What Is Construction Waste and How to Process It
The Regulations on the Management of household waste in Shanghai came into force on July 1st, 2019 and several days later, the trend of waste classification has evolved into a new fashion and the pithy formula of waste classification has spread across the Internet.
Household waste has been classified in a refined and scientific way, so how to deal with the garbage giant “construction wastes” around us?
Construction waste dumped at random
With the development of infrastructure, the speed of urban building is accelerating gradually. A large number of old buildings have been demolished for constructing bigger, more beautiful buildings. At the same time, a large amount of construction waste is produced, which becomes a metabolic product hindering urban development.
The current global construction waste has a big quantity, but the utilization rate is very low. People always find suburbs as the construction waste dump sites which has a terrible impact on our environment.
Nowadays, due to the shortage of natural sand resources and the rising prices, the construction waste recycling becomes the new investment hot point and construction waste management gets more and more important.
In Beijing, Shanghai, Guangdong, Henan and other cities have introduced policies, encouraging the construction waste recycling, and as early as a few years ago, America and Germany have issued policies of construction waste recycling, even controlling construction waste from the source.
This article will discuss the construction waste and share eight uses of it, hoping that after learning, everyone can make more rational and thorough use of construction waste, so that construction waste can continue to contribute to our environment.
First of all, what is the construction waste?
The construction waste refers to the waste soil, waste concrete, waste bricks, waste stones and other wastes produced by people in the building activities of the construction industry such as demolition, construction, decoration and repair.
According to the classification of source, the construction waste can be divided into engineering waste, decoration waste, demolition waste, engineering mud, etc.
According to the classification of composition, construction waste can be divided into waste soil, concrete blocks, stone blocks, brick and tile fragments, waste mortar, mud, asphalt blocks, waste plastic, waste metal, waste bamboo and wood.
These materials are useless to the construction itself, but they are the materials produced in the construction process, which need to be treated accordingly, so as to achieve the ideal construction of engineering projects.
Second, what damage will it cause to the environment if not treated in time?
- I Putting construction waste randomly causes safety hazards
- Construction wastes around us
- The location of most urban construction waste dumps is always random and leaves many security risks. The construction site has become a temporary storage place for construction waste.
- Due to a lack of proper protective measures, under the influence of external factors, construction waste will collapse, hinder roads and even damage surrounding buildings.
- II Water resources are seriously polluted by construction waste
- Water resources are seriously polluted by construction waste
- During the process of stacking and landfilling construction waste, the leaching and scouring of fermentation and rainwater, as well as the soaking of surface water and groundwater, will cause serious pollution of surrounding surface water and groundwater.
- The polluted water contains a lot of metal and non-metallic pollutants, and the water elements are very complicated. Once drinking this contaminated water, it will do great harm to the health of human beings.
- III Construction waste has a bad impact on air quality
- Air quality is polluted by construction wastes
- During the process of stacking construction waste, some organic substances are decomposed under the action of temperature and moisture, which may generate harmful gases.
- For example, construction waste gypsum contains a large number of sulfate ions, and sulfate ions will be converted to hydrogen sulfide with a rotten egg smell under anaerobic conditions.
- Bacteria and dust in the garbage are scattered with the wind, causing pollution to the air; A small amount of combustible construction waste will produce toxic carcinogens during the incineration process, causing secondary pollution to the air.
- IV Construction waste lowers soil quality
- Construction waste lowers soil quality
- As the amount of urban construction waste increases, the number of garbage dumps is also increasing, and the area of garbage dumps is gradually expanding. The phenomenon of garbage and people arguing has reached a very terrible degree.
- Most of the suburban garbage is mostly dumped in the open air. After a long period of sun and rain, the harmful substances in the garbage penetrate into the soil through landfill leachate, resulting in a range of physical, chemical, and biological reactions, such as filtration or absorption by plant roots thereby lowering soil quality.
In addition, urban construction waste piled up in the open air under the influence of various external forces, smaller gravel blocks will also enter the nearby soil, change the material composition, destroy the structure, and reduce the productivity of the soil.
The content of heavy metals in urban construction waste is high, and under the influence of various factors, chemical reactions will occur, which will increase the content of heavy metals in the soil, so that increases the content of heavy metals in crops.
Contaminated soils generally don’t have the natural self-purification ability, and it is difficult to reduce the degree of pollution by dilution and diffusion. It must be solved by a costly method of transforming the soil.
There are so many construction waste hazards, while what are the uses of it?
Applications of construction wastes
- A The construction waste is initially cleaned, the recyclable steel and wood are sorted out, and the masonry and cement concrete blocks are crushed into aggregates, which are sieved to remove impurities to form building materials that meet certain particle size requirements.
- According to the grading design requirements, cement and fly ash and other auxiliary materials are added to the raw materials, and a part of the water is added and stirred to form different construction and road construction products, which can completely replace ordinary sand and gravel materials for the road base layer.
- B Recycled aggregates generated by using waste bricks are made into recycled bricks, blocks, wall boards, floor tiles and other building materials by brick making machine.
- Among them, these recycled bricks are highly environmental, including three kinds of ecological permeable bricks, such as floor materials, ecological permeable bricks, pouring permeable bricks, and permeable road bricks.
- They are widely used in squares, sidewalks, slow lanes, open plazas, gardens, slope protection, and protection foundations, highways and overpasses, etc.
- C Waste soil can be used for road construction, pile foundation filling, land base and so on.
- D For waste wood construction, the wood that has not been obviously damaged can be directly reused for reconstruction. The damaged wooden components can be used as raw materials for wood recycled board or paper-making.
- E Waste pavement asphalt mixture can be directly used to reclaim asphalt concrete in an appropriate proportion.
- F The waste road concrete can be processed into recycled aggregate for the preparation of recycled concrete.
- G Waste steel, scrap steel and other scrap metal materials can be directly reused or recycled.
- H Separate the construction waste. The remaining sludge and stone powder as raw materials, and add other various wastes (mainly including sludge from sewage treatment plants, waste from wineries and food factories) and trace elements in peat soil.
- The quality ratio is mixed with the construction waste to regenerate the planting soil. In addition to the characteristics of natural soil, it also has the characteristics of high fertilizer efficiency, good ventilation and strong water retention.
- According to the introduction, the relevant analysis and demonstration, the soil characteristics of the reclaimed planting soil reached and exceeded the national soil standards, in line with the fertility requirements of high-yield farmland.
Construction waste is very versatile, but how to deal with it?
First, the general process of construction waste disposal is mainly:
- 1 Pre-processing, which will sort the garbage, and removal of the bulk, impurities, etc.;
- 2 Crushing, this process is mainly carried out by crushers, and choose crushers according to different production needs;
- 3 Screening, this part mainly involves the iron removal operation of the finished construction waste after the crusher treatment, and re-processing the materials that don’t meet the production requirements;
- 4 Grinding, this stage is the grinding operation of the material after the crusher processing, and choose different mills for processing according to different needs of the finished product.
Secondly, in the treating process of construction waste, the crusher will be used in the crushing stage, and the type selection of the crusher needs to be based on different production requirements. If you need to make a coarse crushing, you can choose a jaw crusher.
In general, the PE series jaw crusher can crush materials with compressive strength below 320 MPa, and the feed size reaches to 1500 mm. At the same time, because the structure of jaw crusher is simple and it is sturdy, it can save a lot of cost in daily maintenance.
If you need medium and fine crushing, you can choose PEX series jaw crusher or cone crusher. The PEX series jaw crusher has a feed size of 250 mm, while the cone crusher has a feeding size of 300 mm. Both of these machines can be shredded to varying degrees with a particle size of 6-30 mm.
Among the types of crushers mentioned above, we discuss their specific uses, and for different types of crushers, they also have different models. Depending on the production needs, specific models can be selected for the treatment of construction waste.
Although the construction waste is large in volume, it is basically a “helpful material” that can be transformed.
However, it is limited by the overall low concentration of the recycling resource industry, and the “low, small and scattered” pattern is difficult to undergo a qualitative transformation in the short term, and the construction waste “collect-crush-reuse” system is still some distance away from maturity.
With the improvement of people’s environmental awareness and the government’s guidance, the application of resource-based products will have a broad market, the management of construction waste will naturally be smoother, and our environment will be more and more beautiful.