SMHDA: Low-carbon Model Practitioner - Pioneer in Construction Waste Transformation!

With the acceleration of urbanization and small-town construction, the scale of urban residential, office, commercial and industrial building renewal and municipal relocation is constantly increasing. On the one hand, a large number of old buildings have been demolished, generating a large amount of construction waste. A large number of new buildings also generate a lot of construction waste during their construction process.

Statistics show that if construction waste is measured by mass, concrete waste accounts for approximately 48.35%, and waste bricks and stones account for 37.42%. These two types of waste together make up 85.77% of construction waste. Turning waste into treasure is a relatively proper way to handle construction waste and is also the inevitable path for the current practice of building a low-carbon society.

Smanda has conducted in-depth research on the treatment of construction waste and utilizes crushing and screening technology to handle and transform construction solid waste with the greatest efficiency.

Recycled aggregates have a wide range of applications as substitutes for natural sand and gravel

Recycled aggregates from construction waste can be used as construction materials to replace natural aggregates in various fields, such as recycled concrete, mortar, blocks, bricks, and panels, which are applied in construction projects. Recycled permeable concrete, permeable bricks, inorganic mixtures, graded crushed stones, backfill materials, etc. are applied in municipal transportation projects. Recycled aggregates are used as infiltration and storage materials in the field of sponge city construction. Recycled concrete products are used in underground pipe galleries and the like. The application project covers an area of tens of millions of square meters and has a duration of 15 years, with reliable project quality.

In China, the concrete strength grades of concrete structures are mostly below C30. After concrete waste is crushed by proper methods, a large number of original particles stripped off along the aggregate interface can be obtained. The surface roughness of these particles has significantly improved compared to before, and the slurry adhering to them provides favorable conditions for their reuse as aggregates. Due to the external force during disintegration and fragmentation, a small number of particles will break along the rock cleavage of the original particles, which not only adds new rough surfaces but also intensifies the angular effect. In addition, through repeated disintegration and crushing processes, the soft particles in the original aggregates will be eliminated, and those with poor particle shapes will also be improved. The above-mentioned measures such as increasing roughness, enhancing edge and corner effects, improving particle shape and optimizing the arrangement of firmness all contribute to the optimization of aggregates. Tests have confirmed that the strength value of the concrete made from the unprocessed aggregates taken from waste concrete through screening is significantly higher than that of the concrete made from unused aggregates of similar materials with the same gradation and mix ratio. After disassembly and crushing, waste concrete can yield lumps (mortar aggregates) composed of more than half cement, sand and fine gravel. The particle shape they present is much more ideal than that of some natural crushed stones with layered cleavage. Mortar aggregates also have advantages such as numerous micro-pores on the surface, a relatively high water absorption rate, and water hardness, which often make the strength of mortar aggregates higher than the designed strength of the original concrete. After the mortar aggregates are re-mixed into the concrete, they will crystallize and coexist with the new cement slurry, thus creating favorable conditions for the densification of the hydration products in the contact zone between the aggregates and the cement slurry. Eventually, a denser contact zone is formed, making the bonding force between the cement stone and the aggregates greater than the strength of the cement stone. Because the surface of this aggregate is hydrophilic, it can be moistened by the liquid phase relatively quickly. Many new cement particles will be sucked into the numerous micro-pores on the surface, making the hydration of the contact area more complete. Experiments have proved that as long as the particle size of mortar aggregates and their ratio in fresh concrete are properly controlled, the strength of the prepared concrete can be guaranteed to meet the design requirements.

The application of recycled concrete aggregates in pavement construction

The aggregate obtained by crushing, cleaning and grading waste concrete blocks and then mixing them in a certain proportion is called recycled concrete aggregate. Concrete recycled aggregates can be classified into recycled coarse aggregates (with particle sizes ranging from 5 to 40 mm) and recycled fine aggregates (with particle sizes ranging from 0.15 to 2.5 mm) based on their particle sizes. Concrete prepared with recycled aggregates as part or all of the aggregates is called recycled aggregate concrete. Due to the fact that recycled concrete produced from recycled aggregates has physical and mechanical properties similar to those of ordinary concrete, recycled concrete is an important development direction for the reuse of waste concrete.

Recycled coarse aggregates can be used for the cushion layer, base layer of road engineering and the backfilling of the foundation of building engineering. The reasonable gradation of recycled coarse and fine aggregates can prepare recycled concrete and recycled mortar, which are used in the masonry and plastering of non-load-bearing structures and non-load-bearing walls in building engineering. Recycled fine aggregates are made into recycled blocks (bricks) and wall panels. Recycled blocks (bricks) can be used for building fences and non-load-bearing walls in construction projects. Recycled sidewalk bricks, permeable bricks, etc. can be used for pavement in municipal projects such as sidewalks, squares, parks, and parking lots. Recycled wall panels can be used for non-load-bearing wall partitions. Waste asphalt, after being recycled, is made into pavement asphalt concrete, which can be used for the pavement of road engineering.

The Ministry of Housing and Urban-Rural Development of the People's Republic of China has also issued a document, suggesting that the proportion of recycled blocks (bricks) and other products used in housing construction projects should be no less than 10% of the same type of products. The proportion of recycled coarse aggregates, recycled blocks (bricks), recycled asphalt concrete and other products used in municipal infrastructure projects among the same type of products shall not be less than 20%. Highway engineering and ready-mixed concrete enterprises should give priority to using recycled coarse and fine aggregates from construction waste.

The preferred raw material for permeable bricks and craft shaped bricks

Taking advantage of the environmental friendliness and low cost of recycled aggregates, through advanced equipment and technology production and processing, it has a stable structure, durable strength and strong water permeability, and can be used to produce permeable bricks. Ecological permeable bricks can be laid in areas such as squares, sidewalks, slow lanes, open-air squares, gardens, slope protection, foundation protection, expressways and overpasses, etc. They have both hardness and permeability, allowing precipitation within the range to quickly seep into the ground surface, keeping the ground from accumulating water, which meets the functional requirements of "infiltration, storage and detention" of sponge cities.

The decorative bricks for gardens or ancient-style buildings also represent a brand-new market for recycled aggregates. Recycled aggregates are processed by adding corresponding proportions of ingredients, mainly from crushed bricks, artificial sand, natural sand, stone chips, slag, furnace slag or coal slag in construction waste, through processes such as crushing, screening, batching, mixing, pressing and curing.

Outlook on China's Construction Solid Waste Treatment Market

The recycling and utilization value of construction waste is huge. It is estimated that for every 100 million tons of construction waste utilized, 24.3 billion standard bricks, 36 million tons of mixed materials can be produced, 15,000 mu of land can be saved, 2.7 million tons of coal can be saved, 1.3 million tons of carbon dioxide can be reduced, and an additional output value of 8.46 billion yuan can be added. Based on an annual production of 3 billion tons of construction waste and an estimated processing cost of 30 yuan per ton, the annual disposal space for construction waste across the country amounts to 90 billion yuan. Take the production of pavement bricks from recycled construction waste as an example. Compared with natural materials, using recycled materials saves 1.31 yuan per square meter of pavement bricks. To produce 1 million square meters of pavement bricks, using recycled materials saves 1.31 million yuan compared with natural materials. It is not only more environmentally friendly but also significantly reduces production costs.

The implementation of the new Solid Waste Law has promoted the classification, recycling and full-process management of construction waste in China, and changed the current situation of unstandardized treatment and disposal of construction waste in the country. With the country's increasing emphasis on ecological and environmental protection, restrictions on mountain and stone mining are becoming increasingly strict. The resource utilization product of construction waste - recycled aggregates - can largely replace natural sand and gravel. The resource utilization of construction waste has ushered in new environmental protection market opportunities.

Smanda

SMHDA

Guangxi Simanda Construction Machinery Co., Ltd. is not merely a supplier of crushing and screening equipment: the shipment of the machines marks the beginning of our long-term cooperative relationship. Our professional service personnel are always willing to provide support for the machines and any problems that may arise during their operation. They ensure prompt responses and timely plans.

The products of Smanda Company mainly include a variety of series and all-round material handling equipment such as jaw crushers, impact crushers, cone crushers, sand making (shaping) machines, screening machines, conveyors, and sand washing units

With its well-established branch network, Guangxi Simanda Construction Machinery Co., Ltd. has become a reliable local partner with a global presence. Whether it is machine sales, application consultation, original spare parts or mobile on-site direct services, our branches will provide support to our users through all possible means.