b'RUNWAYS CWA57Under drains were constructed along each runway edge toThe project team also applied a major lesson learned from drain the subbase. Shallow bedrock ledges were blasted andprevious work on Runway 8-26. Cihlar reports that its pavement excavated to provide a base layer of even thickness to supporthas held up beautifully, but the centerline joint on the crown of the pavement layer. the runway has posed some challenges. Winter operations crews Another challenge CWA faced was alkali-silica reaction,try to avoid riding the snowplow on the joint, but its sometimes commonly referred to as ASR. Aggregates sourced locally areunavoidable, particularly in low-visibility conditions. When a susceptible to the condition, so Type F fly ash was used insnowplow does run over the joint, it damages the plow blade and the concrete mix to mitigate the ASR. This poses a secondarycenter joint. That center joint is really the one area of pavement problem, however, because Type F fly ash is known to slow thewhere we know in the next 10 years, were going to have to do a curing time of concrete. During quality assurance testing at CWA,rehab, says Cihlar. the 28-day breaks on the concrete did, in fact, come up short onTo avoid the possibility of similar damage on Runway 17-35, strength. But samples taken at 90 days far exceeded the 28-dayCWA modified the design to offset the centerline joint from the requirement.crown. Trierweiler Construction fabricated a custom screed for the Originally, the pavement design for Runway 17-35 called forslip form paver to form the crown breakpoint in the slab. Special the crushed rock subbase, then 5 inches of cement-treatedtools were made for finishing and checking the offset centerline permeable base course with 10 inches of concrete on top.joint as well. By using two stringless pavers for mainline paving, But the contractor offered a no-cost change order, which wassetup time was reduced for 24- and 26-foot slab widths needed PHOTO: BECHER HOPPEapproved by FAA, to pave a single-pass 15 inches of concretefor the offset crown. Now, if plows accidentally get on the crown, (instead of 10) in lieu of paving the cement-treated permeableits still hard on our plows and on the crown of the pavement, but base.it wont be the joint of the pavement, notes Cihlar. #1water blasting choice for airportsrubber removal, paint removal, paint rejuvenation, terminal cleaningwww.TheHog.comAirportImprovement.comSeptember 2022'