Affordable housing – straight from the factory
Elematic has created an example case of an Affordable House designed for emerging markets: a four storey, walk-up building with 64 apartments, which was converted to be constructed from precast elements from the foundation to the top. This example project gives a very hands-on view of a precast building project and the advantages precast can offer. A concept that takes you from the foundation to the top The building’s frame is made from a wall-slab design system so no beams or columns are used in these structures. Columns and beams are replaced with structural concrete walls and precast hollow-core slabs with topping. The topping is there to provide earthquake resistance and water tightness for the structure. All joints are made with pin connections with a concrete cover so no welding is needed during construction and installation of the components. Precast building enables rapid erection on site. For instance, the example building can be erected in three weeks. All the parts are factory-made, which guarantees consistent quality. The molds used in the factory are long-lasting. The products are highly compatible as the connection details and joints are thoroughly investigated. On site, installed products provide an instant work platform, which improves work safety and saves time. Precast is an efficient and economical choice for builders. “Hollow-core slabs have a particularly efficient load bearing capacity relative to the concrete that goes into the slab: about 40 per cent less concrete and 50 per cent less reinforcing steel,” explains Mellanen. In India, material wastage has been a big problem at construction sites. Precast technology and a well-managed process will solve this problem. In a precast factory, the residue of fresh concrete as well as hardened concrete and water are fully recyclable. Most precast factories in Europe have all their waste material processed and reused, which further improves the efficiency rate. The thermal mass of concrete makes it ideal for low energy buildings as concrete can function as a carrying medium for both heating and cooling, which are substantial factors when calculating maintenance costs. The smart builder chooses precast All precast element factories are tailor-made for specific needs. “In order to give perspective based on our example case of the Affordable House: a typical precast factory designed to for produce three such houses per week,” explains Mellanen. Imagine the savings when buildings can be ready in less than one third of the time used to build in the conventional way, Mellanen points out. With precast technology it is possible to build much higher level buildings than with conventional methods. Quality is an automatic feature and as precast building is a dry method (no plastering or casting on site) the construction site is more efficient.