Lies, damned lies and statistics
Statistics were part of our everyday lives long before anyone had heard of COVID-19. Pick up a newspaper any day of the week and see how many stories you find […]
Testing
What is a pooled sample?
The engineers’ code of ethics requires us to “hold paramount the safety, health, and welfare of the public“. Here’s one way public health officials use statistics to do just that. […]
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 […]
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 […]
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 […]