Specifying tests for durable concrete
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 […]
Durability
What is sulfate attack?
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, […]
Comparing ASTM C1556 and NT Build 492
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 […]
Background on ASTM C1866
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
“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 […]
When concrete cures at elevated temperatures
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 […]
Hot-weather concreting
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
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 […]
Specifications for high-performance concrete
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 […]
Concrete “permeability” tests
For the most part, so-called concrete “permeability” tests measure something other than permeability. Permeability is the ease with which fluids can move through a porous material. That matters because most […]