I’ve been scouring the Internet looking at photos and videos of concrete rubble in Haiti. As you probably know, much of the concrete there was reduced to rubble in the earthquake (largely due to poor quality construction). But what is less apparent is a great deal of the concrete was pulverized. There is a tremendous amount of rubble available – pulverized and in chunks – so much that it is blocking roads and hindering reconstruction. Utilizing this abundant local resource would cut building costs, save transport, create jobs turning what is essentially a waste product into much needed housing.
Up until now, this rubble has primarily been used for rubble trench foundations, gabions and road construction. It has not been widely recommended for earthbags because sharp edges on the rubble could cut the bags. But after studying images on the Internet I’m convinced the rubble could be screened down to 1” or so (1” minus) and used as bag fill. This is experimental since I’m not Haiti, but I would like to explore this possibility with someone who’s building there. Please email me from our Contact Us page if you’re interested.
Suggested earthbag rubble method (subject to further tests):
– Search for piles near the building site that contain mostly pulverized rubble
– Separate large pieces of rubble and save for other uses (urbancrete, mortared rubble walls, paths)
– Screen remaining rubble down to about 1”
– Use screened rubble for lower courses (rubble bag foundations) until you’re above the level where moisture will cause problems. Be careful not to overtamp and tear the bags. Only light tamping is needed to settle the contents. And always double-bag foundation courses – one bag inside the other – for added strength.
– Use typical soil-filled bags for remainder of walls for increased stability or build a lightweight wall system above windowsill height
List of possible uses:
– Use medium and small sized pieces for rubble trenches
– Raise the site if necessary using rubble fill
– Build the floor on a base of rubble
– Use rubble bags for benches and stairs
– Add screened rubble to improve characteristics of heavy clay soils
Note: some groups in Haiti have had difficulty obtaining good fill soil for earthbags. Sometimes the soil on site is mostly rocks, and trucked in soil is ridiculously high. Filling lower courses with screened rubble can reduce the amount of soil needed.