10-14-2014, 11:14 AM
Concrete Work
For RCC work, the ingredients of concrete should be in the ratio of 1:1.5:3 (cement one part, sand 1.5 parts and coarse aggregates 3 parts). All of these items are measured by volume and are best measured using a container of wood or steel. Traditionally, the size of this container would be 350x250x400 mm, which holds 35 litres. While preparing the mixture, 25 litres of water must be added per bag of cement. If the mix is prepared in a machine, it should be mixed for at least 2 minutes so that the mixture blends well with the water. If you are mixing by hand, then it is advisable to prepare a dry mix of cement and sand in a tray. After blending, when the colour appears uniform, the coarse aggregate may be added and then finally add the water.
The concrete mix should be cast before it begins to set. Normally, concreting should be completed within 30 minutes to an hour. In case of any delay, do not add any more water just to improve its flowing consistency. The casting of concrete should be done continuously, i.e., layer over layer. The mixture should be poured from a maximum height of 1.5 metres. This avoids the ingredients separating. The mixture must then be properly compacted. It is best to complete this task with a needle vibrator. If this is unavailable, an iron rod could be substituted. This is done to ensure that there are no air bubbles in the concrete, as this would weaken it.
For RCC work, the ingredients of concrete should be in the ratio of 1:1.5:3 (cement one part, sand 1.5 parts and coarse aggregates 3 parts). All of these items are measured by volume and are best measured using a container of wood or steel. Traditionally, the size of this container would be 350x250x400 mm, which holds 35 litres. While preparing the mixture, 25 litres of water must be added per bag of cement. If the mix is prepared in a machine, it should be mixed for at least 2 minutes so that the mixture blends well with the water. If you are mixing by hand, then it is advisable to prepare a dry mix of cement and sand in a tray. After blending, when the colour appears uniform, the coarse aggregate may be added and then finally add the water.
The concrete mix should be cast before it begins to set. Normally, concreting should be completed within 30 minutes to an hour. In case of any delay, do not add any more water just to improve its flowing consistency. The casting of concrete should be done continuously, i.e., layer over layer. The mixture should be poured from a maximum height of 1.5 metres. This avoids the ingredients separating. The mixture must then be properly compacted. It is best to complete this task with a needle vibrator. If this is unavailable, an iron rod could be substituted. This is done to ensure that there are no air bubbles in the concrete, as this would weaken it.