砖粒及粉煤灰掺量对再生混凝土抗冻性能的影响

Influence of Brick Particle and Fly Ash on Frost Resistance of Recycled Coarse Aggregate Concrete

利用含砖粒建筑垃圾再生粗骨料制备再生混凝土,并在工程中推广应用;其强度和抗冻性能是亟待解决的关键性问题。以粉煤灰及砖粒掺量作为分析参数,制作粉煤灰取代率分别为0、10%、15%和20%,砖粒含量分别为0、10%、30%和50%的再生混凝土立方体试件和棱柱体试件;并通过抗压和气冻-气融循环试验,研究粉煤灰取代率及砖粒含量对再生混凝土的强度及抗冻性能的影响规律。研究结果表明:(1)在无粉煤灰掺入条件下,砖粒掺量不超过30%时,再生混凝土的抗压强度和抗冻性能均没有明显下降;当砖粒掺量为50%时,再生混凝土的抗压强度和抗冻性能均有显著下降。(2)在砖粒掺量分别为30%和50%情况下,对再生混凝土抗压强度和抗冻性来说,粉煤灰取代率分别为15%和10%时的最优。

The strength and frost resistance of recycled concrete is a critical issue to be solved urgently. The recycled concrete has been widely used in engineering and its coarse aggregate is made from construction waste with brick. The influence of the replacement of fly ash and brick content on the strength and frost resistance of the recycled concrete was studied through the freeze-air cycle test. The test uses the fly ash and brick aggregate content as the analysis parameters to make recycled concrete cubes and prism specimens and among them,the replacement rates of fly ash were 0,10%,15% and 20% respectively and the contents of the brick were 0,10%,30% and 50%respectively. The results show that： when the content of fly ash is 0,and the content of brick is less than 30%,the compressive strength and frost resistance of recycled concrete are not significantly reduced,while the content of brick is 50%,the compressive strength and frost resistance were significantly decreased; when the content of brick is30% and 50% respectively,the fly ash is 15% and 10% respectively,the compressive strength and forst resistance of recycled concrete are the best.