Piling up mountains to create landscapes and recycling to build houses, urban construction waste is not "garbage"!

We currently have more than 900 million people living in cities, and urban construction is getting better and better. However, in the process of urban construction, a large amount of construction waste is inevitably generated, such as concrete blocks, bricks, steel bars, plastics, wood, slag, etc.

According to statistics, during the construction of every 10,000 square meters of new buildings, 500 to 600 tons of construction waste will be generated; the demolition of 10,000 square meters of old buildings will generate 6,000 to 10,000 tons of construction waste... As of 2022, my country's construction waste output will be about 3.451 billion tons, of which building demolition waste accounts for about 49.61%, building construction waste accounts for about 30.33%, and building decoration waste accounts for about 20.06%. Every 10,000 tons of construction waste occupies an area of ​​about 2 mu at a pile height of 5 meters. At present, my country generates more than 30 tons of construction waste each year, which occupies 600,000 mu of land each year. The traditional way to dispose of construction waste is to store or landfill, with a comprehensive utilization rate of only 5%, which is far from the 90% resource utilization rate in developed countries such as Japan and Germany.

Roadmap for classification and treatment of construction waste, source: literature

So where does all this construction waste go ?

1. Mountain landscaping:

Construction slag and construction mud are the main components of construction waste, generally accounting for 60% of the total construction waste. They are widely generated during the large-scale construction and expansion of cities. Therefore, in the past decade, various "slag mountains" (also called "garbage mountains") have appeared in every corner of cities, and have gradually grown with the construction of high-rise buildings. However, when it rains or blows, "slag mountains" produce dust and mud, which seriously endangers the living environment and personal safety, and has almost become a scar of modern cities.

The predecessor of Tianjin Nan Cuiping Park was a construction waste landfill. In 1986, the planning of the mountain landscaping project began. Later, more than 2 million cubic meters of construction waste were used to build a 50-meter-high artificial mountain. It has now become the most distinctive natural landscape park in Tianjin city; Xi'an Wenjingshan Park used 3.32 million cubic meters of construction waste generated by the construction of Xi'an North Railway Station to build an artificial mountain covering an area of ​​177 acres. It is the first cultural and natural landscape in Shaanxi that was created by piling up mountains with construction waste; in 2008, the Shijiazhuang Municipal Government issued the "Notice on Doing a Good Job in the Disposal and Utilization of Construction Waste and Mountain Landscaping", and the first batch of 7 "mountain landscaping" locations were clarified: Berlin Park, Time Park, the south bank of the Hutuo River, Songying Huanshanshui Park, etc., which can absorb 15.2 million cubic meters of construction waste... Almost all cities have similar situations. Mountains of slag have turned into mountains and parks, and transformed from urban scars into urban green lungs.

Wohushan Park on the south bank of Hutuo River in Shijiazhuang, source: selfie

2. Recycling and building houses

1 ton of construction waste can generate 0.85 tons of recycled aggregate, or produce 24.3 billion standard bricks and 36 million tons of mixed materials... Since the last century, my country has begun to use recycled products from construction waste. In 1994, Beijing Yizhuang Development Zone carried out a pilot project to fill walls with recycled bricks. At the beginning of this century, the recycled bricks developed by Beijing Institute of Civil Engineering have been used in the antique buildings in Caochang Hutong, Beijing; after the Dujiangyan earthquake in Sichuan, construction waste was produced into construction bricks; and the most common one is the "bread bricks" commonly used in interior decoration masonry, which are also made of construction waste. They are light in weight and have good thermal insulation and sound insulation properties.

Ancient-style buildings in Caochang Hutong using recycled bricks Source: Literature

3. Laying the foundation stone and building the road

Highway engineering is a resource-consuming industry, especially with huge demand for sand and gravel materials. Construction waste will reduce the dependence of road construction on natural sand and gravel resources. The road structure can be divided into the pavement surface layer, the pavement base layer and the roadbed treatment layer (cushion layer). The use of recycled fillers and recycled aggregates from construction waste can replace materials such as ash, sand and gravel. It is estimated that the cost can be saved by 38%-50%, which has good economic value. Xixian North Ring Expressway is the first road in China that uses construction waste as the main road construction material (122 kilometers, consuming 6 million tons of construction waste). After years of traffic, the road surface is still as smooth as before, without any settlement.

Typical road structure, source: Baidu

4. Sponge City

"Waterlogging every time it rains" has become a "headache" for many cities. To solve this problem, cities in China have begun to build "sponge cities" in recent years. "Sponge cities" emphasize that cities are like sponges, able to absorb, store, infiltrate and purify water, and release and utilize the stored water when needed. Recycled aggregates prepared by sorting, crushing and grinding construction waste have higher water absorption and lower density than natural aggregates. Therefore, recycled aggregates are used to make permeable concrete, permeable bricks, permeable ground, shallow grass ditches, etc.

In addition, construction waste also contains a small amount of steel bars and wood, which can be recycled or transformed into works of art; discarded glass and ceramics can be used as flux after being crushed, and made into products such as microcrystalline glass and foamed ceramics... In short, the recycling of construction waste has become a trend and has been integrated into our cities. Usually, there may be construction waste in the foundations of our communities, on the roads we take to work, and in the parks we take a walk.

refer to:

[1] National Bureau of Statistics, China Statistical Yearbook 2023

[2] Zhiyan Consulting, “2023 China Construction Waste Treatment Industry Market Analysis Report”

[3] Xu Changyong, Jiang Dexian. Research on the classification, collection, transportation and treatment system of construction waste[J]. Renewable Resources and Circular Economy, 2023, 16(02):13-16.

[4] Zuo Ya, Chen Jialong, Li Fei, Zhou Wenjuan. Application of recycled construction waste products in practical engineering[J]. Construction Science and Technology, 2014, (01): 34-36.

[5] Gao Lei. Research and benefit analysis of recycling construction waste into road materials[J]. Engineering and Construction, 2023, 37(04): 1316-1318.