Diagnosing ASR
Alkali-silica reaction is a common deterioration mechanism in concrete. Some silicate minerals in aggregates react with hydroxide ions in concrete pore water, forming a gel that imbibes water and swells. […]
Durability
Diagnosing scaled concrete flatwork
Exterior concrete flatwork in a freezing climate experiences the most severe freeze-thaw concrete exposure class, F3. It undergoes cycles of freezing and thawing in the presence of water and deicing […]
Delayed ettringite formation
A few weeks ago I participated in a webinar about mass concrete and thermal control plans. I was dismayed to hear the presenter cite delayed ettringite formation as the reason […]
Concreting in hot weather
Unlike most materials, concrete is often cast and cured on site rather than in the (more) controlled conditions of a factory. That means that temperature and humidity—as well as exposure […]
How engineers came to understand sulfate attack
We’ve discussed the mechanisms of sulfate attack in a previous blog. Soils in the western United States and the prairie provinces of Canada often contain high concentrations of sulfates. The […]
Cold weather concrete
Those of us who live in northern latitudes would do well to review the basics of cold weather concreting every fall. The American Concrete Institute’s “Guide to Cold Weather Concreting” (ACI […]
Why should we care about serviceability and durability?
There are generally three aspects to the performance of a structure. The first is structural. The structure needs to resist the gravitational, wind, and other loads to which it will […]
Q & A: Service life prediction
We’ve discussed concrete durability in quite a few blog posts, but we’ve only alluded indirectly to concrete service life prediction. Hossam Alalaily explains the basics. Q: What do you mean […]
Evaluating aggregates using ASTM C1778
ASTM C1778, “Standard Guide for Reducing the Risk of Deleterious Alkali-Aggregate Reaction in Concrete,” can help you decide how best to mitigate expansions due to reactive aggregates. It covers both […]
Finishing air-entrained concrete requires a light touch
When finishing air-entrained concrete, less is more. Hard-troweled surfaces and air-entrained concrete don’t mix. If you need to entrain air—that is, if the concrete will experience cycles of freezing and […]