Specifications for Cement Prefabricated Houses
The specifications for cement prefabricated houses cover requirements for building materials, structural design, construction techniques, acceptance inspections, and other related aspects, as detailed below:
Building Material Standards: Cement must comply with GB 175-2007 'General Purpose Portland Cement'. Reinforcing steel bars should meet the requirements of GB/T 1499.2-2018 'Steel for Reinforced Concrete - Part 2: Hot-Rolled Ribbed Bars'. Aggregates must adhere to GB/T 14684-2011 'Sand for Building' and GB/T 14685-2011 'Pebble and Crushed Stone for Building'. The concrete strength grade of prefabricated components should not be lower than C30, with load-bearing wall panels requiring a grade of C35 or above. The standard compressive strengths are 30MPa (C30) and 35MPa (C35), respectively. The diameter of main reinforcing bars should be ≥8mm, with a spacing ≤200mm, and a protective layer thickness ≥20mm (≥25mm in exposed environments), in accordance with the 'Code for Design of Concrete Structures' (GB 50010-2010).
Structural Design Standards: Compliance with GB 50010-2010 'Code for Design of Concrete Structures' and GB 50009-2012 'Load Code for the Design of Building Structures' is required to clarify the load-bearing capacity, seismic performance, and durability requirements of prefabricated components. In seismic fortification intensity zones of 6 degrees, the requirement of 'no damage under minor earthquakes' should be met, while zones of 7 degrees or above require special calculations (as per the 'Code for Seismic Design of Buildings' GB 50011-2010). Node connections should use embedded part welding or high-strength bolts, with a bolt tensile strength ≥8.8 grade. The dimensions, reinforcement, and connection methods of the main structure must meet seismic fortification requirements.
Construction Technique Standards: Based on GB 50666-2011 'Code for Construction of Concrete Structures' and JGJ 1-2014 'Technical Specification for Prefabricated Concrete Structures', the production, transportation, lifting, and connection of prefabricated components should be standardized. The length error of wall panels should be controlled within ±3mm, with a thickness error of ±2mm; the position deviation of door and window openings should be ≤5mm. The construction process includes foundation treatment, foundation construction, component installation, and roof waterproofing works.
Acceptance Inspection Specifications: Inspections should be carried out in accordance with GB 50204-2015 'Code for Acceptance of Construction Quality of Concrete Structures', checking component size deviations, appearance quality, and strength. Each batch of components should undergo compressive and impermeability tests, with a sampling ratio ≥5% and an impermeability grade ≥P6 (no leakage under 0.6MPa water pressure). During on-site acceptance, the perpendicularity deviation should be ≤h/1000 (h being the wall height) and ≤10mm; joint waterproofing should use elastic sealant, with a width ≥15mm and a peel strength ≥0.5MPa.
Other Specifications: The thermal conductivity of exterior wall panels should be ≤0.24W/(m·k). Sandwich panels commonly use 50mm-thick expanded polystyrene foam (EPS) or rock wool layers, meeting the 'Code for Thermal Design of Civil Buildings' (GB 50176-2016). Wastewater discharge should comply with the 'Integrated Wastewater Discharge Standard' (GB 8978-1996), with a pH value of 6~9 and suspended solids ≤70mg/l.
