Manual plastering
- 2. What is Plaster? Plaster is a building material used for coating walls and ceilings. Sand-cement plaster is used extensively in building work as a decorative or protective coating for concrete and masonry walls . Plaster is one of the oldest building materials, the most primitive form was mud plaster, used to hold together structures made of branches or wood for example. Today internal plastering is used more as a way of smoothing out surfaces and preparing them for decoration, it also adds strength to the wall or ceiling and helps seal together building materials.
- 3. Materials Required Cement Sand Water Masonry Trowel Smoothening Trowel Metal Float Measuring Tape Plumb Bob Mud Pan Chicken Mesh Hairs Recron Fibre6/9/2014
- 4. Know your Materials! 6/9/2014 Cement Sand Recron Fibre Final Mortar mix (made from mixing Cement,sand,water and recron fibre) present in a Mudpan
- 5. Procedure 1. After the masonry wall made of bricks or aerated blocks is ready, it is first cleaned properly before starting the plastering wall using brushes and trowels. 6/9/2014 Brick wall Aerated Block wall
- 6. 2. The scaffold is prepared for provide the labour a platform to stand and materials required for plastering are transported at the site of plastering. 3. Cement Mortar is prepared by mixing cement and sand in ratio specified. For ex-In our case the ratio specified is 1:4.So we use 1 unit volume of cement for 4 unit volume of sand. The normal cement bag is 50 kg in mass 0.035 m3. So we prepare a container of volume 0.035 m3 and pour 4 containers of cement. 6/9/2014 Scaffolding Container for measuring sand
- 7. 4. Recron fibre is added to it as it helps in avoiding cracks in plaster. We use 125 gm fibre for 1 bag of cement. 5. Water is added .As per as IS standards 0.025 m3 of water is added to 1 bag of cement, but at site it is subjected to the workability requirements. Note: The mortar mix should be used within it’s initial setting time = 45 min 6. Chicken mesh is used at the joint of Lintel and masonry wall to avoid cracks at the joint in future. 6/9/2014 Chicken Mesh Labour putting Chicken Mesh
- 8. 7. Making of Level Pads : Level pads are used for maintaining the thickness of plaster coat required.They act as a reference for checking thickness of plaster. - First we lay a reference line using rope and nails - We check the distance of wall from this reference line and note it(say D1) - Now we put the mortar of wall and smoothen it. We now calculate the distance between the reference line and level pad’s surface(say D2) D1-D2= Thickness of coat required - If the thickness doesn’t matches then adjust the thickness of level pad - Now make one level pad above the first level pad and check if it’s in line with the help of plumb bob.It might happen the wall is not exactly vertical either inwards or outwards which can be checked with help of plumb bob hence thickness of level pad can be adjusted accordingly. 6/9/2014
- 9. 6/9/2014 Labourers checking the distance of wall from reference line Making of level pad
- 10. 6/9/2014 Level Pad Labourers checking distance of level pad from reference line
- 11. 6/9/2014 Plumb Bob No gap between wall and plumb bob, signifying that wall is straight Gap between wall and plumb bob indicating that wall is “Inwards”
- 12. - After checking for vertical alignment of level pads, check for horizontal alignment with the help of a rope( pin a rope parallel to the first level pad also vertical with adjacent wall).Adjust the level pads in thickness if the wall is tilted sideways. 6/9/2014 Checking for vertical alignment of pads Horizontally laid level pads
- 13. 8. After making the level pads, wet the wall with help of diluted cement water slurry to provide better adhesion with mortar. 9. The mason then applies the mortar on the walls with the help of trowel. 6/9/2014 Masonry Trowel
- 14. 10. With the help of metal float the mason creates a smooth reference plain of required thickness by pressing the float against two vertical level pads.The additional mortar is scrapped of with the help of float. 6/9/2014Metal Float Reference Plain
- 15. 11. The finishing of the plaster is done with the help of finishing trowel. 6/9/2014 Removing excess material with float Finishing Trowel
- 16. 12. After smoothening, the plaster is roughened up for providing better adhesion in case of a second coat. A hair is used for it or sometimes labour also uses chicken mesh only. 6/9/2014 Hair used for roughening surface Rough Plaster coat
- 17. Challenges in Manual Plastering 1. A proper hierarchical system is not present on site. Ideally the engineer should teach the supervisor as in what he requires and the supervisor should convey it to the labour.But due to lack of number and agility of supervisors the engineer has to do that part. 2. Due to above point, the engineer is not able to perform his main task efficiently which is Quality Checks .Two examples in this regard are:- (a) Amount of water is not as per as standards and the labour puts water according to his will. This in turn degrades the quality of the mix. (b) Checking of the thickness and alignment of level pads is not proper which leads to lack of uniformity of plaster. Plumb checking is not also proper. 3. The mortar is not used within it’s initial setting time of 45 Minutes and sometimes used beyond 4 hours. This again degrades the quality. 4. The floor is not cleaned properly before starting plaster and sacks are not always laid down to collect the fallen mortar. So the mortar gets mixed with the mud and is then used again which has serious implications on the quality. 6/9/2014
- 18. 5. Due to lack of supervision the labour is idle for a lot of time.Also due to the fear of loosing labour the supervisor also doesn’t say much to them as his performance is judged by the way he handles the labourers.This leads to slow pace of work. 6/9/2014 Fallen Mortar getting mixed with mud