Discussion in 'Building' started by self builder 123, 29 Sep 2008.
Whats the difference between a precast and a prestressed concrete lintel ?
Pre-cast is a generic term - basically its made in a mould and then lifted into place - as opposed to cast in-situ
Pre-stressing is where the reinforcement is pulled tight and the lintel has a slight chamber (or arch shape) and this will take more load than a 'normal' flat lintel
Many people mix up the two terms and actually just mean a concrete lintel
Precast is a concrete lintel formed with "normal" high yield or mild rebar that is placed and the concrete then cast.
Prestressed is a concrete lintel with smaller rebar comprising thin high yield steel tendons which are put into tension ie pulled apart as the concrete is cast. These are cut when the concrete has cured, which puts the concrete into compression as the wires try to shorten themselves. The reason for this is that concrete is strong in compression, weak in tension: it therefore reduces the tensile stresses in the concrete when a load is applied ie it's much stronger.
Oh the Woodster and I posted at much the same time...
That was one structures lesson you went to then, eh, Woodsie?!
there are also two types of builder....
.....pre-cash and pretty stressed!
LOL you can see who charges by the hour/word.
Actually that is basic C&G brickwork stuff ... who needs structural lessons, pah!
BTW, I don't think you would want pre-stressed lintels on your house - it messes up the coursing and there should not really be much need for them in terms of load
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