That the construction joint surfaces are plumb and

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Unformatted text preview: the course of construction. The length of time, the forms would remain in place, shall be decided with reference to weather conditions, slope and position of the structure or structural member and the nature and amount of dead and live loads. 55.1 In no case should forms be removed until there is assurance that their removal is possible without chipping, spalling or defacing the concrete surface. Furthermore, heavy loads shah not be permitted until after the concrete has reached its designed strength. All forms shall be entirely removed from a lift to permit inspection before the forms for the next lift are set. 31 IS : 457 - 1957 6. CONSTRUCTION JOINTS 6.1 Location of Joints - The location and type of all construction joints shall be shown on the drawings, and no other joints or type of joints shall be built unless specifically approved by the competent authority. 6.2 Horizontal Joints - The stipulations of 4.10.5 for cleaning masonry joints and bonding ne\v concrete to old shall apply to all horizontal construction joints. Keyways or dowels for resistance to shear shall be At least 2 hours carefully formed and placed as shown on the drawings. shall elal~ after depositing concrete in columns or supporting walls beAll joints shall be finished fore placing the concrete in the floor system. to present a sharp level, straight line in the exposed face. 6.3 Vertical Joints-Vertical construction joints essentially the same care as other exposed surfaces. the adjoining sections of masonry shall be complete, tailed on the drawings. 6.4 Water-tight shall be built with The break between unless otherwise de- Joints 6.4.1 Whcrc horizontal construction joints are subject to water pressure, special care shall be taken to bond the next lift of concrete. The consistency of the concrete shall be carefully controlled so as to avoid sand streaking; and after compaction no free water shall show anywhere along the joint. The surface shall be carefully cured as specified under 4.15 and shall IX protcctcd from mechauical injury. Before placing the next lift, the joint shall hc cleaned and prel)arcd as sljccified under 4.10.5. 6.4.2 In casting vertical joints reqnir’ed to be water-tight, care shall be taken not to injure or displace the grout pipine \vatcr stops, or seals called for on tile tlrawirlgs. 6.5 for and fied Emergency Joints -- Vv’hcrcvcr plncirlg is interrnptctl long enough the concrete to take its final set. the working face shall be so formed lini~lrctl as to provide union with subscqucnt \\,ork equal to that spccifor regular construction joints. 7. TESTS 7.1 Field Tests - Field tests of all concrete being placed shall be regularly conducted. In general, as a reliable indication of other physical properties, the quality of the concrete being produced shall be judged by a comparison of the compressive strengths developed within a given period. 32 IS : 457 - 1957 7.2 Laboratory Test.- A properly equipped testing laboratory to control the quality of the co...
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