Module 3-b Plastering Civil Engineering PDF

lOMoARcPSD|52327130 Module 3-b - Plastering Civil Engineering (Camarines Sur Polytechnic Colleges) Scan to open on Studocu Studocu is not sponsored or endorsed by any college or university Downloaded by Valshca Balani (balanivalshca@gmail...

lOMoARcPSD|52327130 Module 3-b - Plastering Civil Engineering (Camarines Sur Polytechnic Colleges) Scan to open on Studocu Studocu is not sponsored or endorsed by any college or university Downloaded by Valshca Balani ([email protected])  lOMoARcPSD|52327130 3 MASONRY SURFACE FINISHING Lesson 3-b: PLASTERING Learning After finishing this module, students are expected to: Outcomes 1. Learn to prepare the wall surface for plastering. 2. Establish the vertical and horizontal alignment. 3. Determine the thickness for plastering. 4. Observe correct procedure during plastering. Topics 1.1. Overview 1.2. How to plaster wall surface Note: Read and study about 1. Types and Procedures in Plastering References: Simplified Building Construction Estimates, Max B. Fajardo Jr. Estimating Bill of Materials, Tagayun and Associates. Introduction to building construction Warm Up: Give three things that you expect to learn in this module. 1. _________________________________________________________ 2. _________________________________________________________ 3. _________________________________________________________ _____________ Pre-Test: Please answer the following questions; 1. Discuss the procedures in wall plastering 2. What is the advantage of wetting the surface before applying the Mortar. 1 Masonry - Camarines Sur Polytechnic Colleges Downloaded by Valshca Balani ([email protected])  lOMoARcPSD|52327130 3 MASONRY SURFACE FINISHING HOW TO PLASTER A CONCRETE WALL Plastering is the process of applying mortar to a concrete surface to produce a plain and smooth finish. Plaster is a thin layer of mortar applied over the masonry surface and it acts as a damp-proof coat over the brick masonry work. Plastering is one of the most fundamental tasks in masonry. It requires knowledge of the needed materials, tools and their use and the steps in plastering a wall. Plastering also provides a finished surface over the masonry that is firm and smooth hence it enhances the appearance of the building. The primary objectives of plastering are to protect the surface from atmospheric influences, to cover the defective workmanship in masonry, to conceal porous materials, and to provide a suitable surface for painting. Mortar is a mixture of cement and screened sand which is use for plastering/finishing wall. Types of plastering 1. Lime plaster – a type of plastering which uses lime or hydraulic lime that hardens slowly and damage easily due to absorption of moisture. 2. Cement plaster – a type of plastering which uses cement and sand as main material for wall surface. It is hard and durable than any other plaster. 3. Stucco plaster – a decorative type of plastering which gives an excellent finish and can be compared to marble finish in terms of smoothness and elegance. 4. Mud plaster – a type of plastering which uses mud as main materials for finishing wall surface and the cheapest. Procedures of Plastering Work A. Preparation of Surface for Plastering 1. Keep all the mortar joints of wall rough, so as to give a good bonding to hold plaster. 2. Roughen the entire wall to be plastered. 2 Masonry - Camarines Sur Polytechnic Colleges Downloaded by Valshca Balani ([email protected])  lOMoARcPSD|52327130 3 MASONRY SURFACE FINISHING 3. Clean all the joints and surfaces of the wall with a wire brush, there should be no oil or grease etc. left on wall surface. 4. If there exist any cavities or holes on the surface, then fill it in advance with appropriate material. If the surface is smooth or the wall to be plastered is old one, then rake out the mortar joint to a depth of at least 12 mm to give a better bonding to the plaster. 5. Wash the mortar joints and entire wall to be plastered, and keep it wet for at least 6 hours before applying cement plaster. 6. If the projection on the wall surface is more than 12 mm, then knock it off, so as to obtain a uniform thickness of wall surface. This will reduce the consumption of plaster. B. Groundwork for Plaster 1. In order to get uniform thickness of plastering throughout the wall surface, first fix dots on the wall. A dot means patch of plaster of size 15 mm * 15 mm and having thickness of about 10 mm. 2. Dots are fixed on the wall first horizontally and then vertically at a distance of about 2 meters covering the entire wall surface. 3. Check the verticality of dots, one over the other, by means of plumb- bob. 4. After fixing dots, the vertical strips of plaster, known as screeds, are formed in between the dots. These screeds serve as the gauges for maintaining even thickness of plastering being applied. a. Mixing b. mortar paste 3 Masonry - Camarines Sur Polytechnic Colleges Downloaded by Valshca Balani ([email protected])  lOMoARcPSD|52327130 3 MASONRY SURFACE FINISHING C. Applying Under Coat or Base Coat In case of brick masonry the thickness of first coat plaster is in general 12 mm and in case of concrete masonry this thickness varies from 9 to 15 mm. The ratio of cement and sand for first coat plaster varies from 1:3 to 1:6.Apply the first coat of plaster between the spaces formed by the screeds on the wall surface. This is done by means of trowel. Level the surface by means of flat wooden floats and wooden straight edges. After leveling, left the first coat to set but not to dry and then roughen it with a scratching tool to form a key to the second coat of plaster. b. b. D. Applying Finishing Coat 1. The thickness of second coat or finishing coat may vary between 2 to 3 mm. 2. The ratio of cement and sand for second coat plaster varies from 1:2 to 1:4. 3. Before applying the second coat, damp the first coat evenly. 4. Apply the finishing coat with wooden floats to a true even surface and using a steel trowel, give it a finishing touch. 5. As far as possible, the finishing coat should be applied starting from top towards bottom and completed in one operation to eliminate joining marks. 4 Masonry - Camarines Sur Polytechnic Colleges Downloaded by Valshca Balani ([email protected])  lOMoARcPSD|52327130 3 MASONRY SURFACE FINISHING E. Curing of Plastering works 1. After completion of the plastering work, it is kept wet by sprinkling water for at least 7 days in order to develop strength and hardness. 2. Use of gunny bags or other materials is used to keep the plastering works wet in external works. 3. Improper curing may lead to cracks formation or efflorescence in plaster work. Care be taken after Completion of Plaster Work  Cleaning of doors or frame and floor area is necessary at the completion of work.  Curing should be started as soon as the plaster has hardened sufficiently and must be cured for at least 7 days. 5 Masonry - Camarines Sur Polytechnic Colleges Downloaded by Valshca Balani ([email protected])  lOMoARcPSD|52327130 3 MASONRY SURFACE FINISHING  Curing shall commence, 24 hours after the plaster is laid. The following are video presentation for concrete wall plastering for you to view: 1. https://youtu.be/kTu7s0rnfhA 2. https://youtu.be/Y_PnDo4z9a8 3. https://youtu.be/akYVfhIZtLw 4. https://youtu.be/XDDeUbe1Tk8 5. https://youtu.be/1YbiQLCcS5Q 6 Masonry - Camarines Sur Polytechnic Colleges Downloaded by Valshca Balani ([email protected])