The North Carolina Department of Transportation (NCDOT) is always busy maintaining highways and bridges to keep their roads safe—and turning around road construction work quickly to minimize traffic disruption. For this reason, the DOT specifies concrete that reaches 400 psi flexural strength in four hours for highway panel replacement projects.
One of NCDOT's projects included replacing broken continuous reinforced concrete pavement (CRCP) panels, typically at least 9 inches thick, along a three-mile stretch of Interstate 40 in Asheville. NCDOT contracted Ashville-based NHM Constructors to perform the work, which included removing the existing concrete from the east- and west-bound lanes and on off ramps. As part of the project, the crew spliced new rebar to existing reinforcement and placed and finished fresh concrete made with Rapid Set® Cement and local aggregates.
NHM Constructors was required to perform all work overnight. The repaired pavement had to reach a flexural strength of 400 psi in four hours so it could reopen to traffic by 6:30 a.m. each morning. The contractor faced a penalty of between $1,000 and $2,000 for every 15 minutes the opening was delayed. By using the rapid-hardening Rapid Set Cement, the NHM crew was able to meet and exceed the strength and opening requirements.
Beginning at 8 p.m. each evening, the crew used concrete saws and jackhammers to remove the broken CRCP panels, being careful not to cut through the needed portions of rebar. They then checked the subgrade for correct compaction and spliced new rebar to the old. The concrete was then produced from a volumetric mobile mixer to replace the broken panels.
IVS Hydro produced the concrete as needed each night. The repaired sections were roller screeded, floated, hand-troweled, broom-finished and wet-cured before reopening in time for morning rush-hour traffic. Repairs began May 2021 and the project was completed without any issues in November 2021, with approximately 1,300 cubic yards of concrete placed.
Why Rapid Set Cement
Since 2014, NCDOT has been using concrete mix designs containing Rapid Set Cement to meet performance specifications for the state's roadway panel replacement projects. The hydraulic cement's rapid-hardening properties make it an ideal material for replacing jointed concrete pavement panels overnight and returning them to full service by morning. This fast return to service is needed to curtail traffic delays.
Because Rapid Set Cement is engineered for low shrinkage and superior resistance to chemical attack, its use also maximizes pavement service life and minimizes maintenance needs, such as joint filling and crack sealing as well as more expensive repairs like potholes.
As with previous projects, NCDOT was pleased with Rapid Set Cement's performance and plans to continue using Rapid Set in future projects.
