This civil method statement details general procedures to be followed for repairing work of concrete bulging elements by using a suitable material i.e. BASF’s Emaco S88C T. The method covers preparatory works, bulging repairs and curing. The scope of this civil work method statement is for rectification of the bulges in concrete in which chipping out the concrete will not reduce the cover below the requirements as per the structural specification.
The steps involved in implementation of this method are:
- Identifying bulged area
- Decide on depth of chipping
- Raise the request for inspection
- Chipping to the required depth
- Application of concrete repair material
- Raise final inspection request
Below is list of tools and equipment necessary for doing the concrete bulging repair.
- Wire brush
- Jack hammer
- Blender & mixing container
- Heavy duty slow speed drill with paddle
- Grinding machine
- Air compressor
- Masonry tools
- water pump
- Water / spirit level
- Gloves
- Hammer
- Goggles
- Chisel
- Water Tanker
Roles and Responsibilities for Concrete Bulging Repair Method
Project Manager has the overall responsibility for the implementation of this method statement and shall ensure that Sub Contractors as well other team members are aware of the requirements.
Construction Manager will ensure that the Resources are available to carry out the works as scheduled.
Project Engineer/Site Engineer is responsible for inspection records and carries out the works as per approved Shop Drawings, Method Statements.
The Site Engineer/Supervisor is responsible to ensure :
- That the work has been carried out as per specifications & drawings and inspections are done as per contract.
- To check material being used is approved one.
- Surface preparation is as per the method statement
- Mixing and application are as per the method statement.
Surveyor/Site Engineer/Supervisor is responsible for Setting out the area and measuring, monitoring and controlling the lines and levels.
QA/QC Engineer/ QC inspector is responsible to ensure that the work performed is in compliance with the approved civil method statement for concrete bulging works.
Safety Officer is responsible to ensure that all safety precautions are in place and that the personnel on site possess the necessary and essential PPE. He is also responsible to ensure that essential work permits are available prior to the commencement of the work.
Sequence of Work for Repairing Concrete Bulging
The works shall be performed as mentioned in this procedure and the quality assurance requirements shall be consistent with the relevant sections of Quality System Procedure Manual of “CONTRACTOR” as well with the Project Quality Plan.
Manufacturer’s recommendation to be complied with at the site.
Work shall not proceed without formal approval by the Engineer.
Before commencement of the work, ascertain the nature and location of all existing services on site by visual survey.
If any protection, rerouting, termination or removals of services are required for the smooth progressing of concrete bulging repair work, it will be discussed and written approval will be obtained from Employer as appropriate.
Bulging Repairing Material
EMACO S88CT: Cementations pre-bagged ready to use structure repair mortar in powder form reinforced with acrylic polymer fiber. When mixed with the correct amount of water, it produces a thixotropic, high strength repair mortar, reinforced with acrylic polymer fibers. It possess excellent bond characteristics to steel reinforcement and to concrete
Substrate Preparation
Mark out the area requiring the chipping.
The perimeter of the area should be saw cut with a grinder to a depth of 10mm and the edges cut as neatly as possible keeping the sides square. Feather edging is not permitted and a minimum thickness of 10mm must be maintained over the whole repair area.
Depth of chipping of bulged concrete shall be decided considering the alignment, structure element’s size as per design and approval of the Engineer.
Chipping shall be performed using electrically operated concrete breaker of Hilti, Bosch etc. with pointed chisel of the appropriate capacity. Heavy duty machinery or jackhammers should not be used to avoid damage to the structure element by excessive hammering. For removing a very thin surface a electrically operated scrabbling hammers may be used.
Chipping shall continue to achieve the required decided depth.
Substrate shall be prepared to a rough surface.
The prepared surface must be sound, dense, and free of all oil, grease loose and fractured aggregate or other contaminants that could impair adhesion.
Thoroughly saturate the surface of the concrete to provide a saturated surface dry condition. Any surface water should be removed using oil free compressed air jet.
The waste resulting from the demolition work is to be disposed of as per the requirements of the Construction waste management Plan (CWMP).
Mixing of Concrete Repair Materials
Hand mixing with trowel or similar of EMACO S88CT is not permitted.
For mixing use a heavy duty slow speed drill with spiral mixing paddle attachment.
Water addition shall be between 3.5 liters of potable water per 25kg bag.
Pour the required amount of mixing water into the mixing drum. Start the mixer and add the EMACO S88CT powder rapidly and continuously. Mix for 3 to 4 minutes after all the powder has been added until mortar is homogeneous and lump free.
Add water, if necessary, within the limits given, until required consistency is achieved. Mix for a further 1-2 minutes.
Maximum mixed temperature shall not be more than 35˚C.
As with other products containing Portland cement, the cementitious material in EMACO S88C T grout may cause irritation. In case of contact with eyes, immediately flush with plenty of water for at least 15 minutes. Call a physician. In case of contact with skin, wash skin thoroughly
Application of Repairing Agent
After mixing EMACO S88CT is trowel applied in thickness not exceeding 50mm, forced tightly into substrate to ensure intimate contact with the pre wetted substrate.
Each under lying layer shall be heavily cross hatched with a trowel and allowed to achieve its initial set prior to a subsequent layer being applied in the same manner.
The levelling and initial finishing of the placed mortar surface shall be done using a wooden/plastic float. Final finishing shall be carried out using steel trowel.
When the material has stiffened to the point where finger pressure lightly marks the surface, a firm troweling shall be given using the steel float.
Curing
Good curing is essential for quality results. Curing can be done using properly secured wet hessian and plastic sheet.