PREVENTIVE MEASURES FOR OBTAINING SCALE-FREE CONCRETE BRIDGE STRUCTURES

THE PROBLEM OF SCALING AND SUBSEQUENT DETERIORATION OF CONCRETE HIGHWAY BRIDGE SUPERSTRUCTURE ELEMENTS HAS BECOME A MAJOR CONCERN TO HIGHWAY ENGINEERS, ESPECIALLY IN THE NORTHERN STATES. THIS PAPER DEALS PRIMARILY WITH ADHERENCE TO PROVEN CONTROL PROCEDURES AS A LOGICAL APPROACH TO THE REALIZATION OF SCALE-FREE STRUCTURES. THE SUBJECT IS DIVIDED INTO (1) PREVENTIVE MEASURES BEFORE CONSTRUCTION, (2) PREVENTIVE MEASURES DURING CONSTRUCTION, AND (3) PREVENTIVE MEASURES AFTER CONSTRUCTION. ESSENTIAL FACTORS RELATED TO DESIGN, CONSTRUCTION, OR MAINTENANCE PRACTICES ARE PRESENTED, BASED ON EXPERIENCE OBTAINED FROM MANY YEARS OF FIELD STUDY AND LABORATORY RESEARCH BY THE MICHIGAN STATE HIGHWAY DEPARTMENT. THE PROBLEM APPEARS TO BE ONE OF STRICT ADHERENCE TO SPECIFICATION REQUIREMENTS AND THE ELIMINATION OF CONSTRUCTION IRREGULARITIES THROUGH PROPER CONTROL PROCEDURES. TO ACCOMPLISH THESE OBJECTIVES, THERE MUST BE CLOSER COORDINATION BETWEEN THE ENGINEER AND THE CONTRACTOR. IN ADDITION, GREATER EFFORT MUST BE MADE BY HIGHWAY DEPARTMENTS TO TRAIN CONTRACTORS' MEN, STATE INSPECTION PERSONNEL, AND TRANSIT-MIX OPERATORS IN THE FUNDAMENTALS OF THE PROBLEM. FINALLY, IT MAY BE NECESSARY TO REQUIRE HIGHER PREQUALIFICATIONS FOR CONTRACTROS AND EVEN TO IMPOSE STRONG PENALTIES ON CONTRACTORS WHO CONSISTENTLY PRODUCE STRUCTURES THAT SCALE. /AUTHOR/