A geopolymer thermal energy storage (TES) concrete product comprising at least one binder; at least one alkali activator; at least one fine aggregate with high thermal conductivity and heat capacity; and at least one coarse aggregate with high thermal conductivity and heat capacity.

The method for producing a carbonate bonded, compacted article, which method comprises the steps of providing a particulate, carbonatable material; compacting the particulate material to form a compact; and carbonating said compact. The carbonation of the compact is started and subsequently continued for at least 1 hour with a low partial carbon dioxide pressure in the carbonation gas which is lower than 0.5 bars, after which carbonation of the compact is continued for at least 8 hours with a high partial carbon dioxide pressure in the carbonation gas which is higher than 0.5 bars. By carbonating in two phases with a low and a high partial carbon dioxide pressure, a higher compressive strength of the carbonated compacts can be achieved within a predetermined carbonation time, in particular within a carbonation time of about 24 hours so that every day new compacts can be carbonated.

The invention relates to a process for producing a composite comprising: a. providing a particulate material, wherein the particulate material comprises minerals having a content of at least 30% m/m of calcium, magnesium, aluminium, silicon, potassium or iron, or a combination of two or more thereof. b. providing an aggregate, c. providing a primary additive, wherein the primary additive comprises a sugar or derivative thereof, a polyol or derivative thereof, an organic acid, an organic acid salt or an inorganic acid, or any combination of two or more thereof, d. mixing the particulate material, the aggregate and the primary additive with water to form a mixture, and e. carbonating the mixture in the presence of carbon dioxide, wherein the concentration of carbon dioxide is greater than about 2 vol %.

A method for making a carbonated precast concrete product includes: obtaining a mixture including at least one binder material, an aggregate, and water; molding the mixture into a molded intermediate; demolding the molded intermediate to obtain a demolded intermediate, the demolded intermediate having a first water-to-binder ratio; conditioning the demolded intermediate to provide a conditioned article having a second water-to-binder ratio less than the first water-to-binder ratio of the demolded intermediate; moisturizing at least one surface of the conditioned article with an aqueous medium, thereby causing a weight gain of the conditioned article and providing a moisturized product, a first portion of the moisturized product having a third water-to-binder ratio greater than a fourth water-to-binder ratio of a remainder of the moisturized product; and curing the moisturized product with carbon dioxide to obtain the carbonated precast concrete product.

A method for controlling the volume expansion of a hydraulically setting composition including steel making slag, the method including a step of adding a silica source to the composition. Furthermore, hydraulically setting compositions obtained by such methods and their uses.

A method for making a carbonated precast concrete product includes: obtaining a mixture including at least one binder material, an aggregate, and water; molding the mixture into a molded intermediate; demolding the molded intermediate to obtain a demolded intermediate, the demolded intermediate having a first water-to-binder ratio; conditioning the demolded intermediate to provide a conditioned article having a second water-to-binder ratio less than the first water-to-binder ratio of the demolded intermediate; moisturizing at least one surface of the conditioned article with an aqueous medium, thereby causing a weight gain of the conditioned article and providing a moisturized product, a first portion of the moisturized product having a third water-to-binder ratio greater than a fourth water-to-binder ratio of a remainder of the moisturized product; and curing the moisturized product with carbon dioxide to obtain the carbonated precast concrete product.

A hydraulic binder including (in % by dry weight); A. at least 50 of at least one ground and granulated blast-furnace slag; B. more than 5 of at least one calcium aluminate cement and/or of at least one calcium sulfoaluminate cement; C. more than 5 of at least one source of sulfate ions; D. between 1 and 5 of Ca(OH).sub.2 and/or Portland cement; E. between 0.01 and 1 of at least one alkali metal carbonate; F. and at least one alkalifying reagent consisting of at least one alkali metal carbonate and/or bicarbonate, different from E; under the following conditions: (i) amount of C allows sulfate ions of C to react with B and A; (ii) the amount of F sufficiently causes a reaction with D in water resulting in a wet formulation with a pH not less than 12, for a water-to-mortar mixing rate between 10 and 35% by weight.

A hydraulic binder including (in % by dry weight); A. at least 50 of at least one ground and granulated blast-furnace slag; B. more than 5 of at least one calcium aluminate cement and/or of at least one calcium sulfoaluminate cement; C. more than 5 of at least one source of sulfate ions; D. between 1 and 5 of Ca(OH).sub.2 and/or Portland cement; E. between 0.01 and 1 of at least one alkali metal carbonate; F. and at least one alkalifying reagent consisting of at least one alkali metal carbonate and/or bicarbonate, different from E; under the following conditions: (i) amount of C allows sulfate ions of C to react with B and A; (ii) the amount of F sufficiently causes a reaction with D in water resulting in a wet formulation with a pH not less than 12, for a water-to-mortar mixing rate between 10 and 35% by weight.

What is shown and described is a concrete element including a core concrete layer and a face concrete layer, the face concrete layer being obtained by compacting and hardening a mixture containing a latent hydraulic binder and/or a pozzolanic binder, water, a granular material and an alkaline hardener, with the granular material having, at a screen hole width of 2 mm, a through fraction from 35.5 wt. % to 99.5 wt. % and, at a screen hole width of 0.25 mm, a through fraction from 2.5 wt. % to 33.5 wt. %, each based on the total weight of the granular material.

What is shown and described is a concrete element including a core concrete layer and a face concrete layer, the face concrete layer being obtained by compacting and hardening a mixture containing a latent hydraulic binder and/or a pozzolanic binder, water, a granular material and an alkaline hardener, with the granular material having, at a screen hole width of 2 mm, a through fraction from 35.5 wt. % to 99.5 wt. % and, at a screen hole width of 0.25 mm, a through fraction from 2.5 wt. % to 33.5 wt. %, each based on the total weight of the granular material.