Grand Housing Development Program Volume III - Gtz

CONSTRUCTION GUIDELINE STEP BY STEP(CONTINUED)Grade beams with backfill, hardcore, temperature reinforcement without expansion jointsIn order to get a regular compressive strength of theback fill, the steps of back fill should be marked atconcrete will have consequences (level differences) forthe formwork and later for the grade beam.the columns every 20 cm. This means 20 cm of fillingmaterial (selected material), compaction and another20 cm of filling material till the excavated hole is filledThe construction of the grade beam should be checkedaccording to the following list:and compacted. The heights for compaction should bemarked at the footing columns in order to control the • Is the quality of the reinforcement bars proofed?right compaction.• Is their quality according to the structural design?When the excavated holes are filled and compacted• Are all reinforcement bars installed accordingly tothe structural drawings?the whole area for the construction of the grade beams • Are the right bar diameters installed?has to be backfilled and compacted (roller). This backfillhas to be levelled (theodolite) in order to get the• Are the spacers in between the reinforcement andthe lean concrete installed?required height and a smooth surface for the lean concrete• Have the spacers the right dimensions (height)?under the grade beams.• Are enough spacers installed (middle and outsideparts)?Grade Beams• Is the formwork for the grade beams well installed(height and width)?• Is the formwork straight and levelled?After the backfill is well compacted and levelled, the • Are enough supports for the formwork installed?lean concrete for the grade beams can be placed. • Is the bottom clean and free from organical material?It is important, that the lean concrete is levelled because• Is the lean concrete watered (cured)?it will give the right height in between the spac-ers and the re-bars of the grade beam.• Are the test cubes prepared for concrete checking?Before starting the concrete work for the footings, aAlso the formwork of the grade beam will stay on thelean concrete. Every difference in height of the leanwritten approval from the resident engineer must begiven.FROM TECHNICAL MANUALS VOL I AND II CONSTRUCTION GUIDELINE STEP BY STEP25Addis AbabaCity Government