Sunday, September 1, 2013

Arizona Concrete


John McCollam

Geology 101, Section 12262
Randy Porch
20 November 1996

According to the Mine Faculty at the University of Arizona, cement is manufactured primarily from suitable limestone and shale rocks. Arizona had two dry-process cement plants in 1969, namely the Arizona Portland Cement Company plant in Pima County, near Tucson, and the American Cement Corporation plant at Clarkdale, in Yavapai County (52-53).
The use of cementing materials goes back to the ancient Egyptians and Romans, but the invention of modern portland cement is usually attributed to Joseph Aspdin, a builder in Leeds, England, who obtained a patent for it in 1824. Currently, the annual world production of portland cement is around 700 million metric tons (Danbury).
Many people use the words concrete and cement interchangeably, but they=re not. Concrete is to cement as a cake is to flour. Concrete is a mixture of ingredients that includes cement but contains other ingredients also (Day 6-7).
Portland cement is produced by pulverizing clinker consisting essentially of hydraulic calcium silicates along with some calcium aluminates and calcium aluminoferrites and usually containing one or more forms of calcium sulfate (gypsum) as an interground addition. Materials used in the manufacture of portland cement must contain appropriate proportions of calcium oxide, silica, alumina, and iron oxide components. During manufacture, analyses of all materials are made frequently to ensure a uniformly high quality cement.
Selected raw materials are crushed, milled, and proportioned in such a way that the resulting mixture has the desired chemical composition. The raw materials are generally a mixture of calcareous (calcium oxide) material, such as limestone, chalk or shells, and an argillaceous (silica and alumina) material such as clay, shale, or blast-furnace slag. Either a dry or a wet process is used. In the dry process, grinding and blending operations are done with dry materials. In the wet process, the grinding and blending are done with the materials in slurry form. In other respects, the dry and wet processes are very much alike.
After blending, the ground raw material is fed into the upper end of a kiln. The raw mix passes through the kiln at a rate controlled by the slope and rotational speed of the kiln. Burning fuel (powdered coal, oil, or gas) is forced into the lower end of the kiln where temperatures of 2600°F to 3000°F change the raw material chemically into cement clinker, grayish-black pellets about the size of 1/2-in.-diameter marbles.
The clinker is cooled and then pulverized. During this operation a small amount of gypsum is added to regulate the setting time of the cement. The clinker is ground so fine that nearly all of it passes through a No. 200 mesh (75 micron) sieve with 40,000 openings per square inch. This extremely fin gray powder is portland cement (Kosmatka and Panarese 12-15).
Dany Seymore of Show Low Ready Mix said that the cement used by Show Low Ready Mix is trucked in by Apex Freight Company and comes from the cement plant in Clarkdale, Arizona, now know as Phoenix Cement. Their aggregate comes from Brimhall Sand and Rock in Snowflake, Arizona. Show Low Ready Mix uses Fly Ash from the A.P.S. power plant just out side of Joseph City, Arizona, in their cement. The mixtures they use are as follows:
Silicia Dioxide Cement 21% Ash 62%
Aluminum Trioxide Cement 4% Ash 23%
Ferric Oxide Cement 3% Ash 6%
Calcium Oxide Cement 64% Ash 3.5%
Mag. Oxide Cement 2.5% Ash 1.2%
Sulfur Trioxide Cement 3% Ash .2%
These combine to make:
1. Tricalcium silicate C3S
2. Dicalcium silicate C2S
3. Tricalcium aluminate C3A
4. Tetracalcium aluminoferrite C4AF
1 and 2 make up 75% of cement. 1 and 2 plus H2O equal CSH (Calcium Silicate Hydrate) which is the glue. Fly Ash is C3S plus C2S which equals Calcium hydrazide which is a white stuff and water soluble. Calcium Hydrazide and Fly Ash equal CSH.
The winter and summer mixtures are different due to the weather conditions. For winter, Fly Ash is not used because it inhibits the set time of the concrete. Also used is accelerators to help the concrete set faster. A material called Fibermesh is used in the concrete for reinforcement and to control cracking as the concrete sets. Mr. Seymore also states that heat and moisture are the main components to make concrete set up.
The concrete is mixed out of the plant into the truck so the materials can be feathered together and mixed up properly. The PSI ratings are determined by the mixture of sand, aggregate, cement, water, and chemical additives that are mixed together. The most common mixtures for residential are 2500 to 3000 PSI.
Concrete cannot be delivered any where that is more than 90 minutes away from the batch plant, unless a chemical inhibiter is used to put the concrete to sleep until it reaches the sight of delivery. Then another chemical is added to activate the concrete.
Show Low Ready Mix mixes approximately 25,000 to 30,000 cubic yards of concrete in Show Low per year. That is only 70 to 75 percent of the total concrete poured in Show Low. There are a few other companies that also handle the Show Low area.
Concrete is basically a mixture of two components: aggregates and paste. The paste, comprised of Portland cement, (the term APortland cement@ pertains to a calcareous hydraulic cement produced by heating the oxides of silicon, calcium, aluminum, and iron.) Water binds the aggregates (sand and gravel or crushed stone) into a rocklike mass. The paste hardens because of the chemical reaction of the cement and water.
The paste is composed of Portland cement, water, and intrapped air or purposely entrained air. Cement paste ordinarily constitutes about 25% to 40% of the total volume of concrete. Since aggregates make up about 60% to 75% of the total volume of concrete, their selection is important. Aggregates should consist of particles with adequate strength and resistance to exposure conditions and should not contain materials that will cause deterioration of the concrete.
Aggregates are generally divided into two groups: fine and coarse. Fine aggregates consist of natural or manufactured sand with particle sizes ranging up to 3/8 inches; coarse aggregates are those with particles retained on the No.16 sieve and ranging up to 6 inches. The most commonly used maximum aggregate size is 3/4 inch or 1 inch. A continuous gradation of particle sizes is desirable for efficient use of the cement and water paste.
For any particular set of materials and conditions of curing, the quality of hardened concrete is determined by the amount of water used in relation to the amount of cement . Some advantages of reducing water content are: increased compressive and flexural strength, lower absorption, increased resistance to weathering, better bond between successive layers and between concrete and reinforcement, less volume change from wetting and drying, and reduced shrinkage cracking tendencies. The less water used, the better the quality of the concrete, provided it can be consolidated properly.
The freshly mixed (plastic) and hardened properties of concrete may be changed by adding admixtures to the concrete, usually in liquid form, during batching. Admixtures are commonly used to: adjust setting time or hardening, reduce water demand, increase workability, intentionally entrain air, and adjust other concrete properties (Kosmatka and Panarese 1-2).
After completion of proper proportioning, batching, mixing, placing, consolidating, finishing, and curing, hardened concrete becomes a strong, noncombustible, durable, abrasion-resistant, and practically impermeable building material that requires little or no maintenance. Concrete is also an excellent building material, because it can be formed into a wide variety of shapes, colors, and textures for use in almost unlimited number of applications.
Works Cited
ACement and concrete.@ The 1996 Grolier Multimedia Encyclopedia. CD-ROM. Danbury: Grolier, 1996.
Day, Richard. The Home Owner Handbook Of: Concrete and Masonry. New York: Bounty Books, No Copyright Date.
Kosmatka, Steven H., and William C. Panarese. Design and Control of Concrete Mixtures. Skokie, Ill.: Portland Cement Association, 1990.
Seymore, Dany. President of Show Low Ready Mix. Personal interview. 11 November 1996.
College of Mines Faculty, University of Arizona. Arizona: Its People and Resources. Tucson, AZ.: The University of Arizona Press, 1972.


By: Chris Ojeda

Argentina is a South American country with a population of thirty one million people. Argentina's capital is Buenos Aires, which is one of the largest cities in South America. Buenos Aires is situated on the coast of Argentina, which makes Buenos Aires a major trade route in Argentina and in South America. Argentina's national language is Spanish and the major religion is Roman Catholicism.
Argentina is a country with much natural beauty. It has miles of beautiful beaches and is also surrounded by the majestic Andes mountains. The Andes mountains are among the highest mountains in the world. Argentina's tallest mountain is the Cerro Aconcagua. This mountain reaches an amazing height of 22,200 ft. America's tallest mountain only reaches the height of 20,000 ft.
Argentina has a huge industrial and agricultural base. Argentina has a large amount of natural resources which includes copper, silver, coal, iron ore, uranium and petroleum. Argentina is the #1 copper producer in the world. Argentina also produces huge amounts of coal and is self sustained in petroleum products.
Argentina also grows much more food than it consumes. Its main crops include wheat, tobacco and cattle. Argentina ranks 3rd in the world among wheat exporters, right behind the United States and Canada. Argentina is also one of the largest tobacco exporters as well.
Argentina's large industrial and agricultural base makes it one of the richest countries in South America. With its rich history and its beautiful mountains and beaches, not to mention its wonderful Spanish culture, Argentina is a very special place to visit in South America.

Angina Pectoris

Tropical Africa: Food Production and the
Inquiry Model

Hunger is the result of disasters such as drought, floods, the
.changing of the jet stream patterns and other natural disasters
.They are beyond our control

It has been estimated that one third of the land in Tropical
Africa is potentially cultivable, though only about 6% of it is
,currently cultivated. However, to change farming from a low-input
low-yield pattern to a high-input, high-yield pattern necessitates
the use of more fertilizer and the planting of high-yielding
.varieties of crops

There are a number of environmental factors, related mostly to
.climate, soils and health, resisting easy developmental solutions
.Rainfall reliability is closely connected to rainfall quantity
The rainfall in the equatorial heart is very plentiful and
reliable. However, there is much less rainfall towards the outer
edges of the rain belt. Periodic and unpredictable droughts are a
.characteristic feature of these border zones
:There are three climatic zones in Tropical Africa
,1.a region of persistent rain at and near the Equator
2.a region on each side of this of summer rain and winter
drought, and
3.a region at the northern and southern edges afflicted by

All the climates listed in the previous paragraph are modified
in the eastern parts of Tropical Africa by the mountains and

The soils of Tropical Africa pose another problem. They are
unlike the soils of temperate areas. Soils are largely products of
their climates, and tropical soils are different from temperate
soils because the climate is different. Because of the great heat
,of the tropics tends to bake the soils, while on the other hand
the rainfall leaches them. The combined heat and moisture tend to
produce very deep soils because the surface rock is rapidly broken
down by chemical weathering. All this causes the food's rate of
growth to slow down or maybe even stop and as a result food
production won't even come close in catching up to the rate of
.population increase; therefore starvation and hunger is present
In the process of a flood and drought, the roots of trees are
shallow and virtually no nutrients are obtained from the soil. The
vegetation survives on its own humus waste, which is plentiful. If
the vegetation is cleared, then the source of humus is removed and
the natural infertility of the soils becomes obvious. As being
another factor, this will cause the soil to produce wasteful and
.useless products which in turn will decrease the production

To conclude this essay, the climates in Tropical Africa take
a big role as being factors that could endanger or destroy the
process of plantation. On the other hand, it could also bring good
.fortune if climatic regions are fairly good


Australia is the world's smallest continent and sixth-largest country. With proportionately more desert land than any other continent, Australia has a low population density. Lying completely in the Southern Hemisphere, Australia is bounded by the Indian Ocean on the west and south and by the Pacific Ocean on the east. These oceans merge on the north in the Arafura Sea between Australia and Indonesia and New Guinea, and on the south in the Bass Strait. The coastline length, estimated at 19,200 km (12,000 mi), is remarkably short for so large an area, a result of the relative lack of indentation. Major inlets other than the Gulf of CARPENTARIA and the GREAT AUSTRALIAN BIGHT are few.

A self-governing member of the Commonwealth of Nations, Australia celebrated its bicentennial in 1988z. It is a federation of five mainland states (NEW SOUTH WALES, QUEENSLAND, SOUTH AUSTRALIA, VICTORIA, WESTERN AUSTRALIA) and one island state (TASMANIA), as well as two territories (AUSTRALIAN CAPITAL TERRITORY, NORTHERN TERRITORY). The country's name derives from the Latin terra australis incognita, meaning "unknown southern land," which resulted from a confusion between Australia and Antarctica on early world maps.

In many ways Australia is unusual among continents. It lacks major relief features and has a high proportion of dry land. The continent's isolation from other landmasses accounts for its unique varieties of vegetation and animal life, and for the existence of a Paleolithic (Old Stone Age) culture among the Aborigines. Except for Antarctica, Australia was probably the last continent to be inhabited by humans and the last to be explored and settled by Europeans. It is the only continent comprising a single nation-state.

Dutch explorers first sighted Australia in the early 17th century. Capt. James COOK explored the east coast in 1770 and claimed the land for Great Britain. In 1778 the first settlement (SYDNEY) was founded at an excellent harbor on the southeast coast. British convicts played an important role in the territory's early history. The discovery of gold and other ores attracted immigrants, but Australia remained a primarily agricultural country until World War II.

Subsequent industrialization has been rapid, and today Australia ranks as one of the world's most economically developed countries, although vast areas of the interior, known as the Outback, remain all but uninhabited.

A trip through panama

Day 1:

We arrived at Omar Torrijos airport via American Airlines early in the afternoon. We purchased our required tourist cards (3 balboas, as US dollars are called in Panama) at the airport, then caught a taxi for the 18 mile ride to our downtown hotel. The ride in the battered, un-airconditioned car was rather expensive (30 balboas), but the driver spoke English and was very friendly. We arrived at the hotel and checked in. While my dad was checking in I bought a guidebook in the hotel lobby and read up on the history of Panama City. The original city was founded in 1519 by Pedro Arias Davila, known as Pedrarias the Cruel, because of his eradication of all but three of the local Indian tribes during his tenure in Panama. Davila used the city as a place to store Incan gold before it was shipped to Spain. The original city was sacked and burned in 1671 by a group of buccaneers led by Henry Morgan. The city was rebuilt within a year, this time on a peninsula 18 miles away and surrounded by a strong wall. This old Spanish city is now the in the middle downtown Panama City.
Panama City is an international melting pot and its eating choices range from American fast food to excellent internationall cuisine. Eager to begin our sightseeing, we grabbed lunch at a nearby McDonald's after checking in then caught a bus. The buses in Panama are a tourist attraction in themselves. They are brightly painted, hung with fringe, and have constantly blaring Salsa and Caracas music playing. They are cheap (50 cents a ride). but are very crowded. After asking several drivers "Donde va este autobus?" we finally found one going to the Plaza Independencia. This plaza is the main square of the colonial town and is bordered on one side by a cathedral with twin mother of pearl towers that took 108 years to complete. On two other sides it is bordered by the Archbishop's Palace, now a university and the Central Post Office. While in the old part of Panama City we also visited the Iglesia de San Jose and saw the Golden Aaltar. This altar was in the original Panama City and was saved from Henry Morgan's pirates by a monk who painted it black to disguise it. When we finished touring we returned to our hotel and then ate dinner at El Pez de Ora, one of the city' famous seafood restaurants.

Day 2:
We woke early and headed out for a morning of shopping at the Mercado Publico. I bought some jewelry and some small wooden figurines as souvenirs, but when I asked "Donde esta los sombreros de Panama?", the vendor told me Panama hats were made in Ecuador. The hat most commonly worn in Panama is the "pita", a narrow brimmed straw hat with black and white stripes. The most important phrases to remember when shopping in Panama are " Cuanto cuesta esta?" and " Acceptas tarjetas de credita?" After shopping we had Chinese food in one of the local restaurants.
After eating we went to visit Panama's most famous attraction, the Panama Canal. The Canal was completed in 1914, and is considered one of the greatest engineering feats in the world. We took a shuttle from our hotel to the canal and then went on a 90 minute train ride all the way across the isthmus along the canal. The railroad we were traveling on was built in 1855 to transport '49ers who were on their way to the California gold rush and was the first "trans-continental" rail link. At one of the train stations we got off and walked to the Miraflores Locks, sat on bleachers, and watched the ships go through the canal. After our tour of the Panama Canal we returned to our hotel to get ready for a night of dinner and theater. We ate dinner at an Italian restaurant then went to the Teatro National for a performance of the Folkloric Ballet. The Folkloric Ballet features native folk dances and costumes and was very entertaining.

Day 3:
We rented a car and left Panama City headed southwest along the Pan American Highway. First we visited the Parque Natural Metropolitana, a zoo on the outskirts of Panama with monkeys, deer, sloths, and iguanas. We then drove toward El Valle, about 75 miles away. El Valle is located in the center of a dormant volcano. There we saw hot springs, botanical gardens (with square trees which scientists have been unable to explain!), and golden frogs found nowhere else on earth. We continued down the highway passing through the towns of Penonome, the geographic center of Panama, and Nata, on of the oldest towns in Latin America. The Interior of Panama is mostly farmland and grazing land for cattle. We even saw some cowboys! At night we arrived at Baquette, a village on the side of the dormant Baru Volcano, where we spent the night.

Day 4:
We began our day by visiting Volcan Baru National Park and taking a short hike to see the beautiful plants and birds. The volcano is the highest point in Panama at 3475 meters. After our hike we ate lunch and then drove to Chiriqui Grande where we dropped off our car. We then caught a ferry to Bocas del Toro where we visited Bastimentos National Park. The park has pristine white sand beaches where sea turtles nest. The coral reefs off the coast are home to more than 200 species of tropical fish. While there we also got to visit caves containing the largest population of fruit eating bats in the world! Later we went snorkeling of the coast of Almirante Island where we spent the night.