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DYNAMISM IN CONCRETE INGREDIENTS WHILE IN GREEN STATE
| 题名： | DYNAMISM IN CONCRETE INGREDIENTS WHILE IN GREEN STATE |
| 正文语种： | eng |
| 作者： | Dhrubajyoti Bhattacharya;Amitabha Datta |
| 作者单位： | Macron Technology Pvt. Ltd. Kolkata;Macron Technology Pvt. Ltd. Kolkata |
| 摘要： | 'Concrete' is a very common term in Civil Engineering. It is a composite material composed of fine and coarse aggregate bonded together with a fluid cement (cement paste) that hardens (cures) over time forming a solid mass of requisite strength. The basic materials of concrete are Cement; Water; Stone and Sand. Other materials like Plasticizer, Silica Fumes, Fly Ash etc., can also be used additionally based on specific requirements or conditions. Basic design concept of concrete is to minimize the voids of the graded ingredients, maintaining the workability and binding the ingredients by cement, reacted with water. Concrete, immediately on production, remains in viscous state. This state is known as the green state, that is, plastic and malleable stage. In its simplest form, concrete is a mixture of cement-water paste and requisite aggregates. The paste (slurry) composed of cement and water, coat the surface of the fine and coarse aggregates, through a chemical reaction called hydration. The cement paste/ slurry harden along with aggregates and gain strength to form the solid mass known as concrete. Plasticity of cement slurry in concrete decreases due to increase of viscosity. Viscosity increases mainly for -1.Reaction of cement with water. 2.Finer particles of sand, getting mixed with cement slurry, increases the viscosity. The Plasticity is inversely proportional to the viscosity. All activities related to 'dynamism' amongst the ingredients of green concrete are effective for control of segregation, workability and compaction mainly. Dynamism in green concrete can primarily be analysed in 5 (five) stages till the concrete gets initially set (attains initial setting). 1.Manufacturing requisite concrete at batching plant, carriage by transit mixers, pumping by concrete pump and finally pouring at locations. 2.Pouring concrete at location, immediate and simultaneous vibration by standard mechanical vibrators, tamping etc. 3.Finishing of top layer concrete surface. 4.Slippage in form works or in supports may create movement in concrete while green. 5.Transmission of external vibration to concrete. All the aforesaid stages of dynamism in concrete ingredients are normal phenomenon. But excessive or un-necessary dynamism in green concrete may also damage the quality of the concrete. Optimisation of dynamism in concrete ingredients and time management in totality is the basic objective of concreting. Analysis of optimisation of such movements is also made with its merits and de-merits in concrete quality. This paper is basically a technical description with the analysis of a continuous run of concrete mass from its birth to formation of solid mass, when the ingredients come to rest. This rest indicates rest of the ingredients of concrete, but not of the concrete mass as a whole. In other words, this paper is a background technology of concrete while it would be in dynamism mode. |
| 出版年： | 2023 |
| 期刊名称： | Indian Highways |
| 卷： | 51 |
| 期： | 8 |
| 页码： | 43-57 |
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