Stone Arch Bridge

Here is my first attempt at making a stone arched bridge out of lightweight Thermalite or Celcon building blocks.

First, mark out your arch. I used a 10 inch plant pot as a template.


Next drill through as far as possible with a decent sized masonary drill - no need to use the hammer function, it would probably shatter the block into many pieces. If your drill is shorter than the block is deep you will have to mark the arch on the other side and drill again.


Using a padsaw cut through between the drilled holes.


And voila (that's yer actual French!!) - an arch.


Using the padsaw smooth out the crenelations (is that the right word) between the remains of the holes.


I marked the stonework freeform with chalk.


Using a straight edge and the padsaw the horizontal lines were easy to scribe.


The vertical lines were a little more fiddly but I used a set square and a small, old electrical screwdriver.


Because the bridge will only be seen from one side the reverse was left blank. I was able to get to this stage in just over an hour

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Nice job Ade....

It looks very effective indeed. If I knew where I could get some, I would have a go myself. Not sure how it would stand up to our weather though.

Mick

Very impressive.

trammayo


It looks very effective indeed. If I knew where I could get some, I would have a go myself. Not sure how it would stand up to our weather though.

Mick

I've seen them in Wickes if there's one near you Mick (I think they've got outlets in Ireland) but I got mine from a local builders merchant .

I reckon Celcons are so soft you could cut em with a saw without drilling.

Oh, and in the UK building regs require that they are only  used above DPC level, put in the ground unprotected they can split when soaked up water freezes.

the eels


Oh, and in the UK building regs require that they are only  used above DPC level, put in the ground unprotected they can split when soaked up water freezes.

Thanks for that info. I'll lay a DPC (thick polythene) before fixing their position.

Top job matey.

looks really effective

Great work - looks fantastic and so realistic. Did you colour it or that the natural grey?
Exactly the method I used to make my viaduct.  You could possibly cut without drilling, but sharp curves like this are difficult.
Keep spreading the word about this stuff. I reckon it's the greatest GR material ever.
 
As for all the comments about using outside - I hope you update us after your first freeze. I don't have that problem here in Sydney.
 
Don't forget it's good for buildings, retaining walls and platforms too. Here's one I prepared earlier....

 
 

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gregh


Great work - looks fantastic and so realistic. Did you colour it or that the natural grey?
Exactly the method I used to make my viaduct.  You could possibly cut without drilling, but sharp curves like this are difficult.
Keep spreading the word about this stuff. I reckon it's the greatest GR material ever.

Greg, the blocks come that grey colour . I was wondering how to change it. I read on your site that you use concrete colouring powder. I'll have to look out for some.

To anybody else reading this, look at Gregs website for lots and lots (and I mean LOTS) if inspiration.

That looks the business Ade, well done, and those blocks weather down nicely as well

Greg's www site has some top notch topics on it

Nice job.
 
We have 3 viaducts on the Ruschbahn, all made from Celcons (or whatever your type of Soft Building Block is called). All have been outside for around 4 years now with no damage due to frost. Secret is to paint them with PVA 50/50 mix with water and a drop of washing up liquid. Next for cutting, I used a Jigsaw, blades do not last forever but it is SO much quicker than drilling loads of holes that need to be tidied up. You can shape the stuff with a Surform or indeed use WOOD files as well.
 
As always do not use you best tools if going into this type of tool abuse. Oh can I be arrested for that?
 
Re the question of Colour, Wicks sell Cement Colouring Powders. Your local friendly Building Supply Merchant (not the likes of B+Q or Homebase) will also probably sell cement colour powders. Also do not forget Sulphate of Iron used for feeding azelias (Garden Centre of most DIY Garden sections), this stuff has a warning that it will discolour paths if you use it near them. Just sprinkle the stuff on and water (with a misting spray). Turns Green then Rusty Brown. The more you use, the darker the Brown. Suggest that you experiment with it to get the feel, possibly on the underside of an old paving flag. I use it to add a bit of colour my Concrete Mountains, also works well on LGB Track.
JonD

Brilliant - love it.
As for water - I use Thompsons brick waterproofer - had no trouble with frost in 3 years.

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adeshers

trammayo


It looks very effective indeed. If I knew where I could get some, I would have a go myself. Not sure how it would stand up to our weather though.

Mick

I've seen them in Wickes if there's one near you Mick (I think they've got outlets in Ireland) but I got mine from a local builders merchant .

Hi Ade, here in Mayo (apart from Builder's Merchants not selling blocks - you buy direct) everything is concrete - a 4" (nominal 18 x 9) weighs in at 20kg! The weather here means we only get 4 years out of Dulux Masonry paint and its played havoc with rendering. I mixed some plastiiciser with the render (or plaster as they call it here) and this has the effect of aerating the mortar in a similar way to the Celcon blocks. This has suffered badly in the - 14 degrees this winter. Good job its only a garden wall.! Thats why I was wondering about the effects of the weather. I have seen the other threads and sites and I really like what has been done and would like to have a go.

Mick

the eels

Oh, and in the UK building regs require that they are only  used above DPC level, put in the ground unprotected they can split when soaked up water freezes.

Just for the fun of it I soaked a couple of pieces of Hebel (=Thermalite?) in water for 3 hours then put them in the freezer overnight.  No effect.

We're not using them for load bearing buildings, so I doubt there is a problem.
But Hebel does crack - it's not the strongest stuff in the world - that's why we can carve it etc.
Here's a crack in my big viaduct. Appeared after the 2nd summer and has been there for 8 years now and it hasn't collapsed.  I suspect cause was poor foundations - after all real masonary viaduct have to be in compression at all times or they fall down.

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adeshers

Greg, the blocks come that grey colour . I was wondering how to change it. I read on your site that you use concrete colouring powder. I'll have to look out for some.

Funny - our Hebel is white, weathers to light grey  and sometimes has a pinkish tinge when wet.

My bridge used four bricks and cost under a tenner in total, its been out for a couple of winters now and seem OK,
 

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