Civil Engineering Reference
In-Depth Information
Chapter 4
BALES TO BUILD WITH
The nature of straw
contains an excess of nitrates (owing to the
use of too much fertiliser) and then it gets
wet, the combination of the two can create
great compost! This fact is utilised when
using straw for DIY urinals, as the added
natural nitrate helps it decompose. Too much
nitrate in straw from farming practices has
been a particular problem with thatch, which
obviously gets wet rather frequently in our
climate, but shouldn't be a worry with straw
walls as they will be designed so that they
don't get wet. The time to be aware of this
issue is during transportation and storage.
If we leave a bale of straw out in the field to
be rained on, it quickly becomes too heavy
to lift because of water saturation and is of
no use other than as mulch for trees. How-
ever, if we stack lots of bales carefully out in
a field, raise them off the ground and put a
good roof over the top, they will withstand
the weather and the outside edges simply
get wet and dry out again. Talk to any older
farmer and she or he will tell you that this
is how straw (and hay) was traditionally
stored - in the field for ease of access. The
bales would be raised off the ground first,
usually by using a sacrificial layer of bales
(i.e. those that would go to waste later) laid
on edge, and the rest would be stacked flat,
with a roof of thatch over the top. The sides
of the bales would be exposed to the rain
and wind, but getting wet was not a problem.
Straw does not 'wick' (suck) water into itself
like concrete does. It simply gets wet as
far as the force of the wind can drive the
rain into it. When the rain stops, the natural
movement of air or wind around the bales
dries them out. This cycle of wetting and
drying does not normally damage the bale.
Straw does not 'wick' (suck) water into itself
like concrete does. It simply gets wet as far as
the force of the wind can drive the rain into it.
When the rain stops, the natural movement of
air or wind around the bales dries them out.
Modern growing methods and the develop-
ment of hybrids for grain crops has definitely
changed some of the properties of straw,
making grain for food more commercially
viable but not necessarily improving the
durability or length of straw for building.
Organic farmers often grow older varieties
There have been problems in recent years
in some modern grain crops. If the straw
