Key Concrete Construction Properties

Multiple components are combined to create concrete. This heterogeneous material hardens into a mass that resembles stone. Engineers are extremely concerned about concrete because of its widespread use in the construction industry. A concrete engineer has to be familiar with its qualities in order to participate in its many uses. We have given you an overview of some of the characteristics of concrete in this post.

Concrete comes in the following varieties of strength:

a. Shear strength; b. Tensile strength; c. Flexural strength; and d. Compressive strength

Strength in Compression

Bangladesh uses two different kinds of test specimens: cubes and cylinders.

Concrete cube specimens of the required size, often measuring six inches in cube, are formed in steel or cast iron molds. Standard cubes and cylinders are tested at set ages, usually 28 days, with further tests frequently done at 1, 3, and 7 days. The standard cylinder specimen of concrete is 6 inches in diameter and 12 inches in height, and it is cast in a mold that is typically made of cast iron. Under a testing equipment, the specimens' crushing strength is evaluated. Crushing strength numbers obtained from cube tests are typically 20–30% higher than those obtained from cylinder testing.

A cylinder specimen's strength is equivalent to three-quarters of a cube specimen's strength, according British standard.

Age's impact on the strength of concrete

Concrete becomes stronger over time. Within 28 days, ordinary cement concrete achieves over 70 to 75 percent of its ultimate strength, and over 90 to 95 percent over the course of a year. In many cases, it is preferable to evaluate a concrete's compatibility well in advance of the 28-day test findings being made public. In the absence of precise information about the ingredients used to make concrete, it is reasonable to infer that the 28-day strength will be 1.5 times greater than the 7-day strength. Experiments have indicated that the extrapolation of 28 days' strength from the 7 days' strength is quite reliable, with the ratio of the 28 days to 7 days' strength for concrete made with regular Portland cement typically falling between 1.3 and 1.7, and most results exceeding 1.5; the figure below illustrates the rate of strength gain of the various types of cement concretes.

Tensile power

Tension is not strong in concrete. Ordinary concrete has a tensile strength that is between 7 and 10 percent greater than its compressive strength.

Flexural power

The tensile strength of plain concrete virtually entirely determines its flexural strength. Experiments, however, demonstrate that the modulus of rupture is far larger than the tension strength.

Simple strength

It is the actual deciding element for short columns' compressive strength. Between around half of the compressive strength for rich mixtures and about 0.8 of the compressive strength for lean mixtures, concrete's average strength in direct shear varies.


The degree of compaction has a major impact on the strength of concrete at a particular mix proportion. Therefore, it is essential that the mix's consistency allow for the concrete to be finished, placed, and transported with enough ease and without separating. A concrete is considered workable if it meets these requirements.

The following variables can affect how workable concrete is: water content, mix proportions, aggregate size, shape, grading, surface texture, use of additives, use of supplemental cementitious materials, time, and temperature.

The Slump test is typically used to infer indirectly how workable a concrete mix is.

Flexible Characteristics

Even at low loads, there is a noticeable permanent setting in concrete, which makes it not entirely elastic for all loading scenarios. At any loading stage, the deformation is not proportionate to the stress. Concrete's elastic qualities change depending on the mixture's richness and the degree of stress. The age of the concrete also affects them.


The ability of concrete to endure the conditions for which it was intended, without degrading over time, is known as durability. Concrete's internal agents or external agents originating from the environment can both contribute to its lack of durability.

There are three types of causes: mechanical, chemical, and physical.

While mechanical causes are mostly related to abortion, physical causes are caused by the effect of frost and variations in the thermal characteristics of the cement paste and aggregate.

Lack of permeability

The durability of concrete may be negatively impacted by components dissolved in solution, such as when aggressive liquids (acids) assault the material or when Ca(OH)2 is being leached out. Concrete's susceptibility to moisture and freezing temperatures is significantly influenced by its permeability. Steel will corrode in the case of reinforced cement concrete due to air and moisture penetration. This causes the steel's volume to rise, which causes the concrete to crack and spall. Concrete permeability is crucial for hydraulic and liquid-retaining constructions;


Segregation is the tendency for the coarse aggregate grains to separate from the concrete mixture. When the concrete mixture is excessively moist and lean, it increases. Additionally, it rises when quite large, coarse-textured material is utilized. The following are some ways to prevent the segregation phenomena.

i. Including tiny air-entraining agents in the mixture.

ii. Limiting the quantity of water to the absolute minimum.

iii. Every operation, including handling, positioning, and consolidation, needs to be carried out with caution.

iv. It is not appropriate to let concrete fall from great heights.


Bleeding is the term used to describe the tendency of water to rise to the surface of freshly placed concrete. Sand and cement particles are carried by rising water to the surface, where they solidify to produce a scum layer known as laitance. The following actions can be taken to check for bleeding in concrete.

i. Increasing the amount of cement; ii. utilizing more finely ground cement; iii. Making sure the mix is appropriately designed and utilizing the least amount of water; iv. Using less air entraining agent; v. Increasing the finer part of fine aggregate


When flexured, plain concrete shows signs of fatigue. The endurance limit of concrete, whose value is dependent on the number of stress repetitions, indicates the concrete's ability to withstand flexure. The maximum permissible flexural working stress in concrete pavement design is 55% of the modulus of rupture. 

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