The invention relates to a method for layer-by-layer deposition of concrete by providing extrudable concrete. A first flow comprising a binder material and water and a second flow comprising a carrier material, an additional component and water are mixed in a static mixer to form a third flow of extrudable concrete. The material of the second flow has a shorter initial setting time than the material of the first flow. The first flow has a first viscosity V1 and the second flow has a second viscosity V2 so that the ratio V1/V2 ranges between 1/40 and 40. The third flow has a viscosity larger than the viscosity of the first flow and the second flow and a yield stress larger than the yield stress of the first flow and the second flow. The material of the third flow has an initial setting time shorter than initial setting time of the first flow.

The invention further relates to a system to extrude concrete, in particular for layer-by-layer deposition of concrete.

The invention relates to a method for layer-by-layer deposition of concrete by providing extrudable concrete. A first flow comprising a binder material and water and a second flow comprising a carrier material, an additional component and water are mixed in a static mixer to form a third flow of extrudable concrete. The material of the second flow has a shorter initial setting time than the material of the first flow. The first flow has a first viscosity V1 and the second flow has a second viscosity V2 so that the ratio V1/V2 ranges between 1/40 and 40. The third flow has a viscosity larger than the viscosity of the first flow and the second flow and a yield stress larger than the yield stress of the first flow and the second flow. The material of the third flow has an initial setting time shorter than initial setting time of the first flow.

The invention further relates to a system to extrude concrete, in particular for layer-by-layer deposition of concrete.

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.

A nano-modified dry-mixed alkali-activated cementitious, or one-part geopolymer cement (OPgC), material with high early strength is provided for rapid repair of cement-based infrastructure components. The OPgC may include an aluminosilicate rich material, an alkali material and a nano-modifier, and optionally include other functional admixtures and fibers. The OPgC can be freshly mixed with water to obtain a repairing material. The OPgC may mix with water and fine or coarse aggregate to form mortar or concrete. The OPgC can be an alternative binding matrix for the development of an environmentally friendly and cost effective rapid repair material.

A nano-modified dry-mixed alkali-activated cementitious, or one-part geopolymer cement (OPgC), material with high early strength is provided for rapid repair of cement-based infrastructure components. The OPgC may include an aluminosilicate rich material, an alkali material and a nano-modifier, and optionally include other functional admixtures and fibers. The OPgC can be freshly mixed with water to obtain a repairing material. The OPgC may mix with water and fine or coarse aggregate to form mortar or concrete. The OPgC can be an alternative binding matrix for the development of an environmentally friendly and cost effective rapid repair material.

A method of preparing high strength coral concrete, wherein the high strength coral concrete is prepared from raw materials of the following parts by mass: 25˜63 parts of cementing materials, 45˜58 parts of coral aggregate, 10˜16 parts of mixing water and water reducer 2˜5% the weight of the cementing materials; the weighed coral aggregate, mixing water, water reducer and 55˜85% of the cementing materials are stirred in an agitator for 10˜15 minutes; the rest of cementing materials are added in batches before initial setting and stirred; then poured and removed from the mould after 24 hours, cured in mixing water at normal temperature for 28 days, to get the high strength coral concrete.

A method of preparing high strength coral concrete, wherein the high strength coral concrete is prepared from raw materials of the following parts by mass: 25˜63 parts of cementing materials, 45˜58 parts of coral aggregate, 10˜16 parts of mixing water and water reducer 2˜5% the weight of the cementing materials; the weighed coral aggregate, mixing water, water reducer and 55˜85% of the cementing materials are stirred in an agitator for 10˜15 minutes; the rest of cementing materials are added in batches before initial setting and stirred; then poured and removed from the mould after 24 hours, cured in mixing water at normal temperature for 28 days, to get the high strength coral concrete.

Disclosed is a method for preparing high-strength coral aggregate concrete under low pressure conditions, including the following steps: weighing cement, mineral admixture, coral aggregate, mixing water, water reducer, and defoamer; mixing the cement and the mineral admixture well to obtain a cementing material; putting the coral aggregate, sea water, water reducer, defoamer, and 55-85% of the cementing material into a closed mixing system to stir for 10-15 min under low pressure conditions, and pouring the remaining cementing material into the mixing system to stir for additional 10-15 min to prepare the high-strength coral aggregate concrete. The high-strength coral aggregate concrete obtained has advantages of high mechanical properties, high compactness, excellent impermeability and durability, drawing on local resources in construction engineering on remote islands and reefs, and maximum resource utilization.

Disclosed is a method for preparing high-strength coral aggregate concrete under low pressure conditions, including the following steps: weighing cement, mineral admixture, coral aggregate, mixing water, water reducer, and defoamer; mixing the cement and the mineral admixture well to obtain a cementing material; putting the coral aggregate, sea water, water reducer, defoamer, and 55-85% of the cementing material into a closed mixing system to stir for 10-15 min under low pressure conditions, and pouring the remaining cementing material into the mixing system to stir for additional 10-15 min to prepare the high-strength coral aggregate concrete. The high-strength coral aggregate concrete obtained has advantages of high mechanical properties, high compactness, excellent impermeability and durability, drawing on local resources in construction engineering on remote islands and reefs, and maximum resource utilization.