Page 6 - CSEB Report

Study on Compressed Stabilized Earth Blocks

3. Methodology

Soil from three different locations under Thimphu district was collected for conducting

laboratory tests such as Sieve analysis, Atterberg Limit, and Compaction test. The purpose
of the tests was to determine variation in properties of the compressed stabilized soil
blocks (CSEB) bricks w.r.t different mix ratio of the cement stabilizer and to find out the

optimum compressive strength of the bricks. Only red soil was collected, as conventionally

people choose red color soil for rammed earth construction. Sample I was collected from
Dochula road widening site, Sample II was collected from Bjemina construction site, while
Sample III was taken from Debsi construction site. The proctor test was conducted to

determine the OMC and Dry Density of the soil samples and particle size distribution was

carried out to determine the grain size distribution of the soils.
Later CSEB bricks were molded using Auram press 3000 and CINVA-Ram machine which is
a hand operated press for block making and the water mix ratio was derived from OMC
of the proctor tests. In total around 64blocks were molded and cured for minimum of 28
days in the sun. For the first few days, curing was done by covering the plastic sheet to
prevent immediate loss of water and later the blocks were covered with wet sags for
another few days. Then in the following days, the blocks were kept in the shade for slow

curing.

The dried CSEB bricks were tested for compressive strength and water absorption for

different cement stabilization levels. The objective being to investigate the suitability of
blocks made with stabilized soil at different ratio for use as masonry units. The crushing
strength of the blocks were tested using the universal testing machine. The maximum load
was recorded and crushing strength was evaluated on the basis of equation below:

P=F/A,

Where, P is the crushing stress (N/mm )
2
F is the failure load (N)

A is the area of specimen (mm )
2
The complete methodology of the

3.1 Soil Tests

Characteristic properties:
The laboratory tests results presenting different properties of the soil samples collected
from three different sites are presented in Table 1.

5 Engineering Adaptation and Risk Reduction Division (EARRD), DES, MOWHS