Why Precast/Pre-fabricated Technology?

As per statistics, the Indian real estate market is expected to touch US$ 180 billion by 2020 while the housing sector alone contributes 5-6% of the country's GDP. In countries such as India, where there is massive shortage of housing and dearth of time for fulfilling the targets, pre-cast technology is a boon.

According to the current estimation of the Government of India, the target of mass housing which is due to be achieved by 2020 with low capital investment can be possible by replacement of conventional methods with precast technology and other intermediate type methodologies.

Precast and offsite construction technologies help in creating products such as pillars, columns, beams or walls by casting concrete in a mould followed by curing in a controlled environment. These technologies are found to be most interesting by clients because of their good deliverability of highly complex structures in half the time without any compromise in quality compared to other conventional technologies.

One of the reasons behind the rapidly growing demand of these precast technologies is not only its cost effectivity but also the timely high-quality deliverance. These technologies are very reliable because of their capability of fulfilling situation specific requirements, easy adaptability to the location with making optimum usage of locally available construction materials and transportation facilities.

Advantages of Precast Technology:

• Proper curing in controlled environment

• Greater control over material quality and workmanship

• Better management of quality compared to onsite casting

• Ensures safety throughout the project

• Saves a lot of time

• Affordable

• High profitability

• Less usage of cement, water, steel and labour

• Produces less waste

• Produces much smaller CO₂ than in cast-in-situ construction

• Works in virtually all environments cold, hot, moist or dry

Commonly used Precast Products include:

• Facades from sandwich to cladding and gray walls

• Floors with hollow-core, half, ribbed or solid slabs

• Foundations with precast concrete piles

• Frames with beams, columns, slabs etc.

• Stairs, shafts and other special products

Industrial Production of Pre-Fabricated/Precast Elements using LC³ at Supercast Limited, Noida (Supertech Group):

One of most desirable precast products, which have been recently produced at Supertech Limited in Noida in one of its building projects is hollow core slabs using the new kind of industrially produced cement i.e. Lime Stone Calcined Clay Cement (LC³). The objective of this project was to determine the technical feasibility of pre-stressed hollow core slabs with LC³ at production scale level and establish the properties thereof and to take this product from lab to commercial use. Hollow core slabs are pre-stressed concrete elements which have a constant cross section, manufactured using high tensile strength pre-stressed strands or single wire which are embedded within the element. These slabs are widely used for flooring and wall panels in industrial, commercial, residential and infrastructure construction including different supporting structures such as concrete constructed walls, brick built walls, steel structures, on-site concrete cast structures, prefabricated beams etc. Research trials have been done at IIT Madras with both Ordinary Portland Cement (OPC) and LC³ for M50 hollow core slabs. Lab trials were also done at Supertech, Noida with LC³ and OPC after the getting the desirable spectacular strength at the trials done in IIT Madras. Demonstrating the viability and robustness of the technology, the LC³ obtained was used to manufacture hollow core pre-stressed precast slab. Good results were obtained and test data of LC³ samples are comparable with available conventional cement.

Along with earlier strength development, the new cement has less porosity and it is more difficult for the chloride to get in and damage the steel. This gives the new cement and the structures a longer service life. ■

Pankaj Phulwari
Development Alternatives
pphulwari@devalt.org