Chemical Fasteners, Chemset Injection System
Talking about the chemical fasteners way of fixing bolts into masonry
with epoxy the other day, got me thinking about
another method.
The Ramset "Chemset" injection
system.
I have used this a lot,
partly because these are specified, that is the
engineer gives no alternative, but quite
often I use it because it is so quick and
convenient.
- On a large job with many fixings to do chemical fasteners are a lot cheaper than mechanical fasteners. That is propriety types of expansion bolts. "Dyna Bolts" come to mind.
- What I do is buy a few lengths of threaded rod, all thread. These come in the popular bolt thicknesses from 6mm up to 25mm. The common ones for us are 12mm and 16mm.
- They come in lengths of 1M and 3M. Zinc plated is the usual finish, and Gal is also popular, with stainless steel also an option for harsher environments.
- At the same time I buy a few hundred nuts and washers.
- The rods are just cut to the length of bolt required on a metal cut off saw.
- The fact that the bolts are threaded for the full depth of the embedment give them greater holding power.
- This way of making your own bolts is very cheap. so that quite often if a job specifies 10mm bolts, we put in 12mm because we already have them on hand.
This "chemset" system of chemical fastner an excellent way of fixing bolts into walls, because unlike mixing up your own epoxy
mortar, it is a self contained system that uses
polyester resin, which takes on it's initial
set fairly quickly. Like 20 minutes in our climate.
This is the initial set, and it would allow us to hang something off a wall after that time, with the nuts finger tight. Of course we wait until the next day to tighten up the nuts with a spanner.
Here is a photo of my Ramset chemical fastener gun with an old
cartridge in it.
 |
| Chemical Fastners - The Ramset cartridge system. |
- The cartridge is divided into two
sections with different formulations of
compound and hardener.
- Because the chemical fastener material is mixed in the nozzle, the material left in the gun after a session, can be kept for another time. Just wipe the end clean and put the cap back on. Throw the nozzle away.
- Being polyester resin, it probably has a shelf live of maybe up to a year, longer in cool climates. When I was building sailboards out of the stuff we used to keep all the resins in a fridge.
- You can see that the gun is quite robust,
as the sandy type mixture comes out quite
stiff.
- You get a couple of nozzles (below the
gun) with each cartridge, and they have
a spiral piece of plastic inside them that
mixes the two compounds together.
- Once used, the nozzle is thrown away,
because the mixture sets quite quickly.
- As spare nozzles are not free, $1.80 each
last time I bought any, you have to be
organized to get full use out each nozzle.
- Drill your holes first, typically I would
drill a 14mm hole for 12mm bolts. This lets
the excess material get out of the hole.
Clean them out by blowing the dust out
of them with a section of tube.
- Get all your bolts ready. A
typical job might be bolting a steel or
timber roof member to a wall with M12 bolts.
Put a nut and washer on one end of the
bolt, that way, when you tap the bolts into
the mixture, even if you damage the thread,
the nut is already on there ready to tighten
up later.
- When you have everything ready, put on
your safety glasses. This is MOST
important as when you are tapping the bolt
into the mixture if a bit shoots out and gets
into your eye, you could be in trouble.
The hardener for polyester resin is
just about the worst thing to get into your
eyes.
- When I have had quite a few bolts to set
at one time I get someone else to use the gun
and feed the mixture into the holes while I
follow up putting the in the bolts.
Here's a slight digression to make my last
point on chemical fasteners. A few years ago I had
a job that had some of the roof trusses bolted
to gable walls with M12 chemset bolts. I
gave the gun and a box of cartridges to a young
sub-contract carpenter with the question,
"you know the trick with these things Michael,
don't you"?
The young descendant of the proud people who
built the Parthenon replied
"of course,of course"
thinking me some sort of idiot.
A few days later the structural engineer did an
inspection prior to the roof sheeting being
fixed. On his way up the ladder, in
passing, he idly tugged at one of the bolts
that young Michael had fixed.
It came out of the wall in his hand!
What happens with this type of cartridge
is that when you first start off, only the
thinner compound comes of of the nozzle for
the first few seconds, and you should run it
to waste, until you see the two slightly
different colours mix.
Of course young Michael who was at just
that age where he knew it all, put his first
bolt of every session into the walls without
the benefit of hardener and I was indeed an idiot for thinking that he knew what he was doing.
- So think about this when you use this
product or similar chemical fasteners. Don't
let it stop you from using them though, as it
is a cheap and fast way to get a lot of
fixings into masonry wall.
- I believe that there are smaller
cartridges of the same stuff that fit into
standard size small caulking guns. A
mate of mine used them once and finished up
borrowing the gun shown because it was so
much easier.
Back to top
