Strengthening Research On Building Waste's Recycled Aggregate Concrete

Concrete is a kind of building material,which is widely used nowadays.When buildings made with concrete are demolished because its serviceable life is over or it hinds the pace of municipal construction and when they are destroyed so severely by natural disasters such as earthquake,typhoon and flood that it can not be used as usual much demolished debris is generated.All this waste imposes a great adverse effect on our everyday life and environments we live. One side,if we ignore the phenomenon,it would pollute the environments.On the other hand,concrete and natural aggregate quantity that is demanded in construction grows rapidly,too.But the natural aggregate resources are very limited.Using the recycled aggregate which is strengthened to manufacture regeneration aggregate concrete solves the environmental problem and saves the natural resources.Then based on the thought of environmental protection and sustainable development the technology of recycled concrete can solve this problem efficiently.The poor performance regenerated aggregate that is produced through simply fragmenting restricts the reuse of the abandoned concrete.In this paper,It gives a lot of intensified testing research.The first,the strengthening of aggregate,which is achieved by the physical strengthening,the chemic strengthening,the complex strengthening.The physical strengthening is also called reshape the regenerated aggregate pellets,using the mending ball milling mechanism to strength the simply fragmenting. The chemic strengthening makes use of the alkali liquid or PVA liquid or the combination of alkali liquid and PVA liquid to improve the recycled aggregate,and it is contrasted the performance changes of the capability through the strengthening and without the strengthening.The results showed that the dual composite strengthened to improve the aggregate performance is superior to the physical or chemical enhanced individually in improving aggregate performance.The second,the strengthening of cement phase,it improves the proprieties of concrete through adding silicon ash or water reducing agent.It can see that the ratio of the two in accordance with the corresponding preparation of Q enhancer (0.8% of silica fume +1% of superplasticizer) to improve the effectiveness of concrete is better than a separate add silica fume or superplasticizer significantly.The last,the complex strengthening,called the physical strengthening+the chemic strengthening+the strengthening of cement phase,It is studied the influence of the strengthening to water absorption,apparent density,compressive.From the different strengthening experiments,the best technics condition of the strengthening concrete is:After the dual composite strengthened is achieved,in other words, reshaping the regenerated aggregate,the capacity of the milling is fixed at 8Kg,and the time is 15 minutes;Na2CO3 is added by 0.17 percent,NaOH is occupied for 0.4 percent and the PVA is 1.5 percent,Silicon ash and water reducing agent are occupied 0.8 percent and 1 percent respectively.After all of the the complex strengthening are achieved, the compressive of the 7 days,28days are 35.3MPa,50.1 MPa.Compared to the recycled aggregate concrete, the compressive of the 7 days,28days increase 25.8%,29.3% respectively.Compared to the crude aggregate concrete,they decrease 4.08%,5.47% apartly.