obtained by pull-out test. The principal component analysis method was used to transform the friction coefficient, structure depth and gray value into the comprehensive index of roughness. Finally, the pull-out strength and comprehensive index of roughness were linearly fitted. The results show that when the temperature ranges from 20 ℃ to 28 ℃, the change of pull-out strength caused by increasing temperature by 1 ℃ is equivalent value to the change caused by decreasing roughness by 1 roughness equivalent when the temperature is constant. In this temperature range, the influence of temperature on pull-out strength is obviously greater than that of roughness. Secondly, when the temperature are 20 ℃, 23 ℃, 25 ℃ and 28 ℃, the correlation coefficient between pull-out strength and roughness and the influence of roughness on pull-out strength are higher than other test temperatures. When the temperature is 30 ℃, compared with 28 ℃, the correlation coefficient between pull-out strength and roughness decreases by 62.2% and the slope of fitting equation decreases by 58.2%, indicating that the linear correlation between them and the influence of roughness on pull-out strength both decrease significantly. When the temperature is greater than 30 ℃, the linear correlation between pull-out strength and roughness is very weak. The slope of fitting equation is close to 0, indicating that the change of roughness hardly affects pull-out strength. 5 tabs, 5 figs, 29 refs.