The early decades or so of our lives were spent doing research on portland cement, aggregates, mineral and chemical admixtures, air-entrainment, and many other miscellaneous aspects of concrete. A large part of our lives then dealt with problems involving anything made with portland cement—from brick and stone masonry mortars to plaster, stucco, and even to burial vaults and insulators for electric high-tension lines. We were fortunate to be where we were and at the right time.
Usually there were problems involved and these included: cracked burial vaults; deteriorated mortar; failed brick masonry and dimensional stone facades; soft underlayments; setting beds that didn't function; arch dams that expanded and physically moved measurable distances upstream; double tees used as wall panels that cracked so badly you could see daylight through the cracks; concrete that set up too fast or failed to set up at all to the frustration of placers and finishers; and concrete that expanded so fast and so magnificently during 28 days that it rose from the cylinder molds in which it was contained and in the field caused cracks and undulatory surfaces to slabs on ground.
The problems seemed endless. There were roadways rutted from construction traffic before the concrete had a chance to prove itself; potholes that miraculously appeared almost overnight; persistent efflorescence that wouldn't go away; stucco walls inflicted with pustules that looked like the measles; freeze-thaw-like damage where freezing never occured; trails of purple streaks below wax on terrazzo slabs; concrete dam surfaces that eroded—but only during the wintertime; low strength concrete that was actually high strength concrete; and thin-set terrazzo that partially popped loose from its underlayment and dangled in the air.
Let's not forget fresh concrete that smelled like ammonia; ugly odors wafting from concrete surfaces; concrete stuck in mixers that had to be jackhammered away; white, growing mold (efflorescence, that is) that a family thought was going to do them in; non-pigmented red concrete surfaces—an astonishment when forms were removed; and skin burns to ankles, knees, elbows, and other parts of the human anatomy
There was always the surprise of concrete that didn't setup, so noted when forms were removed; rubbery concrete that not only wouldn't stretch but couldn't be easily placed; impressions of ice crystals in formerly frozen concrete that will remain forever like footprints in the sands of time; and delayed ettringite formation where ettringite, the “cement bacillus,” had run amuck.
You name it and we, or someone else, have probably have worked on something like it.
What a marvelous material portland cement is, from the onset of hydration to the edges of destruction. We use it with faith that it will work, however and whenever used—and it usually does. We all hope that when problems arise they will be easily resolved and we are not on the short end of the problem.
The analytical prowess of our industry provides scientific and engineering approaches that produce facts, which usually point the way to their resolution. Sometimes they also require delving deeper into the mysteries of its life, necessitating more research, field evaluations, and comprehensive and detailed studies. Delayed ettringite was one of the more recent of them, and we now understand the mechanisms involved in its formation and can counterattack with protective measures.
Bernie has always said, “There are two things money can't buy, poverty and experience.” Fiscal poverty doesn't take much doing. Experience evolves during a lifetime and is ever ongoing. Being there at the right time is sometimes luck and sometimes it requires direction. Whichever the case, there is no other way to get the experience. Get it however you can.
Bernard Erlin is president of The Erlin Company (TEC), Latrobe, PA, and has been involved with all aspects of concrete for over 47 years.
William Hime is a principal with Wiss, Janney, Elstner Associates and began working as a chemist at PCA 53 years ago.