Concrete composition

Abstract

Concrete composition based on binder, sand, gravel, water and an elongated vegetable aggregate, wherein the elongated vegetable aggregate is selected from cut stem parts of grasses, hemp, Jerusalem artichoke or flax or palm fronds and mixtures thereof, characterized in that the elongated vegetable aggregate is formed from plant stem parts with a length of 10 - 80 mm, which naturally comprise a hard, predominantly dimensionally stable bark and a compressible pith, wherein the natural volume of the pith is greater than the natural volume of the bark from which the pith has been removed, wherein the volume of the pith after removal is smaller than the volume of the bark.

Claims

[1] Concrete composition based on binder, sand, gravel, water and an elongated vegetable aggregate, wherein the elongated vegetable aggregate is selected from cut stem parts of grasses, hemp, Jerusalem artichoke or flax or palm fronds and mixtures thereof, characterized by that the elongated vegetable aggregate is formed from plant stem parts with a length of 10 - 80 mm, which naturally comprise a hard, predominantly dimensionally stable bark and a compressible pith, the natural volume of the pith being greater than the natural volume of the bark from which the pith has been removed, the volume of the pith after removal being smaller than the volume of the bark. [2] Concrete composition according to claim 1, wherein the bulk density of the plant stem parts after removal of the pith is 20 - 40% higher than the bulk density before removal of the pith. [3] Concrete composition according to claim 1 or 2, wherein the volume of the pith of the plant stem parts after removal of the pith is less than twice, preferably three times and particularly preferably four times the volume of the bark. [4] Concrete composition according to one of the preceding claims, wherein the plant stem parts are selected from cut stem parts of grasses, hemp, Jerusalem artichoke, flax or palm fronds and mixtures thereof, in particular of grasses, in particular from the Miscanthus family, more particularly Miscanthus gigantheus. [5] Concrete composition according to one of the preceding claims, wherein the plant stem parts have a length of 10 - 80 mm, preferably 10 - 40 mm. [6] Concrete composition according to any one of the preceding claims, wherein the average length of the plant stem parts is 10 - 20 mm. [7] Concrete composition according to any one of the preceding claims, wherein the average diameter of the plant stem parts is 2 - 3 mm. [8] Concrete composition according to any one of the preceding claims, wherein the plant stem parts are subjected to a pith removal treatment, which pith removal treatment comprises the steps of: a. Provision of plant stem parts with a length of 10 - 80 mm; b. Providing a straw mill comprising a cutting chamber with knives rotating in a vertical plane and a feed pipe extending laterally from an inlet opening to an outlet opening, the outlet opening being connected to the cutting chamber, and a channel-shaped loading element extending from outside the feed pipe through the inlet opening at a distance of at least the bottom of the feed pipe into the feed pipe, c. introducing an air stream directed from the feed opening to the cutting chamber into the feed pipe of the straw mill, wherein at the feed opening a first air stream is formed through the channel-shaped loading element and a second air stream is formed below the channel-shaped loading element and the first air stream; d. introducing the plant stem parts into the feed tube via the loading element, wherein the plant stem parts are moved into the cutting chamber by the first air stream and the second air stream prevents contact of the plant stem parts with at least the underside of the feed tube; e. the plant stem parts are exposed to the rotating knives in the cutting chamber, the plant stem parts are split and the pith is removed from the bark; f. emptying the cutting chamber and separating the split, pith-free parts of the plant stem and the emptied pith; g. Use of the split, pith-free plant stem parts obtained in step f. as elongated plant aggregate for the concrete composition. [9] Concrete composition according to any one of the preceding claims, which per 1 m 3 Contains 15 - 50 kg of cored stem parts as elongated vegetable aggregate. [10] A concrete composition according to any one of the preceding claims, wherein the binder contains cement. [11] A concrete composition according to claim 10, which contains, by weight per part of cement, 0.2 to 0.7 parts of water, 1.8 to 3.0 parts of sand and 2.5 to 5.0 parts of gravel and / or granules. [12] A concrete composition according to any one of the preceding claims, wherein the concrete composition is an earth-moist concrete composition. [13] A concrete composition according to any one of the preceding claims, wherein the composition is free from a mineralizer. [14] A concrete product containing the concrete composition according to any one of the preceding claims in hardened form. [15] A concrete product according to claim 14, selected from the group consisting of sidewalk slabs, curbstones, concrete paving stones and grass concrete slabs.

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