Reinforced concrete reinforcement

This chapter provides material properties and response criteria necessary to design facilities constructed of reinforced concrete, reinforced masonry, structural stcc and cold formed steel. Static and dynamic properties are covered for the materials used in these facilities. Allowable response criteria are covered for both... 

It is almost paradoxical that in the history of mankind composite materials were earlier used than their "homogeneous" rivals. The earliest "engineering materials" were bone, wood and clay. Wood is a composite of matrix lignin and a cellulosic reinforcement bone is a natural composite where fibres of hydroxyapatite reinforce the collagen matrix and the oldest building material was adobe clay as a matrix, reinforced by vegetable fibres. After the industrial revolution other composites were added reinforced rubber, reinforced concrete, reinforced asphalt, etc. 

Materials - parking garage repair completed with carbon fiber. Civil Engineering, 69(3), 24,1999. 237a. McConnell V, Composites make progress in reinforcing concrete. Reinforced Plastics, 40-46, Jul/ Aug 1999. 

Reinforced concrete Reinforced concrete frame Concrete moment frame... 

Adobe Confined masonry Finite elements Load-bearing masonry Masonry building reinforced concrete Reinforced masonry Seismic analysis Umeinforced masonry... 

Nesvijski, E.G., Nogin, S.I. Acoustic Emission Technics for Nondestructive Evaluation of Stress of Concrete and Reinforced Concrete Structures and Materials. Third Conference on Nondestructive Evaluation of Civil Structures and Materials, Boulder, CO, 1996. Nesvijski, E. G. Failure Forecast and the Acoustic Emission Silence Effect in Concrete. ASNT s Spring Conference, Houston, TX, 1997. 

The ultrasonic tomograph A1230 was developed to visualize in case of one side access the internal reinforced concrete structure at the depth of 1 m. This device uses 36-elements matrix array. 

The most challenging of these applications has been the location and characterisation of anomalies in thick concrete structures using seismic methods and the detection of reinforcing steel and pre-stressing cables in congested structures using radar. 

Measuring concrete eover aecurately where reinforcement is congested and spliced... 

A film image is of course 2-dimensional and the bars are thus projected onto the film without knowledge of their depth from the surface. If the angle of projection is not perpendicular to the film then there may be considerable distortion of the projected images, as is often the case with concrete - typical object (reinforcing) film distances may be 150 mm. The problem can be solved by stereo-imaging but this is ineffective and expensive. 

Radiographic image of 800 mm thick reinforced concrete wall with vertical and horizontal bars clearly visible, in this case some 150 mm from the concrete surface (film side). 

Si, A1,0 and H)). Steel reinforcing can be easily detected and studied in detail in concrete 1000 mm thick and more. For this purpose it is possible to use rapid medical x-ray film, requiring exposure times of 6 to 26 minutes for concrete tliicknesses of 600 and 900 mm respeetively. 

Based on the technology developed for using PVA fiber as a replacement for asbestos in cement products, Kuraray has been developing thick fibers for reinforcing concrete (42). Super-thick fibers with a thickness of 39 tex (350 den) (200 p.m in diameter) to 444 tex (4000 den) (660 p.m in diameter) are now available the 39 tex material is used for reinforcing various mortar-based cement products and the 444 tex material for reinforcing concrete in civil engineering works such as tuimels, roads, harbors, and bays. 

Concrete Products. Limestone aggregate is used competitively with other aggregate in the manufacture of molded, reinforced, and prestressed concrete products in the form of block, brick, pipe, panels, beams, etc. 

Sealers. Mica is used in all types of sealers for porous surfaces, such as waHboard masonry, and concrete blocks, to reduce penetration and improve holdout (see Sealants). It permits a thicker film to be appHed and at the same time reduces sagging. Cracking is reduced by the reinforcing action of the flakes, and gaps and holes in rough masonry are bridged by the mica flakes. 

USSR SU 1,742,254 (June 23, 1992), S. T. Babaev and co-workers (to Scientific Research Institute of Concrete and Reinforced Concrete). 

Fig. 4. Integrated vault technology for low level waste disposal where A represents waste containers that are placed in concrete overpacks and sealed with grout B, closed modules covered with a multiple-layer earthen cover, to direct water away from modules, and short rooted vegetation for erosion control and C, overpacks placed in reinforced concrete modules which are closed with a reinforced concrete roof Courtesy of Chem-Nuclear Systems, Inc.

In concrete, triethanolamine accelerates set time and increases early set strength (41—43). These ate often formulated as admixtures (44), for later addition to the concrete mixtures. Compared to calcium chloride, another common set accelerator, triethanolamine is less corrosive to steel-reinforcing materials, and gives a concrete that is more resistant to creep under stress (45). Triethanolamine can also neutralize any acid in the concrete and forms a salt with chlorides. Improvement of mechanical properties, whiteness, and more even distribution of iron impurities in the mixture of portland cements, can be effected by addition of 2% triethanolamine (46). Triethanolamine bottoms and alkanolamine soaps can also be used in these type appUcations. Waterproofing or sealing concrete can be accompUshed by using formulations containing triethanolamine (47,48). 

Corrosion Inhibitors. Steel-reinforcing wire and rods embedded in concrete containing quinoline or quinoline chromate are less susceptible to corrosion (72) (see Corrosion and corrosion control). Treating the surface of metals with 8-hydroxyquinoline [148-24-3] makes them resistant to tarnishing and corrosion (73). Ethylene glycol-type antifreeze may contain quinoline, 2-chloro-, 4-amino-, 8-nitro-, or 8-hydroxyquinoline to prevent corrosion (74). 

Constmction and dem olition (C D) debris is a potentiahy large source of recyclables. However, as of 1995, generation rates and ferrous scrap content were not weh estabUshed and estimates were highly variable. Eerrous materials in C D debris are typicahy reinforcing bars, wire mesh, and stmctural steel. Some of the scrap is sold for recycling once concrete is effectively removed and the scrap is sized to specification (17). 

Most metals, concrete, and other constmction materials are corroded by hydrobromic acid. Suitable materials of constmction include some fiber glass-reinforced plastics, some chemically resistant mbbers, PVC, Teflon, polypropylene, and ceramic-, mbber-, and glass-lined steel. Metals that are used include HasteUoy B, HasteUoy C, tantalum, and titanium. The HasteUoys can only be used at ambient temperatures. Liquid hydrogen bromide under pressure in glass at or above room temperature can attack the glass resulting in unexpected shattering. 

Type I (Normal). This is the general purpose Pordand cement used for all appHcations where special properties are not needed. Common appHcations include concretes for paving, building doors, roof decks, reinforced concrete buildings, pipes, tanks, bridges, and other precast concrete products. In 1989 Type I and Type II accounted for over 92% of the Pordand cement produced in U.S. plants. Exact data are not available that separate Type I and Type II Pordand cement, but it can be assumed that Type I production was much greater than Type II. 

ACI Committee 318, Building Code Requirementsfor Reinforced Concrete and Commentary, ACI 318-89/318R-89, American Concrete Institute, Detroit, Mich., 1989, 353 pp. 

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