ACPA Pavement Research Update

1. ACPA Pavement Research Update Presented to: FAA Pavement Working Group April 26, 2012 Gary L. Mitchell, P.E. Vice President Airports and Pavement Technology

2. ACPA Pavement Research • Conducted by Innovative Pavement Research Foundation • Cooperative Agreement 01-G-002 • Funded from 2001 until 2006 • Grant closed out in October 2011

3. IPRF Program Status • Over 30 projects – reports on the IPRF website. • Research funded to date over $12.99 million • Program closed out October, 2011. • At least six FAA documents have been revised as a direct result of the IPRF research projects • IPRF still exist – limited funds

4. FAA Documents Updated • Engineering Brief Number 70:  ASR in Portland cement concrete pavements exposed to runway deicing chemicals • Advisory Circular 150/5320-6E – Airport Pavement Design and Evaluation • Advisory Circular 150/5370-10D – Standards for Specifying Construction of Airports (four standards within this AC) • Item P-304, Cement Treated Base • Item P-306, Econocrete Base Course • Item P-501, Portland Cement Concrete Pavement • Item P-219, Recycled Concrete Base Course • First Report – Best Practices Manual • ACPA published and update in 2011 Canceled

5. IPRF Research on Durability of Concrete Pavements at Airports - Summary of what we have learned - • Concrete pavements can provide a long-lasting pavement surface for airports, provided they are designed and constructed per specifications. • Implementation of specifications has been an issue (IPRF 05-7). • Durability problems in pavements were avoidable • The predominant reason for the ASR in the pavements • lack of adequate implementation of existing specifications (in case of newer pavements) and • lack of adequate specifications (in case of older pavements). • Deicers, • Possibly capable of triggering ASR (lab) • Do not appear to be the primary reason for the ASR in the field • inability to penetrate deeper into concrete • results only in near surface impact. • FAA Engineering Brief 70 was ineffective and flawed – result: canceled

6. IPRF Research on Durability of Concrete Pavements at Airports - Summary of what we have learned - • Concentration of accumulated deicer in the near surface region of concrete can have more significant impact on the freeze-thaw durability of pavements rather than ASR. • Laboratory studies showed • Concrete subjected to freeze-thaw test in the presence of deicers failed • Presence of water performed significantly better. • Research need exists to determine the mechanism of freeze-thaw failure in the presence of deicers, and how and why traditional air-entrainment may be lacking in offering adequate protection. F-T Test on Concrete Core in Presence of KAc Deicer Deterioration of Concrete Pavement Subjected to KAc Deicer F-T Test of Concrete Core in Presence of Water

7. Research Needs F-T Durability • The impact of airfield pavement deicers on freeze-thaw durability of concrete needs to be investigated. • The effectiveness of existing air-entraining agents in protecting concrete against the effects of freeze-thaw durability needs to be investigated. Stability of Hydrated Cement Paste • Impact of KAc deicer on stability of certain hydrated cement paste compounds has been identified to be another important durability mechanism. • Detailed studies have not yet been conducted. • Research need exists in determining the impact of interactions between deicer solutions and hydration products on other durability issues such as F-T and Shrinkage characteristics of concrete.

8. Please contact Gary L. Mitchell with questions or comments: gmitchell@ACPA.org