## 7 Discussion  
The behavior of continuously reinforced concrete pavement is greatly influenced by CTE, which affects volumetric changes and stress levels brought on by thermal variations. Temperature-induced dimensional changes can cause structural strains that shorten pavements' service lives by causing cracking, spalling, and warping. Therefore, it is essential to comprehend and manage CTE to guarantee the durability and proper operation of this vital infrastructure. The CTE of concrete is not a fixed property but rather a complex characteristic influenced by a multitude of factors; as highlighted in a review, regulating the choice of material and composition is crucial for controlling CTE. In general, aggregates with lower CTE--like certain igneous rocks--are favored for improving thermal compatibility. On the other hand, aggregates that contain a lot of quartz have higher CTE values, which could result in more thermal stress and cracking. According to studies, under comparable circumstances, concrete manufactured with siliceous river gravel (SRG) has a higher CTE and experiences wider cracks compared to concrete made with crushed limestone (LS) under similar conditions. Available materials could be effectively used with proper construction methods with optimized gradation. The composition of cement also influences CTE, with a higher cement content generally resulting in an increased coefficient of thermal expansion. Concrete's thermal expansion stabilizes over time, particularly after the initial hydration period; therefore, it is important to comprehend this phenomenon in early age and take precautions to lessen its effects. This is due to the continuous cement paste matrix, which is particularly sensitive to thermal expansion. The review highlights that the effect of concrete age on CTE varies. Fresh concrete tends to have a higher CTE due to the presence of unbound water, which decreases as the microstructure develops. While some studies indicate that CTE stabilizes after the initial hydration phase with minimal long-term variation, others report changes within the first year. Relative humidity (RH) and curing conditions also play a crucial role, with peak CTE values typically occurring between 70% and 80% RH, while extremely high or low RH levels result in lower CTE. Sustaining high moisture levels through methods like internal curing can help reduce CTE and prevent cracking. The impact of SCMs on CTE is generally minor and context-dependent, with some research suggesting a slight reduction in early-age CTE when fly ash is used. Notably, incorporating RCA may lead to a decrease in CTE, whereas latex-modified concretes tend to exhibit a higher CTE. For precise prediction of temperature responses and their effect on pavement performance, CTE testing is vital. Various testing techniques aid in understanding the behavior of concrete and its constituents which enable durable pavement design. The inclusion of CTE as an input parameter in the Mechanistic-Empirical Pavement Design Guide (MEPDG) represents a significant advancement for pavement design. By considering variables like joint movement and cracking, this addition improves the prediction accuracy of pavement performance. For CTE input, the MEPDG provides a range of hierarchical levels that balance cost and accuracy. In addition, prediction models show promise in precisely forecasting concrete CTE, providing a substitute for conventional testing procedures or default settings. Various experimental methods for measuring CTE exist, each with its own mechanisms, measurements, limitations, and precision. Advanced techniques such as volumetric methods are valuable for studying early-age CTE, while optical lever systems offer reliable results for road concrete. The choice of testing method should consider the specific research objectives and the limitations of each technique. Therefore, this review reinforces the critical role of concrete's CTE in the performance and durability of rigid pavements.