Shrinkage of hardened concrete is influenced by various factors in a similar manner as that of creep under drying conditions. These factors are: 1. Aggregate Content 2. Quality of Cement Paste 3. Water Content 4. Properties of Cement 5. Chemical Composition of Cement 6. Effect of High Alumina Cement 7. Entertainment of Air 8. Effect of Admixtures 9. Effect of [...]
The strength can be defined as the ability to resist force. With-regard to concrete for structural purposes it can be defined as the unit force required to cause rupture. Strength is a good index of most of the other properties of practical importance. In general stronger concretes are stiffer, more water tight and more resistant to weathering etc. Nature of [...]
In this article we will discuss about:- 1. Definition of Modulus of Elasticity 2. Determination of Modulus of Elasticity 3. Measurement of Strains in Concrete 4. Types of Young Elastic Modulus 5. Relation with Strength 6. Factors Affecting 7. Uses. In the theory of reinforced concrete, it is assumed that concrete is elastic, isotropic and homogeneous and obeys Hooke's law. [...]
In this article we will discuss about:- 1. Tensile Strength of Concrete 2. Flexure Strength 3. Impact Strength 4. Resistance to Abrasion of Concrete 5. Fatigue Strength. Tensile Strength of Concrete: The actual tensile strength of cement paste or similar brittle material as that of stone is very much lower than the theoretical strength estimated on the basis of molecular [...]
Concrete undergoes deformation due to the applied stress. But in addition to this, volume changes due to shrinkage, and temperature variations also take place. In practice these variations are of considerable importance as these movements partly or wholly are restrained and thus they introduce stress. These volume changes affect the long term strength and durability of concrete. Though shrinkage, swelling [...]
In this article we will discuss about:- 1. Definition and Significance of Durability 2. Effect of W/C Ratio on Durability 3. Causes of Non-Durability. Definition and Significance of Durability: The durability of cement concrete can be defined as its ability to resist weathering action, chemical attack, abrasion or any other process of deterioration. A durable concrete should maintain its original [...]
In this article we will discuss about the tests performed to determine the tensile and flexural strength of concrete. Tensile Strength of Concrete: Splitting Tension Test: The splitting tension test was developed in Brazil in 1943. Some times this test is also called as Brazilian test. However at about the same period this test was also developed in Japan independently. [...]
The factors that are significant which influence the core compressive strength of concrete are: 1. Moisture and Voids 2. Length/Diameter Ratio of Core 3. Diameter of Core 4. Position of Cut out Concrete in Structure 5. Direction of Drilling 6. Effect of Age. Factor # 1. Moisture and Voids: The moisture condition of the core influences the measured strength. It [...]
Similar to workability, the rheological properties of fresh concrete are affected by the mix proportions, namely the amount of each constituent, properties of the ingredients, the amount of mixing, the presence of admixtures, and the time elapsed after mixing. Though these factors have properties of fresh concrete, but here these factors are discussed in relation to their influence on the [...]
Sulphates are chemical salts, which dissolve in water forming solution. Sulphates are found in most of the soils as calcium, potassium, sodium and magnesium sulphates. Out of these sulphates the solubility of calcium sulphate is low. Due to less solubility of calcium sulphate in water, ground contains less calcium sulphate than others. Ammonium sulphate usually is present in agricultural soil [...]