Post by jeff on Jan 29, 2016 18:05:49 GMT
JL_Frusha
Jul '15
Just came across FRTP and it seems to combine the best features of steel and composite rebar.
Like steel, it can be shaped, with minimal internal stress built into the design and reshaped (thermoformed) to accommodate construction techniques. UNLIKE steel, but like other composites, it can be used in conjunction with simple zip-ties. or even adhesives/solvent-cements, and has composite spring tendencies to return to shape, if deformed away from its' thermally set shape.
As with most plastice, it does lose some strength, in the reheating/reshaping process, but as with most composites, the tensile strength still seems to exceed steel.
The following pdf shows a technique for reshaping, such as forming hooks and eyes in the end of FRTP rebar, meaning bars can be connected end-to-end, in a shear connection, either directly together, or with another piece acting as the shear-pin.
www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=4&cad=rja&uact=8&ved=0CDEQFjADahUKEwj-uYj79NjGAhVWNogKHT1ABig&url=http%3A%2F%2Fwww.iifc-hq.org%2Fproceedings%2FAPFIS_2007%2FPapers%2FV2-D2-APFIS-150-camera%2520ready.pdf&ei=KBukVf6FDNbsoAS9gJnAAg&usg=AFQjCNEOiekXairzm1_G4Au9v7nmM3yXxA&sig2=T4XaZNBUJP7EHrnR8KgD-g
JL_Frusha
Jul '15
I've just shown that the switch is cost effective. In comparing a ferrocement hull to typical wood and fiberglass construction, the weight savings began at 25 ft long hulls and up. Basalt FRTP runs 0.28kilo vs 1kilo for the same size steel rebar, but costs twice as much, length for length. By saving that 72% weight, you can have a significantly lighter hull, with significant savings possible in time, possibly matching the cost, on otherwise identical hulls.
A typical ferrocement hull has an expected service life of 25-50 years, mostly due to spalling and corrosion of the steel rebar and the wire-ties that hold it together, during construction. I've also eliminated those wire ties, eliminating failure points. Until learning of the Basalt FRTP, the main advantage of steel was the ability to shape it, without the added stress of FRP rebar acting as a spring. I've eliminated that advantage.
Now it's down to cost, but at the same time, since the FRTP has better tensile strength, and is corrosion proof, the hull can be redesigned for more weight savings, since the majority of the cement is to slow the rate of corrosion, so, now we have further materials cost reduction for a lighter hull of the same strength and more service-life.
FRTP just put reinforced cement hulls back into the realm of highly practical, and possibly cheaper than fiberglass, requiring lower necessary skill at constructing.
Line it up, glue and clamp. use an IR heat source to de-stress, before adding mesh, plaster and let it set up.
In the end, you have a sturdier, lighter, more durable hull. Given the exact same specs, you need less flotation foam, meaning you also have an increased capacity. Maybe it saves 30% of that foam, but that's a significant amount of space, in a 25 ft hull.