Study On The Preparation Methods And The Mechanical Propoty Of Recycled Brick Aggregate Concrete Wall Bricks

Due to the acceleration of China's urbanization rate and the rapid development of economic society, engineering construction has entered a peak period. With the increase of new construction and the maintenance,renovation, expansion and demolition of existing buildings,a large number of construction waste are produced, in which abandoned sintered clay brick accounted for the highest proportion. Besides that,earthquakes, floods, typhoons and other natural disasters destroy a large number of buildings and structures. Abandoned sintered clay brick is still a major part of the post-disaster construction waste. However, at present most of the waste clay bricks and other construction waste are simply stacked and buried without any treatment.They didn't get reasonable reuse, not only occupied land resources, but also caused pollution and destruction to the environment.At the same time, there are currently more than70% of wall materials in China's housing construction materials, wherein the sintered clay bricks occupies dominant position. According to the 2005 State Council's notice on further promoting the wall materials innovation and promotion of energy-saving buildings, the pattern that clay bricks and non-energy-saving buildings are main part across the country has not yet been fundamentally changed, now destroying land for bricks is still rampant. The State Council asked for that all aspects need to innovate wall materials and promote energy-efficient buildings in order to effectively protect arable land, save energy, improve the function of the building,improve the efficiency of resource utilization and preserve the ecological environment. Based on the above aspects, we use the abandoned sintered clay bricks and make recycled aggregate concrete wall bricks by crushing and screening them.On the one hand construction waste resource can be recycled to avoid waste of resource and reduce environmental pollution, on the other hand this can advance wall materials innovation in response to national policy requirements and have good social, economic and environmental benefits.This paper is based on the above-mentioned purpose and study the raw materials,proportion design,preparation technology,and mechanical properties of recycled brick aggregate concrete wall bricks.It includes the following sections:(1) introduce the source and production of recycled brick coarse aggregate,research fundamental properties and make comparison with natural gravel coarse aggregate.(2)design the proportion of recycled brick aggregate concrete wall bricks, calculate water-cement ratio, unit water and sand mix rate parameters,then determine the ratiotest program.(3) take reasonable preparation process for preparing recycled brick aggregate concrete wall bricks, and initiate density level test, compressive and flexural strength test.study the brick aggregate replace rate's impact on the strength of wall bricks as well as the adding of fly ash and air-entraining agent. Experimental results show that:(1)Compared with natural gravel aggregate, the surface of recycled brick coarse aggregate is rougher, there are more voids, the apparent density and bulk density are smaller. The water absorption index and crushed of recycled brick coarse aggregate are much greater than natural gravel aggregate, respectively, reach natural aggregate of11.97 times and 3.68 times.(2)This paper designs the proportion of recycled brick aggregate concrete referencing to the ordinary concrete proportion design method.Because of the higher water absorption of brick coarse aggregate,we take extra water method. After the study of fresh concrete workability,we find that additional water effectively improve the workability of the mix, and adding a certain amount of fly ash and air-entraining agent have an beneficial effect on increasing mixture mobility.(3)Recycled brick aggregate concrete wall bricks' density levels can reach B level.(4)Compared with concrete wall bricks without any brick aggregate, the strength of recycled brick aggregate concrete wall bricks decreases,and with the regeneration of brick aggregate replacement ratio increases, it decreases,but the intensity level can reach MU15.In addition, the strength of recycled brick aggregate wall bricks which replacement rate is 50% is the highest intensity, the average compressive strength can reach 19.46 MPa.(5)To recycled concrete wall bricks which replacement rate of brick aggregate is50%,the adding of fly ash and air-entraining agent causes a certain decrease in intensity,and wherein the composite fly ash after air-entraining agent causes a smallest decrease,and its compressive strength can reach MU15.