SMOOTH-RIDING BRIDGE DECKS

METHODS OF ATTAINMENT OF SMOOTH-RIDING BRIDGE DECKS ARE DESCRIBED. BRIDGES WITH CONCRETE DECKS SUPPORTED ON STEEL MEMBERS ARE DISCUSSED BECAUSE THE MAJORITY OF NEW HIGHWAY BRIDGES ARE OF THIS TYPE. CONTROLS AND EQUIPMENT USED FOR FINISHING THE CONCRETE SURFACE ARE DISCUSSED. THE PROPER SETTING OF THE SCREED RAILS IS EMPHASIZED AS A MATTER OF IMPORTANCE. DEFECTS IN DESIGN AND FABRICATION ARE ANALYZED. CONTRASTED WITH THE SITUATION OF PAVING ON GRADE, THE WORKING SPACE ON BRIDGE DECKS IS SEVERELY LIMITED. SINCE BRIDGE PAVING EMPLOYS MANUAL METHODS TO A GREATER DEGREE THAN PAVING ON GRADE, THE EXPERIENCE AND ATTITUDE OF THE LABOR FORCE MUST BE CONSIDERED. IN DESIGNING THE CONCRETE MIX, IN ADDITION TO THE USUAL REQUIREMENTS FOR PAVING ON GRADE, A MORE FLUID CONSISTENCY MUST BE ADOPTED BECAUSE OF THE LARGE AMOUNT OF REINFORCING STEEL IN THE SLAB. METHODS OF OBTAINING THE PROPER DISTRIBUTION OF THE CONCRETE TO THE DECK ARE DESCRIBED. A VIBRATING SCREEN IS RECOMMENDED FOR STRIKING OFF THE WET CONCRETE TO THE PROPER ELEVATION AND SLAB THICKNESS. PRECAUTIONS NECESSARY FOR THIS OPERATION ARE DESCRIBED. USE OF THE SCRAPING STRAIGHT-EDGE IS FOLLOWED BY THE LUTE. THE LUTE IS A SMOOTHING TOOL USED TO SMOOTH DOWN ANY LOCAL IRREGULARITIES THAT MAY HAVE BEEN CAUSED BY THE ACTION OF THE SCRAPING STRAIGHT-EDGE IN TURNING UP PIECES OF COARSE AGGREGATE. TEXTURING AND CURING ARE DESCRIBED. CURING HAS LITTLE TO DO WITH EARLY RIDING QUALITY, HOWEVER, IT IS VITAL TO THE PRODUCTION OF A DURABLE CONCRETE SURFACE. SMOOTH-RIDING SURFACES FOR CONCRETE BRIDGE DECKS ARE DIFFICULT TO ACHIEVE.