Preparation method

A method for preparing a starting product for the manufacture of a concrete-like product,

• wherein the starting product is crushed and homogenized before it is sent for further treatment,
• wherein the crushing and homogenization takes place during wet grinding,
• wherein a starting product is selected which comprises at least 20% by mass of one or more of the following components:
• ultramafic rocks, in particular dunite,
• weathering products of ultramafic rocks, in particular serpentinite,
• a forsterite source in the form of a natural or artificial olivine source,
• wherein the crushed homogenized starting product is treated in a heat treatment apparatus at a temperature of more than 30° C. for at least two hours,
• wherein water is added to the starting product before, after or simultaneously with the crushing and homogenizing and this is mixed with the starting product, and/or steam is introduced into the heat treatment apparatus,
• wherein the crushed homogenized starting product is subjected to dewatering of bound water by means of thermal treatment and/or reaction grinding after treatment in the heat treatment apparatus,
• wherein the converted starting product is treated at a temperature between 180° C. and 1000° C. during thermal treatment,
• wherein a re-arrangement of the crystal structures in the converted starting product occurs during reaction grinding,
• wherein sand and/or gravel are added, and
• is/are placed in a mold and is/are heat-treated.