Rebar Alternatives Save Big $$$

Contact Us

Fill out the form below to request more information from our Bladensburg location.

"*" indicates required fields

Consent*
Hidden
This field is for validation purposes and should be left unchanged.

View our privacy policy

MD: Bladensburg (HQ)

(301) 927-8300

4700 Annapolis Road, Bladensburg, MD 20710, USA

Mon-Fri 6:30AM to 4:00PM Saturday 6:30AM to 12:00PM Sunday CLOSED

Get In Touch with someone at MD: Bladensburg (HQ)
(301) 927-8300

"*" indicates required fields

Accepted file types: pdf, txt, Max. file size: 2 MB.
Hidden
Response time within 4 hours

Plastic Shrinkage Cracking

David Welch | August 27, 2015

Plastic shrinkage cracks appear in the surface of fresh concrete soon after it is placed and while it is still plastic. These cracks appear mostly on horizontal surfaces. They are usually parallel to each other on the order of 1 to 3 feet apart, relatively shallow, and generally do not intersect the perimeter of the slab. Plastic shrinkage cracking is more likely to occur when high evaporation rates cause the concrete surface to dry out before it has set.

Plastic shrinkage cracks are unsightly but rarely impair the strength of concrete floors and pavements. These cracks, however, can permit the ingress of other aggressive chemicals that impact durability and as weak points for the initiation of later age cracking due to other reasons. The development of these cracks can be minimized if appropriate measures are taken prior to and during placing and finishing concrete. Note:

Plastic Shrinkage Cracking in Concrete - Causes and Prevention | For Construction Pros

Source: ACI 305R-10, Guide to Hot Weather Concreting

How to Use:

  1. Begin with air temperature and move up to the relative humidity
  2. Move right to concrete temperature
  3. Move down to wind velocity
  4. Move left to read approximate rate of evaporation

Whenever the chart predicts water will evaporate at a rate approaching 0.2 pounds/square foot/hour (lbs./sq. ft./hr.), the likelihood of plastic shrinkage cracking exists. Of course, other factors, such as elevated air content in the concrete or the presence of fly ash or microsilica, also affect the occurrence of plastic shrinkage cracks. However, ACI’s nomograph is a pretty fair indicator for everyday concrete.

What can you do to minimize plastic shrinkage cracking

  • Dampen the subgrade and forms when conditions for high evaporation rates exist.
  • Prevent excessive surface moisture evaporation by providing fog sprays and erecting windbreaks.
  • Cover concrete with wet burlap or polyethylene sheets between finishing operations.
  • Use cooler concrete in hot weather and avoid high concrete temperatures in cold weather.
  • Cure properly as soon as finishing has been completed.

 

Need a more accurate estimate on the evaporation rate? Check out the ACI Mobile app

Ready Mix Sales ManagerDavid Welch

Phone
Location
MD: Annapolis Junction
Languages
English

Latest News

Ernest Maier and Gomoljak Counter Price Sheet

Ernest Maier and Gomoljak Counter Price Sheet

Pricing accurate as of 10/3/2022 and valid for Annapolis, Bladensburg, and Gaithersburg locations (contact us for bulk pricing and delivery): […]

Read More
How Strong Is Fiberglass Rebar?

How Strong Is Fiberglass Rebar?

Fiberglass rebar is a reinforcing bar constructed from glass fiber and resin. Fiberglass rebar has risen in popularity in construction […]

Read More
Can Fiberglass Rebar Be Used In A Foundation?

Can Fiberglass Rebar Be Used In A Foundation?

Rebar has historically been the most typically utilized raw material in construction. Almost all structures are constructed out of concrete […]

Read More
Answering 6 FAQs About Fiberglass Rebar

Answering 6 FAQs About Fiberglass Rebar

Demand for glass fiber reinforced polymers (GFRP), aka fiberglass rebar, has been growing as an innovation over steel rebar and […]

Read More
Infrastructure Under Attack

Infrastructure Under Attack

With the long awaited passage of the Bipartisan Infrastructure Law (Infrastructure Investment and Jobs Act), America is poised to make […]

Read More