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Surveying the Future: Backsights and Foresights

3/1/2012

My route to the construction industry began with a Surveying Merit Badge. A few years later, I was running surveys and I loved every minute, including the long, cold day I shot wet-screed elevations for a young Dan Baker, who was running the crew with the story pole in one hand and a float in the other. I learned that when transferring levels from the known elevation behind you to establish a new reference ahead, you need to "balance the backsight and the foresight." To minimize error, you have to look back about as far as you want to look ahead—an important lesson for this, my last President's Memo.

Coming onto the Executive Committee, I was blessed with a dynamic and discerning Board of Direction, the wisdom and depth of Luis García, the strategic instincts and vision of Florian Barth, and the incredible energy, enthusiasm, and creativity of Dick Stehly. I was likewise blessed with dedicated staff members who learned the ropes under Bill Tolley. Those folks and their predecessors gave sustainability a home in ACI and a home in the concrete industry through the Concrete Joint Sustainability Initiative. They also welcomed or expanded the scope of more new technical, educational, certification, and board committees than I can list here.

Looking forward, Jim Wight is 100% ready to assume the role of President and is following Terry Holland's advice to "hit the ground running." Anne Ellis is primed to become our Senior Vice President (VP) and is actively leading reviews of our strategic plan and how we communicate with each other and the world. We are excited to bring Bill Rushing's experience, enthusiasm, and deep fiscal understanding of the Institute to the position of VP. And Ron Burg has come up to speed and effectiveness incredibly fast as our "no longer new" Executive VP.

Over the next few years, this new Executive Committee will see continued development in sustainability, be part of the fresh new look in ACI's educational activities, experience the new member-requested convention format, sharpen focus on our chapters, and witness the launch of the exciting new 318 Code format. This inspired new leadership also will be finding ways to more fully integrate international and domestic activities to accurately reflect our truly global industry, where—as United Airlines puts it—"the word 'foreign' is losing its meaning."

To look further into our future, let's reference ACI President S.C. Hollister's farewell speech as a benchmark from our past (delivered almost 80 years ago and reprinted on the following pages). Hollister imagined the consequences of boosting compressive strength from 3000 to 10,000 psi (made possible by imagining admixtures). He predicted: "Smaller columns, thinner and lighter beams and slabs would at once result. Precast units, easy to handle, would be available. The present limiting heights of buildings, of spans of bridges, would at least double. A new basis of design, new codes and specifications, would be required." Wow! Hollister was right on target! But he also warned against growing "so accustomed to the surrounding conditions that they are accepted as a sort of status not subject to review."

Here in the present, I believe that today's concrete industry can pretty much do anything that is asked of it. We can provide strength, stiffness, durability, resistance to cracking, and resiliency; and we can do it sustainably, pretty much on any site, anywhere in the world as long as someone is willing to pay for it. My vision of the near future is that we can do this more reliably, more repeatedly, and on demand—any time those demands are communicated clearly and with precision. I see us increasing our ability to manage the variability of our materials, decreasing the variability in construction processes and testing, and increasing our tolerance for variable weather. I see us reliably, confidently, and profitably serving discriminating owners, while providing a fully satisfactory product to those whose needs are less demanding. As the boy in The Sixth Sense would say, "I see smaller standard deviations."

But as deeply honored as I have been to serve as your President, your individual and collective visions of the future are far more important than mine. The industry and the Institute will go where you take us. That is why I'm so excited when I visit chapters that are talking about new developments, and when I stop by committees that always carve out time in their document development agendas to present and discuss new ideas. I'm convinced that the "Next Big Thing" to influence the concrete industry for the better is already out there in the minds and imaginations of many of you!

Thank you for the honor of serving as your President.

Kenneth C. Hover
American Concrete Institute
kch7@cornell.edu

President's Address by S.C. Hollister^*

It is fitting that a periodic account of stocks be taken concerning the state of the Institute. I choose to view the state of the Institute this evening at this 29th anniversary of its founding not in the traditional light of receipts and disbursements, assets, liabilities, and surplus if any; but rather in the broader view of the Institute's work in relation to the field which it serves.

From a strictly business point of view, it is pleasing to report to you that the Institute is in good health due in part to the far-seeing policies of your former officers to provide for an eventual rainy day and in part to the successful efforts of the present officers in conserving that cushion of protection against insolvency and obliteration in these trying times. The Institute has ridden the storm and has proven herself a sturdy ship. To the whole crew, to each of the membership, goes a measure of credit for his loyalty in this achievement. But perhaps to no single individual goes as much credit for this achievement as should rightfully go to your SecretaryTreasurer, Harvey Whipple, and to him I pay sincere and humble tribute. And so the Institute can and will go on to the service that lies ahead.

But my special theme this evening lies in the answer to a challenging comment passed to me not long ago. Have we not at hand essential rules for the proportioning of concrete to obtain strength, durability, water-tightness? Have we not elaborate equipment, many specifications, and codes by which to construct concrete work? What need for additional data and what data to add? In short, has not the field been served and has not the Institute shot its bolt?

One may grow so accustomed to the surrounding conditions that they are accepted as a sort of status not subject to review. An automobile is ordinary when it is a daily necessity; but today's automobile would have been an unquestioned marvel twenty or even ten years ago. The achievement of today was the goal of yesterday. It cannot be the goal for tomorrow. Great as have been the achievements in the field of concrete today, they are only the dreams of yesterday come true.

If the function of the Institute has been fulfilled, it is because the realization of dreams is accomplished and because the realm of dreams has been wrung dry. If there is a field for the Institute, it is because there still exist dreams of accomplishment—developments not yet realized.

Is the realm of dreams for the Institute really barren? In answer, who is there who would say that in any single major phase of the field we have reached what ten or twenty years hence, we will expect to see as established practice?

But let us be more specific. Judging by the development of the last twenty years, what do we think the cement of twenty years hence will be like? What will be the currently available concrete strength and what the construction methods? In this frame of mind, I have dared to review even the most complacently accepted practices of today and to ask: What reasonably possible developments may be made in the next twenty or ten years?

There are many indications as disclosed by reports to this Institute that a number of interesting developments are possible in the basic product, cement. This is quite aside from the question whether one cement or several cements will be available. Surely a majority of concrete structures may be built of a standard cement in any case. But will it approach in character the present standard portland, or high early strength, or low heat, or still something else? Admittedly this is not so much a question to be solved by the Institute as it is a basis to which concrete work is to
be adjusted.

And what of concrete mixtures? Abrams has made mortar cylinders with the strength of steel. Moreover, they behaved in accordance with the water-cement ratio law. To obtain this phenomenal result, he had to use pressure to cause the minute amount of water to be dispersed throughout the cement. What a challenge this has offered! If this dispersion could be accomplished in other ways, or if only a part of this added strength is made available by easily applied methods, a new era in concrete is born. Imagine, for example, the concrete with an available strength of 10,000 psi. Smaller columns, thinner and lighter beams and slabs would at once result. Precast units, easy to handle, would be available. The present limiting heights of buildings, of spans of bridges, would be at least double. A new basis of design, new codes, and specifications would be required.

Perhaps it may seem to some that these are idle dreams, but let us see whether there is any tangible basis for thinking there is a possibility of moving on from our presently current strength to those of Abrams' cylinders of the strength of steel.

Present methods in use by Earley in the construction of the Baha'i Temple permit them to place their units weighing 3 tons or more and to lift them out and turn them over in 18 hours after filling the mold. And this with portland cement, not with excessively rich mixtures but with much of the excess water removed after placing but before the setting of the cement. It is interesting to speculate on the effect upon concrete design and construction methods such a development would produce in the ordinary concrete field.

Talbot and Richart have contributed valuable information on the physics of wet mortar. This field of enquiry is a fertile one and will likely yield further developments. Who may say, for example, whether it is possible to achieve mobility or workability with an agent other than water thus using only enough water for the hydration of the cement.

In the realm of mass concrete, we have a great deal to learn. Not only must there be much improvement in the understanding of the mechanics of large concrete units, but we must know more of the thermal and shrinkage stresses, and their relation to the chemical and physical changes transpiring. And to cap these effects, we must determine more accurately the aggravating or mollifying effect of plastic flow.

We have by no means exhausted the possibilities in the development of mixing and placing equipment. Even now harsher, stronger mixtures are producible and placeable where in late years they would not have been considered feasible. Extracting the water from the wet mass has been known to be beneficial—in fact, Earley has used this principle for many years; but we have not as yet brought about the practice in general construction.

As new methods of experimentation become available, much remains to be developed in the mechanics of reinforced concrete members. A review of the beam theory, especially at a cracked section, and after considerable plastic flow, will yield many useful data. A study of bond strength and of anchorages will lead to a better design procedure. The work of Davis, McMillan, and others on plastic flow will give new color to the mechanics of reinforced concrete design. The manner in which shrinkage stresses relate to our accepted design procedure has not been fully determined.

A great deal of work is necessary for a better understanding of the mechanical behavior of many forms of commonly used members. This is especially true of the interaction of members of an assembly. For example, in arch bridge design there are at present proponents of both the articulated deck and the monolithic deck. Abroad there are many developments in bridge design and construction that have not as yet been used here, notably the thin flexible arch with rigid deck frame and arches with hinges.

Many developments in structural form are to be seen in Europe. These may in many cases prove of use on this side of the Atlantic. To the ingenuity of the adaptation of structural form in concrete there is no end.

Valuable investigations by McMillan, Young, Viens, Lindau, and others, upon the factors influencing durability of concrete structures have from time to time been reported to the Institute. This work will, of necessity, go on for many years to come before we may be fully satisfied that the subject has been adequately covered.

In review then, we see the many varied and intriguing avenues of development that present themselves both for the immediate and the long-time programs of action. We have not touched yet upon the products field. Little mention has been made, except by implication of questions relating to aggregates to curing methods and the interesting likelihood is that no sooner will we have caught up with one branch of our varied subject than the basic substance, concrete, or its parent, cement, will have moved to new levels.

Surely then, the work of this Institute is not at all done. Each year sees new accomplishments and with them, new objectives appear. Thus, the Institute is but the embodiment of a moving force of progress. It cannot be static. It can never overtake its goal.

Originally published in the ACI JOURNAL, Proceedings V. 30, No. 3, Mar. 1934, pp. 247-250.

^*Presented by the retiring President, Prof. S.C. Hollister, at the Institute's 30th Annual Dinner, Toronto, February 21, 1934.

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