Known for its quality performance, Latex Modified Concrete (LMC) has been consistently used in infrastructure across the U.S. for over 30 years. LMC, whose composition may include Trinseo’s Modifier A™ / NA Latex, can be found in concrete bridge deck overlays, parking decks, and other roadway surfaces. The reliability and consistency of LMC can result in lower maintenance costs and long-term positive performance results, often outperforming common alternatives. Despite its reliability, the pour season for LMC is often seasonal and limited by ambient temperature variance.
Most state departments of transportation (DOTs) specify that LMC for bridge deck overlays must be installed and cured within a temperature range of 50° to 85° Fahrenheit. Following the guidelines set by the DOTs, installers are often limited to only pouring from spring to fall. Trinseo, in partnership with Concrete Strategies and GTS Consulting, wanted to determine if LMC can be installed at lower temperature ranges while still developing excellent performance properties, opening up the potential for installers to extend their pour seasons.
Low Temperature Curing
The study examined the compressive strength, bond strength by slant shear, and ability to resist chloride ion penetration of the LMC to determine its usability at lower temperatures including 35°, 40°, 45°, 50°, and 72° Fahrenheit. The compressive strength of LMC in lower temperature systems exhibited excellent strength development over time. Each tested sample reached the 3,000 PSI minimum requirement for opening a roadway after 5 days, demonstrating how low temperature curing can quickly meet the DOTs’ necessary requirements.
When testing bond strength by slant shear, testing samples maintained at lower temperatures developed a higher bond strength compared to higher temperature systems at every testing interval, demonstrating how LMC delivers excellent bond strength when poured at low temperatures.
Results of the 90-day chloride penetration testing found that while the lower temperature samples began in the moderate range in resisting chloride ion, the rates continued to decrease to transition into the low range. Knowing that chloride ion penetration resistance improves over time due to polymer film formation and coalescence, low-temperature curing is not expected to negatively impact LMC’s chloride ion resistance.
Overall, the study found that installing LMC overlays under low temperature conditions develops exceptional compressive strength, delivers excellent bond strength performance, and is not detrimental to chloride ion penetration resistance. DOTs and installers alike can be confident in pouring in low temperatures. DOTs should consider reexamining temperature specifications while installers can look to expand their LMC pouring season from an earlier start to a later finish.
Looking ahead, we’ll continue to evaluate the implications of pouring in lower temperatures. By further understanding the capabilities of LMC, we can potentially determine expanded uses for other applications.