Making use of marginal fly ash
Electric utilities are under pressure to reduce carbon emissions and other pollutants from their power stations. More and more, they are shutting down their coal-fired plants in favor of natural […]
Testing
How many cylinders: a pot roast story
Acceptance testing reflects the compressive strength of the concrete as delivered to the jobsite. We make the cylinders and keep them at the site for 24 hours under—we hope!—controlled conditions, […]
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 […]
Concrete sample size: how big is big enough?
When you submit a concrete sample for petrographic examination, how big a sample do you need? That is, what’s the appropriate concrete sample size? We’ve discussed in previous posts how […]
Do we expect too much from ASTM C1202?
We often — mistakenly — refer to ASTM C1202, “Standard Test Method for Electrical Indication of Concrete’s Ability to Resist Chloride Ion Penetration,” as the Rapid Chloride Permeability test. Permeability […]
Concrete petrography gives a grander view
Many engineers have no idea how informative concrete petrography can be. That’s too bad, because concrete petrography is one of the most useful techniques in forensic engineering. Failure analysis of […]
ASTM C1709 promotes sustainability
ASTM C1709 provides a way to introduce alternative supplementary cementitious materials (ASCMs) into the marketplace. Supplementary cementitious materials include fly ash, slag cement, silica fume, and calcined clay. They can […]
Predict service life with ASTM C1556
ASTM C1556 is a test we use to assess the ability of concrete to resist the ingress of chloride ions. If we’re designing a high-performance concrete for a new parking […]
NT Build 492 provides data for durable concrete
NT Build 492 is a test that determines the diffusion coefficient of concrete. Diffusion is the movement of a dissolved substance under a concentration gradient. That is, ions in solution […]
Can you get a representative sample of concrete?
A representative sample of anything is an unbiased selection from the whole population. It’s a statistical concept that applies to everything from opinion polls to laboratory testing. In principle it […]