Drum Type Concrete Mixer Classification This is also called as free fall mixer or gratify mixer. In this type of mixer, concrete is mixed by lifting the ingredients with the help of fixed blades inside a rotating drum and then dropping the material by overcoming the friction between the mixture and the blades. The drum … Read more
Parameters to Consider Before Selecting Concrete Batching and Mixing Plant 1. Capacity of Plant In order to meet the requirement of project specific parameters as mentioned above, a concrete plant of right capacity should be installed. It should take into account various ingredients proposed for use in the mix like, fly ash, admixtures like plasticizer, … Read more
Concrete Mix Design – Basic Considerations The proportioning of concrete mixes consists of determination of quantities of different concrete-making materials necessary to produce concrete having the desired workability and 28-days compressive strength of concrete for a particular grade of concrete and durability requirements. Emphasis is laid on making the most economical use of available materials … Read more
Maintenance of Ready-Mixed Concrete Batching Plant For an effective production & delivery of concrete, all plant & equipment should be maintained in a clean and efficient working condition. To achieve this, checklists are used by the batching plant personnel. These checklists include daily checks, weekly checks, monthly checks and quarterly checks. Checklists must be prepared … Read more
Effect of Extreme Weather on Concrete Concrete is not recommended to be placed at a temperature above 400C and below 50C without proper precaution as laid down in IS: 7861 (Part-1 or part-2 as the case may be). IS:7861 part-1 deals with hot weather concreting and Part-2 deals with cold weather concreting. Hot Weather Concreting … Read more
Factors influencing Corrosion of Reinforcement In reinforced cement concrete construction the corrosion of reinforcement takes place due to the presence of chlorides and sulphates beyond a critical limit and when sufficient alkalies is not obtained within the concrete to maintain steel in a positive condition. The following factors are responsible for corrosion of steel reinforcement … Read more
Performance Requirements of Needle Vibrators The operational frequency of vibrator when operated in air (i.e. when not immersed in concrete) shall not be less than 100 Hz and should preferably be higher. For different sizes of needle, the optimum operational amplitude when operated in air, measured in the middle of the vibrating needle should satisfy … Read more
Aim This test method describes the procedure for determining the drying shrinkage or change in length of concrete specimen due to changes in moisture content. Apparatus A length measuring apparatus incorporating a dial gauge capable of measuring the length accurately to 0.005 mm. (see fig shown below) Drying oven capable of maintaining a temperature of … Read more
Properties of Fresh Concrete Concrete remains in its fresh state from the time it is mixed until it sets. During this time the concrete is handled, transported, placed and compacted. Properties of concrete in its fresh state are very important because the influence the quality of the hardened concrete. The fresh concrete has the following … Read more
Tremie Method of Under Water Concreting Tremie method is the most acceptable method of concreting under water. In this method a tremie pipe is inserted in the water up to the point where concrete is going to be placed. Generally the diameter of a tremie pipe varies from 20 cm to 30 cm. Depending upon … Read more