Dr Mohammed Alhaj Hussein
الإستشاري الدكتور
Dr Mohammed Alhaj Hussein
Jeddah 21499
Saudi Arabia
dralhaj2
http://www.concrete.org/committees/committeehome.asp?committee_code=0000232-00
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Upcoming and Future Convention Sessions
Title | Convention Location |
Natural Pozzolan - Rebirth of an Ancient Technology | Tampa, FL |
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Fly Ash and Natural Pozzolans in Concrete
ACI Committee 232 Home
Fly Ash and Natural Pozzolans in Concrete (Organized 1988) Chair: Karthik Obla TAC Contact: Kevin MacDonald Mission Develop and report information on the use of fly ash and natural pozzolans in concrete and mortar. Goals ) Work with U.S. Green Building Council, ACI board task group, ACI Committee 130, and others to promote sustainability as it relates to concrete; 2) Continue working on a guide on the use of higher volume fly ash concrete for the green building industry; 3) Develop a performance guide specification for use of fly ash in concrete; 4) Revise "Use of Fly Ash in Concrete" (ACI 232.2R-03).
Active Documents See Bookstore for Historical Documents
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Recent Convention Sessions
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Major US Pozzolan Concrete Projects since 1900
East Bay Municipal Utility District Wastewater Treatment Plant California
Aburn Dam California
Palo Verde (Nuclear) Power Generating Plant Arizona
Sacramento Wastewater Treatment Plant California
Southern Nevada Water Project Nevada
Tehama-Colusa Canal California
George R, Moscone Convention Center California
Port of Richmond California
Pacheco Pass Tunnel California
Idaho Falls Hydro Electric Idaho
American River Falls Power Plant Idaho
Coyote Power Generating Plant N. Dakota
San Francisco Wasterwater Treatment Plant Project California
Pioneer Reservoir California
Chabot Dam California
Dumbarton Bridge California
Peace Valley Water Project California
Pyramid Lake Powerhouse California
Rock Springs Wyoming Power Plant Wyoming
Hong Kong Center California
Graduate Theological Union Building, UC Berkeley California
Pacific Gas & Electric California
Helms Creek Powerhouse Pump Station California
North Point Seawall California
Bechtel Engineering Center, UC Berkeley California
Redding Airport Runway California
Los Angeles Aqueduct (1910-1912)
Los Angeles Flood Control District during the 1920's and 1930's
Bonneville Dam (1935)
Golden Gate Bridge (1937)
Piers of the San Francisco-Oakland Bay Bridge (1935)
Friant Dam (1942)
Nearly all of the concrete in the California State Water Project - Including the California Aqueduct in the 1960's and the 1970's.
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San Luis Reservoir
The water in the mainstem is pumped up California’s hilly terrain by three pumping plants—Buena Vista, Teerink, and Chrisman—until it reaches Edmonston Pumping Plant, the SWP’s largest. Its huge motor pump units, each standing about 65 feet tall and weighing more than 400 tons, lift water nearly 2,000 feet up and over the Tehachapi Mountains through 10 miles of tunnels. As the water reaches the bottom of the mountain, it splits into two branches: the West Branch and the East Branch.
Altogether the SWP is comprised of 33 storage facilities and 21 lakes and reservoirs that can store up to 5.8 million acre-feet of water. The largest reservoir spans over 15,800 acres with a shorline 167 miles in length. The highest Dam is 770 feet tall and the length of the canals and pipelines amounts to 662 miles.
The SWP generates an average of 7.6 billion kWh annually while using an average of 12.2 billion kWh. The highest pump lift that this energy is put towards is 1.926 feet.
The California Aqueduct is nearly 450 miles in length. A Typical section has a concrete-lined channel 40 feet wide at the base and an average water depth of about 30 feet. The widest section of the aqueduct is 110 feet and the deepest is 32.8 feet. The pumping and channel capacities at the start of the aqueduct are 10,670 and 10,300 cubic feet per second, respectively. The largest channel capacity is 13,100 cfs and the largest pumping plant capacity is 15,450 cfs. For perspective, an Olympic-sized swimming pool with dimensions of 2 x 25 x 50 meters holds about 88,000 cubic feet.
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California Aqueduct
Water flows through the aqueduct in a series of abrupt rises and gradual falls. The water flows down a long segment, built at a slight grade, and arrives at a pumping station. The pumping station raises the water, where it again gradually flows downhill to the next station. However, where there are substantial drops, the water’s potential energy is recaptured by hydroelectric plants. The initial pumping station fed by the Sacramento River Delta raises the water 240 feet. Then at Edmonston Pumping Plant a series of huge motor pump units, each standing about 65 feet tall and weighing more than 400 tons, lift water nearly 2,000 feet up and over the Tehachapi Mountains through 10 miles of tunnels.
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History of Pozzolan
Concrete is a compound material made from sand, gravel and cement. The cement is a mixture of various minerals which when mixed with water, hydrate and rapidly become hard binding the sand and gravel into a solid mass. The oldest known surviving concrete is to be found in the former Yugoslavia and was thought to have been laid in 5,600 BC using red lime as the cement.
The first major concrete users were the Egyptians in around 2,500BC and the Romans from 300 BC The Romans found that by mixing a pink sand-like material which they obtained from Pozzuoli with the informal lime-based concretes they obtained a far stronger material. The pink sand turned out to be fine volcanic ash and they had inadvertently produced the first 'pozzolanic' cement. Pozzolana is any siliceous or siliceous and aluminous material which possesses little or no cementitious value in itself but will, if finely divided and mixed with water, chemically react with calcium hydroxide to form compounds with cementitious properties.
The Romans made many developments in concrete technology including the use of lightweight aggregates as in the roof of the Pantheon, and embedded reinforcement in the form of bronze bars, although the difference in thermal expansion between the two materials produced problems of spalling. It is from the Roman words 'caementum' meaninga rough stone or chipping and 'concretus' meaning grown together or compounded, that we have obtained the names for these two now common materials.
Lime and Pozzolana concretes continued to be used intermittently for nearly two millennia before the next major development occurred in 1824 Cement was, made from a mixture of clay and limestone, which had been crushed and fired in a kiln, was an immediate success.Although many developments have since been made, the basic ingredients and processes of manufacture are the same today
The oldest known form of concrete is to be found in the Middle East and it dates back to 5600 BC; the Egyptians (XXVI Century BC) used mixed with straw to bind dried bricks, gypsum and lime mortars in stone masonry (in particular for the construction of pyramids).
The Greeks living in Crete and Cyprus used lime mortars as well (Eight Century BC), whereas Babylonians and Syrians used bitumen to construct stone and brick masonries.
The Ancient Greeks, similarly, used calcined limestone, while the Romans made the first concrete:mixed lime putty with brick dust or volcanic ash. They used it with stone to construct roadways,buildings and aqueducts.
The Romans used pozzolana, a particular type of sand from Pozzuoli,near the volcano Vesuvio (Southern Italy), to construct buildings of crucial importance, such as the Pantheon or the Colosseo.
Pozzolana is an uncommon kind of sand which reacts chemically with lime and water, becoming a rocklike mass; furthermore, it is siliceous and aluminous and it reacts with calcium hydroxide to form compounds with cementation properties.
The domed Pantheon, constructed in the Second Century AD, is one of the structural masterpieces of Roman time: it has a sophisticated structure with a large number of voids, niches and small vaulted spaces aimed at reducing its weight; in particular the dome shows a thicker structure at its base, whereas its thickness tends to diminish gradually, according to the increased height of the dome(in other words, the dome thickness is inversely proportional to its height). Pliny reported a mortar of lime and sand (one part of limeto four parts of sand), and Marco Vitruvio Pollione (First Century BC) reported a mixture of pozzolana and lime (two parts of pozzolanato one part of lime) and we have also an essay of him as regards the properties of concrete.
Fly Ash and GGBS vs. Pozzolan
Known to be much inferior to natural pozzolan, fly ash normally contains excess amounts of carbon and sulfur trioxide, which are trapped inside the spherical envelope while coal powder burns. As the waste of coal-fired power plants, fly ash is inconsistent in chemical composition.
When fly ash cement is hydrated, the envelope covering each fly ash particle prevents or slows down its reaction with calcium hydroxide during cement curing period. When the envelope breaks in a later stage, destructive DEF (Delayed Ettringite Formation) occurs around the partly reacted fly ash particle.
Fly ash is also known to be inferior to natural pozzolan in the control of alkali-aggregate reaction, because the envelope slows down its reaction with calcium hydroxide which is produced by hydration of Portland cement. The envelope also slows down the silicate inside the particle to react with the alkali in the cement.
Natural pozzolan is formed when silica rich magma meets with a large quantity of under ground water in the volcano conduit. Under high pressure and high temperature, water in steam form dissolves into the magma mixing with the dissolved carbon dioxide and sulfur gases. When this magma reaches the earth's surface, it blows off the top of the volcano cone, Because the pressure is suddenly reduced, all the gases inside the magma are released and the magma, blown up like pop-corns, falls to ground and then cools off quickly into small porous rocks.
After being ground into a fine powder, Eco Pozzolan can quickly react with calcium hydroxide and can trap the alkali inside the cement paste. Thus, it helps to form a denser paste with almost no alkali aggregate reaction at all.
GGBS vs. Pozzolan
Good quality granulated blast furnace slag is a good cementitious material. But, in order to produce good quality slag, steel plants have to sacrifice quality and some quantity of their steel products. Therefore, good quality slag is very hard to find.
Uniformity is another problem. The mixture of the left over from burning the iron ore, limestone and coal, can vary from ton to ton in chemical composition.
Water-cooling may help to purify the slag, but there are still certain quantities of gases such as carbon dioxide, carbon monoxide and sulfur gases trapped inside the slag.
Slag cement is well known for its slowness in developing its compressive strength. Adding expensive silica fume can accelerate the development, but the result is still not very satisfactory.
Containing 30~40% silicate and about the same amount of calcium oxide, slag is far inferior to Pozzolan in reactivity with the calcium hydroxide produced by cement hydration.
Pozzolan is unique in its uniformity and high reactivity.
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Research shows that the quality of Eco Pozzolan material surpasses criteria of GB/T2846 for pozzolanic materials used for cement and exceeded all requirements to a natural pozzolan in accordance with ASTM C618.
For construction use as an additive for concrete, conforming to ASTM C-618 in the U.S. and GB/T2846 in China, or use as a major ingredient for producing Portland Pozzolan Cement, conforming to ASTM C-595-98 in the U.S. and BS6610: 1996 in the U.K.
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Dr Mohammed Alhaj Hussein
JEDDAH-SAUDI ARABIA
Mobile 0504331820
جدة -- السعودية
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Tampa- Florida - USA
تامبا - ولاية فلوريدا - امريكا الشمالية
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United Arab Emirates - Dubai
دبي - الامارات العربية المتحدة
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Dr Mohammed Alhaj Hussein
Jeddah 21499
Saudi Arabia
dralhaj2