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 […]
Throughout my career, our industry has been pursuing performance specifications for concrete. That is, we want specifications for what the concrete must do, not what it must be. The sticking […]
Concrete in certain environments is subject to sulfate attack. These include seawater, some industrial environments, sanitary sewers, and sulfate-bearing soils and groundwater. As engineers have known since the early 1900s, […]
ASTM C1556 and NT Build 492 both measure the ease with which chloride ions migrate into concrete. Both test methods estimate the diffusion coefficient, a measure of the rate at […]
We’ve previously discussed a new standard that promotes sustainability through the use of ground recycled glass in concrete. Now let’s get some background on ASTM C1866.* Most glass falls into […]
“Classic” alkali-silica reaction is a reaction between alkalis in cement and reactive silicate minerals in susceptible aggregates. The reaction creates a gel that absorbs water and expands, resulting in the […]
Elevated temperatures affect the mixing, placement, and finishing of fresh concrete. In our blogs about mass concrete and hot-weather concreting, we’ve alluded to what happens when concrete cures at elevated […]
As the weather warms up, it’s good to review best practices for hot-weather concreting. You can incorporate these ideas as needed into your project specifications. The American Concrete Institute defines […]
Concrete exposure classes are part of a decades-long trend toward performance specifications. Traditionally, specifications were prescriptive. That is, they specified what the concrete must be. So there might be limits […]
When I was a graduate student in the 1980s, papers about high-performance concrete nearly always started out by explaining that “high performance” means more than high strength. Then they went […]