Page 14 - CSEB Report

Study on Compressed Stabilized Earth Blocks

Figure 4: Variation of strength of CSEB bricks w.r.t cement content

4.1.1 Discussion on the CSEB Bricks

There is no standards which states about water absorption of CSEB but Auroville Earth

Institute states that the class A CSEB shall have water absorption in the range of 5 to 10%

by weight and that the Class B shall have water absorption in the range of 10 to 20% by

weight. The results of the compressive strengths and water absorptions for sample 1,
sample 2 and sample 3 are presented in Table 4.

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The results shows that highest compressive strength of 66.52kg/cm (6.53N/mm ) was
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obtained from sample 3 with 9% cement content at the curing period of 28 days. And it
was noticed that the strength decreased with 11% cement content and again increased
the strength with 14% cement content. The findings were confusing, thus some international

papers were referred and according to [10] clearly stated that the optimum cement

content for the stabilization is in the range of 5% to 10% where addition above 10%
will affect the strength of the bricks in negative way. However, test result of the blocks
containing 14% cement did not match with the interpretation of [10], but somehow

matched by blocks containing cement of 9% and 11% .

Furthermore, if the cement content is greater than 10% then it becomes uneconomical to
produce CSEB brick [11] and also not eco-friendly. Thus, it was concluded that the

maximum amount of cement to be added in a soil should not be more that 10% for the
Sandy silt of low plasticity soil. The change in strength of the soil bricks with respect to

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