This video is by David Easton, the well known owner of Rammed Earth Works in California and author of The Rammed Earth House, the best selling book on the subject.
Here’s Wiki’s description: “Soil cement is a construction material, a mix of pulverized natural soil with small amount of Portland cement and water, usually processed in a [mixer…]. Hard, semi-rigid, durable material is formed by hydration of the cement particles.”
Soil cement is another great way to make affordable floors, patios and extremely strong fill material for earthbags. [Note for new readers: most earthbags are not stabilized, but there are certain applications where soil stabilization is a good idea.] Google “soil cement” to learn more about this subject.
Even though the video is about making pavers, I was more interested in David Easton’s soil cement recipe. This is why I love the Internet. Thank you David.
3 parts soil
2 parts sand
4 parts pea gravel
½ sack of cement
1 part water
Soil (earth) may be poured (molded) with/without a binder (cement) depending on end use. But, what is soil cement? Are they referring to a paver using soil + cement? I think so, because it’s a common mistake to call concrete cement.
The recipe made no sense. I assume “a half sack” refers to the standard 94 lb sack. What’s a “part”?
Here is some information about formulas: Make it by mixing earth with Portland cement to the desired depth, add water and mix again. Tamp, and cover with plastic to let it cure properly. Use 6 to 16 percent cement by volume according to the density of the soil. The denser the soil (clay, for instance), the higher percentage of cement to use. Six percent translates to 1 part cement to 15 parts soil; 16 percent translates to 1 part cement to 6 parts soil.
Hi there
Are soil cement floors suitable for use in bathrooms? What kind of sealer do they require?
Many thanks
Yes, soil cement can work. Practice on sample blocks to make sure your mix is suitable. Experiment because soil varies from place to place. You want good sandy soil. Check local suppliers and see what type of concrete sealers are available and choose the least toxic option. Or search online for all natural products such as Bioshield. These are usually much more expensive.
New question, I’m needing to fill the cracks between the sandsone irregular stones at the back of an 1880 fireplace i’m wanting to put an iron stove in. I’ve the 330mm tubes to inject the mix through with a silicone gun but was wondering if there is any particular mix I should try that would be fluid enough to go through the nozzle without running and also be resistant, to a degree, no pun intended, to heat. Cheers, James.
Hi Owen
I’m planning building a retention wall to replace a concrete one that is collapsing.
I was thinking on using this recipe in an hyperadobe style.
Should I install a poly on the earth side to protect from water?
could I recycle some of the debris of the existing wall as aggregate in this mixture?
thanks
Max
This is covered in my Earthbag Building Guide. Build multiple small walls instead of one big one. Allow for water to drain through weeper pipes. Lean the wall slightly toward the slope. Use gravel bags (gravel or rubble).
At the end of the video, David Easton mentions a video that will show how to lay the pavers. Has that video been posted yet?
Owen: Not yet. Keep checking David’s RammedEarthworks YouTube channel: http://www.youtube.com/user/rammedearthworks
If you poured an indoor floor with this mix instead of making pavers, how practical would that be? Would it need to be two inches thick? Thicker?
Owen: Yes, this is a good option. Make it about 3″ thick. Mix it thicker like concrete. It will crack if there’s too much water.
Would you have a gravel then sand then vapor barrier then gravel then sand underneath the poured floor?
Owen: I would use gravel, then sand, then vapor barrier. Insulate underneath in cold climates.
But pavers would require a poured or rammed floor of some sort beneath them, right? So doesn’t that more or less double the work and materials required?
A related question – has anyone looked into the possibility of using recycled crushed glass as an aggregate in soil cement?
Pavers are typically set in a bed of sand. Read the previous blog post about making CEB pavers: http://earthbagbuilding.wordpress.com/2011/04/24/cheap-and-easy-brick-floors/
Aahh ok – this is something to consider then. Any ideas about the crushed glass thing? I know there are issues with the alkalinity of glass reacting with and weakening cement, but I wonder if the reaction would be less in a soil-cement mixture. Also most of the studies regarding that reaction refer to cement used in “structural” applications, which I’m not sure a floor is since it’s completely supported underneath…? Just seems like such an obvious sustainable possibility, and it could be really pretty too, if it was feasible.
I don’t think adding glass to a floor will cause any problems as long as it’s been tumbled to eliminate sharp edges.
So you could do a floor with this stuff? Sort of a concrete-earth hybrid?
Sorry – to clarify – you could use the same mix to do the floor itself rather than pavers?
Yes. Pavers give you one more option. Pavers can be made one at a time in your spare time.
Yes. The most common use of soil cement is for floors.
how many parts is the 1/2 sack of cement?
Watch the video. You’ll see they’re using 5 gallon buckets for the other parts. So all you have to do is dump half a bag of cement into a 5 gallon bucket to determine the final ratio.