Abstract: The present publication describes a process for the preparation of lignosulfonate-based mixtures used in particular as additives of concrete. According to the process of the present invention, the sulfite spent liquor is treated with a nitrating reagent, such as nitric acid or nitrogen dioxide, and the reacted lignosulfonate is separated from the reaction product, and, together with the reacted lignosulfonate, the nitrate and nitrite compounds are separated from the reaction product, and the product mixture formed by the reacted lignosulfonate, nitrate compounds and nitrite compounds is purified in a way known per se. The product prepared in accordance with the process is suitable in particular for the liquefaction of concrete, for accelerating the setting of concrete, and for inhibiting corrosion of concrete reinforcement steels contained in concrete, if any.

Abstract: A lignin product for dispersing cement and other finely divided mineral materials, such as clays and equivalent, and for plasticizing their water mixtures. The product is large-molecular such that at least 40 percent of the material consists of molecules whose molecular weight is higher than 10,000. The sulfonation degree of said lignin product is lower than 0.4. The product is obtained from a cellulose cooking to which have been added catalysts preventing the splitting and dissolution of carbohydrates, such as amines, quinone and/or antraquinone derivatives or equivalent, in order to stabilize the cellulose and the hemicellulose during the cooking. The lignin product has been isolated from the spent liquor by using ultrafiltration, and/or complementary ion exchange.

Abstract: A process for producing a binder (cement) to be used in slurry, mortar, or concrete having a low water-to-cement ratio. As raw-material for the binder is used at least 50% by weight of a hydraulic material, such as slag, technical pozzolanas and/or natural pozzolanas. The hydraulic material is ground to a specific surface of at least 400 m.sup.2 /kg. To the raw-material is added 0.1 to 5% by weight of a plasticizing material, such as a sulphonated polyelectrolyte. To the raw-material are also added in total 0.5 to 8% by weight of sodium carbonate and/or sodium hydroxide. Added in small amounts, the sodium carbonate and the sodium hydroxide, separately or in combination, considerably shorten the hardening time of the concrete, yield excellent strengths, and make it possible to use cheap raw-materials.

Abstract: A concrete mixing apparatus with a stationary mixing container and an upper circular cover plate arranged to rotate in relation to said container. The apparatus is provided with a machinery for rotating said cover plate and with a discharge channel for one or several materials. The discharge channel is arranged above the cover plate in substantially coaxial relation thereto. The apparatus further comprises a filling channel, the lower end of which is fastened onto said cover plate and the upper end of which is arranged in substantially coaxial relation to said discharge channel.