KEYNOTE ADDRESS

The Global Advance­ Emerging Opportunities at Home and Abroad

The author discusses worldwide technologi­ cal advances in precast and prestressed concrete and relates these developments to Ben C. Gerwick, Jr. emerging market opportunities in Narth Chairman America and in other countries. Ben C. Gerwick, Inc. Consulting Construction Engineers San Francisco, California (Professor Emeritus oday is Columbus Day- the anniversary of of Civil Engineering, Christopher Columbus first setting foot on the University of California at Berkeley) T Americas. We are celebrating that great adventure of his. Columbus failed in his mission to discover a short route to Cathay, but he did not fall off the edge of the Earth. What he did accomplish was to capture the imagina­ For the past 30 years, Ben C. Gerwick, Jr., has been tion of Western Civilization by demonstrating that the chairman of his own consulting firm, which he founded in world is a globe. 1971. His firm provides worldwide engineering-marketing Today, 499 years later, we are witnessing the globaliza­ services in all phases of precast and prestressed concrete tion of the world's economies, which has its counterpart in construction, particularly for bridges, foundations and the rapidly increasing interchange of ideas, techniques, op­ marine structures. Recent projects include the King Fahd Causeway, Eurotunnel, Great Belt Bridges and Tunnel, portunities and markets. This exchange occurs in both di­ Hibernia Offshore Platform and San Francisco Airport rections. We, in North America, are fed with both fresh expansion. In addition to his consulting practice, Professor ideas and techniques from Europe and Asia while also ex­ Gerwick was for many years on the faculty of the civil periencing growing competition in our own backyards from engineering department of the University of California at well-financed, technically competent foreign companies. Berkeley. Yet, opportunities are also being opened up worldwide for In 1957-'58, Professor Gerwick served as PCI's fourth American expertise in manufacturing, management and president. In recognition of his contributions to the industry, marketing- areas in which we currently excel. he received PCI 's Medal of Honor Award and was also We are well aware of these developments but we have conferred a PCI Honorary Member. Active for many years been slow in reacting to the new realities. Like the Euro­ in the Federation lnternationale de Ia Precontrainte (FIP), pean Community (EC), which has taken so long to consum­ he served as its president from 1974-'78. For his mate, we in the United States fail to recognize the dramatic extraordinary services, he was awarded the Freyssinet changes in our global system, changes that have recently Medal. An honorary member of several professional been made strikingly clear in the political sphere, but which societies, he was elected a member of the prestigious National Academy of Engineering in 1980. Professor are no less far reaching in the economic sector. For exam-

Gerwick is the author of three books and more than 160 Note: This article is based upon the author's Keynote Address delivered at PCI's technical papers. 37th Annual Convention in Minneapolis, Minnesota, October 14, 1991.

32 PCI JOURNAL pie, the birth of the EC is going to ments for which the American precast, highlight a basic inadequacy in our prestressed construction industry can American system of measures and feel justifiably proud. weights, namely, the failure of indus­ Second, from a management view­ try to convert to the metric SI system point, the United States has a unique of units (Systeme lnternationale). competence in precast concrete plant Practically every country in the design and operation. Europe has world has switched to the SI system. largely been captivated by the concept Our neighbor to the north, Canada, has of mechanization and even robots, made the change. Japan has partially which when they work, are labor sav­ moved from metric to SI, which of ing. But plants in the commercial mar­ course, in practice represents only a ket need flexibility. The adaptability shift in decimal point. Unfortunately, of concrete is one of its great assets. the American construction industry, America has simplified the process after a half-hearted effort in the 1970s, and contributed its own ingenuity in has abandoned the task. Already, leg­ material and production flow. islation has been introduced in the EC The third area in which America has to prohibit imports from countries not excelled is in marketing. We are a using the SI system. There is a real po­ market-oriented economy and we have tential for trade barriers to set in, to respond rapidly to the demands of which could exacerbate the discrimi­ our market in order to stay in business. meability. Thus, the European effort nation which American engineering Contrast this with some production­ concentrates on reducing the coeffi­ and construction firms have previ­ oriented, centrally controlled econ­ cient of permeability to 1Q -12 to 1Q -13 ously experienced in Japan. omies which set up year-round pro­ m/sec (3.3 x I0-12 to 3 .3 x IQ-13 There are three areas in which the duction of standardized units - or ft/sec). Contrast this with our prod­ American construction industry has with the philosophy that says, "We ucts in the United States which have shown particular expertise: technol­ will produce our own product effi­ permeabilities of I0-8 to 10-10 m/sec ogy, management and marketing. ciently and cheaply: if anyone wants (3.3 x IQ-8 to 3.3 x 10-10 ft/sec), a fac­ First, the United States excels in to buy it, they can." tor of 1000 to 100,000 times as pretensioned manufacture of precast Before moving on, it should be men­ large! The achievement of these concrete products. Our double tees tioned that there is currently an impor­ very impermeable, durable con­ and hollow-core slabs have captured tant multiyear joint research program cretes is obtained by using carefully the world market as a structurally ef­ between the United States and Japan graded mixes of high cleanliness, fective form. Europe is belatedly rec­ that is partially funded by the PCI. En­ high range water reducing admix­ ognizing the advantages of our !-gird­ titled PRESSS (Precast Seismic Struc­ tures, and the addition of microsilica ers and bulb-tees in bridge construc­ tural Systems), the objectives of the and/or pozzolans to relatively rich tion. Also, the American version of program are to develop effective seis­ cement contents. A secondary bene­ pretensioned railway ties utilizes only mic structural systems for precast con­ fit of this impermeability for ex­ 20 to 50 percent of the labor of many crete buildings and to prepare seismic posed and architectural concrete is European systems. Our prestressed con­ design recommendations for incorpo­ the elimination of efflorescence and crete piles, at least on the West Coast, ration into the model building codes. fungus staining. There are, of course, are now being designed not only to re­ Let me switch my approach now moderate extra costs for such con­ sist seismic-imposed curvatures, but to and examine the opportunities we crete, but the long-term results are support the superstructure during an have to learn from abroad. In a sense, dramatic. earthquake in ductile frame action. the world can be viewed as a global • Another advancement is the use of The Precast/Prestressed Concrete laboratory for research and develop­ high yield strength reinforcement 2 Institute (PCI) has taken the lead in ment. First, let me address the techni­ [75,000 psi (550 N/mm )] as pri­ precast concrete building construction cal advancements. mary reinforcement in convention­ by recognizing the critical role of • One of these is durability. Consider­ ally reinforced elements or as sec­ joints and connections in a structure able attention is being devoted in ondary reinforcement in prestressed and has developed engineering and both Europe and Japan to the pro­ concrete members. In Japan, spiral quality control standards which ensure duction of concrete which will pre­ reinforcement for piles and columns proper performance. The work initi­ vent corrosion of the reinforcement is being applied with yield strengths 2 ated by Armand Gustaferro on fire re­ due to carbonation and chloride ion of up to 150,000 psi (1100 N/mrn ). sistance of prestressed concrete has penetration. The American Concrete • A further advancement is the manu­ been largely instrumental in the devel­ Institute (ACI) is now recognizing facture of elements to very close tol­ opment of worldwide standard fire re­ the durability issue, although some­ erances, enabling their assembly sistive ratings. what belatedly. Corrosion is largely with dry joints. The 750,000 tunnel These are technical accomplish- a function of the coefficient of per- liner segments of the Eurotunnel,

November-December 1991 33 linking France and England under the English Channel, were manufac­ tured to tolerances of curvature of less than 1 mm ( ~5 in.) and toler­ ances in fit of 0.4 mm (Y64 in.). See Figs. 1, 2 and 3. Japanese hollow-core slabs are man­ ufactured to extremely exacting di­ mensional tolerances and surface smoothness to enable their use as ar­ chitectural wall panels. • Alkali-aggregate reactivity, both short-term and long-term, is an in­ creasing problem worldwide. The United States has coped with this problem by restricting alkalis in the cement and banning the use of ag­ gregates with questionable proper­ Fig. 1. Highly impermeable concrete with a water-cement ratio of 0.32 for ties. However, it has been found that Eurotunnel tunnel liners. many aggregates in Europe and Canada have sufficient reactive con­ stituents that result in long-term problems. In the United Kingdom, delayed alkali reactivity is known as "concrete cancer." Recently, long­ term problems have emerged in the United States, and we can expect more of these problems in the future. Historically, the American approach to prevention of alkali-aggregate reaction has been to minimize the alkalis in the cement and the reac­ tive silica in the aggregates. The new European approach is based on the fact that about 4 percent silica is a "pessimum," so by adding silica in the form of pozzolan (fly ash and microsilica), they purposely go well above this pessimum level, to levels Fig. 2. Extremely close tolerances are demanded for tunnel liners. of 15 to 20 percent silica. This is a particularly effective approach for products which will be immersed ip seawater, such as undersea tunnel liners, where the sodium ion can penetrate over time to furnish a sig­ nificant source of alkali. • Efficient methods for recycling of aggregate are being developed on a substantial scale in Europe and ex­ tensive testing is being carried out to fmd the best means for obtaining an acceptable product. • High strength concrete (high perfor­ mance concrete) is a field in which American researchers and industry have played an important role in de­ velopment, yet we still have found only marginal applications for its use in precast concrete products. Fig. 3. Erected tunnel liners, Eurotunnel project.

34 PCI JOURNAL The global industry is now actively defects, such as bleed holes (bug the forested areas of Europe, trees developing its use in precast con­ holes) and air bubbles, are being are considered much too valuable to crete piling, pressure pipe, tunnel eliminated by the use of controlled be used for poles! liners, bridge girders, offshore plat­ permeability formwork which is af­ • Prestressed concrete railroad ties (or forms and other applications. fixed to the inside of the forms. This sleepers, as they are called in many • Some recent advances in reinforcing polypropelene fabric is permeable to parts of the world) are also replac­ patterns have been carried out by water, but not cement paste. ing wood ties in almost every coun­ joint European-American efforts. • Another area from which we can try. They are used on mainline high One of these is the mechanically­ learn from overseas is in the ex­ speed tracks because their stability headed bar (T-headed bar), devel­ panded use of precast concrete mem­ with welded rails minimizes the bal­ oped and tested in the United States, bers in foundations. In France and last maintenance. They are also introduced in Canadian codes, and Hong Kong, precast concrete slabs being utilized for secondary track to first set up on a production basis by are being installed in slurry trenches reduce the deterioration due to inad­ a European manufacturer. It is being in order to enable their direct use as equate drainage. An interesting de­ widely used in offshore structures walls for subways, underground velopment in China is a wide rail­ and protective structures. The rein­ garages and basements. Precast road tie, about 24 in. (610 mm) in forcing bar has excellent potential bearing units are set through slurry width, that is profiled and preten­ for use in highly stressed elements, in predrilled holes and grouted to sioned like our standard American such as the end block of bridge gird­ form high capacity piers which are ties, but it is used to replace two ers, industrial applications and reliable in quality and performance. conventional ties. bridge piers. Similarly, precast, pretensioned tie • Extensive use is being made in Eu­ • Similarly, an anti-bleed admixture, beams are extensively used in seis­ rope of thin precast conventionally with thixotropic properties, was re­ mic areas. The Japanese have devel­ reinforced soffit forms. These stay cently developed in the United oped precast, pretensioned sheet in place. Their use not only saves States, manufactured by a European piles with a deep arch section. the labor of stripping, but shortens company, and first proven in the • Prestressed concrete poles, both ta­ the construction schedule. These field as a means of complete filling pered and constant cross section, are slabs for bridges and buildings are of post-tensioning ducts back in the used almost universally in every similar to those we use, except they United States. country of the world except the are often thinner and sometimes • In the United Kingdom, surface United States and Canada. Even in ribbed to increase the stiffness. Such

Fig. 4. Precast concrete production plant for King Fahd Causeway Bridges, Saudi Arabia to Bahrain.

November-December 1991 35 slabs, in three-dimensional the Great Belt Western shell forms, are used in major Bridge in Denmark, where engineering projects. The several hundred precast con­ shallow domes of the 70 ft crete segments up to 6000 (21.3 m) diameter cells of the tons in weight are being Norwegian offshore plat­ manufactured (see Fig. 6). forms are now formed with These developments reflect two large precast thin shells the growing trend toward with edge stiffeners. It is sur­ precast concrete production prising that while these shells as opposed to cast-in-place are tied to the permanent con­ construction. A further moti­ crete by mild steel loops, no vation is the higher quality de­ attempt has yet been made to mands, especially durability, develop composite behavior which cannot be achieved in in the entire structure. the field. • Major advances have been • Most European countries and made in large scale precast Japan place a far higher prestressed concrete plants value on long life and mini­ for major projects: The Ju' mum maintenance than we Aymah Trestle, 20 km (32 do here. Design lives of 120 miles) in length, and the King years are now becoming Fahd Causeway Bridges, standard. Present value anal­ both in the Arabian Gulf, yses of future expenditure for started with the installation of maintenance, including inter­ large scale production plants ruption to service, are being for the voluminous products used to justify increased first which were required. Figs. 4 costs. The extreme example and 5 show the erection of the Fig. 5. Erecting precast concrete segments for the King of this is the pier shafts of the King Fahd Causeway Bridges. Fahd Bridges between Saudi Arabia and Bahrain. Trans-Tokyo Bay Bridge, Massive housing projects in which have been changed Riyadh similarly required a huge French scheme was a highly auto­ from concrete to titanium-clad steel production facility. mated industrial plant, while the at a cost of $40 per sq ft ($414 per 2 Two plants with entirely different British plant employed a very prac­ m ) of surface area for the titanium production philosophies were set up ticable expansion of conventional sheathing alone! Could we not attain to produce the 750,000 tunnel liner processes. equal durability in concrete through segments for the Eurotunnel. The Most striking of all is the plant for the intelligent use of a portion of

Fig. 6. 6000 ton prestressed girder, 104 m (308ft) span for Fig. 7. Post-tensioned girder for BARTO Metro System, San Great Belt Western Bridge, Denmark. Francisco, California.

36 PCI JOURNAL that extra expenditure? • Another area in which we can and must change is the general aversion which much of our industry has to post-tensioning. I am well aware of the deep split in this country be­ tween the precasters and the post­ tensioners. (I still bear some of the scars of the early battles!) But that should be in the past. Both groups spend excessive unproductive en­ ergy and money in trying to domi­ nate the same market, instead of viewing precasting, pretensioning and post-tensioning as techniques to be utilized by each of us to enlarge the overall market. Let us now look at how the post-ten­ sioning method is being advanta­ geously used by precasters overseas: (a) Where the production runs are too short to amortize the cost of set-up Fig. 8. Elegant and efficient truss of high strength precast concrete segments, of a long-line pretensioning bed. joined by post-tensioning. (b) Where the total prestress force ex­ ceeds the capacity of pre tensioning beds and stands. try significantly. We have the opportu­ Lastly, I fervently believe that our (c) Where biaxial prestress is required nity to enhance our already brilliant industry has not reached its full matu­ in a member or structure. achievements if we stay abreast of the rity or potential. Therefore, we cannot (d) To provide continuity in a struc­ technological advances and product afford to remain complacent, static ture. developments which are occurring and limited. On the contrary, I feel (e) For curved members and complex overseas. In turn, we should take ad­ that the American and world construc­ shapes. vantage of the opportunity to exploit tion industries are on the threshold of (f) To join multiple precast concrete worldwide those areas in which we are a major shift to precast concrete con­ elements in structures such as most advanced. We have three self­ struction which will dominate the tanks and towers. imposed constraints from which our early 21st century. This transformation (g) To provide transverse compression industry must free itself if it is to pros­ is being accelerated by a general and stability in bridge decks. per and lead the way in the 21st cen­ shortage of skilled field construction Twenty years ago, Peter Kiewit tury. labor accentuated by demands for bet­ Son's Co. successfully and profitably Firstly, we have been too compla­ ter quality, greater efficiency and manufactured more than 3000 precast, cent as far as quality is concerned, tighter cost control. prestressed trapezoidal box girders for limiting ourselves to criteria which The question is only whether or not the San Francisco BARTD system today can be equally satisfied by our PCI producer members will con­ using post-tensioning (see Fig. 7) . cast-in-place concrete. The precast tinue to meet the challenges and op­ Many structural members can advan­ concrete industry's unique advantage porturuties, both technologically and tageously utilize a combination of pre­ lies in our capacity to manufacture in market expansion, that are being tensioning and supplemental post-ten­ economically, well-engineered, state­ opened up by the worldwide sruft to a sioning, as shown in Fig. 8. of-the-art products with superior global economy. In that connection, If I were addressing the Post Ten­ strength, finish, tolerances and high the 1994 joint congress between the sioning Institute (PTI), I would only durability. PCI and the Federation Internationale change this list to include the potential Secondly, American industry will de la Precontrainte offers a unique op­ expanded bridge market by the use of have to adopt the international system portunity to enlarge our global per­ higher quality plant manufactured pre­ of unjts. The precast and prestressed spective. cast segments and those incorporating concrete industry should take the lead I congratulate PCI on its foresight in both architectural treatment and struc­ and at least become literate in SI units deciding five years ago to host this tural capability. so as not to miss global opportunities. major international event. I believe the Thirdly, we must increase our versa­ congress will prove especially reward­ Concluding Remarks tility by freely using post-tensioning in ing to our members and our industry at The globalization of world econo­ conjunction with our pretensioning large - leading ultimately to ex­ mies is even now affecting our indus- technology. panded markets and new clients.

November-December 1991 37