What is Density of Concrete? Cement and Aggregate Density

What is Density of Concrete?

The density of concrete is a measure of its unit weight. Density is simply a mass to volume ratio. Perhaps the easiest and most accurate way to calculate the density of concrete is to measure some into a known volume container and weigh it. The density of a concrete masonry unit is expressed as the oven-dry density of concrete in pounds per cubic foot (lb/ft3 [kg/m3])

Concrete is a mixture of cement, sand and coarse aggregates, water, and sometimes some supplementary materials like fly ash, slag, and various admixtures.

Normal Weight Concrete Density

A normal weight concrete  density is  2400 kg per cubic meter or 145 lbs per cubic foot((lb/ft3 [kg/m3]))  (3915 lbs per cubic yard).

The unit weight of concrete (density) varies depending on the amount and density of the aggregate, the amount of entrained air (and entrapped air), and the water and cement content.

The weight of the Concrete

The substantial weight can vary depending on the air and moisture content it contains.

Density of Cement

Cement density (weight) can be 830 – 1650 kg per cubic meter or 52 – 103 lbs per cubic foot.

The cement that is pneumatically loaded into silos is less dense, while cement that has been stored and exposed to vibration, like being transported, is denser. The rule of thumb is to consider that a 94 lb. bag of cement will make one cubic foot when it is freshly packed.

Lightweight Concrete Density

The lightweight concrete density is 1920 kg per cubic meter or 116 lbs per cubic foot (3132 lbs per cubic yard).

Lightweight concrete weighs less because it is made with an aggregate called pumice, a naturally light mineral.

One value of understanding, knowing, and monitoring concrete density is checking strength by using test cylinders. A reduced density of normal concrete almost always means higher water content, which means lower strength concrete.

Concrete must have to ensure satisfactory compressive strength and durability. Its density highly influences the mechanical properties of concrete.

A denser concrete generally provides higher strength and fewer number of voids and porosity. Smaller the voids in concrete, it becomes less permeable to water and soluble elements.

So water absorption will also be less and better durability is expected from this type of concrete. An experimental program conducting on compressive strength, density, absorption capacity, and percent voids of hardened concrete is described.

The variation of these properties with the maturity of concrete was the main focus of this experiment. A comparison is made between two types of concrete’s property test results. One of them is lightweight concrete made with crushed brick  as primary coarse aggregate.

Another type of concrete is a denser one, made with crushed stone as primary coarse aggregate. The comparisons on test results are presented with respect to time.

It was observed from the experiment that strength and density increase with the maturity of concrete, and percent void and absorption capacity decreases with time. Better results were obtained from stone aggregate concrete than brick aggregate concrete in cases of all of the tests.

Concrete, an artificial stone-like mass, is the composite material that is created by mixing binding material (cement or lime) along with the aggregate (sand, gravel, stone, brick chips, etc.), water, admixtures, etc. in specific proportions. The strength and quality are dependent on the mixing proportion.

High Density Concrete

High density concrete is a concrete having a density in the range of 6000- 6400 kg/cubic meters.  High density concrete is also known as Heavy weight concrete.

The High density concrete is mainly used for the purpose of radiation protection/shielding, for counterweights and other uses where high density is required. The high density concrete has a better shielding property and therefore  it can protect harmful radiations like, gamma rays, X-rays and neutrons.

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