Investigating the Use of Calcined Dolomite to Stabilize Expansive Soils for Road Surgrade

Abstract

Expansive soils are characterized by their swelling and shrinking tendencies in response to changes in moisture levels. These soil behaviors pose significant challenges to infrastructure integrity, particularly evident on the Wakiso-Buloba-Matugga road, where sections affected by expansive soils become exceedingly difficult to traverse during the rainy season. In response to this issue, research was conducted investigated the stabilization of these expansive soils along this road using calcined dolomite sourced from the Osukuru Quarry in Tororo District. The calcined dolomite was processed by crushing it into a powder and then subjected to high temperatures reaching 900°C to obtain calcium and magnesium oxides. Subsequent X-ray fluorescence testing revealed calcium and magnesium oxide percentages of 75% and 15%, respectively. Particle size distribution analysis categorized the soil as class CH according to UCUS standards. The soil exhibited Atterberg limits with a liquid limit of 61, a plastic index of 38, and a California Bearing Ratio (CBR) of 6.2, which was below the required minimum for subgrade, as per general specifications. Various proportions of calcined dolomite (5%, 10%, 15%, and 20%) were mixed with the soil and cured for 14 days. Testing on the stabilized soil showed a reduction in Plasticity Index (PI), liquid limit (LL), swell, and shrinkage properties, with linear shrinkage decreasing to 42 and 15. Conversely, the CBR and Unconfined Compressive Strength (UCS) increased from 6.2 to 26 and from 0 to 0.5, respectively, at a 5% dolomite addition. These improvements collectively enhanced the bearing capacity of the soil and rendered it suitable for road subgrade applications.