WO2025196263A1

WO2025196263A1 - Fresh concrete or mortar composition

Info

Publication number: WO2025196263A1
Application number: PCT/EP2025/057792
Authority: WO
Inventors: Qing Zhang; Youcef BOULANOUAR; Pascal DION
Original assignee: Holcim Technology Ltd
Current assignee: Holcim Technology Ltd
Priority date: 2024-03-22
Filing date: 2025-03-21
Publication date: 2025-09-25
Anticipated expiration: 2026-09-22

Abstract

A fresh concrete or mortar composition for 3D-printing comprising a hydraulic cement in an amount of 250-500 kg/m³ based on the total composition, calcined clay, aggregates, water, and at least one plasticizer, wherein the specific surface area according to BET of the calcined clay is > 20 m²/g, the weight ratio of the calcined clay and the hydraulic cement is 0.20-0.60, preferably 0.20-0.50, and one or more viscosity modifying admixtures are present in a total amount of 0-0.15 wt.-% based on the combined mass of the hydraulic cement and the calcined clay.

Description

Fresh concrete or mortar composition

The invention refers to a fresh concrete or mortar composition for 3D-printing comprising one or more cementitious materials, including a hydraulic cement, aggregates, water, and at least one plasticizer.

Further, the invention refers to a method of building structural and architectural components layer-by-layer, such as by means of 3D concrete or mortar printing.

3D printing is a building technique that is commonly called "additive manufacturing" and consists of joining material to produce objects, layer upon layer, from 3D model data or other electronic data source. In particular, successive layers of material are formed under computer control by means of an industrial robot. It has already been proposed to develop 3D printers capable of producing structural buildings from a construction material that can be a mortar or a concrete. According to these proposals, the construction material is extruded through a nozzle to build structural components layer-by-layer without the use of formwork or any subsequent vibration. The possibility to build structures without formwork is a major advantage in terms of production rate, architectural freedom and cost reduction.

Usually, 3D printing of construction materials is a continuous process that comprises conveying fresh concrete, mortar or micro-mortar to a deposition head and placing the construction material through an outlet of the deposition head in order to form a layer of concrete. While placing the concrete, the mortar or the micro-mortar, the deposition head is moved under computer control in order to create a layer of construction material in accordance with the underlying 3D model. In particular, the deposition head places a ribbon of fresh concrete or mortar material. For allowing the fresh concrete or mortar to be moved smoothly through each part of the delivery process to the deposition head, a consistent rheology of the fresh material must be safeguarded.

However, the construction material must not only be sufficiently fluid for conveying and extrusion purposes, but also sufficiently firm in order to provide the required mechanical stability of the 3D printed structure before the hydraulic binder sets. In particular, the lower layers of the construction material should sustain the load imposed by upper layers without collapsing or deforming.

3D printed elements also require a strong bonding strength between the deposited layers, to ensure an adequate overall strength of the 3D printed structure. For this purpose, it is beneficial to place a layer while the preceding layer is still fresh.

To accommodate some of the above requirements, it has been proposed to add various admixtures to the flowable construction material, in particular structuring agents, such as viscosity modifying agents, and plasticizers.

Another challenge in designing 3D-printable mortar and concrete compositions is the phenomena of creeping, which is the time-dependent deformation under a sustained load. Since creep originates in the calcium silicate hydrates (C-S-H) of hardened Portland cement paste, the high paste volume in 3D- printable mortar and concrete makes creep more pronounced in 3D printed applications than in standard applications. Another aspect of optimizing 3D-printable concrete or mortar compositions is to reduce their environmental impact by reducing the carbon footprint associated with cement production. This is achieved by altering the composition and manufacturing process of the cement, in order to decrease the amount of CO2 produced per unit of cement produced. One of the main ways in which low-carbon cements achieve this reduction is by replacing some of the clinker with other materials. Examples of such substitutions include the use of industrial byproducts such as fly ash and slag, as well as naturally occurring materials like pozzolana, or calcined clays. An example of a low-carbon cement is the Limestone Calcined Clay Cement (LC3), a composite binder comprising clinker, calcined clay, limestone, and gypsum.

The use of synthetic viscosity modifying agents that are present in most 3D-printable compositions in order to increase the yield stress before setting occurs, such as HASE polymers (hydrophobically modified alkali-swellable emulsions) and ASE polymers (alkali-swellable emulsion), can also have a negative impact on the environment. This is due to the fact that synthetic viscosity modifying agents are derived from nonrenewable resources, including petroleumbased compounds. The extraction and processing of these resources contribute to resource depletion and environmental degradation. Further, the production of synthetic viscosity modifying agents typically requires significant energy inputs, contributing to greenhouse gas emissions and climate change. Finally, the presence of synthetic viscosity modifying agents in printed concrete formulations may raise concerns about the long-term durability of the structures. These agents may degrade over time due to environmental exposure, and can leach into soil and water systems, posing risks to ecosystems and human health. Therefore, it would be desirable to reduce or eliminate the need of using traditional structuring agents, such as synthetic viscosity modifying agents.

The invention aims at providing a fresh 3D-printable concrete or mortar that meets the above rheological and buildability requirements, including sufficient flowability to be conveyed to the deposition head, yield strength, compressive strength and interlayer bonding capability, and that also has a reduced negative environmental impact.

In order to solve this object, the invention according to a first aspect thereof provides a fresh concrete or mortar composition for 3D-printing comprising a hydraulic cement in an amount of 250-500 kg/m³ based on the total composition, calcined clay, aggregates, water, and at least one plasticizer, wherein the specific surface area according to BET of the calcined clay is > 20 m²/g, the weight ratio of the calcined clay and the hydraulic cement is 0.20-0.60, preferably 0.20-0.50, and one or more viscosity modifying admixtures are present in a total amount of 0-0.15 wt.-% based on the combined mass of the hydraulic cement and the calcined clay.

Thus, the invention is based on the idea to use calcined clay as a structuring agent. It was surprisingly found that by using calcined clay the need for traditional structuring agents can be minimized or eliminated. By minimizing or eliminating the use of traditional structuring agents, the environmental impact can be improved. At the same time the buildability is not only maintained, but further improved. According to the invention, the total amount of conventional viscosity modifying admixtures is limited to 0-0.15 wt.-% based on the combined mass of the hydraulic cement and the calcined clay. Preferably, the viscosity modifying admixture is present in an amount of 0-0.10 wt.-% based on the combined mass of the hydraulic cement and the calcined clay. More preferably, no viscosity modifying admixture is present at all in the fresh concrete or mortar composition.

As used herein, the term "viscosity modifying admixture" is as defined in European Standard EN-934-2 of August 2012, which is an admixture that limits segregation in fresh concrete or mortar, i.e. the separation of the concrete constituents as a function of their respective densities and weight, by improving cohesion. However, the term "viscosity modifying admixture" does not encompass calcined clay.

If the fresh concrete or mortar composition contains a viscosity modifying admixture, the same is preferably chosen from the group consisting of starch, modified starch, hydroxyethylcellulose, cellulose, HASE polymers (hydrophobically modified alkali-swellable emulsions) and ASE polymers (alkali-swellable emulsion).

In embodiments, wherein the fresh concrete or mortar composition does not contain any viscosity modifying admixture, the composition does not contain any admixture that would qualify as "viscosity modifying admixture" as defined in European Standard EN-934-2 of August 2012, with the exception of calcined clay. For example, in this embodiment, the fresh concrete or mortar composition does not contain any component from the group consisting of starch, modified starch, hydroxyethylcellulose, cellulose, HASE polymers (hydrophobically modified alkali-swellable emulsions) and ASE polymers (alkali-swellable emulsion).

Calcined clay, with a specific BET (Brunauer-Emmett-Teller) surface area greater than 20 m²/g, acts as a structuring agent, allowing the reduction or elimination of the use of traditional synthetic structuring agents, such as viscosity modifying agents. It was surprisingly found that the BET surface area of calcined clay impacts the buildability of the mix: the higher the BET surface area of calcined clay is, the higher the impact on better buildability of the mix. The BET specific surface area is measured according to the standard ISO 9277:2010.

Calcined clay increases the yield strength of the material, which is essential for the support and stability of the printed layers prior to the setting of the hydraulic binder. This increase in yield strength ensures the lower layers can effectively support the weight of upper layers, maintaining the structure's shape and integrity during construction.

An additional benefit of using calcined clay in the specified proportions is its ability to allow for a reduction in the content of hydraulic cement, in particular Portland cement, within the composition. This reduction directly contributes to lowering the CO2 footprint of the concrete or mortar, as the production of Portland cement is a significant source of carbon dioxide emissions.

The composition with calcined clay also shows improved behavior in terms of creep, leading to a material that exhibits less deformation over time under sustained loads. The strength of the bonding between layers is another aspect positively impacted by the inclusion of calcined clay. Enhanced interlayer bonding contributes to the overall structural integrity and load-bearing capacity of the 3D- printed construction, making the structure more resistant to external forces and stresses, thus enhancing its durability.

Due to the yield strength increasing effect brought about by the calcined clay, the presence or the addition of a setting accelerator is preferably excluded. A setting accelerator is understood to be an admixture that is added in order to reduce the initial setting time as defined in the European Standard EN-934-2 of August 2012.

According to the invention, the weight ratio of the calcined clay and the hydraulic cement is 0.20-0.60, preferably 0.20- 0.50. While calcined clay is beneficial for improving sustainability and certain mechanical properties when used in appropriate amounts, excessive levels can adversely impact the properties of the fresh concrete or mortar in 3D printing applications. Exceeding a ratio of 0.6 or even 0.5 can lead to a decrease in the workability of the fresh concrete or mortar. This is because the high specific surface area of the calcined clay particles in accordance with the present invention increases the water demand for achieving a given slump or flowability. Otherwise, the mix may become too stiff and not flow easily, making it more challenging to pump, extrude, or place during the 3D printing process. On the other hand, adding additional water to achieve the desired consistency could negatively affect the strength and durability of the hardened concrete or mortar due to the higher water-to-cement ratio. According to a preferred embodiment of the invention, water is present in an amount of 100-250 kg/m³ based on the total composition .

A preferred water/binder ratio is 0.35-0.50, in particular 0.4-0.50 .

In order to enhance the workability of the fresh concrete or mortar composition by reducing water demand, at least one plasticizer is preferably present in an amount of 0-1.5 wt.- %, preferably 0.15-1.5 wt.-%, based on the combined mass of the hydraulic cement and the calcined clay.

Preferably, the at least one plasticizer is chosen from the group consisting of phosphonate-based superplasticizers, polycarboxylate ether based superplasticizers (PCE), and hydrolysable polymers.

According to another preferred embodiment of the invention, the fresh concrete or mortar composition further comprises limestone in an amount of 50-200 kg/m³ based on the total composition. According to an alternative definition, the fresh concrete or mortar composition may preferably further comprise limestone in an amount of 0.35-0.45 wt.-% based on the combined mass of the hydraulic cement and the calcined clay.

Further, the fresh concrete or mortar composition may preferably comprise calcium sulfate, preferably in an amount of 2-6 wt.-% based on the combined mass of the hydraulic cement and the calcined clay. Preferably, the fresh concrete or mortar composition is obtained by using a LC3 cement (Limestone Calcined Clay Cement), comprising Portland cement, calcined clay, limestone and gypsum.

Alternatively, the fresh concrete or mortar composition does not contain added anhydrite, in order to prevent too rapid initial setting which would negatively affect the printability of the fresh concrete or mortar composition. For 3D-printing applications, in order to obtain a strong bonding strength between the deposited layers, it is beneficial to place a layer while the preceding layer is still fresh.

In order to ensure a good early age mechanical performance, the fresh concrete or mortar composition further comprises a defoaming agent. This results in a reduction of the entrained air. The defoaming agent may be added to the composition as a separate admixture or in the form of a superplasticizer that contains a defoaming agent.

Preferably, the defoaming agent is used in an amount so that the fresh concrete or mortar compositions contains less than 5 vol.-% of entrained air.

Generally speaking, any type of aggregates may be used in the fresh mortar or concrete composition of the invention. In order to enable a good extrudability and printability of the fresh mortar or concrete composition, a preferred embodiment of the invention provides that the aggregates consist of sand having a maximum particle size of 4 mm.

Preferably, the aggregates, are present in an amount of 1,200-1,400 kg/m³ based on the total composition. Preferably, the aggregates consist of sand having a maximum particle size of 4 mm and the sand is present in an amount of 1,200-1,400 kg/m³ based on the total composition. Limiting the amount of aggregates to not exceed 1,400 kg/m³ is favorable for achieving the degree of extrudability needed for 3d-printing applications .

According to the invention, the fresh concrete or mortar composition comprises a hydraulic cement in an amount of 250- 500 kg/m³ based on the total composition. A hydraulic cement is understood to be a hydraulic binder comprising at least 50 wt.-% of CaO and SiCy that sets due to a chemical hydration reaction between the dry ingredients and water. The hydraulic cement may contain other components in addition to CaO and SiO2- The hydraulic cement may be Portland cement. Various supplementary cementitious materials, such as, e.g., silica fume, granulated blast-furnace slag (gbfs), fly ash, natural pozzolans, calcined clays or ground limestone, may be added to Portland cement, in order to obtain Portland composite cements. The supplementary cementitious materials, typically between 10 and 50 wt.-% of the total weight of the hydraulic cement, are in most applications ground granulated blast furnace slag, fly ash, pozzolans, ground limestone or mixtures thereof.

Preferably, the hydraulic cement is Portland cement that may be mixed with any mineral addition described in the cement standard EN 197-1 of April 2012.

The hydraulic cement may also be a fine or an ultrafine cement, i.e. a hydraulic cement that is ground to a higher fineness than standard hydraulic cements. The fineness can for example be higher that 5000 cm²/g and reach values up to 13000 cm²/g or even 15000 cm²/g (expressed as cement Blaine fineness) .

Preferably, the hydraulic cement present in the fresh mortar or concrete composition consists of Portland cement, i.e. the fresh mortar or concrete does not contain any cementitious material other than Portland cement. Portland cement is a cement of the type CEM I as described according to the European EN 197-1 Standard of April 2012.

Other suitable cementitious materials that may be used in the invention comprise the cements of the types CEM II, CEM III, CEM IV or CEM V described according to the European EN 197-1 Standard of April 2012.

According to a second aspect, the invention refers to the use of the fresh concrete or mortar composition described above for 3D printing.

The fresh concrete or mortar composition of the invention achieves a yield strength development that is particularly suitable for 3D-printing applications. Preferably, the fresh concrete or mortar composition has a yield strength of 3-20 kPa, measured 30 minutes after the composition has been obtained by mixing the components of the composition, and before setting occurs. The yield strength is measured with a scissometer. A scissometer consists of a vane plunged into the material to be tested and to which an increasing torque is applied. When a failure occurs in the material, the vane starts to rotate, generally as the torque reaches its maximum value, which is considered as the characteristic value that is representative of the yield stress of the material. Further, the fresh concrete or mortar composition of the invention achieves a compressive strength development that is particularly suitable for 3D-printing applications.

Preferably, the fresh concrete or mortar composition has 3h compressive strength of < 3 MPa and/or a Id compressive strength of 5-12 MPa and/or a 2d compressive strength of 7-15 MPa. The compressive strength is measured according to European standard EN-196-1.

As mentioned earlier, it is important for 3D-printing application to prevent a too rapid initial setting of the fresh composition, in order to have a layer of the composition still being resh, when a subsequent layer is deposited thereon. Therefore, a preferred embodiment provides that the fresh concrete or mortar composition has an initial setting time of at least 60 minutes.

The initial setting time is defined in standard EN 196-3. According to the needle penetration test method disclosed in said standard, the beginning of the setting process ("initial setting") is identified, when the concrete paste - due to its stiffness - exerts a predefined resistance to a test needle that is penetrating into the paste. In particular, the initial setting time is the time period between the time water is added to the cement and the time at which a 1 mm square section needle fails to penetrate the cement paste, placed in the Vicat's mold 5 mm to 7 mm from the bottom of the mold.

According to another aspect, the invention provides a method of building structural and architectural components layer-by- layer, such as by means of 3D concrete or mortar printing, comprising the steps of: providing a fresh concrete or mortar composition according to the first aspect of the invention, and placing the fresh concrete or mortar composition through an outlet of a deposition head while moving the deposition head, in order to form a layer of fresh concrete or mortar, wherein successive layers of fresh concrete or mortar are placed on top of each other.

The invention will now be described in more detail with reference to the following exemplary embodiments. In the examples, the mix designs of a fresh mortar composition according to Table 1 were used.

• BL2000 is a limestone provided by Omya France

• Viscocrete 510P and Viscocrete 225 are PCE based superplasticizers provided by Sika.

• MasterGlenium 201 is a PCE based superplasticizer provided by BASF.

• Viscocrete-1LC3 is a PCE based superplasticizer provided by Sika.

• MasterCO2re is a PCE based superplasticizer provided by Master Builder Solutions.

• Mecellose Hiend is a cellulosic thickener provided by LOTTE Fine Chemical.

• Cimsil A55 is clay based viscosity modifying admixture provided by TOLSA S.A.

Reference mix designs: Ref 1, Ref 2 and Ref 3, refer to mix designs without calcined clay. The difference between Ref 1 and Ref 2 is the type of superplasticizer used. The difference between Ref 2 and Ref 3 is the type of aggregate used.

Mix A series: mix designs with the addition of calcined clay from Chateau Gontier (specific surface BET: 40m²/g).

- Mix Al, Mix A2, Mix A3, Mix A4, Mix A5: mix designs having different superplasticizer. No VMA (structuring agent) was used in contrast to the reference mix designs .

- Mix A6: the same superplasticizer was used as in mix A3, but with different aggregates.

- Mix A7: the same as Mix A6 except that gypsum and semihydrate were added for boosting early age strength development .

Mix B series: reference mix designs with the addition of calcined clay Soka (specific surface BET: 4m²/g). - Mix Bl: with reduced VMA addition compared with reference mix designs.

- Mix B2: without VMA, compared with Mix Bl, with a different aggregate.

- Mix B3: compared with Mix B2, the only difference is the addition of gypsum and hemihydrate.

Mix C: compared with Mix A series, Mix C has a reduced addition of calcined clay.

Mix D: compared with Mix A series, Mix D has two types of calcined clays, i.e. Chateau Gontier and Soka.

Key results and figures:

Figure 1 demonstrates that by substituting Portland cement with calcined clay, even without structuring agents (VMA, clay) that are used in Ref 1, equivalent (in the case of mix Bl) or faster (in the case of mix Al, mix C and mix D) yield strength development is observed. The yield strength development is influenced by:

- the type of calcined clay used. More specially the specific surface area of calcined clay used: the higher the specific surface, the faster the yield strength development .

- the dosage of calcined clay used: the higher the dosage, the faster the yield strength development. The calcined clay to cement mass ratio covered by these examples is from 0 to 0.5.

Figure 2 demonstrates that the yield strength development of a composition containing calcined clay can be controlled by the type and the dosage of superplasticizer used. Figure 3 demonstrates the yield strength development of mix designs with sulfate addition (mix A7, mix B3) are slightly higher than that of without sulfate addition (mix A6, mix B2).

Figure 4 shows the effect of the calcined clay addition on compressive strength development. A slight decrease in strength at 24 hours was observed for mix designs containing calcined clay, when compared with reference mix design; the decrease can be partially remediated by the addition of sulfate. For the strength at 7 days and later even higher strengths were observed (compare mix A6 and mix A7 with Ref 3). Comparing mix A6 and mix A7 with mix B2 and mix B3, one can conclude that the specific BET surface of the calcined clay has a significant impact on strength development.

Figure 5 shows the total shrinkage measured from Ref mix 1 and mix Al containing calcined clay, when drying starts at very early age, i.e. 24 hours after mixing. The graphs show a slightly higher total shrinkage at short term (up to 14 days), but a slightly lower total shrinkage at long term, starting from 14 days.

Figure 6 shows a significant lower embedded CO2 for the mix designs containing a calcined clay addition when compared to Ref 2.

Figure 7 illustrates the effectiveness of incorporating calcined clay (mix Al) in mitigating creep deformation. The data indicates a notable 35% reduction in the contact creep function when using mix Al. These findings are based on tests conducted at 28 days on paste samples, derived by excluding coarse aggregate from the initial mixtures. Given the consistent paste volume across the mixes, it is evident that mix Al exhibits a substantially lower creep compared to the reference mix Ref 1. This characteristic is particularly crucial for 3D printed concrete, which typically has a high paste content leading to increased creep. The improved creep resistance of mix Al is vital for 3D printing applications, allowing for optimized use and reduction of material quantities at the structural level. Such advancements hold significant potential for lowering the carbon footprint in the construction industry.

Creep data were obtained from a microidentation test according to the method described in Zhang, Q., Le Roy, R., Vandamme, M., & Zuber, B. (2014): "Long-term creep properties of cementitious materials: Comparing microindentation testing with macroscopic uniaxial compressive testing." in Cement and Concrete Research, 58, 89-98.

Splitting tensile strength tests Further, splitting tensile strength was assessed by performing splitting tensile strength tests following the procedure described below.

5cm cubes with interlayer bonding were created by the following procedure: prepare fresh mortar, fill in half of the mold and flat the top surface, fill the top half of the cubic mold after 15 minutes / 30 minutes and flat the upper surface. Cure sample in sealed condition up to 24 hours and unmold samples and place them in 20°C and 100% relative humidity curing chamber until cube splitting test.

The results presented in table 2 below demonstrate that calcined clay addition improves the interlayer strength after

60-120 min. Thereby the mix design including the calcined clay with higher surface area (mix A7) increases the strength notably compared to mix B7 using clay with lower surface area.

Table 2: splitting tensile strength of different mix designs.

Effect of calcined clay addition on entrained air

Effect of calcined clay on entrained air was investigated for selected mix designs.

It was found that the use of calcined clay in the formulation decreases the amount of entrained air. Furthermore, the choice of superplasticizer seems to play an additional role on the entrained air. The combination of calcined clay with MasterGlenium 201 (contains defoamer in the formulation) results in the lowest values of entrained air.

Claims

Claims:

1. A fresh concrete or mortar composition for 3D-printing comprising a hydraulic cement in an amount of 250-500 kg/m³ based on the total composition, calcined clay, aggregates, water, and at least one plasticizer, wherein the specific surface area according to BET of the calcined clay is > 20 m²/g, the weight ratio of the calcined clay and the hydraulic cement is 0.20-0.60, preferably 0.20-0.50, and one or more viscosity modifying admixtures are present in a total amount of 0-0.15 wt.-% based on the combined mass of the hydraulic cement and the calcined clay.

2. Fresh concrete or mortar composition according to claim 1, wherein water is present in an amount of 100-250 kg/m³ based on the total composition.

3. Fresh concrete or mortar composition according to claim

1 or 2, wherein the at least one plasticizer is present in an amount of 0-1.5 wt.-%, preferably 0.15-1.5 wt.-%, based on the combined mass of the hydraulic cement and the calcined clay.

4. Fresh concrete or mortar composition according to claim 1, 2 or 3, further comprising limestone in an amount of 50- 200 kg/m³ based on the total composition.

5. Fresh concrete or mortar composition according to any one of claims 1 to 4, wherein the viscosity modifying admixture is chosen from the group consisting of starch, modified starch, hydroxyethylcellulose, cellulose, HASE polymers (hydrophobically modified alkali-swellable emulsions) and ASE polymers (alkali-swellable emulsion).

6. Fresh concrete or mortar composition according to any one of claims 1 to 5, wherein the viscosity modifying admixture is present in an amount of 0-0.10 wt.-% based on the combined mass of the hydraulic cement and the calcined clay.

7. Fresh concrete or mortar composition according to any one of claims 1 to 6, wherein the fresh concrete or mortar composition does not contain any viscosity modifying admixture.

8. Fresh concrete or mortar composition according to any one of claims 1 to 7, wherein the at least one plasticizer is chosen from the group consisting of phosphonate-based superplasticizers, polycarboxylate ether based superplasticizers (PCE), and hydrolysable polymers.

9. Fresh concrete or mortar composition according to any one of claims 1 to 8, further comprising a defoaming agent.

10. Fresh concrete or mortar composition according to any one of claims 1 to 9, containing less than 5 vol.-% of entrained air.

11. Fresh concrete or mortar composition according to any one of claims 1 to 10, wherein the fresh concrete or mortar composition does not contain a setting accelerator.

12. Fresh concrete or mortar composition according to any one of claims 1 to 11, wherein the aggregates consist of sand having a maximum particle size of 4 mm.

13. Fresh concrete or mortar composition according to any one of claims 1 to 12, further comprising calcium sulfate, preferably in an amount of 2-6 wt.-% based on the combined mass of the hydraulic cement and the calcined clay.

14. Fresh concrete or mortar composition according to any one of claims 1 to 12, wherein the fresh concrete or mortar composition does not contain added anhydrite.

15. Fresh concrete or mortar composition according to any one of claims 1 to 14, wherein the fresh concrete or mortar composition has a yield strength of 3-20 kPa, measured 30 minutes after the composition has been obtained by mixing the components of the composition.

16. Fresh concrete or mortar composition according to any one of claims 1 to 15, wherein the fresh concrete or mortar composition has 3h compressive strength of < 3 MPa and/or a Id compressive strength of 5-12 MPa and/or a 2d compressive strength of 7-15 MPa.

17. Fresh concrete or mortar composition according to any one of claims 1 to 16, wherein the fresh concrete or mortar composition has an initial setting time of at least 60 minutes.

18. Fresh concrete or mortar composition according to any one of claims 1 to 17, wherein the aggregates are present in an amount of 1,200-1,400 kg/m³ based on the total composition.

19. Method of building structural and architectural components layer-by-layer, such as by means of 3D concrete or mortar printing, comprising the steps of: providing a fresh concrete or mortar composition according to any one of claims 1 to 18, placing the fresh concrete or mortar composition through an outlet of a deposition head while moving the deposition head, in order to form a layer of fresh concrete or mortar, wherein successive layers of fresh concrete or mortar are placed on top of each other.