The ability of concrete to provide structural support, facilitate water and solute movement, and ensure durability can be measured through its bulk density. This parameter refers to the mass of freshly mixed concrete required to fill a container of a particular unit volume. By determining the bulk density of concrete, it is possible to calculate the yield of concrete per cubic meter. This information is essential for assessing the effectiveness of concrete as a building material and ensuring that it meets the necessary standards for use in construction projects. Therefore, understanding the bulk density of concrete is crucial for engineers, architects, and other professionals involved in the construction industry.
Procedure for Bulk Density of Concrete as per IS 1199
Apparatus
The context provided describes two objects, a tamping rod and a cylindrical measure. The tamping rod has a length of 38 cm, while the cylindrical measure has an inner diameter of 250 mm, an outer diameter of 280 mm, and a capacity of 0.01 cubic meters (or 10 liters).
The tamping rod is a tool commonly used in construction and engineering projects to compact soil, concrete, or other materials. Its length of 38 cm makes it a relatively short tool, which may be useful in tight spaces or for smaller projects. The tamping rod is typically made of steel and may have a pointed or flat end to help with the compaction process.
The cylindrical measure, on the other hand, is used to measure the volume of materials such as sand, gravel, or concrete. Its dimensions of 250 mm inner diameter and 280 mm outer diameter indicate that it has a relatively thick wall, which may make it more durable or resistant to deformation. The capacity of 0.01 cubic meters (or 10 liters) means that it can hold a relatively small amount of material, which may be useful for smaller projects or for measuring small quantities of materials.
Test Procedure
The cylindrical measure jar is used for measuring freshly mixed concrete. It is compacted by using a tamping rod, where each layer of the concrete is 50 mm thick and is compacted with a minimum of 60 strokes. The compaction process can be done by using an electric or pneumatic hammer, tamping rod, or a suitable vibrating table, until the desired level of compaction is achieved. The exterior surface of the cylinder is tapped smartly 10 to 15 times to eliminate any large air bubbles that appear on the surface of the compacted layer.
Once the concrete is consolidated, the top surface of the measure jar is struck-off and finished smoothly with a flat cover plate, ensuring that the measure jar is level full. Any excess concrete is then cleaned from the exterior of the measure jar to prevent inaccuracies in measurement.
The filled measure jar is then weighed (W) to obtain the weight of the concrete.
Fig 1: Cylindrical Measuring jar for determination of bulk density of concrete.
Calculation
The density of concrete, denoted by W1, is a measure of the weight per cubic meter of fully compacted concrete. To calculate this density, the weight of the fully compacted concrete in a cylindrical measure is divided by the capacity of the measure in kilograms per cubic meter. This formula is expressed as W1 = W/0.01.
On the other hand, the yield of concrete, represented by V2, is a measure of the volume of concrete produced per cubic meter. In other words, it refers to the amount of concrete that can be obtained from one cubic meter of the raw materials. The yield of concrete is an important parameter in the construction industry as it determines the amount of concrete needed for a given project.
The given context provides a formula for calculating the weight of various components in a mixture for making concrete. Specifically, the formula involves determining the weight of cement (Wc) in kilograms, the weight of fine aggregate (Wf) in kilograms, the weight of coarse aggregate (Wca) in kilograms, and the weight of water (Ww) in kilograms. These weights are essential in ensuring that the resulting concrete mixture has the desired properties and strength.