This article outlines the testing procedures for concrete blocks used in infrastructure projects and provides detailed insights into the testing options available for both tailored precast solutions and excess concrete blocks.
Introduction
In large-scale infrastructure projects, ensuring the quality and integrity of concrete blocks is paramount. Clients often require testing procedures to guarantee the reliability and safety of the construction materials used. Envirocon, through our Tailored Precast Solutions offering, can provide comprehensive testing services that are compliant with the relevant standards.
1. Compliance with NZS 3112: Part 1
When required by a client, Envirocon ensures that concrete blocks manufactured for specific projects comply with NZS 3112: Part 1, a standard that sets the guidelines for precast block manufacture. For repetitive small pours, such as precast concrete barrier pours, undertaken on a regular basis, the testing regime is agreed with the Designer at least two weeks in advance of the pour. Unless noted otherwise, compressive strength testing is undertaken on three standard cylinders made from each of the first five pours of any one concrete mix. Subsequently, three standard cylinders are made from every fifth pour. Moreover, at least three standard cylinders are tested in an IANZ registered laboratory each day of pouring.
Concrete compressive strength is determined from specimens moulded, cured, and capped as necessary, and then tested in accordance with NZS 3112 in an IANZ registered laboratory. A record is maintained for every sample taken for the preparation of compression test specimens for concrete acceptance. The samples are numbered consecutively, and specimens from each set of three are tested at 7 days, with the remaining two tested at 28 days. In specific circumstances, such as the need for information on early age strength for early formwork stripping, cylinders may be tested at different ages as agreed upon with the Designer on a case-by-case basis.
2. Test Reporting and Assessment
A detailed test report is prepared for each batch of concrete tests. These reports include crucial information such as the source of concrete, mix identification, specific compressive strength, project pour reference number, location in the structure, batch or truck number, time and date of placement, time of specimen preparation, slump of concrete, time and date of laboratory curing, time and date of specimen testing, and compressive strength rounded to the nearest 0.5MPa. Relevant comments regarding fractured specimens, including obvious segregation, lack of compaction, large aggregate particles, soft aggregate particles, and contaminants, are also included in the report. The full test report is supplied to the Designer within five days of conducting the 28-day tests. In cases where requested by the Designer, seven-day results are supplied within one day of being carried out. The assessment of compression test results is done in accordance with Clause 9.4, NZS 3109.
3. Additional Testing: Slump Testing and Charges
Envirocon can also provide slump testing to measure the workability of the concrete. The results ensure that the concrete mix meets the desired specifications. However, it's important to note that there are additional charges for compression and slump testing. Envirocon's sales staff consults with Production Management to determine the number of tests required based on the block pouring schedule. Testing is provided by the supplying ready mix concrete company.
Testing Options for Excess Concrete Blocks
For projects utilising excess concrete blocks, Envirocon provides two levels of quality control and testing:
1. Batch Docket Tracking
Each block is meticulously tracked against the specific batch docket, ensuring transparency in the supply chain. Additionally, all blocks have a minimum MPa rating of 20 MPa, indicating their structural strength.
2. Schimdt Hammer Tests
Upon request, Schimdt hammer tests can be conducted to determine the MPa rating of a cured block. These tests offer valuable insights into the block's strength and durability.