How can the raw material ratio be precisely controlled during the production of insulation bricks to improve their thermal insulation properties?
Release Time : 2026-01-12
Improving the thermal insulation performance of insulation bricks relies on precise control of raw material ratios. This process requires a systematic design that combines material characteristics, process requirements, and performance targets. Raw material selection is fundamental, balancing insulation performance, structural strength, and cost. Common raw materials include fly ash, slag ash, clay, expanded perlite, and polystyrene foam particles. Fly ash and slag ash, as industrial waste, reduce raw material costs and environmental pollution; expanded perlite, due to its porous structure, effectively blocks heat transfer; and polystyrene foam particles form an insulation layer through the pores left after high-temperature sintering. The physicochemical properties of the raw materials differ significantly, necessitating optimized ratios to achieve complementary performance.
The particle size distribution of the raw materials significantly affects the performance of insulation bricks. Coarse particles form a skeletal support, increasing brick strength; fine particles fill pores, reducing heat conduction paths. For example, the particle size of expanded perlite is typically controlled between 40 and 60 mesh, ensuring its lightweight properties while avoiding increased water absorption due to excessively small particle size. The particle size of polystyrene foam particles needs to be adjusted according to the brick design requirements. If used for internal cavity filling, larger particles should be selected to form a continuous insulation layer; if used for mixed foaming, particle size uniformity needs to be controlled to ensure foam stability. A reasonable particle size distribution can optimize the internal pore structure of the brick, forming more closed micropores, thereby reducing the thermal conductivity.
The optimization of raw material proportions should be guided by the target performance. To improve insulation, the amount of lightweight aggregates (such as expanded perlite and polystyrene foam particles) can be increased, while the proportion of high thermal conductivity raw materials (such as clay and cement) can be reduced. For example, in coal gangue-based insulation bricks, the addition of 3% calcium carbonate and 6% silicon carbide can significantly reduce the thermal conductivity while maintaining compressive strength. The amount of fly ash also needs to be carefully controlled. Studies have shown that when the fly ash content is in the range of 25% to 35%, the impact on the mechanical and thermal properties of the brick is small, but the strength gradually decreases after exceeding 35%. Therefore, the optimal dosage range of each raw material needs to be determined through experiments in the mix design.
The use of additives can further improve the performance of raw materials. For example, adding wollastonite can reduce shrinkage of the brick body and improve compressive strength; adding composite admixtures can enhance the adhesiveness of the material and optimize fiber dissipation, thereby improving the overall performance of the brick. The type and dosage of admixtures need to be adjusted according to the characteristics of the raw materials. For example, in straw-fly ash composites, the water-cement ratio has the greatest impact on strength, and the optimal ratio needs to be determined through orthogonal experiments. In addition, the addition of activators (such as lime) can promote the pozzolanic reaction of fly ash and improve the strength of the brick, but the dosage needs to be controlled to avoid excessive costs.
The mixing process of raw materials directly affects the uniformity of the mix. When using mechanical mixing, the mixing time and sequence need to be controlled to ensure that each component is fully mixed. For example, when preparing insulated bricks, the insulated beads, binder powder, and reinforcing agent need to be dry-mixed until the color is uniform, and then water is added and mixed again. The mixing time needs to be controlled at about 10 minutes to ensure uniform wet and dry mixing. The mixed raw materials need to undergo aging to homogenize moisture and improve molding performance. Aging time is typically 1 to 2 days, but needs to be adjusted based on raw material characteristics and environmental conditions.
Molding pressure and sintering process have a decisive impact on the final effect of the raw material ratio. Excessive molding pressure will lead to increased brick density, which will reduce insulation performance; insufficient pressure will result in insufficient brick strength. Sintering temperature and time need to be determined based on the raw material composition. For example, the firing temperature of coal gangue-based insulation bricks is usually controlled at around 990℃, with a holding time of 50 minutes, to ensure sufficient reaction of calcium carbonate and silicon carbide to form a low thermal conductivity structure. Temperature curves need to be monitored during sintering to avoid unstable brick performance due to temperature fluctuations.
Precise control of the raw material ratio requires experimental verification and continuous optimization. During production, brick performance needs to be regularly sampled and tested, including indicators such as thermal conductivity, compressive strength, and water absorption, and the ratio adjusted based on the test results. For example, if the thermal conductivity of the brick is found to be too high, the amount of lightweight aggregate can be appropriately increased; if the strength is insufficient, the proportion of cementitious materials needs to be optimized or the sintering process adjusted. By establishing a database of raw material proportions and properties, standardized formulas can be gradually formed, improving production efficiency and product quality stability.