Specification for external plastering

Ordinary Portland cement shall be used .The cement shall conform to IS: 269 latest versions. Fine aggregate shall be natural sand obtained from a river bed and shall conform to 15:383-1 and to the relevant portion of IS: 515- 1959. Sand shall be clean, hard, strong, durable and free from organic matter, dust, clay, shale, alkali, salts, soft or flaky particles or other injurious substances. Potable water shall be used for mixing the mortar. Cement and sand shall be mixed in the proportion of one part of cement to four parts of sand. Mortar shall be mixed in a mechanical mixer of an approved pattern at the site of work The drum shall be rotated for a minimum period of 2 minutes The mortar shall be used within 30 minutes of adding water or by hand mixing. The mortar shall be firmly applied on the surface from top to down and well pressed into the joints. The mortar shall then be rubbed and leveled with a flat wooden rule until a perfectly plane and even surface is achieved. All corners shall be finished to their angles, unless otherwise directed by the engineer: The jambs and reveals Of door and window openings shall be finished perpendicular to the sill and lintel bottom. Plastering shall be done in squares or strips as directed by the engineer. Strips or squares shall be so formed that day-to-day breaks are made to coincide with architectural breaks. While the plastered surface is fresh, a thick coat of cement slurry shall be applied and rubbed smooth. All plastered surfaces shall be kept continuously damp for -a period of 14 days. The unit of measurement shall be the square meter as per IS: 1200.