Specification requirements for sand and gravel for cement concrete construction

In cement concrete projects, sand must be clean, hard, and meet specific grading requirements. It should have a fineness modulus of 2.5 or higher, typically classified as coarse or medium sand. If coarse or medium sand is unavailable, a mix design test is necessary. In such cases, fine sand with less than 3% silt and clay impurities can be used, provided it meets technical standards. The technical specifications for sand are outlined in Table 1. This table includes sieve analysis data, soil debris content, sulfide and sulfate content, and general cleanliness requirements. The sand is categorized into three zones based on its grading: Zone I (coarse), Zone II (medium), and Zone III (fine). Each zone has different cumulative sieve residue percentages, which define the particle size distribution. Additionally, the organic matter content in sand can be tested using a standard solution prepared by dissolving tannin powder in an alcohol solution. This helps identify any excessive organic material that could affect the performance of the concrete. For gravel and crushed stone used in cement concrete, the materials must be strong, clean, and free from weathered or broken particles. They should also meet grading requirements, with a maximum particle size not exceeding 40 mm. Technical specifications for crushed stone are listed in Table 2, including sieve analysis, compressive strength, needle-shaped particle content, and contamination limits. Gravel, when used as aggregate, should consist of non-reactive materials to avoid adverse chemical reactions with cement. Table 3 provides detailed technical requirements for gravel, including void content, soft particle content, and organic matter levels. These parameters ensure the durability and quality of the final concrete structure. All aggregates must be free from foreign materials such as lime, ash, or plant roots. Proper testing and compliance with these standards are essential to ensure the long-term performance of concrete structures in construction projects.

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