WMI Maintenance Facility - Ault, CO

Project Focus
The Waste Management Maintenance Facility project consisted of 19,488 Square Yards of 6” Roller Compacted Concrete for the truck parking areas, and 744 Sy of 8” of RCC for the entry driveway location. The project was placed in late fall under in conditions whereby the daytime highs were in the 40’s, with overnight temperatures reaching as low as 19 degrees. All pavement was covered immediately after placement to protect it from overnight freezing temperatures. The Owner wanted a pavement that could stand up to heavy truck traffic without the rutting or shoving commonly experienced with asphalt in heavy traffic conditions, while at the same time providing the other advantages that concrete pavement brings (environmental durability, resistance to leaking fluids, etc). The Owner chose the RCC alternative because it brought all of the characteristics of a concrete pavement at a price comparable with the asphalt alternative.

Project Details
Construction & Innovation
The RCC material was batched out of an Excel Pugmill that produced a very consistent mix with minimal variations in moisture content. The self contained pugmill was set up at the jobsite location, with 3 tandem axle dump trucks feeding an Ingersoll Rand Titan 423 ABG asphalt paver. Moisture Density readings taken immediately behind the paver prior to compaction by the rollers yielded densities between 85 and 90 percent. The compactive effort behind the paver consisted of a 10 ton dual drum vibratory roller, followed by a 5 ton dual drum roller for surface sealing. The 6” RCC pavement was placed on top of 6” of asphalt millings used as base material. All pavement placed on the project was covered utilizing either heavy mil plastic or paving blankets depending on the overnight temperatures expected. Pavement temperatures were monitored each morning under the blankets to assure adequate freeze protection, and temperatures of the pavement under the blankets were maintained in the low 40’s. Blanket protection was maintained for a full 7 days to assure adequate curing and freeze protection.

Quality
Moisture content and density tests were taken at specified intervals behind the finished pavement section, utilizing a Nuclear Moisture/Density Gauge in accordance with ASTM C1040. The Standard Proctor for density testing was in accordance with ASTM D1557 with an optimum moisture established at 12.5%. Recycled Concrete Base materials were used which required a higher moisture content to obtain specified density. All tests performed indicated moisture content within specified parameters, with all density tests exceeding 95%. Aggregates were selected and blended in accordance with the Portland Cement Association’s (PCA) gradation specification for RCC Pavements. Replacement of a 6” asphalt section with a 6” RCC section required a mix design which yielded a minimum 3,000 lb compressive strength for the RCC pavement. In place strength results yielded 3,200 lb compressive strength results at 28 days.

Summary
RCC in this application provided a very serviceable concrete pavement at a significant cost savings to the customer. While the surface characteristics vary slightly in appearance and aesthetics from that of a concrete pavement, RCC can prove a very cost effective alternative to either concrete or asphalt pavements for industrial applications.