GAIL (India) Limited

28The minimum interval between the concreting of adjacent pours separated by vertical constructionjoints shall be three (3) days, or as directed by the Engineer.3.29 Finishes to Exposed Surface of ConcreteThe Contractor is to include his quoted rate for concrete, the provision of normal finishes in bothformed and unformed surfaces as and where required by the Engineer without any extra cost to GAIL(INDIA) LTD., Some common finishes are indicated below:3.29.1 Surfaces which do not Require PlasteringSurface in contact with casing shall be brought to a fair and even surface by working the concretesmooth against casings with a steel trowel while it is being deposited and also by working over thesurface with a trowel immediately after the removal of the casings or centering, removing anyirregularities and stopping air holes, etc. Use of mortar plaster is not permissible for correcting levels,removing unevenness etc. However, if in the opinion of the Engineer, such plastering is unavoidable,then the thickness of plaster shall in no case exceed 5 mm and the plastering shall be in CM (1:3).3.29.2 Faces of Foundations which will be Back FilledNeither the smoothness of the surface not the positions of the joints in the form work are important.Small blemishes caused by entrapped air are permitted. No special surface finish is required.3.29.3 Exposed SurfacesSurface of beams/columns flushing with the block work or other structures where it is intended toplaster, shall be backed adequately as soon as the shuttering is stripped off so that proper bond with theplaster can develop.3.29.4 Surface for Non-integral FinishWhere a non integral finish such as floor finish is specified or required, the surface of the concrete shallbe struck off at the specified levels shall be furnished and finished rough.3.29.5 For Monolithic FinishWhere no more finishing course is to be supplied as in the case of basement floor, industrial flooring orthe screed concrete flooring etc., the concrete shall be completed and struck off at the specified levelsand slopes in a screed board and then floated with a wooden float. Steel trowel ling is then started afterthe concrete has hardened enough to prevent the excess of fines and water to rise to the surface but nothard enough to prevent proper finishing. Trowelling shall be such that the surface is flat, smooth andneatly finished.3.30 Curing of Concrete3.30.1 GeneralThe purpose of curing is either to provide sufficient water at optimum temperature or to prevent loss ofmoisture from the concrete itself so that the cement inside the concrete is sufficiently hydrated which,of course, is a slow and prolonged process. As soon as the concrete has hardened sufficiently, thecuring shall be started.3.30.2 Different Methods of CuringAny one of the following may be used for curing as approved by the Engineer.a) Curing by Direct WaterThis is done either by pounding or spraying water.