预浸碳化再生骨料混凝土的动态力学性能研究

Test study on dynamic mechanical properties of pre-impregnated carbonized recycled aggregate concrete

为研究再生骨料的预浸碳化处理方式及碳化循环次数对再生混凝土动态力学性能的影响,将强化后的再生骨料100%取代天然骨料制备再生混凝土试件,分别开展静、动态压缩试验。研究结果表明,静态加载时,预浸碳化组的抗压强度随碳化循环次数的增加而增大,而直接碳化组的抗压强度仅在第1次碳化循环后有所提升,继续进行碳化循环对再生混凝土强度的提升效果不明显。动态加载时,预浸碳化组再生混凝土呈现出明显的应变率强化效应,动态抗压强度与动态增加因子均随应变率的增大而提高,相较于普通再生混凝土,再生骨料预浸碳化循环3次后制备的再生混凝土试件动态抗压强度提升了23.8%,而直接碳化组仅提升了5.7%,且动态增加因子与应变率的对数存在良好的线性关系,随应变率的lg10线性增加;当应变率相同时,随着碳化循环次数的增加,动态抗压强度也增大。从能量的角度看,预浸碳化组在高应变率下的比能量吸收值大于低应变率下的比能量吸收值,再次说明了预浸碳化再生骨料混凝土仍具有应变率效应,相同应变率条件下,预浸碳化组的比能量吸收值大于直接碳化组,说明预浸碳化再生骨料提升了再生混凝土的抗冲击性能,且效果优于传统的直接碳化处理。上述研究也为预浸碳化强化再生骨料及再生混凝土在工程结构中的应用提供了可靠的试验结果和理论依据。

Here,to study effects of pre-impregnated carbonization treatment method and carbonized cycle number of recycled aggregate on dynamic mechanical properties of recycled concrete,reinforced recycled aggregates were used to fully replace natural aggregate,and prepare recycled concrete specimens.Static and dynamic compression tests were conducted for these specimens,respectively.The study results showed that under static loading,compressive strengths of pre-impregnated carbonization group increase with increase in number of carbonization cycles,while compressive strengths of direct carbonization group only improve after the first carbonization cycle,and continuing carbonization cycles has no obvious effect on improving strength of recycled concrete;under dynamic loading,pre-impregnated carbonized group of recycled concrete has an obvious strain rate strengthening effect,dynamic compressive strength and dynamic increase factor both increase with increase in strain rate;compared with ordinary recycled concrete,dynamic compressive strength of recycled concrete specimens prepared with pre-impregnated recycled aggregate after 3 carbonization cycles increases by 23.8%,while that of direct carbonation group only increases by 5.7%;there is a good linear relation between dynamic increase factor and logarithm of strain rate,the former increases linearly with lg10 strain rate;when strain rate keeps the same,dynamic compressive strength also increases with increase in carbonization cycles;from the energy point of view,specific energy absorption value of pre-impregnated carbonized group at high strain rate is higher than that at low strain rate,so pre-impregnated carbonized recycled aggregate concrete still has a strain rate effect;under the same strain rate condition,specific energy absorption value of pre-impregnated carbonized group is larger than that of direct carbonized group,so pre-impregnated carbonized recycled aggregate improves the anti-impact performance of recycled concrete and has a better effect than traditional direct carbonization treatment;the study results can also provide reliable test results and theoretical basis for application of pre-impregnated carbonized reinforced recycled aggregate and recycled concrete in engineering structures.