All materials expand and contract to some extent as their temperatures rise or fall.
Given that changes in length are typically very small, T-coeff is usually expressed in microstrains per degree Centigrade. During pavement design, this variable is normally represented as an average value rather than a mix-specific one, even though it may vary significantly depending on factors such as type of aggregate used in a mix. The use of an average value may therefore lead to erroneous assumptions about the pavement's thermal response and possible distress. The data collected on hundreds of pavement cores from around the country will become part of the LTPP database and will be used to investigate the impact of the T-coeff of concrete on the response and performance of pavements. The modified design procedures will result in pavement designs that are more compatible with the environmental conditions at a particular paving site.