EFFECT OF LIME-STABILIZATION ON STRENGTH CHARACTERISTICS OF BRICKS

EFFECT OF LIME-STABILIZATION ON STRENGTH CHARACTERISTICS OF BRICKS

Abstract

Clay soils have been used locally in Sokoto to make bricks without stabilizing the soil. The bricks usually experience structural failure such as cracking and seasonal swelling when used for the construction of wall. Collapsing of wall also occurs in the area where non-stabilized bricks are used for wall construction. This research aims to assess the effect of lime-stabilization on strength of bricks made with Sokoto Red Clay Soils with a view to determining the physical properties of the soil and the optimum level of lime-stabilization required in the case of Sokoto Red Clay Soil (RCS). RCS used in this research were stabilized by lime and the method adopted for the stabilization is additive method. In this process, a certain percentage of stabilizers are added to the soil to improve its strength properties and durability. This study involves physical testing of soil samples and laboratory work on compressive strength testing of manufactured bricks. The optimum water contents of soil and stabilized soil were determined to be 14.6% and 16.8%, respectively. The lime stabilization rates used in this study are 0%, 3%, 6%, 9%, 12%, 15%, 18%, and 21%. A total of 120 bricks were produced and tested for compressive strength after the specified curing time. Curing methods of choice are 3, 7, 14, 21 and 28 day wet curing methods. Compressive strength results at 0%, 3%, 6%, 9%, 12%, 15%, 18% and 21% over 28 days: 0.5 N/mm2, 1.35 N/mm2, 1.24 N/mm2, 0.85 N/mm2, 0.82 N/mm2, 0.63 N/mm2, 0.47 N/mm2, 0.37 N/mm2. Furthermore, a continuous increase in brick compressive strength from 3 to 28 days was observed at both 3% and 6% stabilization. At 3% and 6% stabilization, the highest average compressive strengths recorded over 28 days are 1.35 N/mm2 and 1.24 N/mm2, respectively. However, the maximum value is not BS 5628 Part 1 (1978) of 2.8 N/mm2. This may be due to the low value of the plasticity index (10.4) and the stabilizers used. We also found that the maximum compressive strength of the stone at 0% stabilization was 1.11 N/mm2 at 21 days and the compressive strength decreased to 0.50 N/mm2 after 28 days. The decrease in compressive strength obtained at 0% stabilization over 28 days may be the result of cracks appearing in the brick surface, which may be due to the lack of stabilization. A compressive strength of 1.11 N/mm2 was measured in 3 days due to the lime effect on the bricks, compared to 3% stabilization. The highest value recorded at 3% stabilization indicates that lime alone cannot be used to stabilize red clay soils for brick production. This indicates that lime should be used to stabilize the red clay soil along with one or two stabilizers to improve the strength properties of the brick. It is also recommended to use red clay soil with a high plasticity index to stabilize the lime.

chapter One
Foreword
1.1 Research background
Different types of stabilizers have been used in different parts of the world to improve the engineering properties of laterite (Moh, 1962). The most common are cement, lime and bitumen, and the choice of specific stabilizer depends on the type of soil and the level of effectiveness of the stabilizer (Rahaman, 1968). Mustapha (2006) defined soil stabilization as soil treatment to improve the soil.