If there is any such thing as a holy grail of concrete it has to be shrinkage cracks. The industry has conquered just about everything else. For example, we already make it stronger – 20,000 psi for columns, weaker for fill at 300 psi, lighter for insulating at 30 pcf, and heavier for radiation shielding at 180 pcf. We even make self-compacting concrete for easier placement and extra stiff concrete so it will stand up behind a slip form paver.

Wait, there’s more. We can make it set faster for quick repairs or slower for delivery to remote locations. We can make it beautiful for architectural appeal or plain ugly to be buried in the ground and never exposed to the light of day, while efficiently capturing and removing storm water run off before it can collect and cause millions of dollars in flood damage.

What’s left? How about crack-free concrete? I don’t doubt that someone can provide, without a minute’s worth of research, evidence of concrete that will out-perform the examples I have casually listed above, yet the problem of crack-free remains. Concrete shrinks and that irrefutable fact results in cracks that sometimes lead to reduced service life or costly repairs.

Can concrete that is cured from the inside out eliminate all shrinkage cracks? Probably not, but how about reducing cracks by almost half in 500 feet of mainline paving¹ or how about 250,000 cubic yards of paving in an inter-modal yard that has to be studied on hands and knees to find a crack.²

Please visit the Menu for Internal Curing with Lightweight Aggregates for valuable internal curing resources.

For additional information about Internal Curing, read the white paper “INTERNAL CURING Using Expanded Shale, Clay, and Slate Lightweight Aggregate” published by Expanded Shale, Clay & Slate Institute.

Bio: The author is a long time practitioner in the concrete industry with over 38 years of experience in inspection, testing, production, quality control, and sales.

¹ Friggle T.; Reeves D. “Internal Curing of Concrete Paving: Laboratory and Field Experience” ACI Fall Convention 2007 symposium

² Villarreal V.H.; Crocker D. A. Better Pavements through Internal Hydration” Concrete International February 2007