I'm about to put some foundations down for a dwarf garden wall; the
trench will be 9m long, 300mm wide and 200mm deep, with 100mm of
hardcore and 75mm of 1:5 concrete - so that's approx 0.2m3 of concrete
and 0.3m3 of hardcore.

According to www.lifewater.ca/Appendix_J.htm#quantity I estimate the
total volume of dry material by multiplying the volume of concrete by
1.65 (why?) - so that's 0.33m3, of which 5/6 is ballast and 1/6 is
cement: 84kg of cement (0.056m3 at 1515kg/m3) and 0.28m3 (or 500kg of
ballast at 1760kg/m3). Are these academic densities roughly right in the
real world?

That's an awful lot of 25kg bags, or an awful lot of waste if I get a 1T
bag of scalpings and a 1T bag of ballast.

What does the hardcore actually do? Is there any reason not to use
ballast as the hardcore, or to dispense with the hardcore and do the
whole thing as concrete? This would mean I could do it with 1T of ballast.

Dave

On Jul 10, 11:05 am, NoSpam wrote:
I'm about to put some foundations down for a dwarf garden wall; the
trench will be 9m long, 300mm wide and 200mm deep, with 100mm of
hardcore and 75mm of 1:5 concrete - so that's approx 0.2m3 of concrete
and 0.3m3 of hardcore.


For I guess a half brick wide wall of only a few rows, if the groun
dis firm then I'd just use concrete. The foundations of a brick wide
wall I dug up from my yard were only 100mm thick.

adder1969 wrote:
On Jul 10, 11:05 am, NoSpam wrote:
I'm about to put some foundations down for a dwarf garden wall; the
trench will be 9m long, 300mm wide and 200mm deep, with 100mm of
hardcore and 75mm of 1:5 concrete - so that's approx 0.2m3 of concrete
and 0.3m3 of hardcore.


For I guess a half brick wide wall of only a few rows, if the groun
dis firm then I'd just use concrete. The foundations of a brick wide
wall I dug up from my yard were only 100mm thick.


If you use enough ties on the wall, you don't really need ANY
foundations hardly.

A quick solution is a course of concrete blocks laid flat in a rough
mortar mix.

On 10 Jul, 11:05, NoSpam wrote:
I'm about to put some foundations down for a dwarf garden wall; the
trench will be 9m long, 300mm wide and 200mm deep, with 100mm of
hardcore and 75mm of 1:5 concrete - so that's approx 0.2m3 of concrete
and 0.3m3 of hardcore.

According towww.lifewater.ca/Appendix_J.htm#quantityI estimate the
total volume of dry material by multiplying the volume of concrete by
1.65 (why?) - so that's 0.33m3, of which 5/6 is ballast and 1/6 is
cement: 84kg of cement (0.056m3 at 1515kg/m3) and 0.28m3 (or 500kg of
ballast at 1760kg/m3). Are these academic densities roughly right in the
real world?

That's an awful lot of 25kg bags, or an awful lot of waste if I get a 1T
bag of scalpings and a 1T bag of ballast.

What does the hardcore actually do? Is there any reason not to use
ballast as the hardcore, or to dispense with the hardcore and do the
whole thing as concrete? This would mean I could do it with 1T of ballast.

Dave

The trench should go down to something approching solid ground. How
neer you approch solid ground depends on what the wall is for. I
normally dig off the vegtable matter, but I am lucky as I hit rock
qucikly where I live.

The hardcore fills up the trench a bit, so as you need less concrete,
broken bricks, old stones, rocks etc all work fine.
Balast as hardcore, I would imagine over time the sand would wash out.

Rick

On Jul 15, 7:44 pm, Rick wrote:
On 10 Jul, 11:05, NoSpam wrote:



I'm about to put some foundations down for a dwarf garden wall; the
trench will be 9m long, 300mm wide and 200mm deep, with 100mm of
hardcore and 75mm of 1:5 concrete - so that's approx 0.2m3 of concrete
and 0.3m3 of hardcore.

According towww.lifewater.ca/Appendix_J.htm#quantityIestimate the
total volume of dry material by multiplying the volume of concrete by
1.65 (why?) - so that's 0.33m3, of which 5/6 is ballast and 1/6 is
cement: 84kg of cement (0.056m3 at 1515kg/m3) and 0.28m3 (or 500kg of
ballast at 1760kg/m3). Are these academic densities roughly right in the
real world?

That's an awful lot of 25kg bags, or an awful lot of waste if I get a 1T
bag of scalpings and a 1T bag of ballast.

What does the hardcore actually do? Is there any reason not to use
ballast as the hardcore, or to dispense with the hardcore and do the
whole thing as concrete? This would mean I could do it with 1T of ballast.

Dave

The trench should go down to something approching solid ground. How
neer you approch solid ground depends on what the wall is for. I
normally dig off the vegtable matter, but I am lucky as I hit rock
qucikly where I live.

The hardcore fills up the trench a bit, so as you need less concrete,
broken bricks, old stones, rocks etc all work fine.
Balast as hardcore, I would imagine over time the sand would wash out.

To where?

I can't remember ever seeing hardcore on a foundation. It just went
into the slab to make the bulk up so only 4" of concrete was needed
for the floor (beneath screed.)

Weatherlawyer wrote:
On Jul 15, 7:44 pm, Rick wrote:
On 10 Jul, 11:05, NoSpam wrote:



I'm about to put some foundations down for a dwarf garden wall; the
trench will be 9m long, 300mm wide and 200mm deep, with 100mm of
hardcore and 75mm of 1:5 concrete - so that's approx 0.2m3 of concrete
and 0.3m3 of hardcore.
According towww.lifewater.ca/Appendix_J.htm#quantityIestimate the
total volume of dry material by multiplying the volume of concrete by
1.65 (why?) - so that's 0.33m3, of which 5/6 is ballast and 1/6 is
cement: 84kg of cement (0.056m3 at 1515kg/m3) and 0.28m3 (or 500kg of
ballast at 1760kg/m3). Are these academic densities roughly right in the
real world?
That's an awful lot of 25kg bags, or an awful lot of waste if I get a 1T
bag of scalpings and a 1T bag of ballast.
What does the hardcore actually do? Is there any reason not to use
ballast as the hardcore, or to dispense with the hardcore and do the
whole thing as concrete? This would mean I could do it with 1T of ballast.
Dave
The trench should go down to something approching solid ground. How
neer you approch solid ground depends on what the wall is for. I
normally dig off the vegtable matter, but I am lucky as I hit rock
qucikly where I live.

The hardcore fills up the trench a bit, so as you need less concrete,
broken bricks, old stones, rocks etc all work fine.
Balast as hardcore, I would imagine over time the sand would wash out.

To where?

I can't remember ever seeing hardcore on a foundation. It just went
into the slab to make the bulk up so only 4" of concrete was needed
for the floor (beneath screed.)


For once I agree with you.

Hardcore is used WITH concrete and cement, purely as a way of bulking it
out.

The purpose of a foundatin is to spread the load of what is on top,
across a wide area. That can be done with DEEP hardcore, as a road bed
does, but not with a few inches.