A METHOD AND DEVICE FOR MANUFACTURING A PELLET-LIKE HALF-PRODUCT SUITABLE AS ADDITIVE TO A CONCRETE MIXTURE

Abstract: A method for manufacturing a pellet-like half-product suitable as additive to a concrete mixture, wherein the starting point for this additive is a fine inorganic material in powder form, wherein the inorganic powder material is subjected to a wetting treatment and to a compacting treatment in order to form a volume of pellets with a size of 2 to 25 mm to enable easy and homogenous mixing of the additive with other basic fractions for the concrete mixture.

Description: A METHOD AND DEVICE FOR MANUFACTURING A PELLET-LIKE HALF-PRODUCT SUITABLE AS ADDITIVE TO A CONCRETE MIXTURE The invention relates to a method for manufacturing a pellet-like half-product suitable as additive to a concrete mixture, wherein the starting point is a fine inorganic material in powder form. During the making of a concrete mixture, which consists among other things of diverse fractions of additive of different granular size, obtaining a homogenous mixing of the fractions is a great problem. High-grade concrete preferably has as few cavities as possible, this determining the strength, i.e. the fewer cavities, the greater the strength. For this purpose fine inorganic material is usually used as additive to fill these cavities. The drawback of fine inorganic material is that loss can occur during transport and dosing because the material is blown away as dust. It is known from EPC-A-0697379 to add admixtures to a concrete mixture, wherein the concrete can be coloured, which admixtures are first made into a pasty mass which is then formed into pellets by drying and processing so as to be added to the concrete mixture. This method is however unsuitable for the addition of additives to the concrete mixture. The invention has for its object to provide a method which is particularly suitable for additives. The method according to the invention is distinguished in that the inorganic powder material is subjected to a wetting treatment and to a compacting treatment in order to form a volume of pellets with a size of 2 to 25 mm to enable easy and homogenous mixing of the additive with other basic fractions for the concrete mixture. Surprisingly, it has been determined experimentally that the fine inorganic additive material can be mutually adhered relatively easily using a quantity of liquid, in particular water, whereafter the inorganic material can finally be formed by a determined compacting treatment into pellets which are of such a size and strength that they can be readily transported and dosed. Owing to the pellet form, this additive fraction can be easily distributed homogeneously in the concrete mix, wherein as a result of the absence of further additives the pellets disintegrate again into the original inorganic fine material during the concrete mixing, wherein water is used. This provides a sufficient distribution of the fine inorganic additive material whereby a homogeneous mixing in the concrete is achieved, a desired plasticity of the unhardened concrete is obtained and the strength of the concrete can be considerably increased. Use is made for production of a modified granulation pan or a mixer adapted for the purpose. According to the invention the compacting treatment preferably consists of a pressureless friction treatment on the inorganic material in powder form. By exerting a determined friction the material will, as a consequence of the wetting, automatically be rolled into pellets. This can take place wholly without pressure. Wetting can be effected by spraying water over the fine inorganic material, which can take place prior to or during the compacting. The inorganic material in powder form is preferably smaller than 500 microns in grain size. The pellet form produced by the method according to the invention has a size of 2 to 25 mm, depending on the field of application. It has been determined experimentally that the most suitable device for obtaining the pellet-like half- product consists of a per se known pan with a bottom inclining relative to the vertical, wherein means are present for setting this bottom at least partially into an upward motion. The powdery material will initially want to roll downward on the bottom, this being compensated by the upward movement thereof, so that the desired pellet form can be obtained in pressureless manner. The pan is preferably circular and the drive means will set the pan into a movement rotating round the axis thereof, wherein a continuous process could be realized. The invention is not limited to the above described method and device. The process can take place continuously or batch-wise.

Claims: CLAIMS 1. Method for manufacturing a pellet-like half- product suitable as additive to a concrete mixture, wherein the starting point for this additive is a fine inorganic material in powder form, characterized in that the inorganic powder material is subjected to a wetting treatment and to a compacting treatment in order to form a volume of pellets with a size of 2 to 25 mm to enable easy and homogenous mixing of the additive with other basic fractions for the concrete mixture. 2. Method as claimed in claim 1, characterized in that the compacting treatment consists of a pressureless friction treatment on the powdery inorganic additive material . 3. Method as claimed in claim 1 or 2, characterized in that the moisture is added to the powdery additive material by a spraying operation. 4. Inorganic material in powder form suitable for use in the method as claimed in claim 1, characterized in that the grain size thereof is smaller than 500 microns. 5. Device for performing the method as claimed in claim 1 or 2, characterized by a pan with a bottom inclining relative to the vertical and means for setting this bottom at least partially into an upward motion. 6. Device as claimed in claim 5, characterized in that the pan is circular and the drive means cause the bottom to rotate round the axis thereof.

Inventors: HAPPEL ANNELIES JOHANNA ELISAB, KOUWENHOVEN HENDRIKUS ANTONIUS, HAPPEL, ANNELIES, JOHANNA, ELISABETH, KOUWENHOVEN, HENDRIKUS, ANTONIUS, PETRUS
Applicants: GRINT & ZANDEXPL MIJ VH SMALS, HAPPEL ANNELIES JOHANNA ELISAB, KOUWENHOVEN HENDRIKUS ANTONIUS, B.V. GRINT- EN ZANDEXPLOITATIE MAATSCHAPPIJ V/H GEBRS. SMALS, HAPPEL, ANNELIES, JOHANNA, ELISABETH, KOUWENHOVEN, HENDRIKUS, ANTONIUS, PETRUS
Application year: 2000
Main classification: C04B18
IPC codes: C04B18