A supplementary cementitious material used in combination with an activator such as Portland cement to produce a hydraulic binder. The supplementary cementitious material is based on physico-chemically treated filter cake product extracted from dredged sediments and can partially replace Portland cement clinker in conventional concrete applications with positive effects on sustainability (reduction of CO2 emissions, upcycling of residues).

A supplementary cementitious material used in combination with an activator such as Portland cement to produce a hydraulic binder. The supplementary cementitious material is based on physico-chemically treated filter cake product extracted from dredged sediments and can partially replace Portland cement clinker in conventional concrete applications with positive effects on sustainability (reduction of CO2 emissions, upcycling of residues).

The invention relates to a method for the expansion of sand grain-shaped raw material (1) in which the raw material drops downwards through a substantially vertical heated shaft (3) provided with means (2) for heating, in which a shaft flow (4) prevails and to a dosing element (6) which can be connected to a substantially vertical shaft (3) and a conveying line (7).

In order to prevent the pressure fluctuations coming from the conveying line (7) in the area of the shaft (3), a dosing element (6) is attached between the shaft and the conveying (7) line, in which the quantity of granulate which goes over from the shaft (3) into the conveying line (7) is regulated via means for regulating so that a defined material collection of the granulate is formed as a buffer is the dosing element (6), which decouples the shaft flow (4) from the conveying flow.

A method for preparing lightweight clay-based aggregates, the aggregates being suitable for use notably in civil engineering works, in particular road uses, and construction. The method for preparing lightweight aggregates includes at least the following steps: a) a step of granulating a clay-based mixture, so as to obtain aggregates, b) a step of drying the aggregates obtained, so as to obtain dried aggregates, c) a step of heat treatment of the dried aggregates, this step having two successive substeps: i) a first substep of heat treatment carried out under a reducing atmosphere at a temperature Ti of between 900 C. and 1200 C. approximately, ii) a second substep of heat treatment carried out under an oxidizing atmosphere at a temperature T2 of between 1050 C. and 1300 C. approximately, and d) a step of cooling the aggregates.