Photo courtesy of ACI

Built to Last:
Celebrating a Century of Concrete

One hundred years ago, the concrete market was highly competitive, expanding fast and seriously lacking in standard practice. Concerned about this state of affairs, three enthusiasts formed an organization in the summer of 1904, to bring some order to the use of concrete. 

They were Charles C. Brown, editor of Municipal Engineering, Indianapolis, IN, A.S.J. Gammon, Universal Concrete Machinery Co., Norfolk, VA, and John P. Given, Cement Machinery Co., Circleville, OH. Encouraged by an immediate and hearty response, the trio called an informal meeting during the Louisiana Purchase Exposition in St. Louis that fall. It was decided that the organization should cover all the various uses of cement in order to bring about a better knowledge of the art. The first convention was held the following year where a surprisingly large number of people, 605 in total, showed up. Originally known as the National Association of Cement Users, the society later changed its name to the American Concrete Institute.

The first reinforced concrete skyscraper in the world was the Ingalls Building, completed in Cincinnati in 1902. Sixteen stories and 210 ft tall, the structure demonstrated for the first time the safety and economy of reinforced concrete frames for high-rise construction. It was a vital stimulus for using reinforced concrete in fireproof construction. Up until that time, no building that was more than two stories tall had been constructed using reinforced concrete. Henry N. Cooper, the structural engineer, prepared the design using the Ransome system of reinforced concrete.

The first mile of concrete highway in the world was paved on Woodward Avenue in Detroit, MI, in 1909. Road builders came from near and far to see how concrete successfully stood up under the heavy traffic of that period, which ultimately speeded the development of modern automobile highways. The entire project cost $13,537, but the original road was replaced by a broad thoroughfare in 1922.

ACI ‘s building codes are used worldwide. With the 2005 edition nearly ready to be released, ACI 318: Building Code Requirements for Structural Concrete remains the industry’s most influential standard. It provides uniform design procedures widely adopted by the jurisdictions that regulate construction in the U.S. and a large part of the world. It recently was approved as an international standard by the International Standards Organization.

Since the code was first adopted in 1910, it has swelled from a 12-page document to 443 pages, complete with commentary sections and appendices. Nearly a century of progress in structural concrete design is reflected in the provisions filling these pages.

INNOVATIONS WORLDWIDE

Photo courtesy of ACI

Among the most significant innovations in recent years is decorative concrete. It now is accepted worldwide as an aesthetic medium of choice for a multitude of reasons—including permanence, beauty and cost-effectiveness. The exponential explosion of concrete technology and coloring alternatives have brought about both interior and exterior decorative concrete flatwork applications. Various options include integral or color dry-shake, stamping or texturing, staining (both passive and reactive), dying, stenciling and overlaying. Additional options include wall systems that simulate stone, brick or other materials; polished concrete; and high-performance coatings (such as epoxies and urethanes). Each of these products or applications provides its own distinct appearance and performance, ensuring that all the needs of today’s consumers can be met. Numerous books have been compiled dealing with tips and best practices for decorative concrete, and many are available through the American Concrete Institute.

Another innovation is self-consolidating concrete. A highly flowable and stable concrete that can spread readily into place, fill formwork and encapsulate the reinforcement without any mechanical consolidation has been gaining rapid acceptance in Japan and others parts of the world since the late 20th century. Self-consolidating concrete develops mechanical properties independent of the vibrating crew, reduces noise and labor cost, increases productivity and creates a safer work environment. Properties such as compressive strength, uniformity and homogeneity are similar to or better than those of comparable conventional slump concrete without bleeding and segregation, and at a much lower overall cost.

Perhaps the most exciting new technology is light-transmitting concrete. Invented by Hungarian architect Aron Losonczi, it is currently being demonstrated in Europe and may be ready for market as early as this year. Each precast LiTraCon block is composed of thousands of glass optical fibers formed into matrices running parallel between, and transverse to, the bounding two surfaces of the block. Consequently, light can be conducted through the concrete by means of the glass fiber matrices. Objects reflected against one side of a wall built with the material will transmit a crisp shadow through it, to be projected distinctly on the face of the opposite side of the wall.

Economic demands are also driving change. There is an increased interest in the durability and sustainability of structures and in life-cycle costing. Owners are beginning to require longer service lives—often reaching 100 years or more in severe environments—and justifications for the consequent additional costs of manufacturers’ products.

Advances in design and structural systems, materials, production, delivery and placement, repair and rehabilitation—plus a global market—will all play a major part in the evolution of the world’s most used building material. As ACI celebrates its 100th anniversary, it has retained the same basic mission: develop, share and disseminate knowledge and information to utilize concrete to its fullest potential.

Concrete has been a foundation of sustainable design for centuries. Some of the world’s earliest examples of architectural greatness are made of concrete—the Roman Colosseum is an architectural and engineering wonder and the Pantheon is an undeniably impressive piece of Roman architecture. More than 2,000 years later, those concrete structures and many others still stand.

Today, concrete is equally as valuable. Modern technologies in architectural innovation and sustainable development have placed concrete at the forefront of sustainable building, and architects, designers and builders are increasingly looking to concrete because of its durability, versatility and performance.

A fundamental tenet of sustainable architecture is responsible design that takes into account land use, conscientious choice of materials and environmentally sound building practices. It also means a long-term architectural vision for the life cycle of a building and an enduring style and structure that won’t easily deteriorate or need to be replaced.

The concrete industry and the Portland Cement Association (PCA) recognize the seminal role of concrete in historical architecture as well as its influence on design today. Concrete is an evergreen resource. It is the most widely used building material on earth and has the longest lifespan of any traditional building material.

PCA has launched a new initiative focused on making concrete an even “greener” building material for architects, builders, designers and engineers. Concrete Thinking for a Sustainable World is an action plan for the concrete industry designed to balance today’s need for cement-based products with stewardship of the land, air and water by conserving energy and natural resources, and reducing emissions.

An integral element of the Concrete Thinking initiative is the Cement Manufacturing Sustainability Code (CMS). Launched at the American Institute of Architects’ 2004 National Convention, CMS is a defined plan that outlines principles to guide the manufacturing industry in adopting more stringent waste management practices, conserving resources, improving energy efficiency and making and using concrete in a more environmentally sound manner.

As awareness heightens that U.S. buildings use nearly 10% of the world’s energy, there is increasing demand for sustainable development and green building practices. The U.S. government is adopting unique programs to meet those needs and an increasing number of states are offering tax benefits for related practices.

The cement manufacturing process is designed to minimize emissions and waste, utilize energy efficiently and ensure product quality. Major steps have been taken by the cement industry to strengthen their commitment to green manufacturing processes.

The industry utilizes industrial byproducts and has reduced its own waste by recycling more than 75% of cement kiln dust (CKD)—nearly 8 million tons each year—directly back into the cement kiln as raw materials.

ASTM standards recently were revised to allow for ground limestone to be used as a raw material in cement, which will ultimately reduce C02 emissions by more than 2.5 million tons per year.

New technology and equipment, coupled with increased use of alternative fuels and raw materials, have reduced energy consumption by 33% since 1975.

As a result, concrete is becoming an integral part of the sustainable development movement. PCA is defining that role by encouraging the industry to take an active part in sustainable development practices and become more educated through the Concrete Thinking initiative. These actions will make concrete green designs more durable and long lasting, help preserve the beauty of the architecture and reduce environmental impact.

Powered by a vigorous membership, plus new technologies and research, the concrete pipe industry is regaining market share. After several years of declines due to competition from new, less-costly, flexible pipe materials, concrete pipe manufacturers are addressing the major issue facing the industry: educating the market as to the long term benefits of their product.

Flexible pipe relies on proper trench design to perform well, says Doug Mohrman, chairman of the American Concrete Pipe Association (ACPA), while concrete pipe offers a choice of trench designs—including one where the pipe itself carries the load, says Mohrman. As an aid to its members, the association has produced a software program called CAPE (Cost Analysis Pipe Envelope), which analyzes the comparative costs of different pipe materials.

The association has established a strategic plan to increase market share by targeting state highway construction, which makes up over one-third of its market. While states continue to wait for approval of federal funds before committing projects, manufacturers can take some consolation in the fact that the growing size and scope of major civil works are requiring increasingly larger concrete pipes and box culverts. However, the cost of steel reinforcement has ballooned since the beginning of the year, which is proving a problem for those with fixed-price contracts.

The new technologies in the industry are less about what is manufactured than how it is manufactured. To the untrained eye, today’s reinforced concrete pipe may look the same as one 10 years old, but is quite a different product. In the last decade, there have been tremendous advances in plant automation and robotics that have significantly reduced costs and improved quality by achieving stricter dimensional tolerances. An alliance with the Portland Cement Association is providing technical data on mix designs that optimize the use of fly ash, slag and chemical additives that increase concrete strengths.

ACPA also is involved in several research projects. It has asked several universities and consulting firms to submit a proposal to conduct research on joint shear, while another project at the University of Texas at Arlington is investigating pipe abrasion. Michigan State is studying the elimination of concrete deterioration from sulfuric acid, which should have a significant impact on not only the concrete pipe industry, but on concrete in general. Chemical additives in concrete mix can stop the growth of bacteria, which in turn prevents the production of acid and subsequent pipe corrosion.

Workers place concrete to widen U.S. Rte 50/Salisbury Bypass in Salisbury, MD.

Industry and the public sector, working in tandem, have made great progress in improving the safety and performance of the national highway system. However, an estimated 13,000 people still die each year on American highways because of roadway conditions.

In addition to the significant issue of improving safety, there are compelling economic arguments that support increasing investment in our surface transportation infrastructure. A U.S. Department of Transportation study found that for each $1 billion of federal spending on highway construction nationwide, 47,500 jobs are generated annually. The same study also stated that every dollar invested in the nation’s highway system yielded $5.70 in economic benefits because of reduced delays, improved safety and reduced vehicle operating costs. Also worth noting is that 84% of the $7 trillion worth of commodities delivered annually from sites in the U.S. are transported on the nation’s highways.

Quality Pavements. Concrete pavements often are selected because they provide excellent durability and performance, while costing less than alternate paving materials. One reason for this is that maintenance and rehabilitation expenditures for well-designed and constructed concrete pavements are minimal over the entire life-cycle of the pavement, as are the associated costs of road-user delays. There also are many cases where the initial costs for concrete are the same or lower than other materials. Also important is the fact that concrete pavements typically provide many years of reliable service without the constant cycle of repairs. One need only consider the costs associated with work zones, vehicle damage and disruptions to imagine the magnitude of the cost savings. The defining measure of quality in highway or road construction is whether long-term performance expectations are met with only minimal maintenance and rehabilitation along the way. When concrete pavement maintenance is required, it usually means periodic joint re-sealing or replacement.

Construction workers placing concrete during a bonded overlay project.

Surface Characteristics. The American Concrete Pavement Association (ACPA) continues to investigate and communicate information about surface characteristics and environmental benefits of concrete pavements. Some of the key topics include sound related to tire/pavement interaction, improved air quality, storm water management through the use of previous pavements, friction, skid resistance and a range of other current and emerging related technical issues. ACPA is compiling a database on friction numbers and other variables from state agencies. The goal is to develop a range of reasonable surface friction (skid resistance) values, which factor in a host of variables, including mix design, aggregate type, and other contributing factors that affect surface characteristics.

Through innovation in equipment and processes, concrete pavements are being built smoother than ever before. Good long-term performance is greatly affected by pavement smoothness, which should not be confused with texture. Smoothness is essentially the absence of “bumps” in the pavement. A bump is a variance in the pavement that measures 0.05-in. or more for a distance of 2 ft or more. Surface texture is imparted to the pavement to enhance its safety and overall performance. It is, therefore, possible for a pavement to be both textured and smooth. Smooth pavements do not experience the dynamic loads of rough pavements, which means less wear-and-tear on vehicles and the pavement. There are tangible benefits in terms of reduced costs to road-users, agencies and the taxpaying public.

Traffic Management. Many of the nation’s most outstanding examples of quality projects have from the earliest stages involved a comprehensive outreach effort to ensure communications among those involved. This not only includes specifying agencies and the industry, but also the general public, law enforcement agencies, business leaders and others. Outreach may be through media campaigns to encourage alternate routes or the use of public transportation. There are even examples of how outreach efforts have actually stimulated business in otherwise unaffected areas.

Research & Technology. The need for applied research cannot be overlooked. It is essential to developing safer, more cost-effective, and better-performing highways, airports and roadways.

The ACPA points out that the best type of research and technology transfer program is one that includes input from all key stakeholder groups, including federal agencies, state departments of transportation, academia and industry, with equal representation in terms of creating the agenda, developing the strategies and producing and implementing key deliverables.

Addressing Safety. ACPA urges that all safety aspects of the highway be examined, including some basic pavement construction variables such as pavement geometry and surface texture. In the area of work zone safety, ACPA has developed innovative solutions to improve safety and minimize traffic disruptions—examples include traffic management solutions, as well as fast-track paving, ultra-thin whitetopping, concrete overlays and more.

To serve the wider world of road users, the association has delivered a wealth of information to specifying agencies and the industry with satisfying results—expedited projects and improved communications are two areas—that help return the greatest value on dollars invested in highway construction.

Photo depicts state highway K-150, in Marion County, KS, after reconstruction. The contractor, The Wittwer Group, received incentives for pavement smoothness, concrete strength and uniform thickness. The project received an award from the American Concrete Pavement Association in the state roads category.

Concrete pumps continue to expand the use of concrete by placing farther and faster with more precision than ever before. Last year, the world’s pumping record was set on the Taipei Tower in Taiwan at 1,460 ft. Massive basemats for highrise structures routinely are placed by multiple pumps in record time. Meanwhile, cast-in-place concrete for residential applications grows because its structural benefits are helped by the pump’s ability to place material precisely in a variety of forms including insulated concrete forms.

As the sale of concrete pumps proceeds at a healthy pace because of labor savings, speed of placement and quality of the final product, pump manufacturers are creating new and better equipment. Boom lengths now stretch to nearly 200 ft, which opens new possibilities for economically placing concrete. Specialized boom pumps with low unfolding heights can enter and place concrete in enclosed structures, while more powerful trailer pumps continue to break the boundaries of vertical placements. Reliability concerns from the early days of pumping have been cast aside by the latest technologies incorporated by leading manufacturers.

But as the use of concrete pumps increases, workers are more exposed to the hazards of working with a pump. In order to raise awareness, the American Concrete Pumping Association (ACPA) is sponsoring seminars across the nation on co-worker safety. It has also developed a number of safety materials. Aimed at educating placing crew, laborers and ready mix concrete truck drivers, they spell out safe concrete pumping procedures that begin when the pump pulls up to the jobsite and end when the pump is cleaned out and ready to head off the job.

The ACPA Co-Worker Safety Manual is a 70-page booklet outlining safety precautions during set up, electrocution hazards, crushing, pumping and clean-out procedures as well as illustrating where the emergency stops (e-stops) are located and the industry-standard hand signals for working with a concrete pump. A video available in VHS or DVD titled Co-Worker Safety Rules depicts actual footage of a concrete pump on a job and instructs the viewer on safety precautions while working around a pump. The Co-Worker Training CD is a comprehensive tool for safety directors, supervisors and others to present to workers in PowerPoint format.

Last year, ACPA began concentrating its focus on industry-specific safety materials such as a safety manual for ready mix truck drivers. A video will be ready for distribution by early January 2005.

Photo courtesy © Bill Luken, Contractors Materials Company, Cincinnati, OH

The Concrete Reinforcing Steel Institute (CRSI) has modified its long-standing position on using welding as a means for assembling reinforcement for site-cast construction.

Traditionally, CRSI has strongly recommended that reinforcing bars be assembled with tie wire. At the same time, citing several sections of the ACI 318 building code, it has discouraged welding of crossing bars as a means for assembling reinforcement for site-cast, reinforced concrete construction becuase such welding of crossing bars could seriously affect the strength and ductility of the reinforcing bar.

In recent years, however, high-technology welding machines have become available. Welding machine technology from Europe now has impacted shop fabrication practices in the U.S. Several California fabricator/placer firms, as well as a few fabricators in other parts of the country, currently are using state-of-the-art welding machines to produce fusion-welded assemblies of reinforcing bars. Employing electric resistance, a fusion weld results from the fusion process that uses a combination of pressure and heat generated by electric impulses.

There are several advantages to using fusion shop-welded assemblies of reinforcing bars. First, it eliminates the time-consuming field placing and handling of small reinforcement elements such as stirrups and ties. Second, it results in very accurate positioning of stirrups or ties in the cage. Third, it provides for better overall dimensional control of the beam and column cages. Moreover, a large number of tensile and bend tests by independent labs have confirmed that controlled welding does not adversely affect the mechanical properties of the bars.

As a result of these findings and recognizing their benefits, CRSI has endorsed the use of fusion welding in the fabrication shop, while still recommending that field tack welding should not be permitted unless authorized by the architect/engineer. The institute also urges the use of shop-welded assemblies be permitted in higher-risk earthquake areas. Its Engineering Data Report, Number 53, Assembling Reinforcing Bars by Fusion Welding in the Fabricating Shop, reviews current code requirements, and new practices in welding reinforcing steel. It should be of interest to architects, engineers, contractors and others involved in the design and construction of cast-in-place steel reinforced concrete structures.

Grant Park South Garage.

The International Concrete Repair Institute (ICRI) is the only association in the concrete industry devoted solely to repair and restoration. Formed in 1988 in response to the concerns of people who were disturbed by the quality of many of the repairs in the industry, ICRI now holds two independent conventions each year, while the repair market as a whole occupies one of the largest areas in the World of Concrete exhibition.

A multi-billion-dollar industry in the U.S. that is largely independent of economic cycles and congressional funding delays, the concrete repair sector is worldwide and covers the gamut of building type and concrete technology. While much of the work addresses maintenance issues such as repairing parking garages, concrete cracks or leaking foundations, other projects are about restoring historic structures that could be 100 to 2,000 years old. Yet all concrete repair and restoration require both management and technological expertise, especially with the growing legislative demands for green construction.

Last year’s ICRI Project of the Year was the rehabilitation of Grant Park South Garage, a 40-year-old underground parking facility in downtown Chicago. An important component of the project was cost control that included life cycle cost analysis, service life evaluations and phasing the project so that it could move at an accelerated pace. New full-depth slab replacement and partial depth repairs included calcium nitrate corrosion inhibitor and moisture protection systems. The rehabilitation extended the service life of the garage by more than 25 years—and achieved the goal of minimal operational and maintenance costs,

Frank Lloyd Wright’s Fallingwater.

Another ICRI winner, Frank Lloyd Wright’s Fallingwater, is a virtual textbook of concrete materials and repair design planning. Strengthening was required due to severe cracking and deflections that threatened the building’s structural integrity. After documenting the condition of the building and developing a strengthening and repair strategy, the work was organized into a closely monitored step-by-step process. Repair materials included post-tensioning strands, carbon fiber rods, cast-in-place concrete, epoxy grout, cementitious grout epoxy crack injection and structural steel members.

In collaboration with ACI, ICRI has developed a free resource Web site (fixconcrete.org) on repair, protection and upgrade of concrete structures. Included are more than 500 videos, industry case studies, design and field procedures, articles and papers. It also produces the bi-monthly Concrete Repair Bulletin and the ICRI Publications Catalog, which lists virtually every available North American publication including all ICRI Guidelines on concrete repair.

The ready-mixed concrete industry is a $30-billion industry. It consumes approximately 75% of the cement in the U.S., producing an estimated volume of 405 million cubic yards last year, with a projected 5% increase in 2004. That's enough concrete to build 12 coast-to-coast four-lane highways every year.

The face of the industry continues to evolve from the smaller independent local family owned companies to larger multi-national vertically integrated and publicly traded corporations. Large corporations account for more than 50% of the volume of concrete produced in the U.S. today. It is estimated that the ready mixed concrete industry in the U.S. operates 7,000 production facilities, uses 80,000 mixer trucks and employs 140,000 people. Delivering a perishable product, concrete production facilities have to be located within a 90-minute travel distance from a construction project.

Being part of a workforce intensive industry, the membership of the National Ready Mixed Concrete Association (NRMCA) has made significant investments in education and certification programs. Besides elevating performance levels, these programs establish an industry standard. NRMCA Plant Certification, in place since 1966, for instance, represents the only structured program that verifies conformance to minimum standards for producing ready mixed concrete. In order to better serve design professionals and owners, NRMCA will shortly define a producer designation system that documents qualification levels.

The next natural step is for the industry to have more control over the product. A remnant of older days is the propensity of design professionals to include prescriptive provisions relating to the concrete mixture. In response, the NRMCA has initiated a P2P Initiative to promote a voluntary shift from traditional prescriptive (P) to (2) performance (P) specifications for concrete, and is collaborating with concrete contractors, material suppliers, engineers and architects to make changes.

Performance-based specifications that address requirements for mechanical and functional properties of the concrete have many benefits. They include verifiable results through measurement or testing; clear assigned responsibilities for achieving certain objectives; and specifications that are free of process limitations such as mixture proportions and construction methods. Performance-based specifications encourage partnering within the construction team, the creation of innovative products and construction methods, plus rigorous quality management systems that lead to superior structures and satisfied customers.

Since its founding in 1986, the Tilt-Up Concrete Association (TCA) has become an influential voice in innovative construction technology.

Probably the most dramatic advancement related to tilt-up is in architectural treatments. Although long known for its attributes of durability, energy-efficiency and economy, tilt-up also is a growing solution for today's emphasis on architectural appeal and creativity. From features such as cornice lines and accent bands; to facade enhancements like thin brick, block and stone; as well as a multitude of textured coatings, architects now have limitless possibilities for creating an aesthetically appealing structure that can celebrate concrete or mimic other materials.

History has shown that tilt-up fares well in hurricanes, tornadoes and earthquakes compared to non-concrete materials, with structures dating back to 1906 still in service today. The medium withstands wind and hail storms, is impenetrable by the smallest rodent, insect or even the most determined human. Tilt-up concrete construction was validated in the January 1994 Northridge, CA, earthquake, when walls remained standing, even though roof connectors failed. Subsequent earthquakes and hurricanes have further shown the strength and durability of the tilt-up method, as evidenced by the number of tilt-up structures that stood up to hurricanes Charley and Frances.

With developments such as larger cranes, self-consolidating concrete, new bracing technologies and new finishes, tilt-up continues to grow. With more than 450 members in 13 countries, TCA is a voice in code matters, technical information and resources. It has instituted a rigorous Certification Program developed in concert with the American Concrete Institute (ACI). Full certification as a tilt-up supervisor requires passing the exam and a minimum of five years (7,500 hours) of verifiable construction experience. Three of the five years must be in the role of a tilt-up supervisor. Those lacking the work experience to qualify as a tilt-up supervisor may become certified as a technician by successful completion of the same written examination. Many companies throughout the industry already have embraced the program to the extent that they worked with TCA and ACI to bring the test to their facility. Owners now are writing certification requirements into their specifications.

TCA Executive Director Ed Sauter believes that the future of tilt-up lies with its growing acceptance by design professionals, and has expanded its educational offerings beyond the contractor and engineering markets to the architectural community with a program offering AIA Learning Units.

San Tomas Aquino/Saratoga Creek Trail, Santa Clara, CA. Artist: Linda Patterson of Santa Clara, CA. Photo courtesy of Scott System Formliners, Denver, CO.

Last March members of the American Concrete Institute sat entranced as they watched one striking image after another express the beauty and power of concrete. Two sessions “Celebrating a Century of Beautiful Concrete” at the spring convention were co-moderated by Ray Pisaneschi, marketing & technical manager of Lehigh’s White Cement Division, and Mary Hurd, author and owner of Engineered Publications. The program was dedicated to the memory of Eugene Figg, president of Figg Engineering Group, who achieved an international reputation for designing award-winning bridges.

Twelve presenters discussed achievements ranging from Chicago’s Baha’i Temple, whose doors opened new architectural precast and cast-in-place possibilities like the Cathedral of our Lady of the Angels in Los Angeles, to entire buildings that are sculpted art. Designers of both large and small bridges explained how they dealt with aesthetics, while others discussed how advances in craftsmanship and materials technology spurred the development of decorative concrete flatwork and skillful shaping of vertical surfaces. Featured products and projects included concrete masonry, architectural precast concrete, architectural cast stone and terrazzo.

PowerPoint presentations of “100 Years of Innovation and Artistry,” “Architectural Cast Stone,” and “Designing Precast Bridges in Harmony with Historic Sites” are available from Lehigh White Cement (800-523-5488 - Ray Pisaneschi).

One of the biggest advances in recent years is colored concrete technology. In addition to a dramatic increase in residential construction, where colored and textured concrete is being specified for patios, pool decks, driveways, interior floors and even kitchen countertops, designers of commercial and industrial properties are using the versatility of colored concrete to add interest and value in a variety of projects.

One of the first to enter this expanding market with solutions for the building industry was Degussa Admixtures (formerly Master Builders Inc.) and L. M. Scofield Co. In early 2002 they formed an alliance to promote Color-Conditioned™ Concrete that is colored with CHROMIX® Admixtures. Degussa supplies the liquid coloring admixtures, while Scofield provides the engineered systems for coloring, texturing and improving performance.

The high-performance CHROMIX admixtures ensure distribution of color throughout the ready mixed concrete for enhanced quality and aesthetics, while new computer-controlled dispensing equipment ensures repeatability—reliable, exact color from batch to batch and project to project.
Yet the appeal is more than an aesthetic upsell. The material is durable, non-fading, UV- resistant and economical. “The installed cost-per-sq-ft of colorful concrete is often less—in some cases dramatically so—than a majority of the materials it can replace,” observes Steve Somerville, product line manager for CHROMIX® Coloring Admixtures at Degussa Admixtures.

Available in a wide range of integral colors (the color is present all the way through the material) from warm earth tones, vivid hues and any shade of gray, the new colorful concrete offers limitless flexibility. Color combinations, textures, exposed aggregates, staining, sandblasting and imprinted patterns can mimic natural materials such as slate, tile, limestone, cobblestone and even wood. Finishing techniques such as swirl float, broom and sandblasting can improve slip resistance and add design appeal. A variety of clear or color-matched curing compounds and sealers are available to provide correct concrete curing, facilitate optimum color development, improve stain-resistance and reduce maintenance.

Through the alliance, Degussa Admixtures and L. M. Scofield Co. are a full-service supplier of colored concrete admixtures and accessories. With nearly 200 years of experience in the concrete industry between the two companies, they provide extensive experience, technical service and support. They also offer an accurate and efficient system for production to address increased demand, thus allowing designers, builders and contractors to create structures and surfaces that offer superior strength, beauty and economy.

At the turn of the 19th century, St. Louis blacksmith Arthur H. Symons developed a method for lowering both the time and skill necessary to prepare and pour concrete columns in commercial buildings. Since perfecting and patenting the “Symons Column Clamp,” his company followed with many other significant innovations, virtually single-handedly creating the manufactured concrete forming industry—and arguably establishing itself as having the longest advertiser/publication relationship in the nation.

Today, with 22 unique forming systems consisting of thousands of products, Symons also offers contractors design and management tools such as software for quickly and accurately creating form layouts with a complete bill of materials.

For a recent project requiring forming and shoring for two large turbine pedestals and a 10 ft-6 in. deck, Symons proposed its Max-A-Form system to provide high strength and top quality finish for 31-ft-high columns connected by a concrete tie-beam. The deck at the top of the structure was supported with Symons ShorFast aluminum shoring system and aluminum joists. By providing 60% more stability than conventional steel framing, the system reduced the need for extra pipe or wood bracing. It is certainly a far cry from the construction project depicted in the 1919 ENR ad, but nontheless a reminder of what Symons started two hundred years ago.

There is an increasing demand for upgrading structural strengthening, for reasons ranging from seismic and blast-resistance requirements, to code changes. Commonly used methods include span shortening, externally bonded steel, external or internal post-tensioning systems, section enlargement, or a combination. But new products on the market are offering alternatives.

According to Jay Thomas, Vice President of Structural Preservation Systems’ (SPS) Strengthening Division, fiber reinforced polymer (FRP) composites and steel reinforced composites (SRC) offer owners additional economical strengthening solutions. Selected for their non-corrosive properties, ease of installation, lower cost and aesthetic appeal, FRP systems are thin fabric sheets bonded to concrete members with epoxy adhesive to increase load-carrying capacity.

In contrast, SRC is a steel-based composite technique that utilizes Hardwire, a system comprised of steel wires—made from the same wire metallurgy found in steel belted tires—twisted together to form reinforcing steel cords. With a tensile strength approximately ten times higher than conventional structural steel, the steel wires have a deformed surface that allows for the optimal bond with the surrounding matrix. The result is a cost-effective option offering numerous applications, including those subject to terrorism requirements. "Hardwire is an ideal blast-resistant solution for many structures including buildings, tunnels and bridges," notes Thomas.

The living area of the Visiting Artists House (2002), by Jim Jennings Architecture, showing the inscribed concrete walls by artist David Rabinowitch. Photo by Tim Griffith, courtesy Jim Jennings Architecture.

Awed by spectacular architecture by Richard Meier and Santiago Calatrava, visitors to Liquid Stone: New Architecture in Concrete at the National Building Museum in Washington, D.C., may well find new respect for concrete.

Sponsored exclusively by Lafarge, the world leader in building materials, the exhibition presents concrete as structure, surface and sculptural forms. Poured concrete walls embedded with seashells by Tadao Ando look and feel like rare stones, reports the Washington Post, while a new bridge by Lord Norman Foster is supported by svelte piers taller than the Eiffel Tower.

The stunning, wave-like roof of the Auditorio de Tenerife (2003), in the Canary Islands, designed by Santiago Calatrava, exemplifies the sculptural possibilities of reinforced concrete. Photo by Alan Karchmer for Santiago Calatrava.

Yet equally intriguing are displays about concrete that make these structures possible. Concrete mixes incorporating supplemental cementing materials, for example, offer significant performance advantages over straight portland cement. These materials such as fly ash, slag and silica fume each have properties that enhance concrete performance, including reduced permeability and higher strengths. Additionally, as most supplemental materials are by-products, they would otherwise be destined for landfills.

Two products exclusive to Lafarge—Ductal® and Agilia®—are featured in the exhibit. Ductal is an ultra high-strength concrete product used to create long-span canopies of incredible thinness. Agilia, a self-compacting concrete that flows like water, can be used for difficult pours and complex designs.

The exhibition closes on April 17, 2005.

When forming contractor Verdi Group needed a well-designed system that could be erected with minimum effort, time and manpower for the Mississauga, Ontario, City Gate II, a 36-story residential project, it chose Aluma Systems’ brand new Aluma Dek®.

The Verdi Group’s satisfaction with the system was so compelling that it retained the equipment for use on additional proj-ects. "The Aluma Dek® system increased my productivity by 40%, decreased my need for manpower by 50% and has decreased stripping time by 50%, as compared to a traditional frame-shoring system," reports Paul Borges, Verdi Group foreman, City Gate II Project.

On another project, Caesars Casino South Tower in Las Vegas, Aluma’s longtime general contracting client, Perini Corp., needed to provide the formwork that would keep the 27-story project on schedule. Perini, renowned for its hospitality and gaming industry projects, asked the company to keep up with its rigorous 24-hour-a-day work schedule. Using the Aluma Hi-Flyer® column-hung system minimized cycle times by giving trades floor access below while the concrete cured above. The system adjusted to any bay size and virtually eliminated the need for re-shoring. The result was that Perini saved thousands of man-hours.

Scheduled for completion in February 2007, the $1.04-billion Skyway segment of the eastern span crossing San Francisco Bay from Yerba Buena Island to Oakland, CA, is well under way. The largest single contract awarded by the state of California, the section has a single 230-ft-tall single-tower self-anchored suspension span. To install the concrete—which will eventually total 185,000 cu yd—Kiewit Pacific, Vancouver, WA, leader of the joint venture, invested in an S 58 SX and a KVM 39 X, two long boom Schwing America concrete pumps.

The pumps are set up on barges to complete pours from the center of the bay. On-site engineers designed a state-of-the-art supply system involving a conveyor-equipped temporary batch plant and specially designed mixer drums and remixers to provide a continuous, homogenous mix to the pumps.

“We used the 187-ft boom on the 58-meter pump to its fullest extent to reach up and over for some of the larger pours at the column and pier table levels, and the 39-meter boom for the piling and footing pours which needed a shorter reach,” explains Kiewit’s concrete superintendent Grant Scott. The X-style outriggers on the KVM 39 X also allow for compact, efficient set up that is particularly important on the barges.