In 2007 a collaborative partnership was developed between Holcim (US) Inc. and Castle Rock Construction (CRCC) to provide the Colorado Department of Transportation (CDOT) with a sustainable concrete pavement solution to help with the Governor’s initiative to lower the environmental impact of construction. An industry task force worked to create the CDOT “Green Concrete” specification that allowed portland-limestone cement in concrete paving (via the ASTM C1157 performance cement specification, prior to the creation of ASTM C595 IL in 2012). CDOT approved the use of portland-limestone cements in 2008 and today there are over 500 lane miles of concrete paving.

Castle Rock Construction utilized an optimized concrete mix on all of these projects. The mix design was a flexural strength mix with portland-limestone cement, 20% Class F fly ash, water reducing admixture, air entraining admixture and four aggregates; #4 coarse aggregate, #7 coarse aggregate, #9 aggregate, and concrete sand. The purpose of this proportioning and mixing was to aid in the production of a more consistent concrete batch and a better platform for the concrete paver with the ultimate goal of producing a smoother ride on the concrete paving. Portland-limestone cement proved to be consistent and helped contribute to the achievement of the quality performance incentives per CDOT standards.

“CRCC and Holcim have been partners in the use of Envirocore Portland/Limestone cement to build over 300 lane miles of bright shining concrete pavement over the last six years. On more than fifteen projects in the State of Colorado, this product has been successfully used to satisfy demanding flexural strength specifications with virtually no problems. It has been an integral part of our intense effort to improve the quality and rideability of the pavements we are privileged to build for the traveling public.” Ralph Bell, Chief Executive Officer, Castle Rock Construction Company.

Colorado Department of Transportation, Castle Rock Construction and Holcim (US) Inc. have taken the initiative to be leaders in innovation and sustainable pavement construction while lowering the environmental impact associated with concrete construction through the use of portland-limestone cements. CDOT approved the use of portland-limestone cements in 2008 and today there are over 500 lane miles (including other contractor’s work) of concrete paving with Holcim Envirocore™ Portland/Limestone cement.