At present, the amount of construction waste in China has accounted for 30%-40% of the total urban waste. In many areas, construction waste is transported to the suburbs or the countryside by construction units without any treatment, and is disposed of by means of open piles or landfills, which not only encroaches on valuable land resources and consumes a large amount of construction funds such as land acquisition fees and waste removal fees, but also causes serious environmental pollution due to scattering and dust, ash and sand flying in the process of clearing and piling.
On the other hand, many of the construction waste after sorting, rejecting or crushing, most of the waste can be reused as renewable resources, such as scrap steel, scrap wire, and a variety of scrap steel parts and other metals, after sorting, concentration, back to the furnace, can be reprocessed into a variety of specifications of steel; bricks, gravel, concrete, etc. after crushing, can be used instead of sand, for fatigue I building mortar, plastering mortar, playing concrete Bedding, etc., can also be used for roadbed bedding, making blocks and paving bricks and other building materials products.
The main types of domestic construction waste at this stage
Construction waste, also known as construction waste, refers to the residual mud, residue, slurry and other wastes generated during the construction, demolition, repair and decoration of buildings and structures by construction and construction units or individuals.
According to the source classification, construction waste can be divided into five categories: land excavation, road excavation, old building demolition, building construction and building materials production, mainly consisting of slag, gravel blocks, waste mortar, broken bricks and tiles, concrete blocks, asphalt blocks, waste plastics, waste metal materials, waste bamboo and wood, etc.
The composition of construction waste generated by different types of buildings differs, but its basic composition is the same, mainly composed of soil, slag, scattered mortar and concrete, chiseled masonry and broken concrete, piling cut off the head of reinforced concrete piles, scrap metal, bamboo and wood, waste from decoration, various packaging materials and other waste.
Domestic construction waste treatment methods
Affected by resources, concepts, policies and regulations, comprehensive utilization of construction waste has not attracted sufficient attention in China. At present, the annual output of China’s cities is about 6 billion tons of waste, of which construction waste is about 2.4 billion tons, which has accounted for 40% of the total urban waste.
China’s treatment of construction waste can be broadly divided into two categories, one is the construction waste for light sorting, recycling scrap metal, waste concrete, etc., using this type of treatment of construction waste accounted for only 2%, the second is not any treatment of construction waste was transported to the suburbs or rural areas, buy or rent a piece of land, using the open pile; or landfill treatment, using this type of treatment of construction waste accounted for about 98%.
This unreasonable treatment method not only occupies a lot of farmland and increases transportation costs, but also causes a lot of waste of resources, making construction waste a problem in China’s waste management. In order to solve this problem, some domestic construction companies have made some attempts in the recycling of construction waste.
The development of renewable building materials also called green building materials
(A) The concept and characteristics of green building materials
The so-called green building materials refer to non-toxic or low-toxic health-oriented building materials, fireproof or fire-retardant safety-oriented building materials, energy-saving building materials with low energy consumption and various new multifunctional building materials. From the perspective of the characteristics of green wall materials, the development of green wall materials is a major initiative to achieve energy conservation and emission reduction.
(B) The characteristics of green wall materials are obvious
1. Save resources: the manufacture of such materials uses as little natural resources as possible, reduces energy consumption and uses a large amount of waste as raw materials
2. Save energy: save energy for production and save energy for use in buildings;
3. Land saving: not only does not destroy the land (field) to take soil as raw materials, but also can increase the service life of the building.
4. Adopt the production technology of clean production that does not pollute the environment. In the production process, no or very little emission of waste residue, waste water, waste gas, significantly reduce noise, to achieve a high degree of automation.
5. The products not only do not harm human health, but also are beneficial to human health.
Therefore, the development of green wall materials is conducive to the realization of the strategic goals and tasks of energy conservation and emission reduction.
New green wall materials include agricultural waste type, construction waste type, gypsum type and composite wall materials, etc. Wood is the only renewable and recyclable material among the four major materials (steel, cement, plastic and wood) today, and is a renewable resource that can be used forever.
Foreign experience shows that as long as we follow the policy that the amount of forest resources harvested is less than the amount of growth, forest resources can be developed sustainably and the supply of wood can be guaranteed.
Among wood building products, wall material products fill the main role, mainly used in partition walls and the inner side of composite exterior walls. The wood used is not solid wood, but processed man-made panels or engineered wood, such as fiberboard, plywood, particle board, oriented board, and glued laminated wood.
The construction application is generally to form a composite wall by combining wood panels with a keel, or with other lightweight panels such as gypsum board. With the increasing depletion of ore-based resources, the use of wood as a renewable resource is bound to be taken seriously. No doubt, from the long-term development perspective, wood wall products belong to the green wall materials.
The importance of developing green building materials and building energy efficiency
In recent years, the state attaches great importance to energy conservation and emission reduction, putting it on the strategic height of safeguarding the long-term interests of the Chinese nation to persistently promote, and clearly put forward the strategic task of building a resource-saving and environmentally beautiful society.
The economic development policy proposed at the Central Economic Work Conference in December 2009 highlighted the importance of saving resources and protecting the environment in economic development. When low-carbon economy becomes a hot topic of economic development, how to save energy, promote new building materials and improve the utilization rate of resources has become a widely concerned issue.
Conclusion
At present, most areas in China still use traditional brick, tile, ash, sand and stone to build houses, and the vast majority of them are produced by small enterprises with backward technology and small production scale, which not only destroy a lot of good land and consume a lot of energy, but also destroy the ecological environment and make it difficult to improve the building function of houses.
On the other hand, with the development of industrialization throughout the country, the industrial waste piles up in large quantities, and these harmful substances cause serious pollution to the environment, which has increasingly attracted the high attention of the whole society. The development of green building materials is one of the important ways to achieve the strategic task of energy saving and emission reduction.