Abstract:
Rammed Earth (RE) is an ancient house construction technique which stood the test of
time in various parts of the world. As the name indicates, it is literally built by compacting
natural earth, soil and gravel between wooden plank shutter formwork forming the RE wall.
The earth was traditionally compacted with hand tampers in succeeding layers of
approximately 100 mm to 150 mm to refusal density in widths of 300 mm to 500 mm and
even thicker walls. The parallel with road layer construction is obvious in the layer lifts of
compaction and the compactive effort done at optimum moisture content (OMC). The only
difference is this construction is done in successive layers compacted vertically between
the boxed in shutter works. The vertical progression of such compacted layers forms the
Rammed Earth (RE) wall when the formwork shutters are removed. This layered
compacted earth wall forms a sturdy aesthetically pleasing ‘earthy’ wall structure. The wall
is basically compacted to “refusal density”, thus being very solid and durable. The RE wall
is a solid thick walled structure capable of significant load bearing and suitable for house
wall construction. It has very good temperature and humidity control in the house due to
the generally thicker walls than normally found in brick wall houses. In South Africa there is
not a national guideline or SANS code for such house type construction. It is presented for
acceptance as an engineered or engineered design per SANS definition. Australia
upgraded their RE specifications and guidelines to include cement stabilisation of the
rammed earth, thus resulting in an Engineered Rammed Earth (ERE) solution with obvious
improvement in strength and durability. House building technology with a green footprint
are promoted on Boschhoek Mountain Estate inclusive or mini wetland systems for
sewerage, and mostly solar electricity, etc. Previously (2015), such an ERE house was
designed and constructed to pleasing aesthetical standards and strength at half the cost of
conventional brick-built houses. The latest roads stabilisation technology with Nano-silane
in Nano Modified Emulsion (NME) and Nano Polymer Nano Silane (NPNS) offered an
opportunity to replace the cement stabilisation. Various advantages with the Nano Silane
were realised, inclusive of the desired water resistance, strength and encapsulation of clay
particles or any deleterious minerals that would normally lead to the cracking of a road or
such a cement-stabilised ERE wall panel. The technology transfer from roads to the house
construction field is described and the end result or end use is clearly demonstrated
meeting the end use specifications advocated in the new TRH 24 (2023) for gravel road
upgrade to surfaced standards.
