The members of the project are Jürgen Neubauer, Frank Bellmann, Saskia Franke and Florian Rafalski.

A new binder based on magnesium silicate was developed by Frank Bellmann, patent [1,2]. This binder is theoretically CO2-neutral, since the raw materials, namely natural magnesium silicates such as olivine (Mg,Fe)2SiO4, do not contain chemically bound CO2 and the production process requires only electric energy, which can be received from renewable sources. For this, olivine is hydrothermally treated, which leads to formation of mainly serpentine Mg3Si2O5(OH)4 and brucite Mg(OH)2. Thermal activation of these hydrate phases produces an amorphous meta-serpentine compound, which is reactive and hardens when mixed with water. In addition, this binder provides the possibility of becoming CO2-negativ by mineral carbonation.

For our studies, synthetic magnesium silicate, namely forsterite Mg2SiO4, is used to investigate a simplified pure magnesium silicate system. Autoclavation of forsterite leads to formation of serpentine, brucite and an M-S-H compound. During thermal activation, these hydrate phases decompose and form periclase MgO and a partially dehydrated amorphous M-S-H compound, described as meta-serpentine before. Activated M-S-H and periclase are reactive with water and form an M-S-H compound during hydration. Our studies are focussed on investigation of activation parameters, characterization of the three types of M-S-H (autoclaved, activated and hydrated) and description of hydration mechanisms. Another focus is investigation of carbonation mechanisms. The materials show reactivity with CO2 by formation of magnesium carbonates such as nesquehonite MgCO3*3H2O. For this, the carbonation behaviour of all three materials (autoclaved, activated and hydrated) is investigated by application of wet carbonation and semi-dry carbonation via dynamic vapour sorption. The results from the pure magnesium silicate model system can then be applied to the technical product with natural raw material.

[1] F. Bellmann, Sequestration of CO2, WO2023/134849A1, 2023

[2] F. Bellmann, Method for producing a hydrated cement, WO2025/012209A1, 2025

Applicants: Jürgen Neubauer, Frank Bellmann