My Project Management Internship

INTRODUCTION

The mega housing scheme which was launched in 2018 by the Maharashtra State Government with an idea of housing development on the lines of 'Transit Oriented Development'. As per the plan, the housing complexes were planned near the bus terminals and railway stations to bring down traveling distance and also encourage the use of public transport.      

 As the Pradhan Mantri Awas Yojna (PMAY) for Economically Weaker Section (EWS) and Lower Income Group (LIG) families was announced, the Maharashtra State Government along with CIDCO planned the Mass Housing Scheme. This is the largest mass housing scheme in a single city.

With a total of 1 lakh housing units being planned to be allotted by Maharashtra State Government and CIDCO, the Navi Mumbai region got Package II of mass housing which is spread across 7 sites. Aimed to construct approximately 21346 number of EWS-LIG type dwelling units.

   

CONSTRUCTION PROCESS ON-SITE

A.   SITE PLANNING AND SURVEYING

Surveying typically helped determine the scope of the project and planned it on a map. The Kharghar Bus Depot project is one of the first projects in the state which consist of a Bus Depot (a public space) below a Residential Building. The Buses will come in and halt over for the next trip or even for maintenance for days. The building is designed with 2 separate entry points with an entry and exit ramp for residential use and a separate main entrance for Bus entry and exit.

Survey report help in excavation for the tower and non-tower area. Land surveys which are done to know the condition of the soil and its history with details regarding soil consolidation and soil density are reported. Land and Site Surveying is used for laying site plans, creating cadastral maps showing boundaries and their properties.

B.    EXCAVATION AND FOUNDATION WORK

As per the survey reports and site plans the site execution team starts with clearing the site and excavation work for the foundation and footing work.

As per site reports and building type, various types of footing are incorporated in the building design.

Pile foundation typically requires the boring of piles and then casting a pile cap and using it as a base for casting footings. Wherein for Isolated footing with its PCC resting on hard strata and then casting footing on it no pilling is required.

Here in KHBD Site, we had Major work with Isolated footing and a few Combined and Step footing. The excavation was carried out till hard strata is reached. This is verified by Geotechnical Engineer wherein it is verified that the excavation has reached hard strata and is ready for PCC and Footing work.

Procedure:

a.      Marking on land with white chalk powder.

b.     Excavator, excavates the soil till the hard strata are reached.

c. The slopes alongside are also excavated with safety precaution and geotechnical standards.

d.     The strata are dressed (leveled) for proper PCC work.

e.      Surveyor marks coordinates and points for the formwork of PCC.

f.       Formwork is fitted and PCC work is done (Isolated and Raft PCC is done).

g.   Footing Mesh is brought in and placed with appropriate covers then placed over PCC and again points are marked to check formwork is in place.

h.     Footing concrete is poured and settled. 

C.   SHUTTERING

Shuttering is used to provide support to wet concrete mix till it gets strength and is able to self-support with having proper finishing. The Shuttering or Formwork is made of timber, plywood, metal and now with aluminum and other material.

Shuttering as the whole consist of various components such as

·        Weller: Horizontal Channel Support

·        Tie Road: Holds the Shuttering from both sides

·        Wing Nut: Helps in Tighten tie road

·        U Jack: Used to Support Weller and anchored to the ground

·        Wedge Pin: Used to tighten two adjacent shuttering.

D.   CONCRETING PROCESS

a.     Pre-Concreting

The surface on which concrete is being poured is cleaned and chipping is done. This helps the new layer of concrete to have contact and increases the bonding of the new layer with the previous one.

The Formwork is also greased with shuttering oil so as to have a better finish of the concrete surface and an easy de-shuttering process without disturbing the concrete surface.

b.     Concrete Pouring Machinery Placement

As this is a huge process with cement concrete mixture coming in huge quantities, simple and traditional methods of pouring concrete are not used.

The concrete is either poured with Huge Concrete Pouring Bucket or Concrete Pumping Method. The pump is placed and pipes are laid till the pouring point.

c.      Concreting

As soon as the concrete truck comes on-site, the truck challan is checked with proper characteristics and site name on it. It also contains a few details such as cement, coarse aggregate, fine aggregate, fly ash, admixtures, and water The concrete sample is taken and the slump is checked. The remaining concrete sample is used to make concrete blocks for compressive strength checking.

The Concrete truck was then taken for the pouring process and pumped to the required element. The concrete should not be poured from free fall height i.e., 1.5 meters. At the time of pouring, to prevent honeycomb and air void formation, needle vibrators are used. At the time of Mivan formwork alongside needle vibrator, hammers are used to remove air voids and prevent honeycomb. The concrete is filled to the level required it is given proper finishing on the top surface.

d.     De-Shuttering

This process takes place only after the setting time of concrete is reached or prescribed time according to the manuals.

The de-shuttering process is different for different elements such as:

Element	Period
Vertical Sides (Column, Beam, Wall)	16-24 hours
Slab Deck	3 days
Beam Deck	7 days
Slab (Span 4.5m)	7 days
Slab (Span Exceeding 4.5m)	14 days
Beam (Span 6m)	14 days
Beam (Span Exceeding 6m)	21 days

After de-shuttering if the concreting is done in traditional formwork, then only finishing is to be checked and necessary polishes are required. If Mivan shuttering was used, after removal of the tie rod and plates the holes are to be filled with grouting material which is a cement bonding paste that is mixed with cement paste that doesn’t shrink. This is also called the core hole filling process. The holes are filled in 10-15 mm

e.      Curing

This is a crucial step in the concreting process as the concrete releases heat of hydration it is required to cool down the temperature. Avoiding this would result in cracking of concrete surface which would lead to an atmospheric connection of teel and as result corrosion of rebars.

Thus, proper and timely curing of the elements cast and de-shuttered is required which is carried out by covering the element with a gunny bag cloth and then sprinkling water on it and keeping it wet throughout the day for at least a week.

 WATERPROOFING - COAL TAR BITUMEN COAT

After the grouting process, the concrete surface is cleaned and leveled with grinders to have a smooth and undisturbed surface for the application of waterproof coating. The cleaned surface is now given epoxy coal tar paint and thinner which are mixed in a ratio by weight 5:1. The surface is given 2 coats with a brush or roller. The first should be in the range of 110-125 and the second (final) coat should come 250 um. This is verified by placing small metal plates along the surface to be coated and taken out once it is dried. That plate is used to check the thickness. This check is done by Dry Film Thickness (DFT) Meter. 

After this, the shear walls are given a coat of glue for placing dimple board which helps in reducing the friction and overall pressure of the backfilling material which will be poured into the pit. The boards are stuck onto the surface and at junction and intersection, they should overlap at least 10 mm.

BACKFILLING

After proper waterproof coating and dimple board placement, backfilling is carried out. The process takes place in layers. The first layer will be of 300 mm and then compacted with a sheet roller or compactor. Second to successive layers are to be filled till 150 mm and the same process of compaction is applied on the new surface each time. Where the roller cannot reach small compaction machines are used to compact the layer. After each compaction, the density and water content are checked and reported by geotechnical engineers.

PLINTH AREA CONSTRUCTION

Once the groundwork is completed and backfilling is done, the plinth area is constructed. To construct the beams and spare out dowel bars for the non-tower and plinth portion. The column top is chipped and made rough for new concrete to have a proper bond.

The reinforcement bars are then tied according to structural specifications. After the proper cover and binding as per drawings the contractor checks the work and prepares a pour card which has a section for points (remarks) to be noted by PMC, Architects, and Structural Consultants.

After, only the PMC green signal for pouring or other work, the contractor moves ahead with the task. This ensures structural soundness of work and proper utilization of budget poured into the project.

COLUMN AND SHEAR WALL

As the plinth is completed, the reinforcement of columns, walls, and shear walls are erected on and the same process is carried out. The previous concrete surface is chipped and new bars are bound. As soon as the inspection is completed, the shutter or formwork is installed and again the level and distance of the shuttering and formwork is checked with a temporary grid line. Again, PMC has to inspect the work and level with the grid line.

After all the points and remarks are solved, concreting work is done as mentioned previously. As the prescribed period is achieved de-shuttering work is done and the curing process is taken.

BEAM AND SLAB

The beams and slabs decks are constructed with formwork and supported with Cup-Lock system scaffoldings. The area to be concreted is first covered with battens which are laid horizontally and act as mesh. The Plywood or traditional formwork is then developed on it. Here at KHBD the Traditional method is used till Podium Stilt level and then after MIVAN formwork.

Then the laborers take over the top of the deck. The work on reinforcement and binding it is carried out. The bars are brought from the fitting and welding shed which are cut and bend according to the structural detailing and drawings provided. The level is checked by the surveyor and reported to the PMC. The contractor does the inspection and cleans down the deck with any dust, extra bars, and binding wires which are left in the sections with help of a compressed air blower or water jet. After the inspection of the contractor, the process of inspection is carried out again before concreting the elements.

MIVAN FORMWORK

A strong and sturdy formwork that is made of aluminum and is known for its smooth and even finish - Mivan Formwork, now widely accepted and used in the construction of all types of construction. As a result of its use for mass housing projects and construction, formwork is often used repetitively. Easily installed, adaptable, and modifiable in response to changes in structural and MEP designs.

The formwork comes on-site in packages. They need to be separated i.e., segregated, then brought up to the floor and first inner wall and element panels are fitted, then the outer. The design and panels have specific names and positions pre-declared. The nomenclature for Mivan form is

Wall Components

1.     Wall Panel

2.     Rocker

3.     Kicker

4.     Stud Pin

Beam Components

1.     Beam Side Panel

2.     Prop Head & Panel for Soffit Beam

Deck Components

1.     Deck Panel

2.     Deck Prop & Prop Length

3.     Soffit Length

Miscellaneous Components

1.     External Corner

2.     Internal Corner

3.     Internal Soffit Corner

4.     External Soffit Corner

5.     Pins

6.     Wedges

After placing the formwork around the reinforcement, we can now start the concrete pouring process, and thus we need to know the capacity and strength of the formwork. The formwork can carry up to 7-8 tonnes per square meter while its self-weight is around 17-18 kg per square meter.

The vertical panels can be removed after 12 hours of concrete pouring or when it reaches 10% of strength and horizontal deck panels after 36 hours of pouring or when it reaches 30-40% of desired strength. The panels are to be cleaned as soon as they are removed with brushes and scrubbers. The panels thus can be used around 200 times due to this durability and the easy modification process also creates a minimum slab cycle of 7 days.

SCOPE OF BIM ON-SITE

As we know BIM is Building Information Modelling that deals with Drafting and creating 3D models. They are created by Architects-Engineers who incorporated information about the building. The Models on a typical stage can provide Site Engineers virtual but actually, look at how building on the construction stage can be built and how it will look in the real world. This will help in easy inspection and less confusion in the placement of elements without any clash.

Here we can see how the sections of the ramp and actual building can be taken and help understand easily how it should go on-site and how will it look after concreting.