Used in all types of construction from foundations to garden walls to countertop, concrete is a simple and basic mixture of aggregates and paste. The aggregates used in creating concrete are sand and gravel while the paste consists of water and cement. To establish your concrete’s consistency, air content and strength, you can conduct different tests.
The consistency of the concrete determines how well the concrete will pour, handle and compact. The measurement used to gauge the consistency of concrete is called slump. Problems with consolidation and mortar loss can occur if your slump is too low (runny) or too high (thick). To perform the slump test, take a sample of your recently mixed concrete and pack it into a cone 2 inches high, 8 inches wide at the bottom of the cone and 4 inches at the top which must be open. Level the concrete at the top rim of the cone then lift it so the bottom of the cone remains unsupported. The distance between the top of the cone top and the level the concrete settles at gives you your slump. Compare this number with the slump value on the package your concrete mixture came in to find out if your concrete contains good consistency.
Air Content Test
The air content of concrete determines how it will fare when frozen by cold weather then thawed by warmer weather. Since air is lost during transportation, consolidation, placement and finishing, the air content test only tells you the air amount in recently mixed concrete. There are three different devices for performing this test. The pressure type B meter applies pressure to a sample of your concrete to condense the entrained air; it then uses the change in air to determine the air content of the concrete. You can also use a volumetric air meter. This device removes air from a determined volume of concrete. You can compare the new volume of the sample to the rest of your concrete to determine air content. Finally you can use an air indicator kit. Place a sample of concrete into the provided vial, then add alcohol. The change in the alcohol level indicates the concrete’s air content.
Compressive Strength Test
Compression test lets you know the strength of your concrete once it hardens. The compressive strength test is performed by assessing the force needed to break concrete cylinders in varying levels of hardness. When using concrete for buildings or other structures, the compressive strength of the concrete must comply with the Building Code Requirement for Reinforced Concrete.