As an engineer, I respect concrete as a building material. It is essentially a combination of coarse aggregate (stone chips, gravel, small rocks, etc.), fine aggregate (sand), water, various admixtures, and cement. The Romans used concrete to make their wonderful structures such as the Pantheon, so it isn't really that modern. The Romans had a recipe for cement which was lost until the 1800s. When water is added to cement it causes a chemical reaction that binds the various other components of concrete together and gives strength. This can make the completed product stronger than stone.
Concrete has the great compressive strength of stone with several major advantages. Concrete can be poured and cast into the desired shape (even with patterns). It also allows structures to be built without large pieces of stone. Concrete is weak in tension, so weak that we neglect its tensile strength in design. This is why it can crack. Stone has the same problem and requires arches and other structural components to be used to keep the structure in compression. You can reinforce concrete with steel (or other materials) and let the steel take the tension. This creates a much better, stronger, and more versatile building material.
Precast concrete is used to save time (normally you must wait for lower levels of a structure to cure before adding higher levels). Panels can be cast on or off site ahead of time and then added when needed. Precasting concrete also allows for controlled conditions because things such as temperature and humidity have a huge impact on concrete curing and resulting strength. Precast panels can also be prestressed, giving them even greater strength. Intricate designs can be cast into precast panels and even stone finishes or other finishes can be added to precast panels.
Okay, so I've probably bored all the non-engineers out there, so I'll move on to the temples using precast concrete. You might think it odd that a temple would use concrete. Concrete can be an ugly material, or even just have an unfinished look not appropriate for a temple. It can also be finely finished and make some of the most beautiful buildings in the world such as the Sydney Opera House or this Bahaii Temple.
So on to LDS temples with exposed precast concrete exteriors. I was a little surprised that a few temples didn't make the list as they were actually stucco or plaster exteriors and not precast concrete. Here is the chronological list I came up with after reviewing all the temples on ldschurchtemples.com :
Ogden Utah Temple (original only - remodeled will have stone)
Provo Utah Temple
Tokyo Japan Temple
Seattle Washington Temple
Jordan River Utah Temple
Atlanta Georgia Temple
Mexico City Mexico Temple
Denver Colorado Temple
Las Vegas Nevada Temple
Toronto Ontario Canada Temple
Orlando Florida Temple
St. Louis Missouri Temple
Billings Montana Temple
Albuquerque New Mexico
Rexburg Idaho Temple
Twin Falls Idaho Temple
Gila Valley Arizona Temple
Kansas City Kansas Temple
Brigham City Utah Temple
I don't think all of these work well, but the most recent are very nicely done. I think that the "cast stone" version of concrete panels tends to just look like fake stone; whereas, the temples that fully embrace concrete as their material tend to look better. Temples with detailed cast panels also tend to look better than those with flat panels. The temples with my favorite uses of precast concrete are Jordan River, Mexico City, Rexburg, and Twin Falls. Let me elaborate:
The Jordan River Utah Temple is very modern. It uses inverted parabolic (hyperbolic?) arches as an architectural motif. Using cast stone allows the temple to hold these details without prohibitive engraving costs. White marble chips have been added to the concrete to give it the bright white color. The spire is actually a type of fiberglass (you don't want to throw the weight of concrete that high up a building in Utah for seismic reasons).
The Mexico City Mexico Temple has intricate Mayan designs incorporated into the precast stone panels. Unfortunately, due to the horrible pollution in Mexico City, the panels turned a nasty brown color. Fortunately, the church recently replaced all the exterior panels with exact replicas. I assume the replicas now how a special finish that makes dirt and pollution fall off (they can finish the concrete and make it do that now). I also love how the Mexico City Temple incorporates local ancient architecture and uses modern precast concrete to make a temple in a successful fusion of old and new. The temple won an award for its artistic use of precast concrete (see ldschurchtemples.com)
The Rexburg Idaho Temple refreshingly uses precast concrete. According to ldschurchtemples.com,
The exterior walls of the Rexburg Idaho Temple are made of 637 precast panels from 45 different molds, including the retaining wall. The material is called China White—a white quartz finish (mined in Washington state) on concrete panels. A water-proofing compound allows dust to wash off in the rain, keeping the temple a radiant white.I also love the art deco influences (I'm a huge art deco fan). I love how columns and pilasters resemble wheat (wheat is used throughout the temple stained glass, carpets, stair railings, wall designs, etc.). I think the concrete works because it is finely finished, detailed, and kept immaculate.
The Twin Falls Idaho Temple was built at the same time as the Rexburg Temple and shares many similar features. I must state that I don't think it is as well proportioned as Rexburg or in general design; however, I like the temple and loved attending it (the inside is very well executed with the exception of ductwork making the terrestrial room windows fake). The precast panels are the biggest strength of the exterior and are well done. They incorporate a waterfall theme. The panels have a nice white quartz finish. I think the panels are the same concrete used in the Rexburg Temple.
Other notable precast concrete temples are:
The Las Vegas Nevada Temple with desert lilies, sun, moon, and earth "stones" cast into the concrete.
The Denver Colorado Temple's modern designs cast in concrete.
The Albuquerque New Mexico Temple with its use of sun and moon "stones" made of precast concrete.
The Seattle Washington Temple has shafts of wheat cast into the panels.
I also like that several new temples will use precast concrete. The Kansas City Temple is already sheathed in its precast panels and will have a sleek look. Some nice details have been cast between windows. The Brigham City Temple will also use precast concrete panels, despite being heavily influenced by stone pioneer temples. I like the design and think it will be more interesting in person than in the rendering.
I used to think that using concrete was somehow being cheap. When nicely done, it is not cheap. In fact, a major reason that precast concrete isn't used for temple exteriors in many parts of the world is that the countries don't have the skill, technology, or quality control to produce the panels. They are advanced and a very good building material. In many temples they have been a beautiful building material as well.
Please comment and let us know what you think about precast concrete as a temple building material.