This civil engineering article focuses on the test method required for evaluating the concrete work.
Concrete construction activities should be done on the basis of the job site specifications, methods and drawings. Concrete inspection and testing should be executed by experienced personnel to ensure that requirements of the specifications, methods and drawings are satisfied.
Tests of concrete is conducted to make sure that the compliance to specifications should be performed by a certified Concrete Field Testing Technician.
If not mentioned anywhere else in the specifications and/or drawings, at least six concrete cubes should be developed and treated as a set. If not mentioned anywhere else, the cubes will be tested in the following ways :-
2 cubes at 7 days
2 at 28 days
2 held in reserve
2 at 28 days
2 held in reserve
The results obtained from the test, should be noted on a spreadsheet and in a way conformable to QC procedure: Statistical Techniques.
Unless stated otherwise in plan specifications or drawings, one set of cube should be created for each 150 cubic yards of concrete laid as defined in building codes. Minimum one set of cubes should be formed on each day concrete is laid irrespective of the quantity of concrete.
Application of QC procedures: Process Control as a guide, Contractor should fix a meeting with the subcontractor before pouring the first concrete. This meeting will be conducted so that the subcontractor can narrate his/her plans for the concrete pour along with all the areas scheduled in this section of the procedure.
Batch Plant Inspection: Contractor retains the power to examine any and all concrete batch plants which will deliver concrete to the construction site. A “walk through” inspection should be carried out before the production of concrete is started.
If it is required, examinations can be done throughout concrete production. Given below, the major inspection items for every type of batch plant inspection:
Preliminary Inspection
• Check that aggregates are loaded in exact bins
• Examine that aggregates are not polluted
• Examine that scales and measuring devices contain current calibration stickers and seem to function perfectly
• Examine that the plant contains a current local authority approval certification
• Examine that concrete trucks remain in proper working condition
• Examine that entire operation of the plant seems to be professional, systematic, relatively clean, well maintained, etc.
• Examine that batch plant operators should have adequate knowledge (verify their certificates or certifications)
• Examine that batch tickets provide crucial information (amount of hold back water, list of ingredients, batch times, size of load, indication of mix ordered, etc.)
• Examine that the plant and delivery equipment can form homogeneous concrete as per the requirements of ASTM C-94
• Make sure that the plant and delivery equipment satisfy the capacity requirements of the job
• Examine that aggregates are not polluted
• Examine that scales and measuring devices contain current calibration stickers and seem to function perfectly
• Examine that the plant contains a current local authority approval certification
• Examine that concrete trucks remain in proper working condition
• Examine that entire operation of the plant seems to be professional, systematic, relatively clean, well maintained, etc.
• Examine that batch plant operators should have adequate knowledge (verify their certificates or certifications)
• Examine that batch tickets provide crucial information (amount of hold back water, list of ingredients, batch times, size of load, indication of mix ordered, etc.)
• Examine that the plant and delivery equipment can form homogeneous concrete as per the requirements of ASTM C-94
• Make sure that the plant and delivery equipment satisfy the capacity requirements of the job
Throughout Concrete Production (if necessary):
• Examine that correct mix has been loaded into the batch plant computer
• Examine that equipment is working properly (admixture dispensers, scales, moisture indicators, etc.)
• Examine that truck counters have been reset to zero once the mixing water has been added to the mix
• Examine that water used to “wash down” the concrete truck prior to leaving the plant area does not enter the concrete mix
• Examine that the amount of hold back water is stated on the batch ticket
• Make sure that the concrete coming out from the plant will satisfy the specifications for temperature, air content and slump (testing at the plant should be conducted if required)
• Examine that equipment is working properly (admixture dispensers, scales, moisture indicators, etc.)
• Examine that truck counters have been reset to zero once the mixing water has been added to the mix
• Examine that water used to “wash down” the concrete truck prior to leaving the plant area does not enter the concrete mix
• Examine that the amount of hold back water is stated on the batch ticket
• Make sure that the concrete coming out from the plant will satisfy the specifications for temperature, air content and slump (testing at the plant should be conducted if required)
Concrete Mix Design: All proposed concrete mixes should be provided to Consultants via main contractor for verification and approval before application. The projected mixes delivered for use shall comprise of a concrete strength break history as stated in ASTM and shall include suitable test results and/or certificates of conformance on all constituents which will be applied in the certain concrete mixes.
