Testing for quality
The quality and consistency of our products is something we take very seriously. We operate within an approved BS EN 1917 quality system. We are one of the few manufacturers of precast concrete products in the country that can boast of having their own, purpose built, testing facility. We regularly perform a number of tests on both finished products and the materials used to manufacture these products.
Making the grade – aggregate sieve analysis
A sieve analysis, or gradation test, is a procedure used to assess the particle size distribution within aggregates. An aggregate with an acceptable particle size distribution will depend on the particular product that the aggregate is to be used for and the end use that the product is required to perform.
The gradation test is performed on a sample of aggregate and involves a nested column of sieves with wire mesh cloth. A representative weighed sample of aggregate is poured into the top sieve which has the largest screen openings. Each lower sieve in the column has smaller openings than the one above. At the base is a round pan, called the receiver.
The column is then placed in a mechanical shaker and shaken, for a specific amount of time. After the shaking is complete the material on each sieve is weighed. The weight of the sample of each sieve is then divided by the total weight to give a percentage retained on each sieve.
The size of the average particle on each sieve is then analysed to get a cut-off point or specific size range, the results of which are then recorded. The grade and quality of the aggregate is then determined.
Performance under pressure
– compression testing
Samples are taken from the concrete as it is poured into the product mould and, depending on the product being poured, cast in to a number of either 100mm or 150mm standard cube moulds. The samples are then left to cure under normal conditions. Once the samples have properly set they are removed from the moulds and catalogued with identification and batch numbers.
Cube samples are then placed in to the concrete compression apparatus and crushed to destruction. The test results indicate the maximum compressive strength of the concrete and results are recorded and filed. All the concrete used in Elite products is high strength 50N/mm2.
Proving the product – cured stock testing
We take regular cores from our products to check concrete strengths and aggregate distribution.
Daily tests are taken for aggregate moisture content, concrete hardness and reinforcement placement to ensure sufficient concrete cover to steel.
There are also several bespoke compression testing rigs to ensure product performance under specified usage conditions.