Concrete road kerbs, like any concrete structure, are subject to expansion and contraction due to temperature fluctuations and moisture changes. To accommodate these movements and prevent uncontrolled cracking, joints are strategically incorporated into the kerb design. However, the placement of these joints is not arbitrary; it requires careful consideration and coordination with the joints in the adjacent concrete carriageway.
The Ministry of Transport, in a 1955 publication, highlighted the importance of aligning kerb joints with carriageway joints. If these joints are misaligned, it creates points of stress concentration within the kerb. As the carriageway expands or contracts, the misalignment prevents the kerb from moving in unison, leading to localized stresses that can exceed the concrete’s tensile strength. This ultimately results in cracks forming in the kerb, typically at the location of the mismatched joints.
This phenomenon can be understood by envisioning the kerb and carriageway as interconnected systems. The joints act as release points, allowing for independent movement of each segment. When the joints align, the movements are synchronized, and stresses are distributed evenly. However, misalignment disrupts this harmony, causing localized stress buildup and subsequent cracking.
Therefore, adhering to best practices and aligning kerb joints with carriageway joints is essential for maintaining the structural integrity and longevity of road kerbs. This meticulous attention to detail ensures that the kerb and carriageway function as a cohesive unit, capable of withstanding the stresses induced by environmental factors.