Some Hydraulic, Mechanical, and Physical Characteristics of Three Types

R. Medjo Eko(1), Mamba Mpele(2), M. H. Dtawagap Doumtsop(3), L. Seba Minsili(4), and A.S.

Wouatong(5)

CIGR Journal, Volume VIII, 2006

1. Senior lecturer, Dept of Agric. Engineering, FASA, U. of Dschang, Cameroon

Dept. of Earth Sciences, Faculty of Science, U. of Yaounde I, Cameroon

[email protected]

2. Senior lecturer, National Polytechnic Advanced School, University of Yaounde I,

Cameroon

3. Graduate student, Department of Earth Sciences, Faculty of Science, University of

Dschang, Cameroon.

4. Lecturer, National Polytechnic Advanced School, University of Yaounde I,

Cameroon

5. Senior lecturer, Department of Earth Sciences, Faculty of Science, University of

Dschang, Cameroon

 

ABSTRACT

Three types of compressed earth blocks (CEB) were processed to carry out a comparative study on some of their hydraulic, mechanical, and physical characteristics. They were namely the unstabilized CEB, the partially stabilized CEB, and the fully stabilized CEB. The partial stabilization of the CEB was achieved by wrapping its unstabilized earthen inner part all round with a stabilized earthen crown. Soil stabilization was done using Portland cement.

Levels of cement mixed with soil were 0, 6, 8, and 10%. Two wrapping crown thicknesses

were tested: they were 0.75 cm and 2.25 cm. Mechanical tests consisted of running the

compressive and the flexural strengths on CEBs. Physical and hydraulic properties evaluated

were respectively their abrasion loss of matter and water absorption.

 

Results show that the fully stabilized CEB performed better in regard to all the tests. The two

remaining types of CEB displayed similar mechanical characteristics. However, abrasion loss

of matter of the partially stabilized CEB was lower than that of unstabilized CEB. In addition,

unstabilized CEB did not sustain the water absorption test.

 

This investigation shows that the partially stabilized CEB with 2.25 cm crown thickness is

mechanically safe and meets the requirements for earthen construction. Therefore it might be recommended to the earthen construction industry as an interesting alternative for the fully stabilized CEB since its processing requires a lesser amount of cement.

 

UPDATE

The cost of cement is in rise in Cameroon. Stabilizing an unfired earth block in this economical environment consequently becomes more and more difficult for the low income earners. To search for a way out, an investigation aimed to efficiently lower the level of cement used in processing stabilized unfired earth blocks was undertaken by a research team of University of Yaoundé I and University of Dschang.

 

The investigation was carried out by first designing a partially stabilized unfired earth block made up of unstabilized inner soil and crowned all around by a thin layer of cement stabilized soil. Partially stabilized earth blocks with wrapping crown thicknesses of 0.75 and 2.25 cm were processed for this purpose. They were tested in compression, flexion, water absorption, and abrasion loss of matter together with unstabilized and fully stabilized unfired earth blocks.

 

Results show that only unstabilized unfired earth blocks are disintegrated during immersion in water. Fully stabilized unfired earth blocks satisfactorily went through the entire test series but its cement content is too high compared to that of partially stabilized earth blocks. It was observed that partially stabilized earth blocks with 2.25 cm crown thickness are mechanically safe and meet the requirements for resistance to abrasion loss of matter. Therefore they can be recommended to the earthen construction industry as an interesting alternative for the fully stabilized unfired earth blocks.

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