There are two main reasons for grouting the ducts of post-tensioned concrete members. One is to provide efficient bond between the prestressing steel and the concrete member so as to control the spacing of cracks at heavy overload. This increases the ultimate strength of a structural member. The other is to prevent corrosion of the prestressing steel. Both of these objectives require complete filling of the void spaces within the duct. Filing will be most effective if the grout mix has the necessary properties, if efficient equipment is used for its injection, and if careful workmanship is employed under good supervision. Several important points should be borne in mind when designing ducts. Grout injection points must be provided and sudden changes in alignment must be avoided. Vents must also be provided for the exhaustion of air at high points and drainage of water at low points. Grout openings advents must be securely anchored to the duct and to either the forms of the rebars so that they are not displaced during concrete placing. After all tendons, reinforcing and forming have been placed but before concreting has begun, ducts should be inspected for flaws such as misalignments, dents, separations or holes. How serious a fault may be and whether repair is justified must be a matter for judgement. Yet it should be borne in mind that a fault which goes undetected or one that is ignored can result later in costly remedial action or large scale rebuilding. Neat cement grout may be made with Type I, II, or III portland cement, water and an admixture. For best results, it is recommended that all materials be weighed at the job site with conventional weighting equipment. However, it is acceptable , if necessary, to batch cement by whole bags and measure water volumetrically or by a water meter. All weighing and measuring equipment should be calibrated for accuracy and operated within the tolerances normally allowed for conventional concrete material weighing.