Concrete is a conglomerate, non-natural stone which is typically made up of cement, aggregate and water. The cement is what improves the binding properties of the concrete. The chemical reaction known as hydration occurs between the cement and the water, where the concrete changes from a plastic state to a solid-state. The compressive strength and density of a concrete-cement paste are typically affected by various parameters. This can include parameters such as water-cementitious materials ratios, use of an admixture, supplementary-cementitious materials, the cement type and more.
Curing is a process that endorses the hydration of the cement and involves a control in temperature and the moisture movements into and from the concrete. The correct curing application has a direct impact on the compressive strength and density of the concrete. The W/C (water-cement) ratio will be defined in a proportion by the mass of “free water” to the cementitious materials within the concrete mixture. The lightweight structural concrete is a type of structural concrete that features a low-density aggregate which has air-dry densities that do not exceed over 1840kg/m3.
The correct mixture of concrete must have the correct density, elasticity and strength to make sure it won’t deteriorate or crumble over a short-period of time. The most effective way to decide on these aspects would be to use a process of concrete tests.
There are a number of ways to test the strength of concrete, that includes using a rebound-hammer like the “Digital Schmidt Hammer”. This is a non-destructive method of testing records the estimation of the megapascals of the concrete. Used with GPR to determine the areas that do not feature reinforcing to avoid false readings, these hammers record and analyze the impact as well as the post-impact data that determines the estimated concrete strength.
One of the other popular methods used to test the strength of concrete it to use the Windsor probe. These techniques involve penetrating the test samples surface with the use of a steel probe. The strength of this test sample will correlate with the depth that the probe is able to reach. However, it is important to know that the strength will vary from one testing point to the next.
The 3rd method which is classified as destructive testing involves a compressive-strength test which entails applying axial loads to the concrete specimen at uniform rates until the specimen fails. This technique involves delivering core samples that are not smaller than 75 wide and 150mm in length (Ratio 2/1) and crushing the sample in order to deliver a MPa of its core. Again, GPR is a necessity to ensure the core is free from reinforcing.
Concrete Density Tests
One of the methods used to determine the density of concrete is to fill a container of a known volume up with the concrete and then to weigh it. This gives the concrete contractor an accurate idea about the volumetric-quantity of the concrete and its air content. Construction experts are also able to determine the density of concrete by using pressure meters.