Study On The Recycled Autoclaved Brick

Building rubbish is endangering the social environment, which needs to be used reasonably. Recycled brick is a kind of autoclaved brick which is made of building rubbish as aggregate, fly-ash and industrial waste residue, by autoclave curing technology. This kind of autoclaved brick not only has many advantages, including lightweight,high strength and freezen resistance, but also most of the raw materials are industrial and building rubbish. In this way, it will save natural resources and protect the enviroment, so, it has MUch more economic and social significance than common walling materials, and broader prospect. Autoclaved brick has become an important direction of walling products.A good reaserch on the development of autoclaved brick was made and the actuality and utilization of building rubbish both at home and abroad were studied. Then it propose that making MU15 recycled autoclaved bricks using building rubbish as aggregate and industral waste (fly-ash, calcium, high-sulfurpetroleum coke ash,high-sulfurpetroleum coke waste). This study consistents with sustainable development and was funded by the country "11th Five -Year" plan focused on scientific and technological support issues (2006BAJ02B0504).The study has been done are as follows:Firstly, some influences to the performance of autoclaved brick were researched, such as molding pressure, autoclave curing system, excitant and so on. And it selects the best molding pressure: 15 MPa; autoclave curing system: 1.0 MPa, time: 6 h; and excitant: 1%A+1%B.Secondly, on the basic of autoclaved brick which is made of building rubbish as aggregate, fly-ash and quicklime, it use other industrial wastes (calcium, high-sulfurpetroleum coke ash, high-sulfurpetroleum coke waste) to make autoclaved bricks and get four systems of mixture ratio: building rubbish-fly ash-quicklime system, building rubbish-fly ash-calcium system, building rubbish-fly ash-high-sulfurpetroleum coke ash system, building rubbish-fly ash-high-sulfurpetroleum coke waste system.And then, with the selected molding pressure,autoclave curing system and mixture ratio, we produce standard bricks, and detect their compressive strength, flexural strength, volume densities, 24 hours water absorption, compressive strength after freezing-thawing, weight lost, dry shrinkage result.According to amount of experiments, the result for the four-different systems we got separately are:1. The building rubbish-fly ash-quicklime system: building rubbish 65%, fly ash 27%, quicklime 8%; compressive strength: 18.3 MPa, flexural strength: 3.5 MPa, volume density: 1578.9 kg/m~3 , 24 hours water absorption: 19.2%; compressive strength after freeze-thaw: 15.9 MPa, weight lost: 0.38% , dry shrinkage: 0.382 mm/m.2. The building rubbish-fly ash-calcium system: building rubbish 65%, fly ash 25% calcium 10%; compressive strength: 19.0 MPa, flexural strength: 3.9 MPa, volume density: 1575.2 kg/m~3, 24 hours water absorption: 19.7%, compressive strength after freeze-thaw: 17.5 MPa, weight lost: 0.30% , dry shrinkage: 0.436 mm/m.3. The building rubbish-fly ash-high-sulfurpetroleum coke ash system: building rubbish 65%, fly ash 20%, coke ash 15%; compressive strength: 16.9 MPa, flexural strength: 3.7 MPa, volume density: 1524.1 kg/m~3, 24 hours water absorption: 21.0%; compressive strength after freeze-thaw: 13.9 MPa, weight lost: 0.40%, dry shrinkage: 0.526 mm/m.4. The building rubbish-fly ash-high-sulfurpetroleum coke waste system: building rubbish 55%, fly ash 25%, coke waste 20%; compressive strength: 26.1 MPa, flexural strength: 4.3 MPa, volume density: 1538.0 kg/m~3, 24 hours water absorption: 17.5%, compressive strength after freeze-thaw: 20.3 MPa, weight lost: 0.22% , dry shrinkage: 0.312 mm/m. All of the performance indexs of four-system recycled autoclaved bricks reach national standards of MU15. The results indicate that regenerated autoclaved bricks have sound performance index, which will be ideal new walling product. Its nature of protecting the environment and against pollution will make building materials used recyclly. Thus, regenerated autoclaved bricks will be developed and used actively.