Monolithic Construction
Technology
Cast-in-situ concrete with aluminium formwork — speed, precision, and structural permanence at scale.
Construction Methodology — Mivan Shuttering Construction Technology
Mivan Shuttering is a fast-paced construction technique which offers strength and durability to a building by use of Aluminum Formwork System.
With a growing focus on affordable homes and Housing for All, Increasingly emphasizing on the use of new and innovative construction techniques. One such technology is Mivan shuttering which is being promoted for its ability to aid mass construction activity.
Its use is being promoted in India to realize the most ambitious government scheme – Housing for All by 2022.
Construction Technique
Setting up the Wall Reinforcement Steel
The wall reinforcing with steel is used to give a structure to the building and support the concrete until they gain half of the required strength. The aluminum formworks are cast around the steel mesh, which is factory made and directly erected on the construction site.
Placement of Aluminum Formwork
Along the wall reinforcing steel, prefabricated room sized walls and floor slabs are erected. These aluminum alloy slabs are accurately made and are easy to handle. Spaces for windows, ducts, doors and other features such as staircases, façade panels, Lofts slabs (Kitchen counter slab with supporting walls) and chajjas are also integrated in these structures. The forms are joint together using the pin and wedge system, which can be dismantled quickly after the concrete structure is made for vertical surfaces and even for horizontal surface with immediately propping systems.
Pouring of Concrete
After casting the forms, high-quality concrete is poured such as SCC type concrete with good and acceptable flow rates specially designed with rich mix. This concrete takes the form and shape of the cast reaching nuke and corners of the form works easy, which is later removed to make way for a structure made entirely of cement concrete supported by wall reinforcing members. The aluminum forms can be reused at least 250 times, resulting in minimum waste from the construction site.
The resulting structure is accurate, smooth and finished. It has high tolerance and requires no further plastering. As a result, it saves time, effort and money.
Mivan Technology reduces the construction time by almost half in comparison to conventional practices. Since it has a set procedure to be followed accurately, it minimizes the need for skilled labour and completely eliminates labour intensive activities such as masonry and rendering.
On the structural front, the technology makes the buildings more seismic-resistant and durable. Since there are lesser number of joints, the building faces reduced leakages, hence requiring negligible maintenance.
There is uniformity in Mivan construction and the walls and slabs have a smooth finish. Moreover, the technology gives the scope to take out more carpet area in comparison to conventional techniques.
Stages of Construction Works
| Sl No. | Stages of Works | Days |
|---|---|---|
| 1 | Marking of surface for Form Panels placing and Reinforcement works | 01st day |
| 2 | Vertical reinforcement works | 02nd day |
| 3 | Vertical and Horizontal Form works Placing and Fixing in position with all accessories | 03rd Day |
| 4 | Concreting works for the complete units including Walls, Chejja, Lofts and Top Slabs including the sunken portions | 04th day |
| 5 | Wall Panel de-shuttering works after minimum 16 hours of continues curing and check on cube strength | 05th day |
| 6 | Slab Panels de-shuttering works after a period of 36 hours/ 3 days of concrete time of completion with immediate re-propping the slabs with continuous curing methods/ Curing compounds on surface application. | 06th day |
| Note: Continuous curing will be carried out for 28 days as per standards. As these above days are for 1 Pouring unit of a house complete, same system will be continued in vertical and horizontal directions depending on the speedy of works systems. | ||
Structural Design Basis Report on Monolithic Construction Using Aluminium Shuttering
1. Preamble
These houses are intended to be constructed in multiples of 2 houses / day on an average using Cast-in-situ concrete for all structural elements with aluminium "Wall Ties and Forms" (WTF) shuttering system. This procedure is adopted as one of the "Fast Track Construction Techniques", resulting in reduced cycle time, better quality control at site, less material mobilization and minimum labor involvement. In this methodology walls, lintel, beam, slab, chejja & kitchen platform are cast monolithically.
2. Fire Rating
As height of the building exceeds 15.0m, 2.0 hours fire rating is considered in the analysis and design of proposed structure.
3. Shuttering System
The Shuttering system is precisely-engineered system fabricated using aluminum conforming to architectural and structural requirements. Wall forms are used for wall shuttering connected through wall ties and clamps. Slab forms are used to support slabs for concreting. Slab forms are supported on props at appropriate location based on structural requirements, easy deshuttering sequence and handling of materials. Aluminium being lighter, shuttering material is easy to handle and place in position. The resulting structure has a good quality surface finish and accurate dimensional tolerances.
5. Concrete
Self compacting concrete (SCC) of suitable grade as per mix design and structural requirements will be used for concreting. The inherent property of SCC is self compaction without segregation. Hence, SCC is more suitable for this technology. Free flow of concrete is maintained to be 600mm minimum, during the pour, to ensure the proper flow and compaction.
6. Deshuttering (Stripping of formwork)
Self compacting concrete (SCC) of suitable grade as per mix design and structural requirements will be used for concreting. The inherent property of SCC is self compaction without segregation. Hence, SCC is more suitable for this technology. Free flow of concrete is maintained to be 600mm minimum, during the pour, to ensure the proper flow and compaction.
7. Curing
Curing is the process of controlling the rate and extent of moisture loss from concrete during cement hydration. Curing is designed primarily to keep the concrete moist, by preventing the loss of moisture from the concrete during the period in which it is gaining strength. Curing has a major influence on the properties of hardened concrete such as durability, strength, water-tightness, wear resistance, volume stability, and resistance to freezing and thawing. Membranes forming curing compounds (BASF Mastercure-107) are the liquids which are applied directly onto the concrete surfaces and which then dry to form a relatively impermeable membrane that retards the loss of moisture from the concrete immediately after removal of wall shuttering. This compound is wax based. Slab are cured by ponding method for a minimum of 7 days.
8. Foundation
Conventional type of foundation such as wall strip foundation/Raft foundation based soil conditions will be used.
9. Advantages
This type of construction is adopted due to the following advantages:
- Fast track construction technique
- Total unit is made up of concrete, which is stronger, durable and solar heat resistant
- Forms can be custom made to the requirements
- Reduced cycle time
- Better quality control at site as less material mobilization at site
- Cost effective
- Plastering can be completely avoided
- Forms can be placed in position even with unskilled labour
- Aluminium forms though costly works out to be cheaper with more number of repetition
Keeping in view the above advantages with the alternate technology, this construction technology is more suitable for this project.
About Design Procedures
RCC is the primary material used in this construction. In conventional methods, RCC walls are cast first and slab is cast later. But, in this technology both walls and slabs are cast simultaneously. Walls are designed as shear walls using limit state method as per the standard design equations given in IS 13920 and IS 456. Slabs are being designed as per IS 456. Element thickness (Walls, slabs and beams) are chosen based on fire rating and structural requirements. Limit state of strength is used for the structural design of various elements of the housing units. Limit state of serviceability (Stability, Cracking and Deflection) will be followed to ascertain durability criteria. RCC is intended to be used in the proposed project. Guidelines conforming to IS 456, IS 13920, IS 1893, IS 875 are followed to design the structure. Concrete (Portland cement + 30% (maximum) GGBS) and concreting procedures will be followed as per the Indian standard guidelines and practices. GGBS/Flyash reduces the micro cracks and protect the rebar thus increases the durability of concrete. Thus the structure built will be sound enough to be used as habitat building.
Use of Software
NISA/CIVIL (Numerically Integrated Elements for System Analysis) developed by M/s Cranes software International or ETABS will be used to analyse and design the proposed structure.
About Indian Green Building Council Requirements
Best Indian practices would be followed during Planning, design and construction stages.
10. Sustainable Architecture and Design
The orientation of the building will be worked out based the energy conservation (Solar heat and light), without disturbing the existing site features.
11. Site Selection and Planning
Site selection and planning requires connectivity to infrastructure and public transport network. The proposed site is well connected to public transport network.
12. Water Conservation
Rain water harvesting is envisaged thus meeting the requirements of during scarcity days and recharging the source of water. Dual piping system for treated water (Recycled water) and potable water will be adopted by using efficient plumbing fixtures. Water Usage: As curing compounds are used, usage of water for curing is minimized during the time of construction.
13. Energy Efficiency
Solar passive building design concept will be followed in order to reduce or even eliminate the use of mechanical cooling and heating systems and the use of daytime artificial lighting. These parameters may be ensured with proper planning of building, its orientation, and location of windows, doors and window shades.
14. Building Material and Resources
30% GGBS/Flyash is used in concrete construction. The following are the advantages:
- Per unit embodied energy of concrete is reduced
- Use of GGBS increases the workability of the concrete.
- GGBS/flyash better protection to steel against corrosion
- Windows are UPVC, thus usage of Wood is minimized
- Flooring is Ceramic/Vitrified thus 100% recycled content in the form of recycled glass
- Aluminium shuttering enables use of more number of times, avoiding the use of ply wood as shuttering
- Appropriate artificial lighting system and their location may be used to reduce the electrical energy requirements
Code of Practice
| Sl No. | Code | Title |
|---|---|---|
| 1 | IS 456 | Plain and reinforced concrete – codes of practice |
| 2 | IS : 875 (Part 1) | Code of practice for design loads (other than earthquake) for buildings and structures Part 1 Dead loads – Unit weights of building material and stored materials (Incorporating IS 1911 : 1967) |
| 3 | IS : 875 (Part 2) | Code of practice for design loads (other than earthquake) for buildings and structures : Part 2 Imposed loads |
| 4 | IS : 875 (Part 3) | Code of practice for design loads (other than earthquake loads) for buildings and structures part 3 Wind Loads |
| 5 | IS 1893 | Criteria for Earthquake Resistant Design of Structures – Part 1 : General Provisions and Buildings |
| 6 | SP 16 | Design Aids for Reinforced Concrete to IS 456 : 1978 |
| 7 | SP 34 | Handbook on Concrete Reinforcement and Detailing |
| 8 | IS 13920 | Ductile Detailing of Reinforced concrete structures subjected to Seismic forces |
Description of Analysis Parameters
Structural Layout
Structures are with Raft + Floors or Ground + floors are applicable. The height of the floors is 3.0m taken generally. Layout Dimensions as per the Architectural drawings are considered.
Material Properties
| Property | Value |
|---|---|
| Grade of concrete | M25 & M30 |
| Grade of reinforcement steel | FE-500 & FE-500D |
| Density of concrete | 2500 kg/m³ |
| Poisons ratio | 0.2 |
| Young's modulus | 27386 N/mm² |
Structural Element Dimensions
| Element | Dimension |
|---|---|
| RCC Walls | 160mm minimum |
| Roof slab | 125mm minimum (Changes upon design) |
| Toilet slabs are sunk by | 400mm (Indian W/C) and 200mm (EWC) |
Foundation
Strip footings/Raft Footings are designed for RC Walls. SBC of soil as per soil reports to be assumed for design of foundation. A factor of 1.25 for SBC has been used while designing due to seismic.
Finite Element Model
The Finite Element Model is created using NISA/CIVIL version 16, software, for performing structural analysis. RC Slab, RC Walls are modeled using four noded shell elements. RC columns and beams are 2 noded beam elements having 6 degrees of freedom per node.
Foundation System
The foundation is strip footings for wall or Raft foundation.
Basic Load Cases and Combinations
15. Dead Loads (DL)
Self weight of the structure is automatically computed by the software. Floor Finish = 1 kN/m², Additional Dead Load = 0.5 kN/m² applied as pressure loading in –ve gravity direction (Global Z). Sunken portions filled with Aerated concrete/Cinder — 3.2 kN/m² applied as additional pressure loading.
16. Live Loads (LL)
Super imposed Live Load = 2 kN/m² for all floor slabs above stilt level. Live load of 3 kN/m² applied on corridors and staircase area.
17. Wind Loads +X
| Parameter | Value |
|---|---|
| Basic wind speed | 33 m/s |
| K1 | 1.00 |
| K2 | 1.05 |
| K3 | 1.00 |
| Design wind speed | 33 x 1.0 x 1.05 x 1.0 = 34.65 m/s |
| Design wind pressure | 720.37 N/m² |
However, 1 kN/m² is applied as pressure loading.
18. Wind Loads +Y
1 kN/m² applied as pressure loading.
19. Seismic Loads +X
| Parameter | Value |
|---|---|
| Zone factor | 0.10 |
| Importance factor | 1.0 |
| Response reduction factor | 5.0 for concrete |
| % Live loads considered during seismic weight calculation | 25% |
| Soil Type | Medium |
- Fundamental Time Period T = 0.09 H/ √d, Hence T = 0.39s.
- Only Pseudo static analysis has been performed as per Cl 7.8.1 of IS 1893 (Part:1)-2002.
- Seismic Base shear Vb = Ah × W, where W = Full Dead Load + 25% Live Load, Ah = Design horizontal acceleration spectrum value.
20. Seismic Loads +Y
Same parameters as Load Case ID-5.
Load Combinations (IS-456: Table 18) — Member Design
| Load Case ID | Combination | Load Case ID | Combination |
|---|---|---|---|
| 501 | (DL + LL) | 510 | 1.5(DL+WL(-Y)) |
| 502 | 1.5(DL+LL) | 511 | 1.2(DL+LL+WL(+X)) |
| 503 | 1.5(DL+SL(+X)) | 512 | 1.2(DL+LL+WL(-X)) |
| 504 | 1.5(DL+SL(-X)) | 513 | 1.2(DL+LL+WL(+Y)) |
| 505 | 1.5(DL+SL(+Y)) | 514 | 1.2(DL+LL+WL(-Y)) |
| 506 | 1.5(DL+SL(-Y)) | 515 | 1.2(DL+LL+SL(+X)) |
| 507 | 1.5(DL+WL(+X)) | 516 | 1.2(DL+LL+SL(-X)) |
| 508 | 1.5(DL+WL(-X)) | 517 | 1.2(DL+LL+SL(+Y)) |
| 509 | 1.5(DL+WL(+Y)) | 518 | 1.2(DL+LL+SL(-Y)) |
Note: Load combination 501 is not used in member design. Foundation sizing uses unfactored combinations (strip the load factors automatically).
Foundation Sizing
| Load Case ID | Combination | Load Case ID | Combination |
|---|---|---|---|
| 502 | (DL+LL) | 511 | (DL+LL+WL(+X)) |
| 503 | (DL+SL(+X)) | 512 | (DL+LL+WL(-X)) |
| 504 | (DL+SL(-X)) | 513 | (DL+LL+WL(+Y)) |
| 505 | (DL+SL(+Y)) | 514 | (DL+LL+WL(-Y)) |
| 506 | (DL+SL(-Y)) | 515 | (DL+LL+SL(+X)) |
| 507 | (DL+WL(+X)) | 516 | (DL+LL+SL(-X)) |
| 508 | (DL+WL(-X)) | 517 | (DL+LL+SL(+Y)) |
| 509 | (DL+WL(+Y)) | 518 | (DL+LL+SL(-Y)) |
| 510 | (DL+WL(-Y)) |
Boundary Conditions
Fixed boundary conditions (restraining both rotations and translations in all three directions) are applied below the Stilt columns.
Structural Analysis and Design
General
Structural analysis is based on the linear elastic theory to calculate internal forces produced by design loads using NISA/CIVIL analysis and design software package.
Minimum Thickness and Cover
| Sl. No. | Element | Min. Dimension | Cover | Remarks |
|---|---|---|---|---|
| 1 | Slab | 125mm | 25mm | — |
| 2 | Beam | 200mm | 40mm to links | — |
| 3 | Column | 300mm | 40mm to links | — |
| 4 | Footings | — | 50mm | Minimum depth of foundation 2.0m |
| 5 | Walls | 160mm | 25mm | Two face Rebar Minimum 0.4% Rebar |
| 100mm | 50mm | Midside Rebar Minimum 1.0% Rebar |
Exposure: Mild · Fire rating: 2.0 Hours
Structural Design
Structural design carried out as per Limit state design conforming to IS 456-2000. SBC of 12 T/Sqm assumed at a depth of 1.5m from EGL. M25/M30 Grade of concrete & FE-500/FE-500D Rebar assumed. Design of shear wall: In plane and out of plane stress resultants computed by software, conforming to IS 456 and IS 13920.
Results
Reinforcement in columns, Beams, Slab and Footing is calculated using software. Shear walls are computed as per IS 13920 & IS 456.