This process is also called as mix design. Most popular nominal mix are in the proportion of 1:2:4.ĭesign mixed concrete are those for which mix proportions are finalized based on various lab tests on cylinder or cube for its compressive strength. Nominal mix is used for normal construction works such as small residential buildings. There are two types of concrete mixes, i.e. Concrete GradeĬoncrete is manufactured or mixed in proportions w.r.t. For reinforced concrete construction minimum M20 grade of concrete are used. For plain cement concrete works, generally M15 is used. Regular grades of concrete are M15, M20, M25 etc. Then compressive strength test is conducted to find the strength. Cube or cylinders are made during casting of structural member and after hardening it is cured for 28 days. The strength is measured with concrete cube or cylinders by civil engineers at construction site. For example, for M30 grade, the mix proportion can be 1:1:2, where 1 is the ratio of cement, 1 is the ratio of sand and 2 is the ratio of coarse aggregate based on volume or weight of materials. The first letter in grade “M” is the mix and 30 is the required strength in MPa.īased on various lab tests, grade of concrete is presented in Mix Proportions. For example, M30 grade signifies that compressive strength required for construction is 30MPa. Grade of concrete denotes its strength required for construction. Soon after mixing the components, hydration reaction starts which provides strength and a rock solid concrete is obtained. The cement paste coats the surface of the fine and coarse aggregates when mixed thoroughly and binds them. Sometimes rocks are used instead of aggregates. So, concrete can be called as a mixture of paste, sand and aggregates. Mixture of Portland cement and water is called as paste. Components of ConcreteĬomponents of concrete are cement, sand, aggregates and water. These have special properties and features which improve quality of construction as per requirement. Various types of concrete are manufactured these days for construction of buildings and structures. Admixtures or additives such as pozzolans or superplasticizers are included in the mixture to improve the physical properties of the wet mix or the finished material. There are different types of admixtures which are used to provide certain properties. are constructed with concrete.ĪCI 318 Building code requirements for structural concrete and ACI 301 Specifications for Structural Concrete are used in United States as standard code of practice for concrete construction. Various structural members such as beams, slabs, footings, columns, lintels etc. Since it is a plastic material in fresh state, various shapes and sizes of forms or formworks are used to provide different shapes such as rectangular, circular etc. This reaction helps ingredients to form a hard matrix that binds the materials together into a durable stone-like material.Ĭoncrete can be casted in any shape. When water is mixed with materials, cement reacts with water and hydration reaction starts. Adequate water cement ratio is required for production of workable concrete. Water cement ratio plays an important role which influences various properties such as workability, strength and durability. In United States, concrete strength is specified in PSI which is Pounds per Square Inch. Strength of mix is specified as M5, M10, M15, M20, M25, M30 etc, where M signifies Mix and 5, 10, 15 etc. Materials are mixed in specific proportions to obtain the required strength.
0 Comments
Leave a Reply. |