Reinforcement concrete

Hayfield, P. C. S. and Warne, M. A., Titanium Based Mesh Anodes in the Cathodic Protection of Concrete Reinforcing Bars , presented at UK Corrosion, Brighton (1988)... 

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... 

The stability of the concrete mix can be considered in terms of its cohesion , which is a subjective term used to describe its ability to maintain a homogeneous appearance when subjected to applied stress. Lack of cohesion leads to segregation of the mix components into layers relevant to their densities. A further term associated with mix stability is that of bleeding , which is the movement of water to the surface of the fresh concrete. This phenomenon can occur either in isolation or as a manifestation of segregation. Bleeding in excess is normally considered to be undesirable because of the dangers of water runs at the shutter/concrete interface and cracking due to plastic settlements, and there is also the possibility of adverse effect on the concrete-reinforcement bond due to the collection of water beneath the steel. 

The formation of the passive layer at the concrete/reinforcement interface referred to earlier (Section 1.4) is due to the alkaline nature of the concrete. The alkalinity is due to calcium, sodium and potassium hydroxides which, over a period of time, react with atmospheric carbon dioxide to form carbonates. This reduction in alkalinity in reflected in a diminished protective capacity towards the steel reinforcement. 

Ferroconcrete. One of the names for concrete reinforced by steel in various forms, usually rods... 

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. 

ASTM Standard A 955-96, Standard Specification for Deformed and Plain Stainless Steel Bars for Concrete Reinforcement (Type 304, 304L, 316, 316L, 316 LN and duplex 2205)... 

Polybenzazole fibers have been prepared containing blended organic pigments that are heat, moisture, and light resistant with thermal decomposition temperatures exceeding 200°C. These materials are useful as fibers for high-strength rope, cement/concrete reinforcers, and bullet proof vests. 

Ferroconcrete, concrete reinforced with steel, is invented by Monier... 

It is of note that during the 1989 San Francisco earthquake, certain overhead road supports that were retroactively strengthened by cladding with a relatively thin layer of carbon fiber-reinforced concrete allowed them to survive while conventional concrete pillars failed [20]. Similarly, in Japan, which experiences several hundreds of earthquakes each year of widely ranging intensity, carbon fibers have been extensively adopted for concrete reinforcement. More carbon fiber is employed in the Japanese construction industry than anywhere else [21]. 

Fig. 6 Processes of environment-conscious material design of precast lightweiht concrete reinforced with continuous fiber reinforced plastic (FRP) reinforcement...

Various reinforcement methods based on the principal of concrete reinforcement were examined. After consideration of the requirements below, glass fiber was decided upon as the reinforcement material. 

Fibers commonly used for concrete reinforcement include polypropylene, steel and alkali-resistant glass. The fibers are often of short length (<30 mm) and are randomly mixed in concrete. 

This paper summarizes the results of an experimental program to evaluate the effectiveness of using recycled fibers from carpet waste for concrete reinforcement. It also discusses issues that need to be addressed for the application of such FRC in large scale construction projects. It then reports on a building construction project using carpet waste fiber reinforced concrete. The results suggest that using carpet industrial waste fibers in construction would not only improve the reliability and life of the concrete structure, it but also could reduce the landfill spaces needed to dispose the waste material. 

The carpet industrial waste generated each year and that accumulated in landfills represent an abundance of useful resources, as they can provide effective reinforcement for concrete. As to be discussed in the following sections, concrete reinforced with recycled fibers from hard carpet waste is indeed a suitable material for construction. It suggests that using carpet waste in construction could be a very cost-effective way to improve the durability and performance of the concrete structure, and to reduce the needs for landfill spaces. 

Cost is another concern associated with the use of recycled carpet waste fibers in concrete. Currently a vast amount of carpet waste is disposed of each year and therefore the cost of raw material for the recycled fibers is negligible. The disassemble process to convert the waste into fibers suitable for concrete reinforcement requires only simple, inexpensive shredding operation. Therefore the cost of the recycled fibers will remain very competitive with virgin fibers for FRC. 

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