Concrete in Compression (ACI 318)

Concrete in Compression It is generally accepted that the behavior of a reinforced concrete member under load depends on the stress–strain relationship of the materials, as well as the type of stress to which it is subjected. With concrete used principally in compression, the compressive stress–strain curve is of primary interest. The compressive strength of concrete …

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Effect of Age on Concrete Strength

effect of age on concrete strength

Effect of Age on Concrete Strength The strength versus gel/space ratio relationship has a general application because the amount of gel present in the cement paste at any time is itself a function of age and type of cement. The latter relation thus allows for the fact that different cements require a different length of …

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Cement Setting and False Set

concrete

Cement Setting Setting of Cement, or cement setting, is a term used to describe the stiffening of the cement paste. Setting refers to a change from a fluid to a rigid stage. Although, during setting, the paste acquires some strength, for practical purposes it is important to distinguish setting from hardening, which refers to the gain …

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What is Concrete Durability?

Concrete structures are designed to achieve a certain service life. For instance, bridges are designed to achieve a 100 – 120 years of service. However, concrete life can be compromised or ended before the specified life. A durable concrete will guarantee the achievement of structures with long life. In other words, it can last longer and withstand …

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Types of Concrete Admixtures

Before stating the types of concrete admixtures, let us start first by the definition of “Admixtures”. According to ACI Committee 116, an admixture is ‘a material other than water, aggregates, hydraulic cement, and fiber reinforcement, used as an ingredient of a cementitious mixture to modify its freshly mixed, setting or hardened properties and that is added …

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How to Reduce Bleeding in Concrete?

Bleeding is the development of a layer of water at the top or surface of freshly placed concrete. The cause of bleeding is the settlement of solid particles (such as cement and aggregates) and the simultaneous upward migration of water. It is worth noting that some bleeding is normal and will not reduce the quality concrete if it …

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Workability of Concrete and the Factors Influencing its Value

The term “workability of concrete” refers to the ease with which freshly mixed concrete is placed, consolidated and finished without segregation. According to the ASTM, workability is defined as “the property that determine the effort required to manipulate a freshly mixed quantity of concrete with minimum loss of homogeneity”. Factors Affecting the Workability of Concrete It is …

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