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. […]
Specifications
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 […]
Writing from the reader’s point of view
As a former editor, I often find myself wondering why so many writers don’t seem to consider the reader’s point of view. It’s the editor’s job to advocate for the […]
Concrete cube tests
In previous blogs we’ve discussed various aspects of acceptance testing of concrete. The standard concrete compressive strength specimen in North America is a cylinder, either 6 x 12 inches or 4 x 8 inches. In most […]
Q and A: Low-carbon concrete
My project requires low-carbon concrete. What is that, anyway? There’s no universally accepted definition of low-carbon concrete. Typically, though, low-carbon concrete has a lower global warming potential than traditional concrete […]
ACI PRC-132.1 assigns responsibilities in caring for concrete test specimens
ACI PRC-132.1-22, “Responsibility for the Care of Test Specimens for Acceptance of Concrete“, describes who should do what to ensure accurate acceptance testing. As a TechNote rather than a standard […]
ASTM C1077
ASTM C1077 is the “Standard Practice for Agencies Testing Concrete and Concrete Aggregates for Use in Construction and Criteria for Testing Agency Evaluation.” Agencies such as AASHTO provide independent accreditation […]
Prescription to performance
As part of its Prescription to Performance (P2P) initiative, the National Ready Mixed Concrete Association surveyed its members. They wanted to know which prescriptive requirements kept them from optimizing concrete. […]
Overdesign and sustainability
Acceptance of concrete delivered to the job site is usually on the basis of compressive strength tests in accordance with ASTM C31 and ASTM C39. To compensate for variability in […]