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.

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Keywords

Soil Block Masonry, Pumice, Stabilization

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