Precast in India – Latest Thinking
Saurabh Purandare, Director – Innovela Building Solutions Pvt. Ltd., Pune.
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The face of realty market in India has changed rapidly over the past few years. Large projects comprising of Townships, Mass Housings, IT/ITES parks and SEZs’ are of common occurrence these days and will only grow exponentially in the near future.
Majority of such projects are still being constructed using the conventional methods. Thus the inherent advantage that these projects offer in terms of repetitions and huge volume turnover remain unexploited. In addition, these large scale projects constructed using conventional methods complicates the Project Management in terms of speed and quality of the construction.
Precast Concrete Technology, the so called unconventional method in an Indian Space can facilitate both speed and quality of the construction and at the same time exploits the advantages |
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that these large scale projects offer in terms of volume turnover and the repetitions.
With the changing face of realty sector in Indian market, the change of construction methodology is inevitable. This paper aims at demonstrating how the Precast Concrete Technology can be efficiently and effectively used on various Indian Projects in the light of Projects under execution.
Low-cost / Affordable Housing Projects
The Advantages that Precast Concrete Technology has to offer can be exploited to the fullest for Mass Housing projects comprising of small, compact size apartments in large volumes. This Technology can be implemented on such Projects in two ways-Site based precast Plant and Dedicated precast Plant.
The Site based precast plants form a lucrative option for Indian Market as the excise duty which otherwise gets attracted from Factory made precast components is saved.
Example Project- Santushti Homes at Bhiwadi
Project Features: 250 affordable homes- G+3 Storied 3 Blocks- Load bearing Precast walls- Precast Solid Slabs (room size)- Site Based Precast Plant- Design Approved by IIT Delhi
Anyhow for adopting this option, there has to be sufficient volume of construction to justify the initial cost of setting up such Precast Plant on site.
The Structural Frame for such buildings using precast concrete technology is essentially a Load-Bearing type of construction (cross-wall frame) eliminating the ugly column & beam offsets inside the compact rooms. The flooring slab can be in the form of solid reinforced precast units of room size (for site based plant) resting on the load bearing walls on all fours thus eliminating the requirement of structural topping. In case of dedicated precast plants, the flooring units have to be in the form of precast planks of not more than 2.4m width from transportation constraint. For monolithic action, these planks need to be topped with cast in place structural screed.
Project Features : 2500 apartment scheme-Slum Rehab Project-G+23 Storied 6 Blocks-Load bearing Precast walls- Precast Solid Slabs (room size)- Precast WC & Bath Pods-Site Based Precast Plant-Design Approved by VJTI, Mumbai
SRA scheme at Bhoiwada, Mumbai
The medium / large size apartments can be conveniently constructed using precast concrete technology by adopting precast pre-stressed hollow-core planks as flooring which have a large load / span carrying capacity thereby eliminating the need for load bearing walls between the rooms or even the apartments.
By minimizing the need for load bearing walls, the interior layout of the apartment becomes more flexible; which is a strong sales point for such apartments. The elevation treatment of these buildings can be made interesting by adopting decorative precast walls / spandrels on exterior.
Example Project- “Lakeside” at Chennai
Project Features: 300 apartment scheme-Stilt + 4 Storied 6 Blocks-Load bearing Precast walls-Precast Hollow Core slabs-Dedicated Precast Plant-Design Approved by IIT Delhi.
Hospitality Buildings
Generally, the hospitability buildings like hostel, hotel or hospital are plaza type structures needing large column free space to house amenities like dining halls, restaurants, OPD’s, operation theatres etc. at ground floor while modular rooms in superstructure.
This requirement can be effectively catered for by adopting precast portal frames at ground floor supporting the precast load bearing walls of superstructure. The requirement of modular rooms in superstructure makes the precast concrete technology effective due to repetitions and volume.
Example Project- Hostel Building at Trichi
Project Features: 210 hostel rooms-Dining Hall at Ground floor-G+10 Storied 2 Blocks-Load bearing Precast walls- Precast hollow-core slabs-Precast Portal Frames at GF-Dedicated Precast Plant.
Commercial Buildings
The commercial buildings are essentially the column-beam framed structure requiring large column free areas requiring large span / load carrying capacity of floors. The precast pre-stressed hollow-core slab units are obviously the best solution for such projects. The Columns & Beams in such structure can also be in precast & the structural stability can be achieved by adopting precast / cast in place concrete walls at core areas.
Project Features: Commercial Building of 250,000 sq ft-Shops at Ground & Mezzanine floor-B+G+3 Storied 3 Blocks- Load bearing Precast walls-Precast hollow-core slabs-Precast Portal Frames at all floors- Precast Retaining Walls at
Basement- Precast Plant located at Pune.
Swot Analysis – Precast Technology
Strengths
- Speed, Quality, Economy
- Low Maintenance
- Seismic Resistant
- Quick Turnover of Money
- Universal Application
Weakness
- Lack of awareness, acceptability & availability
- Resistance to Change
- Fear of Unknown
- Unfamiliarity of Architects and Engineers
- Lack of Exposure to the technology in Technical Institutes
Opportunities
- Huge Requirement of Affordable Houses
- Shortage of Skilled Labor
- Large Size Projects
- Exposure to Global Market
- Demand for Quality Construction
Threats
- Govt. Tax Policy, Lack of Govt. Support & Encouragement
- Bad Past Experience with Substandard Technology & execution
- Vested Interests
- Lack of Standardization
- Imaginary Problems
Conclusion
The Precast Concrete technology has already arrived in India due to large size projects, need for quality construction with speed & reduced labour force. All these advantages can be exploited to the maximum by careful planning & designing.
EXPERT SPEAK
Saurabh Purandare, is a well known and reputed Structural Engineering Professional from Pune, a Post Graduate in Structural Engineering with nearly two decades of design experience in performing structural designs of world class residential, commercial, industrial & utility structures. He is a part of design team consisting of reputed Architects, Electro-Mechanical & Plumbing consultants, Project managers & Owners.
His obsession towards new and innovative technologies, of late, has made him to be one of the leading consultants of Precast Technology in India. He is a part of ‘Innovela Building Solutions’, a Young and Dynamic consulting engineering group operating in the niche segment of Precast Concrete Technology. The Innovela team posses a widespread experience in the field of Precast Concrete Technology and has been involved in Design & Project Management of some of the finest structures in Europe, USA & India.
He can be contacted on: saurabh@innovela.in
Built Expressions talks to Saurabh Purandare, a well known and reputed Structural Engineer from Pune, known for his expertise in designing buildings using Precast Technology. His design experience includes High rise buildings, Commercial and Industrial Structures, Bridges and Culverts, All types of RCC and Steel buildings. His passion towards engineering inspired him to fix his goal in early stages of his career- to gain and continue the excellence in providing structural engineering services using the spectrum of national / international experience, strong technical knowledge, advanced technologies, innovative concepts, leadership qualities and effective project/quality management systems combined with processed approach. Excerpts of the interview below;
BE: With many years of experience in the precast industry, your organisation today is one of the leaders in Precast Industry. Brief us about the changing technological trend witnessed in the precast industry?
SP: The Precast Technology in India is being used since 1980’s. In the beginning, this Technology was adopted in Low cost housing Govt. Projects of mass scale. The main aim of using this technology on such projects was to avoid shuttering on site. The technology implemented at that stage was with Precast columns, beams and slabs to reduce the crane requirements in terms of lifting capacities.
The current trend is to use Precast Technology with Load bearing Precast walls (cross wall frame or spine wall frame) with plank slabs in residential buildings thus avoiding the requirements of columns, beams, masonry walls and plaster which results in faster & economical construction without the need for scaffolding at site.
BE: Can you briefly explain your expertise in designing and detailing of Pre-cast building structures?
SP: I personally have been involved in designing the precast structures since 1995. I have designed various precast structures in India, USA & Europe. These structures include low cost housing, high end condos, office buildings, schools, retail malls, parking garages, warehouses, culverts, bridge beams & stadia.
BE: Which are the signature projects in India that you are currently involved with? With reference to India, what standard practice you adopt?
SP: I can name three important projects at present.
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Slum Rehab building at Boiwada (G+23) for L&T ECC.
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Mass housing for Tata Housing at Bangalore (1900 apartments/ 12-14 storied towers).
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Golf country- at Noida for Supertech limited (20 storied towers).
BE: Please tell us about the various services your organisation can offer?
SP: We are the only structural consultants in India, operating in the niche segment of Precast Concrete Technology for Indian Construction Projects. Our services include,
BE: What are the technologies, design software and codes of practice you adopt while providing your services to your customer?
SP: In our office we have state of the art Analysis & Design Software’s like Etabs & Staad-pro. We follow Indian codes of practices for our designs. We also have know-how about British & American Codes of Practices.
BE: What are the various components involved in the construction of a Pre-cast building?
SP: There are two basic elements in construction of Residential Precast Buildings namely walls & slabs. The types of several of walls and slabs that can be used in a project depend on type of building and its location and functionality.
Precast walls:
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Structural Precast Walls.
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Non- structural Precast Walls.
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Architectural Facades
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Sandwiched walls (insulated)
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Twin walls
Precast Slabs:
BE: How sustainable precast concrete elements are? And how do they contribute to support the green movement?
SP: As the concreting happens in a more controlled factory environment, the concrete produced is dense resulting in increased durability, reduction in water cement ratio & hence lesser use of cement. Also, use of Precast Concrete technology results in reduced wastages (7% against 20% in case of conventional method) and also reduces the cement & sand requirement as Plastering is eliminated altogether. Further, the precast structures have better fire resistance & acoustic control & eliminate the dust particles on construction site.
BE: What are the factors to be considered when deciding to implement precast concrete construction?
SP: Precast technology can be implemented in two ways,
- Site based Precast Plant
- Dedicated Precast Plant
The choice of implementation & choice of precast elements depend on Type of Projects to be undertaken, Client’ vision & speed of construction desired.
BE: India is facing in general acute construction labour shortage. How is this problem addressed by Pre-cast technology?
SP: The labour requirement in case of conventional construction method is around 600-700 nos for a speed of 1Million sq ft per year. For the same speed, precast concrete technology needs hardly 150 labours.
BE: How do we ensure the structural integrity between two different precast elements?
SP: The structural integrity of precast structure in ensured by provision of Vertical, Horizontal & Peripheral ties.
The due consideration is given for the resistance to disproportionate collapse in case of accidental loads.
SAURABH PURANDARE
302, KOREGAON PARK, RAG-VILAS HSG. SOC.,
BUNGLOW NO. A/1 “BHARADWAJ”,
PUNE 411 001
PHONE NO: +91 (0) 20 26152255 (LANDLINE);
+91 9689141416 (CELL)
E-MAIL: saurabh@innovela.in