重复再生混凝土性能和环境影响研究

基于生命周期评价方法，考虑混凝土重复再生利用的环境影响分配，对重复再生混凝土的性能和环境影响进行研究，并基于功效系数法优化出混凝土最佳重复再生次数.研究结果表明，再生混凝土的坍落度，强度和电通量随着重复再生循环次数的增加而下降，经3次重复再生后，混凝土28d立方体抗压强度为33.3MPa，满足设计要求，而坍落度和电通量与普通混凝土相比，分别减小和增大了38.9%和85.7%；混凝土材料的生态效率随着混凝土重复再生次数的增加而提高，混凝土材料的GWP、CED和CMR的值均随着混凝土重复再生次数的增加而降低，降低幅度从高到低依次为：CMR > GWP > CED；综合考虑混凝土的坍落度，混凝土抗压强度、电通量、GWP、CED和CMR等6个指标，4种混凝土配合比情景中，混凝土总功效系数从高到低依次为：一次再生混凝土 > 二次再生混凝土 > 三次再生混凝土 > 普通混凝土.

Properties and environmental impacts on repeated recycled aggregate concrete

According to the cradle-to-gate life cycle evaluation method and taking into account the environmental impact distribution of concrete recycling, this research studies on properties and environmental impacts of repeated recycled aggregate concrete, and the optimum number of repeated regeneration of concrete is optimized on efficiency function method. The results concluded that, the slump, strength and electric flux decreased with cycles of repeated regeneration of concrete increasing, the 28d compressive strength 33.3MPa after 3repeated cycles, which arrived the design strength requirements. Compared with ordinary concrete, the slump decreased by 38.9% and electric flux increased by 85.7%, respectively; The ecological efficiency of concrete material increases with the repeated cycles increasing, the values of GWP, CED, and CMR of concrete materials are reduced with the increase of the repeated cycles increasing, The reduction variation from high to low is:CMR > GWP > CED; Taking into account the slump, the compressive strength, the electrical flux, the GWP, the CED, and the CMR in four concrete mix scenarios, the total efficiency coefficient of concrete from high to low is:the first generation recycled concrete > the second generation recycled concrete > the third generation recycled concrete > ordinary concrete.