Concrete NZ Readymix members place onus on quality

Concrete NZ’s Readymix Sector Group strives to research, develop, promote and protect the interests of the ready mixed concrete industry by implementing a range of targeted initiatives.

The Group’s areas of activity include representing the industry before Government, disseminating technical information, participating in standards development, offering health & safety advice, and first and foremost ensuring members maintain a high standard of quality control.

Concrete Quality Scheme

The Group’s members can choose to have their concrete plants audited by the Plant Audit Scheme as defined in NZS 3104:2003 Specificati on for Concrete Production.

The Plant Audit Scheme provides a thorough audit of a ready mixed concrete plant’s own quality system.

Audits are carried out by the Plant Audit Committee of five or more registered engineers. The committee is resourced to conduct reviews to a high and consistent standard throughout New Zealand.

The Scheme’s operations are carried out under a quality assurance programme certified to ISO 9001 and audited by Bureau Veritas (NZ) Ltd.

Without the scheme, purchasers and specifers would be faced with a costly and time-consuming audit of concrete quality for each construction project.

What the scheme requires

Compliance with NZS 3104 and the relevant parts of related documents is mandatory under the Scheme, along with an appropriately qualified employee to perform concrete testing at each plant, as well as a plant engineer who is either a chartered professional engineer or a registered engineering associate.

Records must be maintained, with the following original records retained on-site to provide an audit trail confirming the test records analyzed are correct and complete:

• The original day sheet compiled by the batcher showing each load sampled
• The original technician’s record of tests carried out on samples referenced to the batch record
• The original summary of results forwarded to the plant engineer, referenced to the above test and batch reports
• An annual report from the plant engineer to the Plant Audit Committee (and at other times should they require it) on the performance of the plant, and quarterly reports on the frequency of sampling and testing of concrete
• On-site audits of plant performance by an auditing engineer appointed by the committee, some without prior notice

Specific benchmarks audited

Plants report quality performance data to the Committee annually and are subject to an annual review of data, together with an on-site audit every second year. Among performance criteria audited are:

• Mean concrete strengths and coefficients of variation
• Aggregate quality by testing and monitoring
• Weigh scale calibration and accuracy
• Mixer efficiency tests
• Laboratory equipment calibration
• Production and testing record keeping
• Technician training
• Plant operator performance.

Maintaining an audit certificate

In addition to the specific benchmarks audited, the frequency of testing within each quarter year must be submitted to the Plant Audit Commitiee.

Failure to maintain testing requirements can result in the withdrawal of an Audit Certificate. Certificates of Audit are issued for a period not exceeding 12 months.

Where plants fail to meet the criteria, their Audit Certificate is removed. It is necessary for such plants to resubmit to an initial reassessment with at least 30 results indicati ng compliance with NZS 3104.

When using concrete from unaudited plants, the purchaser is responsible for the implementation of the audit process required by NZS 3104 to ensure compliance with the NZ Building Code.

A full list of audited plants is available on the Scheme’s website:

www.rmcplantaudit.org.nz.