METHODOLOGY FOR CONCRETING
GENSET POWER HOUSE BUILDING – MACTAN CEBU
In order to standardize the site works and regulate the activities of the workers, we issue the
aforementioned methodology for compliance of the involved workers. It’s suitable for the cast-in-
place structural frames.
Such a Method includes the following:
1. Scope of Works
2. General Requirements
3. Preparation
4. Inspection
5. Concreting
6. Finishes
7. Curing & Protection
8. QA Usual problems analysis and precautionary measures
9. Safety
10. Responsibilities
Scope of Works
This methodology describes the practices and methods to be used with regards to placing, curing
and defect rectification of concrete works.
General Requirements
The falling height for each concreting shall be less than 2 meters particularly for the columns, if
succeeding than this limitation, the necessary chute or other measures shall be taken. The pouring of
the concrete shall be continuously for each layer and each area; each layer of the pouring should be
strictly controlled within 50cm as well. If standby time more than 45min due to conveying, the grout
will be applied prior to continue the pouring. Vibrator shall be handled by skilled concreting
personnel, the essentials of the utilization of vibrator fast insert then slowly pull-out, the spot shall be
equally and in sequence, most likely 30-40cm, the insert shall penetrate the first poured layer 5cm in
order to eliminate the joints. Ensure the vibration cover all the area that has been casted. Undersigned
standby carpenter shall always monitor and assist the formworks, if any movements or abnormal
signs, the reflected action shall be taken or stop the pouring until it’s fixed.
Preparation
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Clear the site, verify the formworks is stable and signed by formworks engineer, clear the
scheduled casting area like as garbage, dust, engine oil both inside of the forms and rebars. Conduct
initial inspection by rebar engineers, such an inspection including the quantity and size of the rebars ,
spacing, spacer and arrangement. At the meantime, the surveyor shall check the layout and verticality
of the elements.
Inspection
Once the preparation works has been done by each related engineer, QA/QC shall call inspection
upon the punchlist has been done from initial inspection, the necessary co-worker should standby for
the immediate action for the comments from inspector. Depend on the punchlist; the maximum
rectification will be limited in 0.5 hours, then ready for pouring. Inspections documents shall in place
for consultant approval.
Concreting
Concreting engineer will be the only one staff that will call the supplier for the pouring schedule,
take note the 1 week look ahead schedule should be complied with mater schedule, the pouring
schedule shall be given to suppliers at least 2 days in advance accordingly.
Verify the dispatch time from each D.R to ensure the concrete quality; if more than 4hours, the
concrete shall be rejected because it’s over mixed.
Upon the approaching of the mixers, the slump test will be conducted and witness by construction
managers prior to proceed with the pouring. The limitation of the slump test shall be 6-8”only for
PCD and 3-5 for ORD.
For Column
1. Provide the grout to moisturize the rebars and formworks, aside from the vibration of vibrator, the
undersigned carpenter shall assist with the vibration by hammering the side forms using rubber
mallet.
2. The pouring of the columns shall be poured in one time, if the pouring shall be divided into 2or 3
lifts, its subject for approval by consultant, the joint shall be tho roughly cleaned.
For Slab & Girder
1. The pouring of the slab and girders shall be at the same time, first girders then slab.
2. If the joint is required, especially for Footing which will be connected to SOG, the joint shall be
located at the soffit of the slab extend 2-3cm.
3. Provide lower size of the vibrator to accommodate the spacing of the bars for particular girders if
needed.
4. The construction joint shall be L/3 from the length of the span on the shorter aspect.
5. All the details shall in compliance with the structural specification as well, or stated otherwise.
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1. The pouring shall be continuously for each floor.
Finishes
All finish and elevation shall be monitor by survey team especially for slab and concreting
engineer shall monitor the finishing work in accordance with structural specification.
Curing and Protection
The curing shall be proceed after 8hour from the completion of pouring daily and last 7 days, since
the concrete reach the final setting strength, no activities will be allowed for the newly casted area.
Curing can be burlap sack with water or water only just ensure area shall be watered 3 times a day or
using a concrete compound just ensure material is approved with consultant.
In case of the rain during pouring, provide polyethylene sheets to isolate the water to ensure the
quality of the concrete.
The usual problems analysis and precautionary measures
Honeycombs
Problem analysis: The pouring of each layer is too thick imposing more than the specified thickness
(30-40cm) or lack of vibration; the gap on the formworks will lead such problems; the spacing of
rebar too close result in the concrete cannot flow down.
Precautionary measures: Use the proper aggregates to fit to the pouring area in conjunction with the
verification of the formworks carefully to prevent the gaps particularly at the bottom of the forms.
Control the vibration strictly like indicated in this method.
Rectification Work: Contractor will submit methodology for remedial works accordingly.
Rebar exposure
Problem analysis: Movement of the spacers while pouring or the spacing of the spacer too big result in
the rebar contact the formworks; lacking of vibration at bottom also be the cause of exposure.
Precautionary measures: Provide sufficient spacers and tie it to the bottom bar, ensure the vibration
reach the bottom layer.
Rectification Work: Contractor will submit methodology for remedial works accordingly.
Pitted surface
Problem analysis: Early stripping of the forms, or lack of form oil result in the concrete stick to the
phenolic board.
Precautionary measures: Strip the forms as per requirements: side forms—24hours after pouring, the
forms for slab—7days upon pouring; provide form oil always for the installed phenolic board.
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Foreseen/unforeseen holes
Problem analysis: The area where with thick rebars that the aggregates cannot penetrate but still
continues pouring. Or without/lack of vibration.
Precautionary measures: Provide concrete with proper aggregates, QA/QC monitor the pouring with
sufficient vibration.
Rectification Work: Contractor will submit methodology for remedial works accordingly.
Gaps and slag layer
Problem analysis: The uncleaning of the construction joint or no grout applied prior to pouring.
Precautionary measures: Clean the constsuction joint and provide grout for each pouring.
Safety
Ensure that adequate access and working platforms are in place for the concreting gang and that toe
boards and guardrails are provided.
All workers should wear appropriate Personal Protective Equipment (PPE) while working.
Make sure that housekeeping is conducted regularly to avoid any accident due to poor housekeeping
management.
Permit to work shall be applied to monitor and identify possible hazard in the activity.
Safety officer, Engineer and foreman shall give awareness to his/her worker regarding site hazard.
Responsibilities
Site Engineer – Oversee the execution of the projects, which involved constant interaction with
construction workers and safety of the structures and must make informed decision regarding the
reliability and risk.
QA/QC Engineer – To check and ensure the concrete mix delivered is accordance with structural
specification. QA/QC Engineer shall make documentation process for any inspection done with
consultant.
Safety Officer – To ensure all necessary platforms and PPE’s shall in place. To eliminates all hazard
in the area and prevent the safety of all worker.
