Load transfer across cracks and joints
journal contributionposted on 20.05.2010, 10:40 by Stuart J. Arnold, Simon Austin
There is a growing demand for in-situ concrete industrial floor slabs throughout the world. The increase of internal floor space required for warehousing and manufacturing processes has led to the majority of this growth. This demand has been coupled with client requirements for extended life expectancies and tighter tolerances in both level and flatness. Whilst new machinery such as laser screeding plant has helped in providing quicker and more accurate concrete placement, the greater size of the pour creates an increased risk of thermal and hygral movement. All concrete slabs must consequently accommodate significant shrinkage throughout their lifespan, because if restricted, additional stresses and cracking will occur. Some form of control to prevent premature degradation is therefore required within the structure. This is commonly achieved with the use of joints (controlled cracks) to enable the concrete to move at designated locations, leaving the remainder of the slab relatively free of restraint-induced stress. Unfortunately, these areas often become the main cause of failure if incorrectly designed or constructed.
- Architecture, Building and Civil Engineering