Performance Criteria for Ready Mixed Concrete: Where Are We Today? (Part 2)-Regional Differences in Concrete Performance (PDF)

Regional Differences in Concrete Performance (PDF)

Pdf Summary

The document, authored by Paul Treacy, examines performance criteria for ready mix concrete, highlighting developments and practices in Chicago and Los Angeles. These cities provide contrasting approaches to concrete specifications: Chicago is more performance-based whereas Los Angeles adheres to a highly prescriptive model.<br /><br />The Chicago section emphasizes critical aspects for successful Concrete-In-Place (CIP) projects, focusing on design, financial feasibility, mix design compliance with Engineer of Record (EOR) criteria, operational collaboration, and adaptability. Projects cited, such as the Park Tower and Aqua Tower constructed between 1997 and 2009, illustrate these principles. The mix designs highlighted in Chicago feature characteristics such as high slump, large spread, pumpability, cohesive flow, and high early strength, contributing to workability and early tensioning abilities.<br /><br />Conversely, the Los Angeles market prioritizes a prescriptive base, focusing on goal-oriented strategies for improving concrete performance. Success in this context involves identifying necessary properties, fostering education and Research & Development, and leveraging admixture technologies like supplementary cementitious materials (SCM) and water reducers. The aim is to modernize mix designs and reduce dependency on type A water. Essential attributes of successful mix designs include being pumpable at high rates, longer-life mixes, high slumps, significant spreads, fast setting, and high early strength for stress applications.<br /><br />Ultimately, both regions emphasize the importance of collaboration among engineers, contractors, and mixologists to ensure concrete projects meet contemporary standards and performance expectations.

Keywords

ready mix concrete

performance criteria

Chicago

Los Angeles

Concrete-In-Place

mix design

prescriptive model

admixture technologies

collaboration

high early strength