Abstract: Improvements for soil are described that include a first particle in dry or powder form with a calcium oxide content greater than a second particle, the second particle, also in dry or powder form, with a calcium oxide content less than the first particle and preferably a low sulfate content. When added to soil the improvement maintains a low sulfate content, generally 5,000 ppm or less. Methods of improving soil are also described. When added to soil, the improvement described increases the original soil strength, sufficient for foundation and piling structures, road works and/or buildings or equipment. When soil is modified as described, the improved soil will have an unconfined compressive strength of less than 100 psi or less than 75 psi in 28 days. The improved soil is stronger, suitable for large scale projects while satisfying or maintaining a low sulfate content and a desired UCS value.