Building Design and Erection Using Prefabricated Concrete - Code of Practice
2011 Edition

IS 15916 mandates that prefabricated concrete structures ensure sufficient strength, stability, and durability under all expected service and ultimate loads. Design must integrate all building services such as piping and wiring within components or provide for their installation. Components should be modular and connectable, allowing for straightforward assembly and disassembly with secure joints. Standardized dimensions promote mass production and interchangeability. Materials and workmanship are required to meet durability criteria, considering environmental exposure. Safety aspects including compliance with loadings like wind and seismic forces, fire resistance, and safe erection procedures are integral. For composite or mixed systems, IS 15917:2010 provides additional guidance.

The standard recommends using concrete that meets relevant Indian Standards, encompassing both reinforced and prestressed types. Aggregates and cement should preferably be sourced locally, ensuring the necessary strength and durability. Specialized materials such as lightweight, cellular concrete or sandwich panels are encouraged for improved thermal insulation and cost efficiency. Moulds can be made from steel, timber, concrete, or plastic, all requiring adequate rigidity, watertightness, and ease of demoulding. Reinforcement steel must conform to quality standards as per applicable codes. Depending on the element type, hollow or solid blocks, battens, and brick panel units may also be utilized. The selection aims for a balance of economy, quality, rapid production, and local resource availability.

IS 15916 outlines various curing approaches including normal curing through water sprinkling or immersion for smaller elements, and steam curing conducted under controlled environments such as tents, chambers, or autoclaves ensuring uniform steam distribution. Accelerated curing methods using admixtures to reduce water content are permitted, though the use of aerating agents and calcium chloride for reinforced concrete is prohibited. Quality control is emphasized through systematic planning to achieve efficient and economical manufacture, mechanization for consistent quality, minimal weather impact, and improved working conditions. Additional curing methods include steam injection during mixing, heated air curing with high relative humidity, hot water baths, and electrical curing by current passage. These ensure the structural quality and durability of precast elements.

IS 15916 classifies mechanization into three tiers: Simple mechanization involves basic tools and predominantly manual labor, suited for small-scale operations. Partial mechanization eliminates most manual labor in specific stages using equipment such as batching plants, hoists, and earthmoving machinery, enhancing productivity. Complex mechanization refers to fully automated, factory-like production systems operating under sheltered conditions with skilled workers, including automated batching, casting, curing, and handling lines, ensuring high-quality and high-rate manufacturing. This classification aids in optimizing cost-effectiveness, quality control, and production efficiency.

The code mandates that all seating and support locations for precast units be robust enough to resist maximum stresses and impact from possible mishandling during transportation and erection. Only skilled and trained foremen, fitters, and laborers who have received comprehensive safety instructions should be involved. Equipment must be operated strictly in accordance with the manufacturer’s guidelines, with all safety measures adhered to during handling and erection. Lifting points must be clearly identified and provided with special provisions such as bolt holes or loops. Embedded bolts undergo pull-out testing to verify bond strength, and through bolts are checked for bearing capacity. These measures collectively reduce risks of accidents and ensure secure erection on site.