Abstract: A high water content soft soil, for example from the sea or river bed, may be improved in strength by incorporating thereinto a finely divided, quenched iron blast furnace slag treated with sulfuric acid, and a Portland cement. The sulfuric acid-treated slag is a product obtained by reacting a finely divided, quenched iron blast furnace slag, such as a water-granulated iron blast furnace slag, with sulfuric acid to convert a part of its calcium components into gypsum.

Abstract: A high water content soft soil, for example from the sea or river bed, may be improved in strength by incorporating thereinto an additive composed of ingredient A including a mixture of 5-45% by weight of gypsum and 95-55% by weight of a water-granulated iron blast furnace slag having an particle size within the range of 100-1 .mu.m and ingredient B including a Portland cement. The ratio by weight of ingredient A to ingredient B is within the range of 75/25-55/45. Ingredient A is incorporated into the soft soil before incorporation of ingredient B.

Abstract: A water-saturated soft soil is efficiently improved in its strength by incorporating therein an additive composed of ingredients A and B; the ingredient A comprises gypsum and the ingredient B comprises a mixture of 40-55% by weight of a Portland cement and 60-45% by weight of a water-granulated iron blast furnace slag having a particle size almost equal to or smaller than that of the Portland cement. The ratio by weight of the ingredient A to the ingredient B ranges from 10/90 to 30/70 and the total amount of the ingredients A and B used for the soft soil is sufficient to strengthen the soft soil.

Abstract: A water-saturated soft soil is efficiently improved in its strength by incorporating thereinto an additive composed of ingredients A, B and C; the ingredient A comprises gypsum, the ingredient B comprises a mixture of 40-55% by weight of a Portland cement and 60-45% by weight of a water-granulated iron blast furnace slag having a particle size almost equal to or smaller than that of the Portland cement and the ingredient C comprises a water-soluble ferrous salt. The ratio by weight of the ingredient A to the ingredient B ranges from 10/90 to 30/70 and the total amount of the ingredients A and B used for the soft soil is sufficient to strengthen the soft soil. The ingredient C is used in an amount sufficient to react with hydrogen sulfide contained in the soft soil to be treated.

Abstract: A water-saturated soft soil is efficiently improved in its strength by incorporating thereinto an additive composed of ingredients A and B; the ingredient A comprises gypsum and the ingredient B comprises a mixture of 40-55% by weight of a Portland cement and 60-45% by weight of a water-granulated iron blast furnace slag having a particle size almost equal to or smaller than that of the Portland cement. The ratio by weight of the ingredient A to the ingredient B ranges from 10/90 to 30/70 and the total amount of the ingredients A and B used for the soft soil is sufficient to strengthen the soft soil.

Abstract: This invention relates to a process for desulfurization of exhaust gases wherein the sulfur oxides are efficiently removed in the stabilized form from exhaust gases containing said sulfur oxides and at the same time gypsum of good quality is recovered. More particularly, this invention relates to a process wherein exhaust gases are treated with a slurried solution of gypsum containing a specified organic acid component, sulfuric acid component, and an alkali component at a pH value of 5-3 so that the sulfur oxides in said exhaust gases are absorbed and oxidized to form gypsum which is recovered as a by-product of good quality containing no unreacted lime.

Abstract: This invention relates to a process for desulfurization of exhaust gases containing sulfur oxides. More particularly, it relates to a process which can continuously put in operation to remove the sulfur oxides in exhaust gases in an efficient manner using a slurry of gypsum containing specified sulfate(s) within a single apparatus and can at the same time obtain gypsum as by-product.