When anticipating repair of cracks in concrete, it is important to first identify the location and extent of cracking. It should be determined whether the observed cracks are indicative of current or future structural problems, taking into consideration the present and anticipated future loading conditions. The cause of the cracking should be established before repairs(…)
Concrete Technology provides information on concrete and its properties, mix design, cracking, durability, high strength, prestressed concrete, precast concrete, fresh concrete ,hard concrete, Ready mix, SCC, special types of concrete, sulphate attack etc.
No-fines concrete is a concrete from which the fine aggregate fraction has been omitted. This concrete is made up of only coarse aggregate, cement and water.
Carbonation of concrete Structures The microstructure of concrete is such that it has capillary pores to the extent of 28%. The extent of pores depends upon quality of concrete and the presence of water at the time of mixing of concrete. Making more dense concrete with less water/cement ratio reduces the amount of pores. These(…)
The various factors which affect the performance of concrete admixtures are: 1. Type of super-plasticizer: The admixture will be more effective if molecular weight of the super-plasticizer is high. 2. Dosage: The quantity of admixture should be optimum. Excess of admixture may cause segregation or bleeding. It may also cause excessive retardation. The optimum does(…)
When concrete is permeable it can cause corrosion in reinforcement in presence of oxygen, moisture, CO2, SO3- and Cl- etc. This formation of rust due to corrosion becomes nearly 6 times the volume of steel oxide layer, due to which cracking develops in reinforced concrete and spalling of concrete starts. So, if the concrete is(…)
Ferro-cement In Construction < ?xml:namespace prefix = o /> Ferro-cement is a relatively new material consists of wire meshes and cement mortar. Developed by P.L.Nervi, an Italian architect in 1940. Widely used due to the low self weight, lack of skilled workers, no need of framework etc. Quality of ferro-cement works are assured because the(…)
The testing of concrete cores is carried out according to the ASTM Standard C 42. The diameter of core specimens for the determination of concrete compressive strength should preferably be at least three times the nominal maximum size of the coarse aggregate used in the concrete, and must be at least twice the maximum size of the coarse aggregate in the core sample.
Because precast concrete can be cast at ground level in factory conditions, it has these added features: Better Finishes: Better finishes can be obtained with precast concrete because the inside surface of the mould is kept in good condition. There is no grout loss, such as that from badly fitting formwork, which results in poor(…)