two-lift paving - introduction

Two Lift Paving An Overview

Dr Peter Taylor

With thanks to:Jim Grove FHWA

Two-Lift Paving

• What is it?• History in the US• Advantages• Barriers• Where next?

What is it?• Placement of two wet-on-wet layers

of concrete

History• Concept is not newBlome Granitoid

History• Europeans learned it from us • We learned it again from them in

1992 and 2006

History• FL 1977 US41• MI 1993 I75• KS 1997 Hwy 96• FL 2001• KS 2008 I70• MnRoad 2010• MO 2011 SH141

Benefits

• Lower impact system below• High–end system above• Improved life cycle cost• Improved environmental

impact

Benefits

• Lower levelAggregates not suitable for

surface:Polishing

Local!

Benefits

• Lower levelRecycled materialsHigh SCM contents

Lower environmental impact

Benefits

• Lower levelStrong enough for structural

purposes – but no more~600 psi flexNot necessarily durable

Benefits

• Upper levelExposed aggregate finishQuietGood friction

Benefits

• Upper levelSpecial materialsTiO2

High durability mixStrength likely higher than

needed

Barriers

• Two paving trains• Batching control

Barriers

• CostReportedly initial cost increment

can be smallLCCA indicates savings

• SpecificationsIL Tollway

• ExperienceThere is a learning curve

Where next?

• It is common in Europe• Have to address:Fear The learning curveSpecifications