WO2024110353A1

WO2024110353A1 - Dry mortar composition

Info

Publication number: WO2024110353A1
Application number: PCT/EP2023/082289
Authority: WO
Inventors: Mélanie ARANGALAGE; Yannick SALLIER; Joumana YAMMINE-MALESYS
Original assignee: Saint-Gobain Weber France
Priority date: 2022-11-21
Filing date: 2023-11-17
Publication date: 2024-05-30
Also published as: FR3142186A1

Abstract

The invention relates to a dry mortar composition comprising a hydraulic binder and aggregates, in which aggregates having a size of greater than or equal to 63 μm are in a proportion of at least 50% based on the total weight of aggregates. The aggregates having a size of greater than or equal to 63 μm have a roundness volume distribution such that the median value of the roundness is between 0.01 and 0.40, and the dry mortar composition has a particle size distribution by volume such that the D30/D95 ratio is between 4 and 15% and the D70/D95 ratio is between 60 and 72%.

Description

Dry mortar composition

The invention is located in the field of construction, more particularly in the field of mortars.

Dry mortar compositions are compositions comprising a hydraulic binder and aggregates. After mixing (“mixing”) with water, we obtain a paste (wet or fresh mortar) capable of being shaped and then hardening to form a hardened mortar. Such mortars can have various applications: facade coatings, tile adhesives, floor products such as screeds, pointing mortars, masonry mortars and many others.

Depending on the intended applications, dry mortar compositions must meet a large number of requirements, relating both to their ability to be implemented (spreadability, workability, workability, pumpability, rheology, etc.) and to the hardened mortar (in particular its mechanical strength, for example compressive strength).

For flooring products in particular, the spread of fresh mortar must be high in order to obtain self-leveling properties. For this, a high quantity of mixing water may be necessary, as well as the use of adjuvants, such as plasticizers and superplasticizers.

It is also important to reduce the environmental footprint of mortars, by reducing the quantities of cement and admixtures as well as the use of water and natural resources.

This is particularly the case for aggregates, generally sand and fillers, for which it may be interesting to use, rather than river sand, recycled aggregates, for example from demolition, or industrial by-products. , or even sand from rock crushing.

However, it appeared that this type of aggregate reduced the spreading of fresh mortar, requiring an increase in the quantity of mixing water, to the detriment of the mechanical properties of the hardened mortar, as well as the quantity of admixtures. This deterioration of mechanical properties requires increasing the hydraulic binder content, to the detriment of the carbon footprint of the mortar. It would seem that the slightest spreading comes from the difference in morphology between aggregates of the river sand type and aggregates resulting from crushing (whether from recycled products, industrial by-products or even rocks), the latter being at the times more angular and less spherical than river sands.

The aim of the invention is to obviate these drawbacks by proposing mortars with a lower environmental footprint, however having good spreading in the fresh state and good mechanical performance.

For this purpose the subject of the invention is a dry mortar composition comprising a hydraulic binder and aggregates, including aggregates having a size greater than or equal to 63 µm in a proportion of at least 50% relative to the total weight of aggregates. , said aggregates having a size greater than or equal to 63 µm having a volume distribution of rounding such that the median value of the rounding is between 0.01 and 0.40, and the dry mortar composition having a size distribution of particles by volume such that the D30/D95 ratio is between 4 and 15% and the D70/D95 ratio is between 60 and 72%.

The invention also relates to a hardened mortar, in particular a floor covering, obtained by mixing with water the dry mortar composition according to the invention to obtain a wet mortar, then hardening of said wet mortar.

The inventors were able to demonstrate that in the case of angular aggregates, a particular particle size distribution made it possible to optimize the spreading of the fresh mortar. It is thus possible, despite the use of such aggregates, to improve the mechanical properties of the hardened mortar by reducing the mixing water content or even to reduce the content of hydraulic binder and adjuvants for the same mechanical resistance.

The aggregates preferably include (or even consist of) sands (whose size is between 63 µm and 4 mm), or even sands and fillers (whose size is less than 63 µm).

Preferably, the dry mortar composition does not include particles larger than 4 mm. The mass proportion of aggregates having a size greater than or less than a given value, in particular 63 µm, is preferably determined by sieving.

Rounding (also called roundness ) characterizes the more or less angular side of the aggregate.

The median value of the volume distribution of the rounding (always for aggregates having a size greater than or equal to 63 µm) is preferably between 0.05 and 0.40, or even between 0.05 and 0.35, or between 0.10 and 0.30. The D90 of the volume distribution of the rounding is preferably at most 0.80, in particular at most 0.70, or even at most 0.60 and even at most 0.50. By “D90” we mean here the rounding value such that 90% of the volume of aggregates having a size greater than or equal to 63 µm has a rounding less than or equal to this value.

Preferably, the aggregates having a size greater than or equal to 63 µm also have a volume distribution of sphericity such that the median value of the sphericity is at most 0.90, in particular at most 0.85, or even at most. at most 0.80 and even at most 0.75. Sphericity characterizes the fact that the particle is more or less similar to a sphere.

The volume distributions of roundness and sphericity are determined in particular by dynamic image analysis, using for example the Camsizer X2 device (Retsch-Microtrac).

The total content of aggregates relative to the weight of dry mortar composition is preferably at least 50%, in particular at least 60% and even at least 70%, or even at least 80%. It is preferably at most 95%.

The proportion of aggregates having a size greater than or equal to 63 µm, relative to the total weight of aggregates, is preferably between 50 and 95%, or between 55 and 90%, in particular between 60% and 85%, or even between 70 and 80%.

In order to optimize the spreading of the fresh mortar, the distribution of particle sizes by volume of the dry mortar composition preferably presents at least one of the following characteristics, according to all possible combinations, or even all of these characteristics :
D20/D95 from 1.0 to 5.0%, notably from 1.5 to 3.0%
D30/D95 from 5 to 15%, notably from 6 to 10%
D40/D95 from 10 to 25%, notably from 14 to 20%
D50/D95 from 17 to 40%, notably from 20 to 38%
D60/D95 from 34 to 60%, notably from 40 to 58%
D70/D95 from 62 to 70%, notably from 63 to 68%.

As is customary in the art, “DX” corresponds to the particle size such that X% of the particle volume has a size less than or equal to this value. In order to calculate the values of D30, D70 and D95, or more generally any value of “DX”, the volume distribution of particle sizes is preferably determined by dynamic image analysis (in particular according to the ISO 13322-2 standard) . The measurement is carried out in particular using a Camsizer X2 device (Retsch-Microtrac), the quantity considered being X _c Min, also called “ minimum chord diameter”. To carry out the measurement, the particles are suspended in the air.

The aggregates, in particular aggregates having a size greater than or equal to 63 µm, preferably comprise recycled aggregates, for example from the demolition of buildings or infrastructure, industrial by-products, and/or sand from crushing Rock. This may, for example, be crushed demolition waste, foundry sand and/or crushed glass. Demolition waste is, for example, pieces of concrete, mortar, gypsum or even glass. These different materials are generally crushed in order to reach the desired sizes, and therefore have little roundness and sphericity. In other words, they are angular and rather elongated, unlike river sand particles. The proportion of these materials is preferably at least 50%, or even at least 60%, relative to the weight of aggregates.

The fillers are preferably chosen from limestone fillers and dolomitic fillers.

The total content of hydraulic binder relative to the weight of dry mortar composition is preferably between 1 and 40%, in particular between 5 and 30%, or even between 10 and 20%.

The hydraulic binder can be a mixture of several hydraulic binders.

The hydraulic binder is preferably chosen from Portland cements, aluminous cements, sulphoaluminous cements, hydrated lime, slags (in particular crushed granulated blast furnace slags), fly ash and mixtures of two or more of these compounds. . Portland cements include CEM I and CEM II type cements as defined by standard EN 197-1. A CEM I cement comprises at least 95% clinker while a CEM II cement comprises at least 65% clinker and at most 35% blast furnace slag, silica fume, pozzolan, fly ash, calcined shale and/or limestone.

The hydraulic binder preferably consists of Portland cement, or is a mixture consisting of Portland cement, aluminous cement and a source of calcium sulfate, such as plaster, hemihydrate or anhydrite, optionally with added slag. of crushed granulated blast furnace.

In a preferred embodiment, the hydraulic binder consists of Portland cement, aluminous cement and a source of calcium sulfate. The binder then preferably comprises 5 to 40% Portland cement, 20 to 80% aluminous cement and 10 to 50% of a source of calcium sulfate, relative to the weight of hydraulic binder. Such binders are particularly suitable for producing self-leveling floor products, for example screeds.

The dry mortar composition preferably comprises additives, in particular in a content ranging from 0.1 to 10% relative to the weight of dry mortar composition.

These additives are chosen in particular from plasticizers, superplasticizers, accelerators, retarders, defoaming agents, stabilizing agents, redispersible polymer powders, shrinkage reducing agents, rheology agents and water reducing agents.

Accelerators are, for example, alkaline salts, such as sulfates or lithium (or potassium) carbonates, or organic salts such as calcium formate. The total amount of accelerators is preferably 0.001 to 0.5% by weight. The retarders are for example carboxylic acids such as tartaric or citric acids or their salts. The total quantity of retarders is preferably 0.01 to 1.0% by weight relative to the weight of dry mortar composition. The dry mortar composition preferably includes both accelerators and retarders in order to properly control the setting and hardening of the hydraulic binder.

The stabilizing and water-retaining agents preferably include cellulose ethers. Their content is preferably 0.05 to 1.0% by weight relative to the weight of dry mortar composition.

The redispersible polymer powders are preferably obtained from at least one monomer chosen from vinyl esters (in particular vinyl esters of carboxylic acids, branched or not, comprising from 1 to 15 carbon atoms), (meth )acrylates (in particular (meth)acrylates of alcohols comprising 1 to 10 carbon atoms), (meth)acrylic acids, aromatic vinyls, alkenes such as ethylene or propylene, dienes and halides vinyl. In particular, the redispersible polymer powders suitable for the invention are chosen from polymer powders obtained from at least two of the monomers mentioned above, preferably from powders of copolymers chosen from: vinyl acetate-ethylene copolymers , vinyl ester-ethylene-vinyl chloride copolymers, vinyl acetate copolymers, vinyl acetate-acrylate copolymers, copolymers of methyl methacrylate with n-butyl acrylate and/or 2-ethylhexyl acrylate , copolymers of methyl methacrylate with 1,3-butadiene, vinyl chloride-ethylene copolymers, vinyl chloride-acrylate copolymers, styrene-butadiene copolymers, styrene-acrylate copolymers, vinyl acetate-(meth)acrylic acid-ethylene terpolymers . Their content is preferably 0.2 to 10% by weight, in particular 0.5 to 5% by weight relative to the weight of dry mortar composition.

The dry mortar composition according to the invention can be mixed with water in order to obtain a wet mortar, then after hardening a hardened mortar.

The mixing rate, that is to say the weight of water relative to the weight of dry mortar composition, is preferably between 8% and 28%.

Curing is preferably done in air and at room temperature, therefore without heating or cooling.

The hardened mortar is in particular a floor covering, for example a screed. These are most often interior floors (located inside the building), but they can also be exterior floors (part of the building but located outside it, such as floors of balconies or terraces). The floor covering preferably has a thickness of between 2 and 10 cm, in particular between 3 and 8 cm.

Alternatively, the hardened mortar can be a facade coating, an adhesive, for example a tile adhesive, or even a joint.

Examples

The examples which follow illustrate the invention in a non-limiting manner.

Different dry mortar compositions were obtained by mixing 13% CEM I 52.5 N cement, 0.1% additives (superplasticizers, thickener and viscosity regulating agent) and 87% aggregates.

The aggregates contained two types of sand (maximum size 4 mm) as well as limestone fillers.

The sands had a median roundness (D50 in volume distribution) of 0.35 and a median sphericity of 0.84. These were therefore relatively angular sands.

In order to obtain different particle size distributions, these sands and fillers were mixed in different proportions. The mixing rate was 11% relative to the weight of dry mortar composition.

Table 1 below indicates for each of the compositions tested the proportion “P” of sand relative to the weight of aggregates, the volume distribution of particle sizes (size X _c min, values from D10 to D95, indicated in µm) determined by dynamic image analysis using a Camsizer ring 68 mm in diameter and 35 mm in height.

	C1C1	11	22	33	44	C2C2
PP	64%64%	75%75%	76%76%	78%78%	80%80%	87%87%
D10D10	77	1313	1616	1717	1717	2020
D20D20	1616	3535	7171	8585	7777	320320
D30D30	8484	198198	298298	308308	342342	672672
D40D40	278278	415415	560560	574574	658658	13721372
D50D50	495495	782782	11091109	12261226	12981298	19751975
D60D60	961961	15571557	18291829	19201920	20042004	24312431
D70D70	15571557	22812281	24892489	24602460	24962496	27102710
D80D80	21542154	27672767	29432943	28972897	28352835	29832983
D90D90	26542654	33333333	32463246	33003300	32503250	32553255
D95D95	28182818	36783678	34403440	35173517	35353535	35893589
EE	112112	145145	164164	169169	160160	120120

It appears from the table that comparative examples C1 and C2, which have particle size distributions which are not in accordance with the invention, have a significantly lower spreading than examples 1 to 4 according to the invention. To achieve, in the case of the comparative examples, spreading values similar to those obtained for the examples according to the invention, the mixing rate must be increased to values of 13 to 15%, to the detriment of the mechanical resistance of the hardened mortar.

Similar results were obtained by replacing the sand with cullet (crushed glass) having a median rounding of 0.09 and a median sphericity of 0.72. Spread values were 90 to 100 mm for particle size distributions outside the invention, compared to 120 to 140 mm for particle size distributions according to the invention.

Claims

Dry mortar composition comprising a hydraulic binder and aggregates, including aggregates having a size greater than or equal to 63 µm in a proportion of at least 50% relative to the total weight of aggregates, said aggregates having a size greater than or equal to 63 µm having a volume distribution of rounding such that the median value of the rounding is between 0.01 and 0.40, and the dry mortar composition having a particle size distribution by volume such that the ratio D30/ D95 is between 4 and 15% and the D70/D95 ratio is between 60 and 72%.
Composition according to claim 1, which does not include particles larger than 4 mm.
Composition according to one of the preceding claims, such that the median value of the rounding of aggregates having a size greater than or equal to 63 µm is between 0.05 and 0.35, in particular between 0.10 and 0.30.
Composition according to one of the preceding claims, such that the aggregates having a size greater than or equal to 63 µm also have a volume distribution of sphericity such that the median value of the sphericity is at most 0.90, in particular at most 0.85.
Composition according to one of the preceding claims, in which the total content of aggregates relative to the weight of dry mortar composition is at least 50%, in particular at least 80%.
Composition according to one of the preceding claims, in which the proportion of aggregates having a size greater than or equal to 63 µm, relative to the total weight of aggregates, is between 50 and 90%, in particular between 60% and 85%.
Composition according to one of the preceding claims, in which the aggregates, in particular aggregates having a size greater than or equal to 63 µm, comprise recycled aggregates, for example from the demolition of buildings or infrastructures, industrial by-products and/or sand from rock crushing.
Composition according to the preceding claim, in which the recycled aggregates are chosen from crushed demolition waste, foundry sands and crushed glass.
Composition according to one of the preceding claims, in which the total content of hydraulic binder relative to the weight of dry mortar composition is between 1 and 40%, in particular between 5 and 30%.
Composition according to one of the preceding claims, in which the hydraulic binder is chosen from Portland cements, aluminous cements, sulphoaluminous cements, hydrated lime, slags, fly ash and mixtures of two or more of these compounds.
Composition according to the preceding claim, in which the hydraulic binder consists of Portland cement, or is a mixture consisting of Portland cement, aluminous cement and a source of calcium sulfate.
Composition according to one of the preceding claims, such that the distribution of particle sizes by volume of the dry mortar composition has at least one of the following characteristics:
- D20/D95 from 1.0 to 5.0%
- D40/D95 from 10 to 25%
- D50/D95 from 17 to 40%
- D60/D95 from 34 to 60%.
Composition according to one of the preceding claims, further comprising additives chosen from plasticizers, superplasticizers, accelerators, retarders, defoaming agents, stabilizing agents, redispersible polymer powders, shrinkage reducing agents, agents rheology and water reducing agents.
Hardened mortar, in particular floor covering, obtained by mixing with water the dry mortar composition according to one of the preceding claims to obtain a wet mortar, then hardening of said wet mortar.
Hardened mortar according to the preceding claim, which is a floor covering, in particular a screed.