Ward R. Malisch Concrete Construction Symposium (Part 2)-Achieving Performance-Based Concrete—Challenge for the Contractor, Producer and Owner (PDF)

Achieving Performance-Based Concrete—Challenge for the Contractor, Producer and Owner (PDF)

Pdf Summary

The document titled "Achieving Performance-Based Concrete: Challenge for the Contractor, Producer, and Owner" by Kevin A. MacDonald and Ward Malisch, addresses the complexities and challenges of working with performance-based concrete, highlighting the gap between construction expectations and practical execution capabilities. It underscores the need for effective coordination among trades and preemptive conflict resolution to avoid costly disputes onsite. A major issue is the gap between specified expectations and a contractor’s capacity to meet them economically, often exacerbated by ambiguous language, unachievable tolerances, and reliance on anecdotal evidence rather than data.<br /><br />Failures in concrete projects typically result from either the contractor not adhering to specifications or errors within those specifications themselves. The dialog around concrete specifications is problematic, as it inadequately connects the strengths and water-cement (w/c) ratios needed, with examples such as the difference in shrinkage and permeability between mixtures maintaining the same w/c ratio but differing in cement and water content.<br /><br />Current systems require specifications outlining all requirements, a submittal addressing these, and testing to ensure compliance, highlighting a mismatch between w/c ratio, shrinkage, and other properties. The proposal for a Progressive Performance (P2P) strategy suggests removing unnecessary restrictions, creating a collaborative design approach between producers and owners, and finding ways past code obstacles, especially regarding ingredients and mixtures.<br /><br />Additional focus areas include the durability, constructability, and structural performance of concrete, addressing unwritten owner requirements such as shrinkage and cracking, and constructor needs like workability and setting characteristics. Challenges lie in the implementation due to mistrust, the absence of specific performance specifications, and the knowledge disconnect between designers and suppliers. The data on cement and fly ash characteristics further indicates the importance of understanding material behavior over time.

Keywords

performance-based concrete

construction challenges

coordination

specifications

water-cement ratio

Progressive Performance strategy

durability

constructability

material behavior

collaborative design