Strength Analysis Of Recycled Brick Aggregate Mortar

With the accelerated process of urban-rural integration,construction waste emissions are increasing.According to statistics,China ’s annual construction waste emissions are about1.55 billion to 2.4 billion tons,accounting for about 40 % of urban waste,of which waste brick accounts for at least half of construction waste.In recent years,respond to the call that green water and green mountains are Jinshan and Yinshan,construction waste disposal has become a problem that urban development must face.How to realize the recycling of construction waste,especially the recycling of waste bricks,is an urgent problem to be solved.Due to the characteristics of low strength,large porosity and strong water absorption of waste brick,there is no consensus on the utilization of recycled brick in academia and engineering application,and there is insufficient research results and successful cases.Therefore,this paper uses waste bricks to produce recycled fine aggregate,and conducts the research on the replacement of manufactured sand to configure recycled mortar.Firstly,the variation law of fine aggregate particle size after hammer crushing of limestone,recycled coal gangue brick and recycled clay brick was tested,and the grading curve characteristics of the three materials were analyzed and compared.Secondly,by configuring M10 recycled mortar,the influence of the substitution rate of coal gangue brick aggregate,clay brick aggregate and fly ash on the strength of M10 mortar was studied.Finally,on the basis of previous studies,combined with market demand,by configuring M20 recycled mortar,this paper focuses on the influence of the replacement rate of recycled coal gangue brick,water cement ratio,cement-bone ratio and other parameters on the unconfined compressive strength of M20 recycled coal gangue aggregate mortar.The main research results are as follows :(1)The gradation curves of fine aggregate formed after hammer crushing of limestone,recycled coal gangue brick and recycled clay brick were compared and analyzed,and it was found that the gradation changes of fine aggregate formed after crushing of the three materials were basically the same.(2)M10 mortars with different substitution rates were prepared by using coal gangue brick,recycled clay brick and fly ash.The research shows that the compressive strength decreases with the increase of the substitution rate of recycled materials(Content of coal gangue brick aggregate or clay brick aggregate or fly ash).Among them,when the replacement rate of coal gangue brick and clay brick is 25 %,the compressive strength decreases less than 6 %.The replacement rate of fly ash was 30 %,and the 28 d compressive strength decreased by 36.4 %.(3)For the recycled coal gangue brick mortar with strength grade of M20,the compressive strength of the test block gradually decreases with the increase of the water-cement ratio,the decrease of the cement-to-bone ratio and the increase of the replacement rate of the recycled coal gangue brick.The influence factors of strength are :water cement ratio > recycled coal gangue brick replacement rate > cement-bone ratio.Among them,when the replacement rate of recycled coal gangue brick is 25 %,the 28 d strength is reduced by 7.6 %.Therefore,it can be considered that the replacement rate of coal gangue brick 25 % has no obvious effect on the strength of mortar.Through the research of this topic,it is feasible to use recycled brick aggregate to replace machine-made sand to configure mortar.Using recycled brick aggregate to replace or partially replace natural aggregate to configure recycled mortar can not only reduce the exploitation of natural resources,protect green water and green mountains,but also realize building construction.The effective use of waste turns construction waste into treasure,realizes the harmonious coexistence between man and nature,and achieves carbon emission reduction and carbon neutrality.