Concrete Testing Requirements for Large Commercial Pours
Concrete is a unique product when it is delivered to your construction project. It is delivered in a form that does not reflect its properties in a finished state, it’s a time sensitive product, requires care during placement and time (28 days or more) to develop its ultimate performance and strength properties. To obtain a reliable assessment of its fitness for use on a project, accurately performed sampling and testing is required.
Concrete testing procedures are stipulated in a series of Standards that specify the steps to be followed to obtain a representative sample of what is being used in your project, while enabling test results to be replicated repeatedly during the project to generate a creditable database of strength test results to provide the Designer confidence that what he or she specified, to meet design assumptions, have been delivered to site.
Test data gathered by experienced Allied Concrete Technicians is then used to manage material suppliers (aggregates, water, cement and any admixtures that were selected or specified) to ensure that the concrete meets the strength requirements of the specific concrete strength (Grade Strength) selected by the Designer.
"Allied Concrete test over 1300 different loads of concrete every month to maintain stringent quality control over concrete production."
NZS 3104 is the standard that nominates the safety margin that all reputable ready-mix suppliers need to apply to the nominated concrete strength, to ensure that the concrete supplied meets the strength requirements for the project. NZS 3104 establishes rejection criteria for low strength test results, and the NZRMCA Plant Audit rules defines actions necessary if there is a suspected low-test result.
The nature of concrete is such that for every error or departure from the Standard there is a drop in concrete strength at the time of test. Adhering to all testing procedures is critical for a representative sample result. Allied Technical staff have observed that samples taken on site and then returned to the laboratory also exhibit significant strength loses, even when sampled in accordance with NZS 3104. This is because site samples can be kept at a much wider range of temperatures than those in a laboratory.
Allied Concrete test over 1300 different loads of concrete every month to maintain stringent quality control over concrete production. Allied do not use site derived test data as part of their regular testing regime for this reason and encourage their customers to accept test data that forms part of the NZRMCA Plant Audit Scheme, an independent and rigorous audit of quality systems in place at a ready mixed concrete plant to meet the requirements of ISO 9002, in which all Allied Concrete plants comply and exceed annually.