Better Roads Digital Magazine
Issue link: https://read.dmtmag.com/i/86539
SpecialFeature AMERICAN CONCRETE PAVEMENT ASSOCIATION prevents displacement or faulting. In many instances, sawed joints are not required, but for some applications, longitudinal and transverse joints are cut with concrete saws. Set up is generally fast and relatively simple for trained crews. The mate- rial also can be placed directly on a good quality subgrade, and generally requires no fi nishing work. RCC is cured, but it does not typically need to be covered with curing blankets, plas- tic, or the like. As one might expect, roller-com- pacted concrete is a very strong mate- rial. The Portland Cement Association (PCA) says it has high fl exural strength – from 500 to 1,000 psi. That means it can support heavy, repetitive loads without failure, and can span localized soft subgrade areas, which reduces maintenance costs and pavement to be resistant to chemical attack. RCC also resists abrasion, making it a great surface for large vehicles. A Brief History By most accounts, the U.S. Army Corps of Engineers researched RCC use in the early 1970s for dam construction. RCC was also reportedly used in the 1970s by the Canadian logging indus- try, which switched to environmen- tally cleaner, land-based log-sorting methods. A test plot of RCC was built at Fort Stewart, Georgia, in 1983. The plot consisted of a short road for tracked vehicles; along with the test road, two more RCC test plots were built that same year. The question of freeze/ thaw durability of RCC was addressed in 1984 when a full scale test pave- ment at the Cold Regions Research asphalt supply and pricing has led to a steady increase in number and scale of RCC projects. Task Force Focus "RCC is not new technology, but our position is that it is new to many owner/agencies, contractors, and oth- er stakeholders," says Voigt. "We saw the strong interest in RCC among our members and customers, so that's why we created an ACPA task force." A conference call in April set the Reece Albert crew places roller compacted concrete on a haul road in New Braunfels, Texas. The contractor, working with CEMEX, placed the RCC pavement on a road that will carry heavy truck traffic. Photo depicts a GOMACO RTP-500 rubber-tracked placer, a Wirtgen/Vögele Super 2100-2 high density paver, and, in the distance, compaction equipment. downtime. Moreover, RCC has high compres- sive strength – 4,000 to 10,000 psi, so it can withstand high concentrated loads and impacts from heavy indus- trial, military, and mining applications. RCC is a high-density, low-water- absorption material. That gives it excellent durability, even under freeze- thaw conditions. Water does not seep through RCC. The low water content and low wa- ter/cement ratio of RCC provide its strength, low permeability, and dura- bility. These properties also help RCC Engineering Laboratory completed a range of climate controlled tests. Viewed as a success, the testing prompted a memorandum to fi eld offi ces encouraging the use of RCC paving for "horizontal construction" where applicable for all facilities ad- ministered by the Corps of Engineers in early 1985. Since then, the technology has expanded into other applications, in- cluding parking areas, industrial facili- ties, roadways, shoulders, etc. The lin- gering efforts of the 2007 economic slump, coupled with the volatility of broad direction for the task force, and also served as a forum to dis- cuss an RCC Task Force Meeting and Workshop, held during ACPA's mid- year meeting in June. Co-Chairs Jim Mack (CEMEX) and John Edwards (Interstate Highway Construction) presided over the workshop and meet- ing, which featured presentations and panel discussions that covered contrac- tors' perspectives, agency perspectives, and research associated with RCC. The discussions also covered work- manship, mixture designs, equipment considerations, and specifi cations. At the end of the full-day event, the task force was divided into smaller groups that will focus on education and train- ing (primarily to arm contractors with as much information as possible); specifi cations (to look at existing specs and evaluate gaps and other needs); and technology transfer (with the aim of creating an RCC database and other resources to communicate RCC tech- nology and best practices). Notwithstanding enthusiasm and a strong interest in roller-compacted concrete, ACPA says it is not a replace- ment for conventional forms of con- crete paving (notably jointed-plain and continuously reinforced concrete pavements) but a complementary technology that should be considered seriously for certain roadway, indus- trial, and parking lot applications, among others. Better Roads October 2012 17