Comparative Analysis on Reducing Concrete Shrinkage and Cracking
Can concrete shrinkage and cracking be reduced with our modern materials and testing techniques?
Need and Benefit
Concrete is typically jointed for force cracks to occur at particular locations. Cracks occur to alleviated internal strains that are greater than the materials tensile strength. Internal strain can be generated by restraint, temperature, chemical shrinkage, and/or drying shrinkage. Joint spacing is generally selected using rules of thumb which were primarily based on older cement chemistries. During construction, requests are often made to extending the distances between joints and/or eliminating joints to increase the speed of construction and save in scheduling costs.
Although many products and techniques claim to have an effect on concrete cracking, there is very little consistency in the testing and very little data available to compare the crack resistance of a concrete material.
Previous studies by the Bureau of Reclamation have looked at specific concrete materials for repair type applications. Another study looked at chemical shrinkage (using one test) to evaluate one type of concrete additive.
A more comprehensive program to look at a number of products and/or techniques and compare them using the same suite of laboratory and field tests is needed to be able to quantify the properties that can be achieved with today's cementitious components and to allow Reclamation the tools to specify appropriate and relevant properties when designing large concrete structures.
Contact the Principal Investigator for information about partners.
Scoping study report with findings. Research proposal with partners.