specifications - FAACO - Federal Aviation Administration Contract ...

FTWIC-2235June, 2009be interpreted as the manner and sequence of concrete placing so that construction jointsdo not occur.B. Additional horizontal and vertical construction joints, when submitted and approved bythe Contracting Officer, may have an impact on reinforcing details. Revise reinforcingdetails to reflect additional joints.C. Unless otherwise provided, construction joints shall be square and normal to the forms.Provide bulkheads in the forms for all joints except horizontal joints.D. At the proper time, clean horizontal construction joints for receiving the succeeding liftusing air-water cutting. The surface shall be exposed sound, clean aggregate. The airpressure supply to the jet shall be approximately 100 lbs. per square inch, and the waterpressure sufficient to bring the water into effective influence of the air pressure. Aftercutting, wash the surface until there is no trace of cloudiness in the wash water.E. In areas where air-water cutting cannot be satisfactorily accomplished, or in areas whereit is undesirable to disturb the surface of the concrete before it has hardened, prepare thesurface for receiving the next lift by wet sand blasting to immediately remove all laitanceand unsound concrete prior to placing of the next lift. Thoroughly wash the surface ofthe concrete after sand blasting to remove all loose material.F. For horizontal joints in walls, immediately prior to the placement of additional concrete,draw forms tight against the concrete and place a 3" coating of normal shrinkage grout.G. Provide construction joints with concrete keyways, reinforcing steel dowels, andwaterstops. The method of forming keys in keyed joints shall permit the easy removal offorms without chipping, breaking, or damaging the concrete.3.04 EXISTING HARDENED CONCRETE:Where new concrete or grout, except epoxy structural grout, is to be placed in contact withexisting hardened concrete, texture the existing surface by chipping or other means so that anirregular surface having a height variance of not less than 1/4" is created. The existing concreteshall then be coated with an epoxy bonding agent and new concrete or grout placed.3.05 HANDLING AND TRANSPORTING:A. Arrange and use chutes, troughs, or pipes as aids in placing concrete so that theingredients of the concrete are not segregated. They shall be steel or steel lined. Whensteep slopes are necessary, equip the chutes with baffles or make in short lengths thatreverse the direction of movement. Extend open troughs and chutes, if necessary, insidethe forms or through holes left in the forms. Terminate the ends of these chutes invertical downspouts.B. Keep chutes, troughs and pipes clean and free from coatings of hardened concrete bythoroughly flushing with water before and after placement. Discharge water used forflushing away from the concrete in place.C. Concrete pumping is permitted and shall comply with ACI 304.2R.03300-19