There is a hardware store in Northbrook, Ill., a suburb of Chicago where we both worked, that had a grand opening. Their souvenir for the opening was a yardstick 4 feet long. On it was written, “We give a little more!” What a fascinating way of going beyond the call of duty and getting something extra.
On the concrete foundation of a world-famous high-rise bank building is a facade covered by multitextured, light-colored granite. Girdling the facade at each floor is a rectangular band of olive-mottled granite that from a distance looks like the U.S. greenback. How fitting for a bank building. The owner was delighted, and the architect aglow in this delight. The South American quarried money-like stone was cut into huge rectangular blocks and shipped by boat to Italy. There, it was fabricated to meet architectural requirements and gang-sawed into nominal 1-inch-thick sections, trimmed to appropriate lateral dimensions, with anchor holes drilled into its sides, and its surface flamed to have an antique-like finish. Finally it was stored in wooden crates and shipped to Ireland where it was uncrated, installed on steel trusses, and shipped by boat to the United States, where it was stored and then eventually installed. Wow, what a logistical nightmare. Columbus would have marveled at this feat of water transportation, and Einstein at all of the math and tracking involved. Now we do it all the time. Everyone involved must have given a little more, or perhaps more aptly, a lot more to accomplish all that.
During the last decade or so, concrete mixes have been developed with higher and higher strengths. That would have been impossible if not for supplementary cementitious materials such as fly ash. One of fly ash's advantages is its pozzolanic virtues. It reacts with the strength-weak calcium hydroxide (CaO(OH)2) component of portland cement hydration that accounts for 20% to 30% of the paste, and is replaced by stronger calcium silicate hydrates (3CaO·2SiO2·XH2O) resulting from the pozzolanic reactions. It also consumes the fly ash waste product of coal-fired power plants, so it is patriotic as well—one of the greenings of the industry. All in all, great trade-offs that help keep the concrete industry advancing in many aspects. Those relationships give a little, or is it a lot, more to producers of fly ash, slag, portland cement, and admixtures, and to architects, engineers, ready-mix producers, and eventually society, the ultimate benefactor.
Curing concrete began by using water methods. Now it includes membrane and pigmented-membrane curing methods thought by some to be the penultimate in getting concrete to develop to its finest. Nonmembrane curing compounds have tagged along—like some mysteriously formulated alkali silicates that are reported to not only do the job but provide ancillary benefits like increasing wear resistance—getting something more. Now, internal curing is gaining attention, an inside curing job now needed as lower and lower water-cement ratios used for dramatically decreasing permeability, or increasing strength to five-digit levels do not provide enough water for adequate cement hydration—it provides a needed extra.
A top concrete technologist-scientist, whose name long has been forgotten, gave a lecture on cement and concrete research in the Soviet Union when the iron curtain was still draped around the world. His concept (Or was it a scientific dream?) relayed with emotional gestures during an off-the-cuff one-man seminar back in the 1960s, was about portland cement of the future—cement so finely ground that it set and hardened almost instantaneously. It could be controlled by using varieties of admixtures and get the desired concrete properties, such as controlled time of set and rate of hardening; early, medium, late, and ultimate strength development; reduced shrinkage and creep; higher or lower moduli of elasticity; and color and color tone. You name it! It would create a concrete utopia.
There's still a long way to travel to find that utopia. But, consider just the massive amounts of energy needed for ultra-fine grinding of the portland cement—it is greening in reverse. Wait, what if interground were fly ash, slags of all kinds, silica fume, incinerator ash, and whatever other useful “garbage” that comes along? And because of increased cementitious efficiency of the ultra-fine powder, there is significantly less portland cement used? Greening and patriotism back again? The scheme may give a little more, and benefit, to the future.
A little more from every concrete professional each day can mount up to an enormous package to the industry. We write these columns, not that we have to, but because we want to—give a little more—like that 4-foot yardstick. With everyone's help, maybe even a 3-foot concrete yardstick can be stretched to four, or more, and all because each of us gave just a little more.
Bernard Erlin is president of The Erlin Co. (TEC), Latrobe, Pa., and has been involved with all aspects of concrete for more than 48 years.
William Hime is a principal with Wiss, Janney, Elstner Associates and began working as a chemist at PCA 54 years ago.