Affordable / Low cost Mass Housing Projects.

The Precast Concrete Building Technology can be efficiently and effectively used on various Affordable / Low cost Mass Housing Projects. Being planned by the present Government Policy "House for all by 2020.
Urbanization in India has generated huge demand for housing which neither the cities nor the housing sector is prepared for.
The Construction industry is facing problems such as shortage of skilled labor, poor workmanship, low Productivity & quality of construction plus time and cost overruns etc.
In order to cater the issue surrounds the shortage of affordable and low cost mass housing at a much competitive cost and on time schedule, it is imperative to adopt alternative construction system.
The 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.
Precast construction revolution is under way in India, and soon it will be the major type of construction to be adopted in the construction sector of India.
Concept of precast ("Pre-Engineered Pre-Cast") construction includes those buildings, where the majority of structural components are standardized and produced in bulk quantity in plants at Project site or in a location away from the building site, and then transported to the site for assembly.
If full advantages of precast concrete are to be realized, then architectural Drawings is to be frozen first. Having philosophy of: Long spans, appropriate stability concept, simple design & details, element IDs, element geometry, reinforcement and strand details, concrete specifications, connection details, MEP
Details incorporated with the layouts of each floor. Designers should, from the very outset of the project, consider the possibilities, restrictions & advantages of precast concrete, its detailing remains in scheduling the elements to their respective molds, stockyard, trailers & transportation, Erection & installation by assigning particular dates for each stage & serviceability, before completing a design in precast concrete.

During the development of the basics for your precast project, consulting precast structural engineer ourself give you answers to the following questions:

• You don’t know where to start?
• How much are the costs and the return on investment?
• How long will it take until the plant starts running?
• How must my precast plant be designed for an efficient production?

a). Feasibility Study

If your wish is to build great amounts of High Quality Buildings fast and in a cost-efficient way, the solution is precast construction. In order to provide you with a firm basis for your decisions, the first step in such a project is the feasibility study by Consulting Architects.
They will evaluate if this precast building system is suited for your projects, to what requirements it is bound, They will calculate the investment costs for a plant, the return on investment etc.
A feasibility study by Consulting Architect is a firm basis for your future investment, taking into account all relevant data.

b). Precast elements / Product development

Designing a building that is compatible for precast, means considering every part of it including details of the element connections. Finding the best solution for architecture, structural requirements, production and last but not least assembly of the elements. Time and resources may only be saved if the building is looked at as a whole.
The product that our customers wish to sell is the focus of our considerations. Without a well-thought-out product, there will be no success.

c). Investment and profitability calculation

The most important questions for any businessperson are the prospective costs and the point at which the project yields profits. In order to answer these questions, our profitability calculation is based on real-life figures and covers the whole process from the production to the assembly of the precast elements on site.
Prior to the purchase of machines, you should ask yourself how you can generate profits with precast concrete construction.

d). Business Plan

For such a project, not only figures are crucial for your success. A business plan defines the goals and summarizes all the gathered facts and data. It gives information about the market situation and how the market entry should be carried out. It summarizes the business concept and includes a risk assessment. This instrument is of particular importance if other people like business partners; banks, investors etc. need to be convinced. Together with Consulting architect & precast plant & equipment suppliers like us, we develop your business plan to enable you to present your project convincingly and make its implementation easier.
The feasibility study is often part of the business plan.

e). Plant layout

After having developed the overall concept, we create a layout of the plant taking into account the cost objectives and determine which products should be produced there and how. This enables us to decide which machines and plants are needed for your precast plant.
Good material flow and an efficient production can only be achieved by means of custom-made production engineering.

Precast concrete construction is economical building system - saves money, resources and time
Construction with precast concrete elements offers a great number advantages in this case.
1). Fixed final price and completion date for precast buildings Short construction time compared to traditional building methods
2). Less coordination on site
3). Fewer personnel - both at the production in the plant and at the assembly of the precast concrete elements on site, untrained personnel can be employed.
4). Building material and construction costs savings - Savings in reinforcement and concrete are possible due to the accurate production of precast concrete elements
5). Reduced maintenance costs for precast concrete buildings - do not need any maintenance for a period of at least 50 years because the material is sturdy and durable.
6). Lower construction costs
The concrete panel construction consists of load-bearing walls and floors and substitutes frame and skeleton structures. No additional bracing system is necessary and construction costs decrease.
7). Cost-saving precast concrete construction
Instead of using frame and skeleton structures for the construction of a building, only precast walls and floors are used. Another cost-saving aspect is the standardization of details, which, however, does not constitute a limitation of the architectural design. No scaffolding is needed for the construction of a precast concrete building. Only a temporary bracing of the precast concrete elements is required. This saves costs for scaffolding and reduces construction costs.
8). Many advantages result from the industrial prefabrication of precast concrete elements. Apart from quality and precision, the manpower requirements are reduced tremendously. The actual erection of the buildings on site is executed in a much shorter space of time compared to in-situ constructions. This is environmentally friendly and reduces noise and dust pollution.
Moreover, concrete as a natural building material is 100% recyclable and is, in combination with steel, a safe, sustainable and earthquake-resistant material with little wear and tear. Our individual pages provide interesting facts about the various benefits of precast concrete elements.

Low Cost / Affordable Housing Projects

a). 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.
b). This Technology can be implemented on such Projects in two ways, 1. Site based precast Plant 2. Dedicated precast Plant

Site Based VS Dedicated Precast Plant

a). 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.
b). Anyhow for adopting site based plant, there has to be sufficient volume of construction to justify the initial cost of setting up.
c). Also, such plants have lesser efficiency than state of the art plants for obvious reasons.

Structural Framing

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.

Medium / High End Condos

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.

Swot Analysis - Precast Technology

1). Strengths, Speed, Quality, Economy Low Maintenance Seismic Resistant Quick Turnover of Money Universal Application
2).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
3).Opportunities Huge Requirement of Affordable Houses, Shortage of Skilled Labor, Large Size Projects, Exposure to Global Market, Demand for Quality Construction
4). Threats Govt. Tax Policy, Lack of Govt. Support & Encouragement, Bad Past Experience with Substandard Technology & execution, Vested Interests, Lack of Standardization, Imaginary Problems.

Some Precast Structures in INDIA

1. Santushti Home at Bhiwandi, Maharashtra. 250 affordable home G+3 storied 3 Blocks Load Bearing Precast walls Precast solid slabs(room size)
2. SRA Scheme at Bhoiwada, Mumbai, Maharashtra. 2500 apartment scheme Slum Rehab Project G+23 storied 7 Blocks Load Bearing precast walls Precast Solid Slabs (Room size) Precast WC and Bath pods
3. CIDCO affordable housing scheme, Maharashtra. Total 54 Blocks G+14 storied 32 Blocks G+7 storied 22 Blocks Precast Column Precast Beams Precast Hollow Core slabs
4. Lakeside at Chennai 300 apartment scheme Stilt+4 storied 6 Blocks Load Bearing Precast walls Precast hollow core slabs
5. Commune-1 at Bangalore Basement+G+13 Load Bearing Precast walls, Precast Concrete Slabs
6. Hostel Building at Trichi - 210 Hostel Rooms, Dining Hall at Ground Floor. G+10 Storied 2 Blocks
7. Load Bearing Precast walls, precast hollow core slabs, Precast Portal Frames at Ground Floor etc.
8. Marvel Sangria at Pune, Maharashtra, Commercial Building of 250,000 sq.ft. Shops at Ground and Mezzanine Floor Basement+G+3 storied 3 blocks Load Bearing Precast walls, Precast hollow core slabs, Precast retaining walls at basement

Comparision between Precast & Castin-situ Concreting Method

• Time saving- Precast concrete method requires less time for onsite construction as compared to Cast-in situ concrete method, because as prepared materials are transported to site and can be directly lifted and placed on the desired position. Precast elements can be delivered just in time for fast erection, reducing unnecessary handling and equipment use. With minimal propping and bracing, and with precast flooring providing an immediate working platform, precast concrete allows other trades to begin work more quickly, speeding the construction time and saving costs. Fast construction on site also means fewer disturbances for surrounding properties. Cast-in situ method of concreting requires lots of time because concrete requires minimum 28 days to achieve 99% strength of its total strength. Thus after creating one element, only after 7 days a new element can be created which is dependent on previous one because concrete achieves 65% strength of its total strength in 7 days.
• Quality control and finishing- The main benefit of using precast concrete over cast-in-situ concrete is proper quality which obtained when concrete produced in controlled factory environment. Water cement ratio can be properly adopted in precast concrete than in cast-in-situ concrete, which can lead to better quality control. In cast-in-situ method concrete is prepared on the site, which can be affected by weather. Better-finished concrete surface can be obtained in precast concrete method because inside surface of moulds are kept good in condition. There is no grout loss from badly fitted formwork, which can lead poor quality in concrete. Plaster requirement is also very less in precast concrete as product have way better finish than cast-in-situ concrete method.
• Material Requirement-Precast concrete method requires less material quantity i.e.it requires less concrete cement and steel, as it is factory made advanced mix designs and better vibrations are used. Less quantity of concrete is used in hollow core slabs. No formwork is required on site for precast concrete method. As no need for storage of materials and formwork, precast concrete method is very useful in small sized construction site with less storage space. Number of labors is less in precast concrete method as compared to cast-in-situ method because there is no actual work on site in precast concrete as compared to cast-in-situ concrete method. As quantity of materials is less, wastage is also less in precast concrete method. It is about 50% less than in cast-in-situ method.

There are various Methods for making mass Affordable Housing by Precast technology, some of the most commonly used are discussed below.

Method A - (Suitable up to G + 4 floor. Advantage of this method :- Very low on investment)

1. Plinth, Beam & Column- Made in-situ.
2. Floor & Roof – Made from Precast, Pre-stressed Load bearing Hollow core concrete slab / planks.
   (100/120mm thick slab x 600 / 1200mm width depending on requirement & design) along with structural screed of 30 to 50mm.
3. Outer walls - Made from Hollow block / Solid Block / Hollow core interlocking panels (120 or 150mm thick x 600mm width)
   All to be plastered from inside & outside (120 or 150mm thick x 600mm width)
4. Internal partition - Made from Hollow core Non- load bearing Lightweight interlocking wall panels (90mm thick x 600mm width length to cut as per requirement from long slab)
5. Staircase & Water proof Toilet Pods – Made from Molds.

Method B - (Suitable up to G + 13 floor .Average on investment. (Shapoorji Palloanji).

1. Solid load bearing Outer Wall:- are Precast (160 / 200mm thick other dimension as per design). No Beam & column.
2. Floor & Roof – Made from Precast, Pre-stressed Load bearing Hollow core concrete slab/ planks.
   (150 / 200mm thick slab x 1200mm width depending on requirement & design) along with structural screed of 50mm.
3. Internal partition - Made from Hollow core Lightweight interlocking wall panels (90mm thick x 600mm width length to cut as per requirement from long slab)
4. Staircase & Water proof Toilet Pods – Made from Molds.

Method C. (Suitable G + 23 floor. Fast construction little high in investment compared to above. Used by L & T & TATA - peenya)

1. Solid load bearing Outer Wall: - are Precast (160 / 200/ 250mm thick depending on requirement & design).
2. Floors / Roof from Half floor slab / Semi - finished floor slab
   (up to 3 mtr width x 10 mtr long x 40/60mm thick) made with Lattice girder / Truss for Floor & Roof
3. Internal partition - Made from Hollow core Non-load bearing Lightweight interlocking wall panels (90mm thick x 600mm width length to cut as per requirement from long slab).
4. Staircase & Water proof Toilet Pods – Made from Molds.

I). Precast, Pre-stressed Load bearing Hollow core concrete slab used for Floor & Roof - are made by extrusion process on steel bed / concrete bed.
Size available from 100 x 600, 120 x 600mm, 150 x 1200, 180 x 1200, 200 x 1200, 250 x 1200, 300 x 1200, 380 x 1200mm.
The span depends on the Load, steel reinforcement & thickness of the slab

II). Hollow core Non-load bearing Lightweight interlocking wall panels for making Partition walls. are made by extrusion process on concrete bed / or automatic plant.
Size available from 68 x 600, 90 x 600, 120 x 600mm, 150 x 1200. Most commonly used is 90 x 600mm for wall partition.

III) Solid load bearing walls – are made with Various methods & it’s Plant & machinery.
a). For very Big requirement & Mass production of Walls are done in dedicated factory on Automatic / computerized control Pallet circulating System(PCS) plants.
For more detail study our website. (Investment is minimum INR 18Cr to 24Cr plus.)

But the Most Economical solution to manufacture precast elements at project site used can be: -
b). Pallet circulating system in combination with Central Shifter: - The Job of Central / side Shifter is to Pull & Push pallet for lengthwise and or a crosswise from workstation to workstation for Concreting, Compaction, Leveling, Trowelling, Curing & Tilting for de-molding. Here the Pallets glides on fixed Roller block assembly.
Ideal to install plant at project site. Low on Investment, Expandable, Flexible & Movable. Ideal Size of pallet can be 3.5 x 12mtrs.

OR

c). Pallet placed in-line & Vibrated & Tilted by Mobile vibrating & Tilting shuttle (MVTS): -
The production pallets are placed in-line on pedestal blocks. The MVTS equipment is driven by geared motor & operated by Remote control, which runs on the dedicated guide rail below the pallets. The compaction is done by, tilting frame lifting the pallet & then vibrating as desired. Once the pallet duly concerted is well cured, the MVTS equipment is once again driven below that pallet & on activation it will Tilt the production pallet up to 70 – 80 Degree enabling easy removal of casted element from the pallet. Hence no need to buy multiple Tilting tables. Ideal to install plant at project site. Low on Investment, Expandable, Flexible & Movable. (Ideal Pallets size is 4 x 9 Mtrs. & maximum 29 nos can be in single lane. Or 4 x 12 mtrs & maximum 10 nos can be in single lane. For more pallets 2 lanes can be used & ferry can transfer MTVS from one lane to another)

A). To make Solid Load bearing wall say about 1000 Sq. mtr / day By –
1). Pallet circulating system in combination with Central Shifter
For 1000 Sq. meter / day, We require Total 34 Nos of pallet, Considering pallets of size 3.5 x 12 mtrs.
(Calculation 3.5 x 12 = 42 Sq. mtr x efficiency of precast element on pallet i.e 70% = 29.4 sq. mtr / pallet x 34 = 999.6 sq. mtr / day.
2). Pallet placed in-line & Vibrated & Tilted by Mobile vibrating & Tilting shuttle (MVTS). (Cheaper than above.)
For 1000 Sq. meter / day, We require Total 40 Nos of pallet. Considering pallets of size 4 x 9 mtrs.
(i.e 20 pallets each per lane x 2 lanes & the MVTS will be shifted from lane 1 to lane 2 by ferry cart)
If your requirement is 730 Sq meter / day, We require only 29 Nos of pallet of size 4 x 9 mtrs. (Ferry cart not required)
Calculation 4 x 9 = 36 Sq. mtr x efficiency of precast element on pallet i.e 70% = 25.2 sq. mtr / pallet x 40 = 1008 sq. mtr / day.

B). To make Precast Half floor slab / Semi- finished floor slab 400 Sq. Mtr / day.
There are 2 types of Precast floor slab made on Long line pedestal steel bed for casting of 2.5 / 3 mtr width x 8/10 mtr long x 40/60mm thick: -
1). Slab with Lattice girder / Truss / Filigree.
2). Slabs which being made with Pre-stressing of steel wires.
a). Most commonly used Half floor slab is with Lattice girder / Truss.
Half floor slab with Lattice girder / truss floors slab are manufactured on Long line pedestal steel bed for casting.
By using Half floor slab one can save on Money, erecting Time & very convenient & easy to install