Stabilization of Soil Block Masonry with Pumice
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Date
2018
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Addis Ababa University
Abstract
The old traditional earth block methods of construction are currently reconsidered as a very
environmentally friendly alternative to modern buildings due to the advantages they provide,
such as the complete recycling of materials, low energy consumption during the manufacturing
process and service life, as well as the comfort and health aspects of people living in them. Soil
is widely used in the traditional construction of mud houses called “Chika bet’’. Soil as a
building material is available in most areas of the country.
The weak sides of earth block masonry such as low bearing capacity and low resistance to
moisture have been overcome by stabilizing it with pumicite/volcanic ash. The compressive
strength of the mud blocks increased by the pumicite.
This thesis studies the effect of the proportion between the soil and the stabilizers (such as
pumicite and straw fiber) on stabilized earth blocks strength. It also compares mechanical
properties (compressive strength and absorption) of stabilized earth blocks which are prepared
using only local soils (which is taken from Adama, Boku area) and with the addition of
stabilizers (pumicite and straw fiber).
This research provides detailed technical information on suitable soil types for stabilized earth
house construction, stabilizers and production of stabilized earth blocks. Related literatures
review show that soil types, proportions between soil and amount of stabilizer and compaction
pressure applied to the moist soil mix affects the quality of the stabilized earth block. In this
study pumicite/volcanic ash is used as a stabilizing agent. It is highly porous volcanic rock and
highly deposited in Bulbula, Ziway area. Soil from Adama was the target for testing and
investigation.Laboratory tests were conducted on Boku area soil and provided detailed
information on the soil grading and other engineering properties of the natural soil. The result
was compared with standard values to verify suitability of the soil for soil stabilized earth block
production. It is possible to determine the suitability of other area soils by applying the same
technique.
Using soil from Boku area of Adama and stabilizers (pumicite and straw fiber), ten different
types of samples were prepared. Tests were conducted on these samples in order to evaluate their
performance such as compressive strength and total water absorption capacity on which the
durability of the blocks depends. The effect of the pumicite and the straw fiber content in stabilized mixture was evaluated and
comparisons were made for all block samples.
The investigation has revealed that, out of all block samples, blocks which are produced from
10% pumicite (10P), 10% pumicite with 3% straw fiber (10P3S), 10% pumicite with 6% straw
fiber (10P6S) and 10% pumicite with 9% straw fiber (10P9S) have total water absorption values
that fulfills the recommended value.
This research could help in providing possible solution for adequate shelter problem in Adama
and in Ethiopia in general and to overcome some defects of mud blocks.
Description
Keywords
Soil Block Masonry, Pumice, Stabilization