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It was on a roadbed with concrete ties that the French TGV high speed train established a world record of 237 « miles per hour in 1981.
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Reinforced concrete is inherently a durable and nearly maintenance-free construction material under normal conditions.
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It was imperative that the concrete in the tower of a cable stay concrete bridge under construction have a minimum compressive strength of 6000 psi and be free of entrapped air voids.
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The thermal mass needed in passive solar homes such as this one in Naperville, Illinois, calls for concrete.
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Carefully designed concrete barrier walls can help reduce the homeowner's concern over encroaching commercial development and threatening traffic arteries by shutting out objectionable sights and sounds.
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Durability and energy efficiency were advantages common to all of the concrete homes visited, but prices and architectural styles covered a range of tastes and pocketbooks.
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With a 50-year life expectancy, concrete roof tiles compare favorably with wood, clay, and asphalt alternatives when a life-cycle cost analysis is made.
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This article is about residential concrete basement or foundation walls, but much of it applies also to nonloadbearing partition walls and other concrete walls above or below grade.
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Colorful concrete pavers have begun to change the part of America on which people walk and ride.
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An emerging trend for homebuilders is the construction of smaller homes with a few high-visibility upgrades that serve as selling features.
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A quality assurance program isn't a way of adding another layer of non-productive paper shufflers to the construction process.
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A new concrete rib floor system intended for use on the first floor over a basement can span up to 16 feet and is designed to be competitive with wood joist construction.
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The most elementary quality control efforts one full-time technician with a slump cone, air meter, scale and thermometer assure the concrete producer and his customers that he is providing the level of quality expected.
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Thoughtful detailing practices helped to ease steel congestion at beam/column connections on the Pacific Park Plaza condominium tower in Emeryville, California, and fabric cages cut labor costs while making it easier to correctly position the transverse steel.
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To speed up construction work and help to bring contracts in on schedule, reinforcing steel must be placed accurately and efficiently.
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The Netherlands' nearly two-mile long Eastern Scheldt storm surge barrier required the building of 66 reinforced concrete piers ranging from 100 to 130 feet high and measuring 82 by 165 feet at the base, with a design life of 200 years in a seawater environment.
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Creating 9 miles of seating risers in the first level of the Hubert Humphrey Metrodome in Minneapolis presented some unusual forming problems.
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Fasteners must be strong enough to perform their task, must be the proper type for the particular application, and must give satisfactory service throughout the life of the building.
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More than 15,000 schools in Britain include concrete as a subject for school projects in their curricula. They find it a pleasurable, creative medium for capturing the interest of children and helping them learn how to solve problems. The British Cement and Concrete Association has developed course...
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Water pressures build up under a tire as the speed increases. When these pressures become high enough they lift the tire completely free of the pavement, and when the entire tire footprint is riding on a water layer or film the tire is said to be hydroplaning.
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The corporate office brochure is the single most powerful marketing weapon in a general or subcontractor's marketing arsenal. Following are some guidelines which can help such companies avoid pitfalls in developing the office brochure. These points must be considered if you want to get the most for...
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Thermal mass relates to the ability of a material to store and release heat.
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To build a nature awareness center that did not disrupt the natural environment, the structure chosen was an earth-sheltered, earth-integrated concrete building heated by passive solar energy with electricity provided by a wind generator and hot water by solar collector panels.
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The world supply of readily usable energy is finite and woefully short for the projected needs of an ongoing industrial society.
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Lightweight concrete weighs substantially less than concrete made with gravel or crushed stone aggregates.
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Research and experience show that heating costs can be substantially reduced, especially in colder climates, by insulating concrete walls.
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ACI 301 is a reference standard that the engineer or architect may make applicable to any building project by citing it in the project specifications, supplementing it as needed by designating or specifying individual project requirements.
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One way to build without conventional vertical shores is to use long-span form panels supported by brackets or jacks attached to the bearing walls or columns of the building itself.
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For the first time in 30 years, a major street in Manhattan was paved in concrete rather than the more commonplace asphalt economy being a prime factor.
Used as secondary reinforcement, polypropylene fibers help reduce shrinkage and control cracking.
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Nearly 2,000 people watched a demonstration of concrete placing and finishing at Kansas State University's Weber Arena. The demonstration featured ten different concrete mixes and 21 test slabs, plus a variety of vibrating screeds and other finishing equipment.
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Too many times I have been called to look at some problem only to find that the specifications virtually guaranteed the poor result.
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Safe transportation and storage of liquefied natural gas (LNG) require that the materials used to contain the fluid must withstand sub-arctic temperatures as low as -265 degrees F, the temperature to which the gas must be cooled in order to become liquefied.
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Concrete placement during hot weather can lead to problems if precautions are not taken to control placement temperatures.
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There are some projects where cracking is just not acceptable. In a food warehouse, for example, sanitary considerations may require the filling of all cracks.
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Joints in unreinforced pavements are located to control cracking, aid in construction and delineate driving or parking lanes while insuring the structural integrity and riding quality of a concrete pavement.
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The effect of nearby dynamite blasts, pile driving, or the simultaneous operation of machinery or vehicles on fresh or newly cast concrete is often questioned.
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The final phase of a 10-year study of deep ocean concrete structures conducted by the U.S. Naval Civil Engineering Laboratory (NCEL) in California has provided answers to some important questions.
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High air temperature during concreting, sometimes aggravated by the effects of wind or low relative humidity or both, can impair the quality of the concrete.
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A cooling-water intake structure in Louisiana which provides cooling water for a coal-powered generating plant was built using the sinking caisson method.
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The Naval Regional Medical Center in Bremerton, Washington is an architectural tribute to the region's native Indian heritage.
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In post-tensioned work the concrete is cast in a way that allows the concrete to harden before the tendons are stressed. This can be done by using tendons that have been coated with grease and encased in plastic sheathing during manufacture.
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Where construction difficulties, problems, or accidents develop on a project, litigation may develop relative to liability for financial losses.
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Bonded tendons, installed in ducts or voids within the concrete, must be grouted for protection after tensioning. The grouting of tendons tensioned to 80,000 psi or more is a demanding job that requires special skills and materials.
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The post-tensioned concrete roof of the Ruth Fisher School near Tonopah, Arizona, is not finished with any roofing material. The concrete was simply left as cast. A conventional 4000-psi mix was used, but to keep cracks from forming and to keep cracks that do form watertight, the amount of...
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A good example of post-tensioned segmental construction is the Ely Viaduct in Wales. The highway design features a 2000-foot radius curve crossing the River Ely at an acute angle with a 538-foot-long twin-box girder. The 230-foot central span and 150-foot side spans were constructed by the balanced...
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Shrinkage-compensating cement concrete can complement the benefits of post-tensioning by reducing the normal amount of loss of prestress, reducing flexural cracking and improving durability.
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Construction of Southwestern Bell Telephone Company's 1150-car, 11-floor parking garage at their Texas headquarters complex presented an exciting challenge for the design development team and for the contractor.
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While inspection is not a cure-all, it goes a long way in eliminating jobsite problems and assuring quality construction. The owner can frequently save money when post-tensioning is properly used. However, these potential savings may disappear if the structure is inadequately constructed.
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Our company is renovating a blacktop warehouse floor. The new floor may be used for lift truck traffic. We would like to place about 3 inches of concrete over the existing blacktop but there is grease on some parts of the surface. Would the grease harm the concrete? Should we use welded wire fabric?
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A new slab on grade in a parking garage was found to have 12 percent entrained air, rather than the 6 percent that had been specified. We don't question the accuracy of the air test but we want to know how this air content will affect the strength, durabi
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A new source of Class C fly ash is available. Would we use the same amount as the Class F that we have been using?
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For a job in New Mexico we must site-cast some double-tees. The coarse aggregate in the area contains 61 percent free silica but the Underwriters Laboratories permits no more than 20 percent free silica for fire endurance. Is there any way to treat the ag
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We're intrigued with building an earth-sheltered home to save energy. But we've had enough troubles in the past with a slightly buckled basement wall and with basement dampness so that we wonder how to avoid these and possibly other problems. Can you give
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Some unusual job scheduling is going to require us to apply shotcrete in three layers applied several days apart. We know we'd better not cure the first two layers with curing compound since it would probably interfere with bond. Is covering with polyethy
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I have been asked to repair an area of about 10 feet by 10 feet in a 6-inch-thick floor on grade. This floor, in a building used by an oven manufacturer, had performed well for 15 years. Recently the company tested out a new experimental oven. I believe t
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Is there any general guide or rule of thumb about how much more strength you get from Type III than Type I cement at various ages?
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Our company sold a 10x20-foot sign for use in southern California. This is mounted on legs made of 12-inch-square steel tubes. Another company contracted to set the sign in place. With the legs in 2-foot-diameter holes 7 feet deep, they mixed some concret
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Regarding "Cutting a Mass Concrete Wall" (Problem Clinic, May issue, pages 428 and 429), what's a 400-Hertz winch? One that goes around 400 times a second, or one rented from the Hertz Corporation or neither of the above?
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Some block partition walls are to be left unplastered but painted.
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We have had bad experience repairing the second floor of an industrial warehouse.
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Nobody seems successful in getting financing for earth-sheltered houses in our area. Where can we get some persuasive information to take to lending institutions?
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Two operators did the chiseling to expose the aggregate on some areas of architectural concrete that we wanted to expose. It's pretty clear which operator worked on any particular area. How can we get uniform work when we need more than one operator?
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On Monday, Tuesday and Wednesday we built 4-inch indoor slabs using 3500-psi concrete of 3-inch slump mixed in a transit mixer. The temperature was 90 degrees F and it was humid, with no breeze. Finishing included use of a 3-bladed power float, followed b
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I am involved with the design of an earth-sheltered home. Some of the concrete walls are to contain strips of wood embedded in the surface for the purpose of attaching brick veneer. I am concerned that the wood may soak up water, expand and rupture the co
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We put in a sidewalk for the city in November. By the following summer it had scaled. The city ordered tests made of the air content and found it to be low. Then it accused us of using non-air-entrained concrete. The concrete was air-entrained and it was
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We are placing a floor today and the ready-mixed concrete trucks are arriving on the job faster than we can get the concrete discharged and placed. How long can we allow the concrete to remain in the truck before discharging it?
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We're generally sold on flowing concrete but we've had trouble in finishing flatwork. The mixes tend to be sticky. Finishers find that the concrete moves under their weight, it drags on the trowel, and the surface sometimes tears. Has anyone found what to
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I would appreciate any design and construction literature you have pertaining to concrete water storage facilities. I am particularly interested in specifications for watertightness and information on making joints watertight. Does concrete impart any tas
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Part of a 4 1/2-inch-thick concrete deck that is to be post-tensioned is not hardening, though it is 19 hours old. Only one truckload is involved, and the troublesome area is surrounded by good concrete. All the concrete contains a retarder. Can we do som
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We would like to find a material that sets and hardens rapidly that we can use for repairing concrete in city streets and bridges without disrupting traffic any longer than absolutely necessary. We would prefer that this not be an epoxy or other organic m
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I am designing heated slabs for a do-it-yourself car wash. These will be located in single-car compartments that will be open to the weather on one side. The 5-inch-thick slabs will contain plastic pipe to maintain heat in the slabs at all times during co
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Test cylinders for an upcoming job are supposed to be cured on site. ASTM C 31 (Section 7.3) says that after the cylinders are stripped they should be cured in saturated limewater. How much lime should I add to a 55-gallon drum of water to make a saturate
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If you are using pullout tests to determine stripping time-for-formwork, how do you know when to pull out the specimens?
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Someone told us that fiber balling that occurs in mixing steel fiber concrete is a thing of the past. How has the leopard changed its spots?
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We've had a recent inquiry about how to make nailable concrete. We recall that sawdust concrete was promoted for this purpose at one time. Is there anything new on the subject?
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I have a problem with concrete segregation that appears to be related to the coarse aggregate. When we use crushed stone from one source the concrete segregates in the chute of the mixer truck. When we use stone from another source we get no segregation.
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In South Florida we have a recurrent problem with moisture on top of the slabs in houses and warehouses. We have devised a simple test that consists of using paper towels to dry up the water on top of the slab, then chipping off some concrete to expose ma
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Because it resists corrosion, calcium aluminate cement has been suggested for use in floors in a food processing plant. Some of these floors are above grade. Isn't it true that calcium aluminate loses strength drastically as it gets older? If so, it doesn't seem to be a good choice for a suspended...
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I am seeking information on reinforced concrete construction for a thin-shell one-story house, complete section dome type. It will be curved around a court and have windows facing south for passive solar. The other sides are to be earth berm including som
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What do you think of elastomeric bridge pads, used to allow movement of prestressed concrete girders upon their supports? Do they really deform enough to allow the needed movement and do they last as long as machined steel bearing surfaces lubricated with
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The city is giving us trouble about an 8-inch-thick, cast-in-place reinforced concrete wall we want to build. They say we have to show them a fire rating for such a wall from an established agency, though they say they are ready to accept an 8-inch concre
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In new construction should we remove the rust from rebars to be sure we get good bond to the concrete?
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Stucco panels on one of our structures were treated with a silicone water repellent, flooded onto the surface by brush. Then an asbestos-containing coating was applied. After about 2 years the coating started peeling off in large pieces from about 6 squar
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When using high range water reducers in 3000-psi or 4000-psi concrete we ordinarily introduce the admixture at the plant instead of at the jobsite, though many experts advocate adding it at the site. Does anyone add high range water reducers at the plant
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Where can we get a good manual on concrete finishing?
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Can a concrete wall be made more resistant to intense heat by vacuum dewatering?
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We will be using some high strength concrete and it has been suggested that we make 4x8-inch test cylinders because the capacity of the testing machine is only 250,000 pounds.
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Some of your recent articles ("Can Your Floors Pass This Test?," June 1981, page 512; "The Floor Tolerance Conundrum,"
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Why don't compression test cylinders come with handles? They are awkward to carry, especially over rough terrain, and if you drop one you've lost your test data.
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Our firm is contemplating a job in Saudi Arabia where the cement would be shipped directly from the mill without storage before shipping. Is use of hot cement likely to cause cracking of the concrete in this hot, dry climate?
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Would it be efficient to use concrete coring drills to cut a 3 1/2x8-foot opening in mass concrete? The wall is 6 feet thick at this point, so sawing would not be possible.
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A project consisting of three tennis courts and supplementary aprons is scheduled for bidding. The job is now set up as a blacktop paving project but the engineer will accept an alternate proposal for a concrete court system provided he can be assured of
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Our ready mixed concrete company has received a request for concrete with a flexural strength of 670 psi. We have never had this kind of order before. Can you tell us what equivalent compressive strength such a concrete represents?
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Why do we occasionally run into concrete pavement buckling on hot summer days? So far as we know there is no trouble in our area with expansion from reactive aggregates.
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Specifications for a food factory floor call for 15,000 linear feet of sawed joints 1/8 inch wide and 1 1/2 inch deep and another 5000 linear feet of joints 3/16 inch wide and 1 inch deep. They also require a radius at the top of the saw cuts. How can thi
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Is there a standard way of measuring the depth of frost that still exists in the ground? We would like to know how soon we can start work again after the winter freeze.
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In our part of the country we don't have much trouble with rain.