[...]... certificate of the curvature of the stress/strain line, the concept of proof stress is adopted The proof stress is defined as the stress at which the applied load produces a permanent elongation of a specified percentage of the guage length For prestressing wire a value of 0.1% elongation is used for the proof stress As with concrete, the characteristic strength concept (that value below which 5% of the... types of construction and various techniques demand particular means of handling and in some instances the means of handling combines with the method of achieving compaction, as in placing using pneumatic placers, spray application of concrete and similar processes The supervisor should install and maintain control on a weekly and day-to-day basis in the course of construction to ensure continuity of concrete. .. Retain copies of labels from prestressing tendons, wires and strand to link with test certificates 16 Batching and mixing concrete The objective of all supply and handling must be to provide concrete in sufficient quantity, of acceptable quality and of suitable workability at the point of placing to enable the construction to proceed systematically and economically Determination of the means of batching,... 3201 300 when — number of bars=20 type of steel=T diameter of bars=32 mm mark number of bar=01 pitch of bars=300 mm The detailer will include further information on the drawing using some of the following abbreviations as applicable: B BB T TT EF NF bars in bottom of slab (in two way slabs) bottom layer of bottom reinforcement bars in top of slab (in two way slabs) top layer of top reinforcement bars... racks, concrete sleepers or similar means of storage will avoid formation of excessive rust and scale The use of long brothers or spreader bars, and avoidance of “barring-off” of steel from the delivery vehicle will ensure that the steel is kept in a condition suitable for inclusion in reinforced concrete Fabric must be stored flat to avoid expensive work in attempting to straighten sheets at the time of. .. easily be overlooked in the course of changing or inserting formers onto or into the formwork In the context of reinforcement detail, the author had the opportunity of examining two sets of steel details for a particularly complicated precast concrete component One set of details was prepared by a detail draughtsman in the normal course of preparation of standard reinforced concrete details The second set... all of simple shape Incorrect positioning of reinforcement The exact position, shape and type of reinforcement is shown accurately in the drawings of the designer and detailer Any error in reading the drawings or misfixing the reinforcement may have disasterous results Two simple examples of misplacement are shown below: Points of supervision 1 Maintain up-to-date schedules 2 Record all deliveries of. .. between stirrups to allow access for concrete and for the insertion of poker vibrators to achieve compaction Some points of detail of particular interest to the supervisor will be: The recommendation regarding the use of open stirrups in beams to facilitate insertion of main reinforcement; The considerations regarding the radius of bend and its effect on displacement of the main reinforcing steel; 20... the means of batching, mixing and handling concrete are generally critical decisions made in the precontract planning stages The plant selected will be based on a number of factors: site location and available space; service availability; scale of operation; location of batching plant; distance of transport; type of concrete to be produced; required rate of placement; ground conditions; tide or flow... top of a bay if of considerable length, and may upset successive operations and at least, will require support to avoid damage to the concrete coning in its fresh state or cracking in the hardened form Discussion early in the course of the contract can result in simplification of steel detail and introduction of joints in the bars at points in the structure which best suit the eventual location of construction . 120 Segmental construction 122 Contact casting 125 Lift slabbing 126 Tilt-up construction 127 Battery casting 128 Gang casting 128 Long-line casting 128 Stack casting 1 32 Advantages of. aspects of steel design and location 19 Incorrect positioning of reinforcement 21 Points of supervision 21 16. Batching and mixing concrete 23 Receipt of materials on site 24 Batching 24 Mixing. 20 1 Percentages 20 2 Interpretation of simple mathematical expressions 20 3 Simple equations 20 3 Algebraic expressions 20 6 Perimeters, areas and volumes 21 2 Square roots 21 7 Resolution of