This Method Statement details general procedure for slab deflection testing on any kind of project or building.
Project Manager has the overall responsibility for the implementation of this method statement and shall well ensure that the Independent Testing Agency and as well as other team members are aware of the requirements of the Method Statement.
Construction Manager/ Project Engineer will ensure that the Resources are available to carry out the test as scheduled.
The Project Engineer/Site Engineer is responsible to raise inspection request & carry out the test as per approved Method Statement.
The QA/QC Engineer/ QC inspector to ensure that the test performed is in compliance with the approved method statement & checking and verifying the calibration certificates of the instrucments.
The 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. The Safety Officer is responsible to ensure that essential work permits are available prior to the commencement of the work.
Health, Safety, Environment (HSE)
The entire works will be carried out as per the guidelines established in the Project Specific HSE Plan.
Utmost importance shall be given to safety of personnel and protection of existing above /underground services. It will be ensured that the personnel involved are thoroughly aware of the Employer Safety regulations. To achieve the above the following shall also be ensured:
- Tool Box Meetings will be conducted before starting the works.
- All personnel will be provided with suitable Personal Protective Equipment.
- Required permits will be obtained from the Engineer/ authorities concerned before starting the works.
- Plant & Equipment’s shall be fully tested & certified by an independent testing agency. Copies of certificates shall be submitted to consultant engineer for verification.
- All pneumatic / lifting equipment’s including booms, slings; chain blocks etc. shall be fully tested & certified by an independent testing agency. Copies of certificates should be available at site.
Procedure for Slab Deflection Testing
Location Preparation
Testing area of first floor slab for one room to be clean on top as well as bottom.
Safety support to be prepared below the slab using support system as mentioned in below sections.
Keep all required loads away from the testing slab.
Decking
An approved system will be used as the safety support under the slab on which the deflection test is to be performed. Universal jacks with adjustable base are placed apart at spacing equal to the length of ledgers (as per design drawing-attached) starting from one corner of the room. Standards are then fixed to the jack.
The ledgers of 1.8m length are then clamped to the standards to form first decking.
The second deck of the ledgers is then clamped to standards at height 1.5 M for first and third deck of ledgers is clamped to standards at height 1 M from the second deck.
The standards must be erected in true verticality.
Bracing of standards are done.
Universal jack are then fixed on top of the standards.
A gap of 15 cm shall be provided between the slab bottom and the upper jack.
Specification: BS 8110: Part 2: 1985: Clause 9.5.
Loading Material: Bags of cement shall be used for load application.
Ultimate Load calculation
Live load = 2.0 KN/ M2
Floor Finish = 1.5 KN/ M2
The total load to be carried:
- should not be less than 1.0 times the characteristics dead load plus 1.0 times of characteristics live load i.e., = 1 x 1.5 + 1 x 2 = 3.5KN/ M2 and
- normally be greater of The sum of the characteristic dead load and 1.25 times of the characteristic imposed load i.e., = 1.5 + 1.25 x 2 = 4 KN/ M2 or 1.125 x (1.5 + 2.0) = 3.94 KN/ M2.
Total Ultimate Load = 3.5 KN/ M2 or 350 Kg/ M2
Location for deflection Gauges
The dial gauges are fixed under the structure in such a way that they are totally independent from the structure under test and don’t have disturbance at all by the vibrations/movement in the structure. These gauges must be fixed rigidly so that while showing even minor deflections in the structure when loaded.
Testing Procedure
Pre loading visual inspection is carried out to determine the presence of any type of cracks at the top of structure or at the bottom and recorded if any.
The dial gauges are fixed under the structure.
Suitable arrangement to access the dial gauges for recording the deflection at the end of every loading or unloading cycle shall be provided and care shall be taken such that the dial gauges are not touched or disturbed while taking the reading.
The test comprises of an initial load / unloads / reloads and unloads cycle.
Load stages shall be applied on to the structure incrementally up to the maximum required bearing pressure.
Minimum one hour break shall be given between two loading cycle.
Loading increment shall be about 25% of total ultimate load.
At each loading stage, the load is held constant until further deflection / movements are effectively ceased and the displacement reading stabilizes then deflection is
After each loading phase the structure shall be completely unloaded and the final deflection is taken to estimate the percentage of recovery.
At the end of the test the structure shall be carefully inspected for appearance of new or development in existing cracks in the structure.
Material Requirements
Safety support material (Any approved system)
Loading Material (50 kg Cement bags)
Plant & Equipment
5 nos. Dial gauges to the nearest 0.01mm with calibration certificate.
Telehandler for shifting loading material