A Practical Solution for Processing Construction Waste and Fly Ash with Concrete Brick Making Machines

The large-scale disposal of construction waste and fly ash is a pain point in the construction of "zero-waste cities" and a core application scenario for concrete brick making machine technology. Current mature technologies have proven that through intelligent brick making equipment and scientific proportioning processes, these two types of solid waste can be transformed into recycled building materials that meet national standards, achieving a balance between environmental and economic benefits.

I. Raw Material Pretreatment and Proportioning Design

Construction waste needs to undergo crushing, screening, and iron removal processes to produce recycled aggregate with a particle size ≤1.5cm. The recommended ratio of waste bricks, mortar, and concrete is approximately 5:2.4:2.6 to obtain good particle size distribution. Fly ash, as an active admixture, is typically added at a concentration between 10% and 30%. Its active silica can react secondaryly with cement hydration products, improving the density and later strength of the bricks. The optimized mix design is as follows: 60%-80% recycled aggregate, 10%-30% fly ash, and 5%-15% cement, supplemented with trace amounts of rock sand crystals and other additives to improve workability and crack resistance. The moisture content must be controlled before mixing the raw materials, and forced stirring is used to ensure the cementitious material evenly coats the aggregate particles.

II. Molding Process and Equipment Selection

Production employs a non-fired, non-autoclaved vibratory pressing molding process. The core equipment is a fully automatic block molding machine. Modern brick machines often use servo vibration and hydraulic systems, generating high-frequency directional vibration and static pressure up to 1500 tons, allowing materials to be rapidly compacted and molded within 2-3 seconds. Depending on the characteristics of different solid wastes, the equipment can switch between simulated dual-pressure and single-pressure vibration modes to ensure the strength (up to 35 MPa or more) and appearance quality of the brick blanks. Complete production lines typically include automatic batching and palletizing systems, reducing the workforce to 2-3 people.

III. Curing and Product Application

Made brick blanks are naturally cured for 8-15 days under plastic sheeting before being shipped. Products include paving bricks, hollow blocks, and standard bricks, meeting the performance requirements of standards such as GB/T 21144. Practical examples show that a single production line can process nearly 100,000 tons of construction waste and fly ash annually, producing 800,000 square meters of high-quality building materials. Furthermore, the strength of recycled bricks is more than 50% higher than that of ordinary bricks, and they are widely used in construction site walls, road backfilling, and permeable paving for sponge cities.

IV. Benefit Assessment and Promotion Value

This solution offers significant comprehensive benefits: compared to landfilling, processing 100,000 tons of construction waste saves approximately 6 million yuan in disposal costs, while producing recycled brick products worth over 24 million yuan; energy consumption per unit product is 15%-22% lower than traditional sintered bricks, and each brick reduces carbon dioxide emissions by approximately 0.5 kg. With the advancement of the "Ten Measures for Solid Waste Management" policy, this closed-loop model of "on-site treatment, on-site production, and on-site application" has become a feasible path for the green transformation of the construction industry.