EXPLORATIONS
Poured Earth Wall Sample
Process followed & learnings
Explorer : Joy Patel
Brief :
To concrete our design explorations for having a beautifully articulated arched opening in a Poured Earth Wall, this 1:3 scaled sample becomes the first successful step of our exploration process, guiding us forward along with useful learnings on parameters such as proportions of mix, importance of reinforcement, shrinkage of soil and curing process.
What we used for the sample?
EARTH : Soil from nearby farmlands or soil from any other available sources
CEMENT, SAND & AGGREGATE : Easily available from nearby construction sites.
PLANKS FOR SHUTTHERING : Permutations and combinations of waste from a timber yard
CASTING : Look out for bamboo supports or timber/steel or any sturdy members to support the shuttering
Casting of the wall and deshuttering process :
A pourable mix of proportions 1 : 10 : 8 : 8 (Cement : Earth : Sand : Aggregates (20-25mm) ) was used to cast the wall and after completion of the pouring process, it was allowed to settle and dry for 3-4 days before deshuttering. The deshuttering process is ideally to be done after 24 hours of completing the pouring provided the wall receives direct sunlight and if not, the process is to be delayed considering the amount of sunlight received.
It has to be ensured that the arch formwork remains intact for at least 10 days and curing is done for minimum of 15 days.
72 hours post deshuttering : A crack developed on the top of the arch which was noticed even before the deshuttering process
120 hours post deshuttering : As the sample started drying, the crack seemed to widened itself and was fixed with cement mortar
168 hours post casting : Gained strength and hardened, also the crack was managed properly
240 hours post casting : The formwork was removed with ease and the wall stood sturdy enough, though it developed few cracks at the bottom of the arch.
MERITS :
Proportions of the arched opening with respect to the dimension of the wall and proportions of the mix were accurate, though a slightly higher ratio of cement would have made a great difference. The process with subtle changes would result in desired results.
DEMERITS :
Lack of direct sunlight delayed the deshuttering and further processes and also the use of a vibrator was avoided as this being a sample module, which resulted in formation of airgaps which led to irregularly finished edges and development of cracks.
LEARNINGS :
Shrinkage property of the soil has to be taken into consideration, which in this case was also the reason why the crack developed. This could be avoided by using reinforcement bars and fibers could be use to strengthen the mix.
Casting the sample in a proper location which receives direct sunlight, followed by curing it for a minimum of 15 days and keeping the arch formwork intact for a minimum of 10 days