Assessing Workability Complaints in Mass Concrete Construction

Abstract

Abstract : This report presents and discusses the results of a survey of Corps of Engineers (CE) Division and District staff members familiar with mass concrete construction to determine the extent of mass concrete workability complaints throughout the CE as well as the purported causes of the problems. CE Divisions and Districts having recent experience with mass concrete construction were solicited to provide input describing workability complaints. The results of the survey indicate that while mass concrete mixtures can be harsh and difficult to work, many times the workability problems are the result of aggregates being out of specification requirements for grading or improper transporting, placing, or consolidating equipment or procedures. Almost one-half of the identified problem areas deal with consolidation equipment and procedures. Recommendations are made to disseminate the results of the survey to other CE staff members, to require meeting or training sessions for contractor personnel involved with consolidating mass concrete, to investigate the feasibility of requiring a minimum mortar content for 37.5-mm (1-1/2-in.) nominal maximum size aggregate (NMSA) mass concrete, to investigate the feasibility of requiring a paste-mortar ratio for 37.5-mm (1-1/2-in.) NMSA and 75-mm (3-in.) NMSA mass concrete, and to investigate the feasibility of placing mass concrete at higher slumps.