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Case Studies


STRUCTURAL REPAIRS AND REHABILITATION
(COMMERCIAL OFFICE PREMISES AT MASJID BANDAR, MUMBAI )
STRUCTURAL AUDIT & ESTIMATION EXERCISE:
Survey was conducted in the building using nondestructive testing equipments like rebound hammer, ultra sonic pulse velocity for accessible structural members like columns & beams. Basement was close during tenure of survey and some part of the structural members inside offices were covered by tile or wall panel or false ceiling. The structures happened to be more damaged in areas not surveyed which consumed major part of the estimated amount resulting in to overall enhancement of budgeted amount.  Amount allocated for structural glazing & aluminum composite panel work was swayed away by these hidden area restoration as all of us felt that health issues may better be addressed first than beautification.
ABOUT STRUCTURE
The building structure is GROUND + 5 floor consisting of 37 Units being used as small manufacturing units & few of them as offices. The building is 37 years old having one staircase with lift facility, located on the corner of two very busy road junction.
DIFFICULTIES IN THE PROJECTS:
The building located in highly crowded area and the front two faces of the ground floors are occupied & operational commercial shops where the people are regularly moving in and out.
SAFETY MEASURES & DEBRIS REMOVAL:
A working platform was constructed using structural steel beams, ply wood, old bamboos & G.I. sheets to prevent debris falling from height to fall on commuters / visitors of shop or even people working down below. Safety belt & helmets were strictly used for all workmen. While breaking, the debris over the platform need to be cleared at regular interval to ensure that over load at platform should not create safety hazard. As there was absolutely no space to store them at ground level, we were left with no option but to remove debris at night or off office hours by even paying high & making them stand till loading is done directly from platform to truck. The debris removal trucks were called for even half load also at times.
STORAGE OF MATERIALS LIKE CEMENT AND SAND:
There is no much space to keep construction materials, whenever materials come in truck were un-loaded on the footpath/ road. The MCGM (Municipal Corporation of Greater Mumbai), local authority will not allow any material on the road so contractor has to lift the material before the next day morning. This required extra manpower during nights almost every day. Also it called for acute material management to ensure that either there is no extra material ordered/ arrive at site nor there is delay in ordering/ procuring at site where work suffer due to lack of material availability. Thus it was classic example of serious logistics handling & supply chain management
TIME FRAME:    
Tender period to complete the project was 6 month but the quantum of work increased almost double. It was impossible to complete the work in decided time and value. The project was completed in 9 months time as there were also issues of taking permissions from members by calling special general body meeting for additional contributions & mode of collection as asking members for shelling out additional amount at a time was not a feasible option. Certain members paid their maintenance in advance against society’s decision to take 10% lesser contribution from members who pay in advance. This prevented society to opt for option of loan from bank for special repairs. Society also took permission from registrar of society to withdraw amount up to 85% from sinking fund, repayable in installments in next 3 years. This reduced burden from members to shell out major amount at a time & gave them facility to pay in installments to society to replenish sinking fund meant for using in such emergencies. Consultant’s report helped in finishing this formality in time with all its appropriateness & fairness.
MUNICIPAL PERMISSIONS:
All the govt. deportment kept watch on this project because of the location and we obtained permission from the various departments like Road and Footpath, Buildings, Mosquito and water department.
WORKING ON FOOTPATH:
There were too many incidents that Municipal footpath clearing team took away the chemical cane, cement bags and mixing trays while working on footpath while mixing and lifting of repair material done on the footpath for the two side of the building.  

HIGHLIGHTS OF THE PROJECTS/ BASIC SCOPE OF WORK
The projects assigned for Structural repair, Terrace waterproofing, part replacement of sanitary & plumbing, external waterproofing, re-plastering and then common area painting and external painting.
Erection of Scaffolding:
Due to space constrain, the scaffolding erected in three side of the building, the two sides erected over the footpath and third side in the society compound. The third face has little bit of ground space where the water tank, shuttering materials, debris, cement, construction chemicals and sand were stored, by stacking them one over another.




 Recasting of RCC Sunshade:
The Continuous sunshade was suggested, instead of old ones just over the window openings as a rainwater protection to building, to prevent water running over empty spaces along the walls resulting into growth of moss & fungus showing black spots spoiling paint look. All new re-bars were anchored to the beam with the help of FISCHER MAKE epoxy resin capsules and 100mm thick concrete was casted uniformly with help of waterproof ply shuttering
Plastering:
Old to new plaster joints were joined using bonding adhesive. PP Fibers were used as transverse reinforcement to join first & 2nd coat of plaster, 1: 4 & 1:3 consecutively. Liquid waterproofed was added as admixture in mortar. R.C.C. to masonry joints were stitched using polymer mortar embedded with metal aggregates. Pointing was done in loose brickwork, wherever bedding & jointing mortar was lost. Dash coat plaster was provided wherever loss of brick/block work was resulting into higher mortar thickness than 25 mm.   
RCC Coping:
To protect parapet top leakages, RCC coping laid over the 3.5’ height parapet wall with 1” projection outside,3” projection inside and the top finished in 1” inward slope.
Making of shuttering in three sides has no complication because of the scaffolding support but the 4th side was also casted with additional safety measures

         
Waterproofing of enclosed balcony roof at top floor:
Top floor balcony was enclosed & in use as an office. This has the wooden frame with AC sheet roofing; it was leaking at all junctions between wall and roof. The wooden truss was deteriorated and AC sheets were cracked. AC sheet and wooden support were replaced using new Sheets and Steel structure supports without damaging the false ceiling. A part of false ceiling was damaged while replacing of roof but the false ceiling was also repaired on same day as monsoon showers were expected any day.
Waterproofing of terrace floor using torch applied APP membrane:
 Looking at condition of top floor slab, it was impossible to remove existing brick bat Koba waterproofing plus monsoon foot steps were making decision of new B B Koba impossible as process is time taking & stacking so much debris was never easy. Decision was taken in favor of nondestructive fast application method of bituminous hot application PP reinforced membrane. The APP membrane was fixed in a day after application of bituminous primer on previous night on entire roof and was extended up to drip mould of parapet plaster. The sufficient size of rainwater outlet was made available to avoid water stagnation and APP extended till inside of the rainwater pipe opening. APP laps were maintained uniformly and torched to melt properly to avoid hiccups and make joints watertight.
Parapet top was finished with sand face finish plaster and as a additional protection, the top covered with APP membrane.

                         BEFORE                                                                                                   AFTER


Plumbing and Drainage with KITEC PE-AL-PE PIPES:
WATER SUPPLY Plumbing: Composite plumbing in all our previous projects have proved to be boon against corrosion problems faced using metal pipes & UV instability of many plastic pipes. Large length availability without joint for up to 200 R. Mt. was additional attraction, particularly for loop line. Malleability of composite pipes up to 63 mm dia. Was Proved useful in maintaining curves of parapet wall building periphery without elbows/couplers. All plumbing lines were GI pipe partially embedded in to wall and many joints rusty/leaking. These pipes were replaced with new composite KITEC pipes and fittings. Special clamps were used to fix the pipes at every 5’-0’ intervals and fixed with fisher make anchor fasteners. Client got 50 years manufacturer warranty for pipes. Composite fittings were used in external lines & brass fittings in concealed lines for bathroom leakages. Window was provided with Cudappa stone framing for pipe access through parapet wall for connecting loop line with down take pipe line.
PVC Drainage pipes:
Drainage pipes were leaking at many connector locations and also were not fixed properly. These all PVC pipes were removed and realigned over the special clamps, at all locations.  Wherever the pipes were passing through the RCC weather sheds, a bigger size pipe sleeve was fixed in R.C.C. for easy maintenance to ensure that there is no breaking involved in future for pipe movement. UV resistant Black colored KITEC pipes having carbon black ingredient were used with fittings. All toilets were kept operational by providing temporary PVC pipe lines during repairs @ 1 meter away from wall & were fixed permanently once connector waterproofing was done & civil work behind pipe area was completed.
Structural Repair:
External column/beam/slab in ground floor and column/beams in top most floors were deteriorated very badly and were repaired with Polymer mortar or Micro concrete method. Fiber wrapping to few columns was done to enhance flexural strength of such weak columns.
Basement beam and slab were damaged due to leakages from the common WC block at ground floor, a complete beam was jacketed in micro concrete by drilling hole from top floor. A portion of Slab bottom was sagged & de-bonded. By providing watertight shuttering, slab casting was done using micro concrete with 6 mm down pea gravels, poured from top floor by making few core cuttings for max. Flow up to 2 meter.

                                                                                                                  



All old bars were cleaned with RUST REMOVER. After 24hrs application, the surface cleaned with water jet so that all rust and loose concrete is cleaned thoroughly. Wherever reinforcement bars lost its diameter by more than 25% of its original volume, additional rebar were provided as replacement/replenishment.


Old & New bars were coated with rust preventer as a Passivator coat applied one or more coats using ready to use powder to be mixed with water, modified with powder polymers.
The new reinforcement connected to original concrete by fixing Shear Connectors, fixed using polyester resin anchor chemical.
These connectors fixed by using chemical based grout having high pull out bond strength by drilling hole into concrete minimum 100-150mm long. We ensured that pull out strength of anchor is more than tensile strength of bar.

After 24hrs the entire surface was coated with long pot life epoxy bond coat followed by watertight shuttering prepared to pour micro concrete.

 
TERPROOFING:
There was a large sunk portion at G.F. toilet having Indian W.C., which did not allow usage of area below it. It was also leaking which caused major damage to basement structural members. This was waterproofed using traditional brick bat Koba method & changing over to European W.C. thus avoiding sunk are & casting a flat slab & releasing large area at basement for actual use. Concealed plumbing was changed & tiles were replaced as per owner’s choice of make but in bigger size than original ones to reduce number of joints. Many other toilets at upper floors were also waterproofed in similar manner, one after another as per their availability.
UNDER GROUND DRAINAGE: 
Basement was found leaky on account of failure of joints of old stone ware pipes & bedding pointing mortar of man hole brick work over & above joinery of pipe to man holes. Entire system was made new using UPVC SWR pipes with new manholes with different alignment. Even old cast iron gully traps were replaced using UPVC ones.  New system was connected on Sunday being holiday & offices being closed. Old pipes & manholes, which were not removed, were abolished. Paver blocks were suggested in compound after such repairs. Concrete plinth protection work was done to ensure that no water seep through ground to basement.
External Protection Treatment:
The external surface of the building again was protected with good quality paint of Elastomeric property, with Roller application instead of brush in three coats applied by roller as per manufacturer recommendations. Acrylic paint was avoided for not having crack bridging property, which is very important in old & aged buildings. 5 years warranty against leakages was received & given to client saying that manufacturer will give free material during the tenure & contractor will do free application at no cost to society during defect liability period. Such works will start in a week’s time on written intimation of complain under supervision of consultant till such defects are rectified.


CONCLUSION:
This type of structures needs to be surveyed very carefully. If required sample portion may be opened to identify the condition of core and level of corrosion. Survey must be conducted in all areas and especially enclosed / close areas by getting an access at its availability.
Extra Time should be considered for difficult situations like working on platforms or over the footpath/ public commuting areas.
Execution can be performed well, if owners clear structure-surrounding area in time & mutual cooperation is achieved between members to achieve long-term durability goal.