An investigation of sulfate effects on compaction characteristics and strength development of cement-treated sulfate bearing clay subgrade

ABSTRACT

For road construction on sulfate (saline) soil, whether cement stabilisation could be effectively used must be determined. This study improves understanding of strength reduction characteristics for cement-stabilised sulfate soil subjected to variations in water content, cement content, and curing time. A series of laboratory tests to examine soil properties and compressive strength characteristics of soil-cement mixtures in conjunction with microstructural observations were performed. The compaction curves of cement-stabilised sulfate bearing clay and cement-stabilised high plasticity clay (a benchmark material) were established as nearly identical. This indicated minor effects of sulfate on the compaction characteristics of soil. The experimental results also showed that the rate of compressive strength loss escalated with an increase in cement content and curing time. While producing test samples through the compaction process, a series of unconfined compressive strength (UCS) tests on both materials exhibited a bell-like relationship with a peak at the optimum moisture content (OMC). The UCS of both study materials while compacted with water content below the OMC was lower than that while compacted with water content higher than the OMC. The microstructure observations in this study also supported this characteristic.

KEYWORDS:

• Sulfate bearing soil
• soil-cement stabilisation
• subgrade
• saline soil
• road pavement
• compaction characteristics

Acknowledgments

This research project was supported by Rajamangala University of Technology Isan and Chiang Mai University, Thailand. The research team from the Civil Engineering Department at Chiang Mai University, Thailand is also gratefully acknowledged for providing guidance and valuable input. The second author wishes to express gratitude to the Thailand Research Fund (TRF) under the ‘TRF Mid-Career Research Grant No. RSA 5980070’ for the partly financial support of this project. Furthermore, the last author would like to acknowledge the financial support of the TRF under the TRF Distinguished Research Professor Grant No. DPG6180002.

Additional information

Funding

This work was supported by Thailand Research Fund: [Grant Number DPG6180002,RSA 5980070].