Warping stresses in a C.C. (Cement Concrete) pavement are primarily caused by daily variation in temperature. When the temperature of the pavement changes, it causes the concrete to expand or contract, leading to the development of stresses within the pavement structure. These stresses can result in warping or distortion of the pavement surface.

Here is a detailed explanation of why daily variation in temperature is the main cause of warping stresses in a C.C. pavement:

1. Expansion and contraction of concrete: Concrete is a material that expands when it is heated and contracts when it is cooled. As the temperature of the pavement increases during the day, the concrete expands. Conversely, during the night or in colder weather, the concrete contracts. These expansion and contraction movements can create internal stresses within the pavement.

2. Differential expansion and contraction: Different parts of the pavement may experience varying temperature conditions. Areas that are exposed to direct sunlight or have less insulation from the ground are more likely to experience higher temperatures, resulting in greater expansion. On the other hand, shaded areas or parts in contact with the ground may have lower temperatures and more significant contraction. The differential expansion and contraction can cause warping stresses as the pavement tries to accommodate these different movements.

3. Restraint from subgrade and surrounding structures: The C.C. pavement is often restrained by the base and subgrade layers as well as adjacent structures, such as curbs and gutters. When the concrete expands or contracts, it may be constrained by these elements, leading to the development of warping stresses. The restraint can prevent the pavement from freely expanding or contracting, resulting in the distortion of the pavement surface.

4. Cumulative effect of daily temperature changes: Although the daily variation in temperature may seem small, the cumulative effect over time can be significant. The repeated expansion and contraction cycles can gradually accumulate stresses within the pavement, leading to the development of warping over an extended period.

In conclusion, daily variation in temperature is the primary cause of warping stresses in a C.C. pavement. The expansion and contraction of the concrete, differential movements in different parts of the pavement, restraint from subgrade and surrounding structures, and the cumulative effect of temperature changes all contribute to the development of these stresses. It is essential to consider these factors during the design and construction of C.C. pavements to minimize the potential for warping and ensure the long-term durability of the pavement.