| The key and difficult point for rural housing land reclamation is the disposal of rural construction demolishing wastes (RCDW). Chongqing is a typical city with hilly mountains, influenced by the special natural environment, traffic inconvenience, backward economy and traditional living habits and traditional agricultural production activities in various, the rural settlement distribution and utilization has the character of "small, scattered and disorderly" and low level of intensive utilization, which also are constraints for the disposal of RCDW.The stand or fall of RCDW disposal has a close relationship with the quality of ecological environment and the reclamation cultivated land, as well as influence the reclamation cost.This research investigate the basic information of126reclamation points, which is located in Guanqiao Vollege,Yongfeng Town,Zhongxian County, Chongqing Municipality, such as the material structure, construction time, terrain and the types of construction waste reclamation after the demolition, quantity, disposal way by on-the-spot investigation method. The survey fond that the RCDW have various types, mainly for the waste concrete, waste stone, waste bricks, waste roof-tiles, waste prefabricated slabs, waste wall clay, waste mortar, waste cement, waste wood, scrap metal and other wastes; The quantity of construction waste is big, the average RCDW production by the unit building area is1105.20kg/m2,corresponding to447.60kg/m2by land reclamation area. Chongqing will release0.8-1.0million mu rural residence land, if all reclaimed, construction waste will be accumulated up to0.24-0.3billion tons; the number of Reclamation point with little size some and scattered distribution are too many,the average per hectare will have14independent reclamation points; RCDW could be recycled utilization highly, with99.74%of construction waste can be used, only some harmful substances should be processed specially; In addition to the waste soil wall, the disposal of RCDW is too much extensive with72.68%of the total waste was near piled up or landfilled in reclamation area.At the same time, the disposal results of RCDW will be affected by characteristics of landform, change of building structure, construction methods, management organization, policies and regulations guarantee, special funds, technology and equipment support, project planning and design as well as the public environmental awareness. Among them, along with the progress of The Times, the proportion of brick houses new structured is more than60%, and the proportion is increasing year by year, so as to the waste brick, waste concrete,waste prefabricated slabs, waste mortar. The existing problems of current RCDW disposal is these lacking of special management organization, of special management policies and regulations, of special funds and extensive disposal cause resource waste and environmental pollution.To carry out the rural housing land reclamation work better, and to realize reclamation dismantling reduction, recycling, harmless disposal, this study analyze the disposal feasibility of RCDW from its own value, the demand for rural construction engineering material and the support of technology and economic on the basis of field investigation data.The RCDW disposal methods are mainly used by engineering construction, padded into abandoned pit, landfilled disposal, sort-recycled disposal and sold to collect money. Engineering construction disposal includes land leveling engineering disposal, water conservancy engineering disposal and field-road engineering disposal.This research use waste stone (S), waste brick (B), waste concrete(C), waste tiles (P) as single type and mixed type recycled concrete to prepare specimens by the orthogonal experiment index measurement method based on these norms including 《recycled coarse aggregate concrete (GB/T25177-2010)》,《ordinary concrete mechanics performance test method standard (GB/T50081-2002)》 and 《concrete strength inspection evaluation standard (GB/T50107-2010)》. With the help of TVA-2000S type electric hydraulic pressure tester and SXB high accuracy intelligent dynamometer for testing compressive strength of the specimens and get precise measuring and recording in the construction project quality surveillance station of Beibei District.The research result shows that the waste stone regeneration aggregate material can be used for the strength of below C30concrete (including C30concrete), while the other three types of single regeneration aggregate can only be used for the strength of below C20concrete (including C20concrete), and in order to ensure security, waste tile recycled aggregate had better be used for the strength of below C15concrete (including C15concrete); for mixed type of recycled aggregate concrete, when the water cement ratio (w/c) is0.45, the mixing ratio of B/C among40%60%-60%/60%, B/P among20%80%-40%/80%, B/S among0%100%-60%/100%,(P/C among20%80%-80%/80%, P/S among0%/40%/100%60%, the strength of recycled concrete can achieve C25requirements.When w/c is0.55,the mixing ratio of B/C and S/C can always be achieved the strength requirement of C20.While B/P among20%80%-40%/80%, P/C among0%100%-40%/100%, P/S among0%/60%-100%40%can only satisfy the requirement of C20intensity level; when w/c is0.65,in addition to B/P among60%/80%-40%40%, all mixed recycled aggregate concrete can satisfy the C15strength grade requirements; when w/c is0.75,all recycled aggregate concrete can satisfy the C10strength grade requirements.This study sets up six levels of quantitative system for various types of RCDW and five levels of quantitative system for various types of consumables in new construction firstly, then the RCDW is divided into the usable demolish material on the basis of comprehensive utilization and demolition waste residues comprehensive disposal, starting from the land reclamation point,and from low to high level step by step build various types of construction waste and the fitting relationship between all kinds of new constructions material quantity, within first, after scheduling at the same level, and then scheduling in superior level, and each scheduling must use the same type waste firstly, then recycle alternative waste to realize a comprehensive dispatching management pattern.Finally, the amount of RCDW in certain reclamation area and The total RCDW used of in whole reclamation project can be obtained.In terms of comprehensive benefits, under the optimized disposition pattern, the land reclamation construction investment strength can be reduced by3514RMB/hm2,which suggests that land reclamation construction cost has been greatly reduced in study area; the amount of usable demolish material piled up would be reduced from70.43%to32.73%, and the landfilled demolish waste residue could be reduced from14.42m3/hm2to3.85m3/hm2, which can reduce the land area occupied by surplus RCDW and security risk; Meanwhile, it might reduce the consumption of natural raw material; increase the recycling usage amount of RCDW, which could allocate construction material resources rationally, save building materials resource, and promote the sustainable development of rural society, economy and ecology. The optimized disposition pattern has a good demonstration effect and promotion prospects.This thesis puts forward some policy suggestions and practical measures to ensure RCDW comprehensive disposal go smoothly in hilly area. |
PDF Full Text Request