Pre-stressed concrete

The use of pre-stressed concrete in rigid pavements is not very common. Flowever, the main advantage of pre-stressed concrete is the reduction of the thickness of the concrete slab. The typical thickness of a pre-stressed concrete slab ranges from 100 to 150 mm. 

Thickness reduction results in saving concrete material and the ability to construct a pavement where height clearance restriction is a problem (tunnels, under bridges, etc.) in conjunction with the inability to dig deeply to accommodate the thickness of a typical concrete slab. 

However, these advantages are not sufficient to establish the pre-stressed concrete as an alternative in pavement construction. Problems are also encountered during construction (anchoring, use of special equipment, construction of special type of joints, etc.) the rate of daily output is lower and the construction cost is higher than that of a typical rigid pavement. 

Because of all the above, pre-stressed concrete pavements are rarely used and are only used in very specific locations. 

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Cherry, B., Cathodic Protection of Buried Pre-Stressed Concrete Pipes . In Cathodic Protection Theory and Practice, 2nd International Conference, Stratford upon Avon, June... 

Pre-stressed concrete outer container with steel liner... 

Long filaments Reinforced columns and panels Pre-stressed concrete... 

Phillips Master trainer, 150, 230 Piccadilly tube tunnel, 232, 234 Pickwick Quarry, 45, 207 Admiralty lease of, 151 Pickwick Road, Corsham, 196 Piaor, Alan, 16, 17, 18, 154 Pillboxes, 121-123 Pioneer Corps, 121,131 PlesseyLtd, 148 Pockeredge House, 68 Poison canon, 206 Portal, Lord, 173 Post-war rearmament, 135 Power-egg, 171-172 Power-jets Ltd, 225 Pre-stressed concrete, 86 Priory Street, Corsham, 196 Property Services Agency (PSA), 141,144... 

Fig. 6.37 Pre stressed concrete railway sleeper with cracks caused by the delayed ettringite formation...

According to the recommendation of American Concrete Institute the content of chlorine in cement should be as follows 0.06% for the pre-stressed concrete, 0.10 % for the reinforced concrete stracture in humid environment, exposed to the external attack of chlorides, 0.15% for the concrete in the same conditions but without chlorides access. There are no restrictions for the dry reinforced concrete without contact with the ground. 

The two groups of expansive cements can be distinguish, based on the tensile stress produced to 2 MPa and to 4, or even 6 MPa. They are used in the self-pre-stressed concrete manufacturing. There is an opinion that the tensile stress should... 

Other undergraduate courses in structural engineering may include design of timber structures, masonry structures, advanced structural analysis, and pre-stressed concrete structure design. 

Zhao Qilin, Zhou Wangjin and Jiang Kebing. Analysis and repair of soleplate cracks of pre-stressed concrete box girder during construction. Journal of Highway and Transportation Research and Devel-... 

Fibre reinforced polymers (FRPs) are composed of a reinforcement material (glass, aramid or carbon fibres) surrounded and retained by a (thermoplastic or thermosetting) polymer matrix (unsaturated polyester, epoxy, vinyl ester, or polyurethane). FRPs were first used in the rehahiUtation of reinforced or pre-stressed concrete, but they have also been widely used in the reinforcement of timber structures. 

It must be mentioned that in a small number of projects, pre-stressed reinforcement has been used. The use of pre-stressed concrete has some advantages, but the construction cost tends to be higher and it requires specialised staff and construction equipment. The advantages of using pre-stressed concrete slabs are as follows (a) reduction of slab thickness (usually 10 to 15 cm slab is required), (b) ability to apply greater loads and (c) substantial reduction of total number of transverse joints, when compared to URCP. 

The AASHTO provides only some general guidelines on the design of pre-stressed concrete pavements. Details can be found in the manual (AASHTO 1993). 

Chemical Corp. produce Leadline, made from Dialead pitch based carbon fibers, which has been used for rods and tendons for pre-stressing concrete. 

The reactor has a pre-stressed concrete pressure vessel and several attractive safety features as well as other features to facilitate easier and quicker maintenance ... 

The arrangement of the reactor core, boilers and gas circulators entirely within the pre-stressed concrete vessel ensures a high integrity boundary for the primary coolant flow. 

The 1-565 highway bridge located in Huntsville, Alabama uses 23.17 m long pre-stressed concrete girders. Shortly after construction, large and unexpected cracks were observed close to the girder supports. This bridge was therefore selected by the Alabama Department of Transportation for evaluation of repair techniques. A 6.4 m area was selected to carry out repair... 

Takacs, P. E and Kanstad, T. (2000), Strengthening pre-stressed concrete beams with carbon fiber reinforced polymer plates , NTNU Report R-9-00, Trondheim, Norway. 

The structure involved is a pre-stressed concrete bridge built 30 years ago in the north of Portugal. The bridge deck has a total length of 250 m with... 

Balagaru, P., Nanni, A. and Giancaspro, J. FRP Composites for Reinforced and Pre-stressed Concrete Structures. London Taylor Francis, 2009. 

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