Preventing Plastic Shrinkage Cracks:

Kestrel® Library

Kestrel Pocket Weather Meters & Concrete Installation 

Preventing Plastic Shrinkage Cracks

Content Provided By: Luke Snell, Director of Concrete Industry Management, Del. E. Webb School of Construction, Arizona State University

Articles of Interest

• How to Prevent Plastic Shrinkage Cracks. Luke Snell.
• Estimating Evaporation Rates to Prevent Plastic Shrinkage Cracking. Concrete International, March 2007.
• Estimating Fresh Concrete Temperatures. Luke Snell and Mark Cheek. Concrete International, June 2006.

Computer Program

• Evaluating Concrete Curing Conditions. English Units | Metric Units
  (Luke Snell, Parameshwar Balasubbramanian, and Aamir Munir)

This program computes the Rate of Evaporation for concrete according to Nomographs in the American Concrete Institute Standard Practice for Curing Concrete (ACI 308-92). The Air Temperature, Humidity, Concrete Temperature, and Wind Velocity are variables which may be known by the user to determine if Adequate Curing is being achieved.

Q&A

Q: What causes plastic shrinkage cracking?

A: Plastic shrinkage cracks occur when the surface of the concrete dries rapidly and shrinks before it can gain sufficient tensile strength to resist cracking. When ambient conditions and concrete temperatures combine to produce conditions that create a high evaporation rate, the chances of the surface drying prematurely and shrinkage cracks forming increases.

Q: How can a handheld weather meter help prevent this from happening?

A: Many concrete professionals get information from weather stations after concrete is cracked from large weather stations miles away. Measuring conditions such as relative humidity, ambient temperature, and wind velocity right at the location where concrete is being placed helps prevent plastic shrinkage from occurring.