Dateline: Kapaa, Kauai, Hawaii, USA September 1, 1999

Iraivan Temple is a pioneering project, not only in ancient granite stone carving, but in modern concrete technology. It embodied principals that Dr. Mehta, professor of engineering science at the University of California at Berkeley for the past 30 years and world expert on durable concrete technology. He knew it would work on paper, but had never been given the opportunity to prove. He and his colleague, W.S. Langley of Nova Scotia, Canada, leapt at the chance to collaborate on the design of the temple's 1,000-year foundation, and in the process very likely changed the construction industry forever.

Need for a Special Foundation
Iraivan temple is a traditional Hindu temple for Lord Siva being built on Kauai, northernmost of the Hawaiian islands in the central Pacific, by Saiva Siddhanta Church. The ambitious plan calls for an all-stone temple, the first to be constructed in the Western Hemisphere. Work has been underway in Bangalore, India, since December, 1990, carving the several thousand individual granite blocks which will comprise the completed temple. This part of the construction is deliberately low-tech: hand-tempered metal chisels and hammers are the tools of choice; no machine touches these stones. Even the rough blocks are quarried by hand, without the use of dynamite, which, as the workers say, hurts the stone. Stone Hindu temples easily last a thousand years.

But when placed on Hawaiian clay hundreds of feet deep instead of South Indian granite bedrock, there is a problem: keeping the three million pounds of stone from sinking into the ground, especially when encouraged along by the hundred inches of rain received yearly on this part of the tropical island. Obviously a concrete foundation would be required--a very large concrete foundation.

But initial investigations by the church revealed a startling fact: concrete structures are engineered to last twenty years, fifty years maximum. Even the largest dams are built to these nearsighted specifications. And there was one other detail: the foundation must remain a monolithic slab with no cracks. If the foundation cracked and shifted as little as one-eighth of an inch, the 11-foot long granite roof beams of the temple would break. The considered opinion of many? Impossible to have zero displacement!

Toward a Solution
Jim Adams of JAI Architects in Honolulu conceived the basic solution, a "raft foundation" of four feet of concrete placed upon a larger three-foot bed of compacted gravel, the textbook solution for building on mushy ground. It's a bit like a river raft, large and flat and relatively stable on soft ground. It'd work as long as it didn't crack--ever.

But the requirement of no cracks took the church to the leading edge of technology. No one, it became apparent, had ever created such a slab. Yes, the slab could be reinforced with steel, and that would keep it from developing big cracks, but not a network of small cracks which would cause the steel to rust out in a few decades, a century at the most. And when it did so deteriorate, the rusting rods would expand with great force to five times their original size and break the concrete. Recently developed fiberglass rebar offered no help; it was expected from laboratory tests to disintegrate in thirty or forty years. The inescapable conclusion was to have no rebar. Local contractors with a lot of experience with concrete were astounded by the proposal and felt it was sure to fail.

When concrete is placed in a foundation (engineers don't like to say "poured"), it solidifies by means of a chemical reaction which generates a great deal of "heat of hydration." Depending on the mix formula, it can become quite hot, -upwards of 180* F, and as it cools down to the local air temperature, thermal cracks can and usually do occur due to uneven cooling. Unfortunately, no one consulted about the job had any idea how to avoid the thermal cracking. The ancients took advantage of thermal cracking to break large boulders. They'd build a fire on one side, get the rock hot, then through large amounts of water on it. Boom, two rocks where there was one. Same principal for concrete slabs. One end's hotter than the other, which is OK as long as the concrete is still fluid, but once it hardens, something has to give.

The Hunt for the Experts
Deva Rajan, a long-time devotee of the temple and construction contractor in Canyon, California, puts the problem in perspective, "Every one of our contracts contains the statement 'concrete cracks.' We put it there so owners know from the start that every slab poured is going to have cracks. On a slab this size, made with normal concrete, I'd expect a crack every six to eight feet." Dr. Craig Newtson of University of Hawaii, department of engineering concurred, "With a standard mix, you'll have cracks big enough to put your hand in."

Rajan starting asking his friends, businesses acquaintances, concrete batch plant operators, anyone, about how to design this slab to last 1,000 years. Finally he was directed to Dr. P. Kumar Mehta at the University of California. Mehta, it soon became clear, was a man with a mission, and the temple foundation was the perfect test project. Mehta immediately brought in Langley, whose company was responsible for concrete quality control for Canada's billion-dollar plus Confederation Bridge project. The bridge contains 400,000 cubic meters of concrete. For the last ten years, Langley has pioneered the use of high volume fly ash concrete technology in Canada. This Hindu temple to God Siva, it now was clear, had brought two of the world's foremost experts in concrete to assist. Neither would accept remuneration for their work, though they are highly paid consultants. Mehta is a theoretical materials scientist. "I've never even been asked to design a driveway before," he said, and had no job experience at all. Langley, on the other hand, brought tremendous on-the-job experience which complimented Mehta's theoretical knowledge. Langley is also an expert in soil engineering and the mechanics of surcharging--putting a large weight of dirt upon the foundation after it is poured in order to cause any sinking to occur immediately.

Enter "High Volume Fly Ash Concrete"
Dr. Mehta is an advocate of "high volume fly ash concrete," in which half or more of the cement in the mix is replaced with fly ash, a waste byproduct of coal-burning electrical plants. It's a win-win mix. Aside from concrete, fly ash is useless, destined only as ingredient for one land fill upon another. But in concrete, the "pozzolanic" properties of fly ash allow it to replace cement, up to 60% by weight. Mehta prevailed upon his friend, Richard Halverson of ISG Resources, Inc., Centralia Power Plant, Washington state, USA, to donate the required 160 tons of fly ash to the demonstration project. Coal is not purely plant material. Some of it is soil matter left from the ancient forests which decayed to create coal. That soil can't burn, and goes up in smoke when the coal is burned (hence, "fly" ash). In modern coal-burning plants, the fly ash is capture in special smokestacks and consolidated.

Fly ash concrete has some unique properties, the most important for the temple's case is that it does not get anywhere near as hot as normal concrete due to its slower heat of hydration.

Fortunately for the temple project there was no time constraint on allowing the slab to slowly gain strength. This mix also wasn't that slow, it reached 1,000 psi in three days, 3,000 in three weeks and, as fly ash concrete keeps getting stronger longer than equivalent mixes using cement only, the slab is expected to reach 6,000 psi in a few years. It won't reach South Indian granite bedrock at 16,000 psi, but it's close enough.

Trial Mixes
Mehta first came to Honolulu to do dozens of trial mixes at Steeltech headquarters. After the results of this were in, he refined the formula further with additional trial mixes. Each ingredient had to be carefully considered and adjusted, and the resulting formula is highly dependent upon local conditions. For example, both the Kauai sand and gravel had unique properties which had to be compensated for in the mix. Thus it is not possible to just publish a formula and say, "This is high volume fly ash concrete." Starting with the basic concept of up to 60% fly ash, water and admixtures have to be adjusted to create a placeable mix that will gain strength at the correct pace.

Slump Control and Additives
Tom Meehan of Master Builders company was responsible for inspecting the incoming trucks and adjusting the "slump" or thickness of the concrete to the proper specifications through discrete dosages of "Rheobuild 1000 Superplasticizer." A superplasticizer is a liquid, somewhat oily substance. Its large molecules have the effect of reducing the surface tension of the water in the concrete. The concrete becomes less sticky and able to flow more easily, just as if one had added more water. Additional water, however, makes for weaker concrete. So superplasticizers were invented in the 70s to allow for low-water concrete to be successfully placed. Trucks arrived with a typical slump of 2" to 3" (inches.) Rather than adding water, Superplasticizer was used to raise the slump to 5" or 6", which provided for workability and assured consolidation of one load to another. Vibrators with specially designated frequencies were needed extensively to blend the loads and to remove air pockets.

Checking Out the Local Facilities
Langley expressed concern about the Hale Kauai batch plant, knowing that this was the key link in the entire job. "Batching" means in concrete technology to weigh the ingredients, and a batch plant is a sophisticated, computer controlled weighing station. He, Mehta and Deva Rajan made an appointment to inspect the plant, but missed connections and arrived when it was closed. Langley, who's handled billion-dollar concrete projects, walked around anyway and said, "I've seen enough, there's no need to reschedule the appointment. This is one of the best plants I've ever seen. It's clean, organized, well maintained, obviously run by an expert." That expert, Pat De Busca, had worked at Hale Kauai all his life, beginning by hauling concrete sacks as a teenager, then singled out and trained by the owner to run the batch plant. Now he is a vice president of the company. A subsequent series of meetings with De Busca worked out all the necessary details for the concrete delivery.

The Final Test Mix
A week before the main placement, a test slab of five cubic yards was made, and Steel Tech's masons first got a trowel upon the unusual mix. They found it far different from ordinary concrete, better, actually, in that the fly ash concrete has much more "paste" upon the floated surface, allowing better finishing.

The low ratio of water and use of water reducing admixtures reduced the "bleeding of water" that cement finishers experience in normal concrete. The power screeding, bull floating and finishing of the foundation slabs went along very quickly due to the absence of bleeding and ample cement paste. This also allowed for the immediate application of curing compounds and the installation of 10 mil visquine to contain heat and prevent rapid water evaporation.

A Successful Foundation
The pour went as planned, as described above. The entire temple slab never got above 104* F, a medium fever for a human and just 24 degrees above the pleasant Hawaiian day.

Mehta and Langley required careful curing of the slab through curing compounds, wet burlap and visquine to control uneven cooling and loss of water through evaporation. Thermocouples were buried at strategic locations deep in the center of the slabs with wires that led out to the perimeter of the slab formwork. This allowed for monitoring of temperatures every four hours. In this way, day by day, the engineers were able to evenly cool down the massive slabs at 2 degrees per day. A week later, after it had cooled off close to ambient temperature, the first slab was inspected and found absolutely crack-free, leading to Mehta's triumphant proclamation. The second was found crackless also a week after the placement.

Better Concrete...
Concrete was known to the ancient world, and there remain large Roman and Greek structures--such as the Parthenon in Athens and the Pantheon in Rome with its 140 foot (!) wide dome--made of a kind of concrete related to fly ash concrete. They used volcanic ash deposits in those days to make a kind of concrete. This technology was lost in the dark ages, and only rediscovered in the 19th century. These structures tend to go against modern concepts of concrete engineering, especially in that they are all unreinforced. However, they've stood the test of time, and Mehta has always felt that these ancient technologies deserved more attention from the experts in understanding how to formulate durable concrete today.

Concrete durability is a major issue. Today in the USA, 500,000 highway bridges and overpasses are in need of major repair due to deterioration of concrete. Theories of how to make durable concrete have proven inaccurate. Concrete designed to last twenty years has shown damage in two. Mehta's insisted for years that concrete design take a holistic approach, that demands for rapid construction, for example, do not override principals of creating durable concrete. In recent years very high strength concrete has been developed using heavy steel reinforcing and high ratios of Portland cement. Builders loved it, but unfortunately its proved susceptible to all sorts of deterioration due to temperature cracking and access of water and chemicals to the steel reinforcing. Once this happens, the corrosion of steel quickly breaks up the concrete through expansion and spalling. High volume fly ash concrete is much more durable than normal concrete because it can almost totally eliminate temperature cracking due to its low heat of hydration and slow cure time (90 days.)

And Save the Planet Too!
But durability is just one advantage. So too is finding some place to put all those hundreds of millions of tons of waste fly ash. Our planet's yearly production of portland cement, the ingredient that binds everything together in concrete, is 1.5 billion tons. The production of one ton of portland cement adds one ton of carbon dioxide to the atmosphere--contributing to global warming. Cement production is in fact responsible for putting 6% of all man-made carbon dioxide into the atmosphere. This is a huge amount, more than burning Amazon rain forests. If fly ash is used to replace half this cement, carbon dioxide emission will drop 3%. There is nothing else that could make such a dramatic change in the carbon dioxide levels. And this with no additional expense for fly ash is a waste product already. It would take a lot of education. Fly ash concrete isn't suitable for everything, but it is for a lot. As one engineer watching the foundation project said, "The slow-setting fly ash concrete won't work for the highway engineer wanting to put cars on the road in two days." But Mehta and Langley see numerous uses for the fly ash, especially in India where it could go into brick production. Right now many bricks are fired in kilns, adding to air pollution and using wood. But fly ash concrete bricks could be made more cheaply and be strong also.