Whether you’re building a: bridge, commercial building or another type of construction project it’s important to make sure that the materials you use provide good structural performance- in order to have a successful project delivery. Have you had your concrete tested for your locations’ safety standards?
Concrete testing is crucial for good structural performance. An important part of bridge building is testing that all materials used in these projects are tested against the appropriate standards and specifications. That raises questions about the types of testing involved, what should be done with the results and strategies which engineers, construction contractors and clients should adopt in relation to having their concrete tested. Concrete testing is about quality control and gaining assurance that the material being used conforms to the required standards and specifications.
To be used, concrete must meet the requirements of the National Construction Code (NCC), relevant Australian standards which are referenced under the NCC and any specifications which are given by clients, architects, engineers or builders. Important Australian standards in respect of concrete include AS 3600 (concrete structures) and AS 3700 (masonry structures). Methods for testing concrete are outlined in AS 1012.
Concrete is manufactured from a range of raw materials. These raw materials include cement, supplementary cementitious materials such as fly ash and ground blast furnace slag, coarse and fine aggregate (stone and sand), water and admixtures. Each of these is either derived from natural resources or is manufactured. Experts have stated that concrete’s variability arises out of variations within each of the raw materials, as well as with the different batching and delivery processes of concrete manufacturing. According to experts, the material can be separated into two classes: Normal (N class) or Special (S class). N class concrete allows the manufacturer to determine the mix proportions to achieve standard performance requirements. These include strength and slump (the two primary properties) as well as other properties such as shrinkage, and the chemical and aggregate sources. Concrete becomes S class where the designer includes additional criteria in the specification. These requirements can include limitations in cement concrete, water/cement ratio, or other properties particular to the performance requirements.
When it comes to concrete, the two main tests are the tests for compressive strength and slump tests. Compressive strength tests indicate the capacity of the concrete to support the load of the building or structure. The slump test, meanwhile, assesses the consistency of the concrete and confirms that the correct volume of water has been added to the mix before the concrete is placed within the structure.
Depending on the type of application, other types of testing may be involved. In the case of pavements, for example, the material is often tested for flexural strength to determine how the material flexes – the ability of the concrete to bend without being broken. Since concrete is known to expand or contract, with, for example, changes in temperature, materials used in some other applications such as large slab floors, testing for shrinkage (the degree to which the concrete contracts) may be performed. Once testing is done, results need to be compared with the requirements of the Australian Standards and those of the specifications.