Supplementary cementitious material comprising crude perlite

Abstract

The present invention refers to a supplementary cementitious material comprising crude perlite, a product comprising the supplementary cementitious material in an amount of ≥ 0.5 wt.-%, based on the total weight of the product, a hardened article prepared from the product as well as a method of preparing the hardened article and the use of crude perlite as supplementary cementitious material in concrete or mortar.

Description

[0001] Supplementary cementitious material comprising crude perlite

[0002] The present invention refers to a supplementary cementitious material comprising crude perlite, a product comprising the supplementary cementitious material in an amount of > 0.5 wt.-%, based on the total weight of the product, a hardened article prepared from the product as well as a method of preparing the hardened article and the use of a crude perlite as supplementary cementitious material in concrete or mortar.

[0003] Technological background

[0004] Since centuries, supplementary cementitious materials (SCMs) are added to cement to prepare concrete or mortar for enhancing various properties such as mechanical, processing, and structural properties or for replacing cement in order to reduce costs or the carbon footprint. Also today, natural pozzolans such as volcanic ashes, tuffs, diatomaceous earth and the like are used as SCMs and standards exist, e.g. EN197. For example, ordinary Portland Cement has a high carbon footprint, mainly originating from clinker. Thus, the reduction of clinker by supplementary cementitious materials (SCM) is the main strategy to reduce the carbon footprint of concrete today. However, traditional SCMs such as fly ash or granulated blast furnace slag become more and more scarce. Furthermore, such natural pozzolans usually suffer from a high water and / or superplasticizer demand which is a clear disadvantage in cement / concrete / mortar technology.

[0005] In the art, several approaches of using natural pozzolans as supplementary cementitious materials in cement are disclosed. For example, WO17171808 A1 refers to a cement composition comprising water; a cement; and a slag co-grind comprising slag and a cement component. The cement component is selected from the group consisting of metakaolin, shale, perlite, pozzolan, zeolite, aluminum silicate, wollastonite, and combinations thereof. It is further described that the slag co-grind has a particle size of about 1 nanometer to about 1 micron. WO12085509 A1 refers to a settable composition comprising ground unexpanded perlite; cement kiln dust; and water.

[0006] However, there is still a need in the art for an effective and efficient supplementary cementitious material which can be used in cement, concrete or mortar. More precisely, there is a need for a supplementary cementitious material that provides a sufficient water and / or superplasticizer demand. Furthermore, there is a need for a supplementary cementitious material that provides a sufficient pozzolanic reactivity index.

[0007] Accordingly, it is an objective of the present invention to provide a supplementary cementitious material for use with cement in concrete or mortar. It is a further objective of the present invention to provide a supplementary cementitious material providing a low water demand. Furthermore, it is an object of the present invention to provide a supplementary cementitious material providing a low superplasticizer demand. It is a further object of the present invention that the supplementary cementitious material provides a sufficient pozzolanic reactivity.

[0008] These and other objectives of the present invention can be solved by the inventive supplementary cementitious material, the product comprising the supplementary cementitious material, the hardened article prepared from the product as well as the method of preparing the hardened article and the use of a crude perlite as supplementary cementitious material in cement, concrete or mortar. Summary of the invention

[0009] According to one aspect of the present invention, a supplementary cementitious material is provided. The supplementary cementitious material comprises crude perlite having a volume median particle size cfeo of < 6 pm, as determined by las diffraction, and a BET specific surface area of > 1 .4 m2 / g, measured using nitrogen and the BET method according to ISO 9277:2010.

[0010] A second aspect of the present invention relates to a product, preferably a concrete or mortar, comprising the supplementary cementitious material in an amount of > 0.5 wt.-%, based on the total weight of the product.

[0011] A third aspect of the present invention relates to a hardened article prepared from the product.

[0012] A fourth aspect of the present invention relates to a method of preparing the hardened article according to claim 12, wherein the method comprises the steps of a) mixing the supplementary cementitious material as defined herein with cement and water, and b) hardening the product obtained in step a) to form the hardened article.

[0013] A fifth aspect of the present invention relates to the use of a crude perlite as supplementary cementitious material in concrete or mortar, wherein the crude perlite has a volume median particle size cfeo of < 6 pm, as determined by laser diffraction, and a BET specific surface area of > 1 .4 m2 / g, measured using nitrogen and the BET method according to ISO 9277:2010.

[0014] The inventors surprisingly found out that crude perlite is a very suitable supplementary cementitious material in concrete or mortar. Furthermore, the use of the supplementary cementitious material results in a comparable or equal water demand of the obtained concrete or mortar. More precisely, the concrete or mortar including the crude perlite of the present invention as supplementary cementitious material provides a water demand that is comparable to the same concrete or mortar being free of the crude perlite. Furthermore, the use of the supplementary cementitious material with cement results in a comparable or equal superplasticizer demand of the obtained concrete or mortar. More precisely, the concrete or mortar including the crude perlite of the present invention as supplementary cementitious material provides a superplasticizer demand that is below the same concrete or mortar comprising metakaolin or silica fume instead of crude perlite as supplementary cementitious material. Furthermore, the use of the supplementary cementitious material with cement results in a satisfying pozzolanic reactivity index of the obtained concrete or mortar. More precisely, the crude perlite provides a pozzolanic reactivity index of at least 82 % if used with cement in concrete or mortar.

[0015] Advantageous embodiments of the present invention can be found in the corresponding dependent claims.

[0016] In one embodiment of any one of the aspects of the present invention, the crude perlite has a a volume median particle size cfeo of < 4 pm, preferably < 3 pm and most preferably in the range from 2 to 3 pm, as determined by laser diffraction, and a BET specific surface area of > 2.0 m2 / g, preferably > 2.5 m2 / g and most preferably in the range from 3 to 5 m2 / g, measured using nitrogen and the BET method according to ISO 9277:2010.

[0017] In another embodiment of any one of the aspects of the present invention, the crude perlite has a top cut particle size da of < 250 pm, preferably < 200 pm, more preferably < 150 pm, and most preferably < 125 pm, as determined by laser diffraction.

[0018] In yet another embodiment of any one of the aspects of the present invention, the crude perlite comprises silica in an amount ranging from 50 to 75 wt.-%, based on the total weight of the perlite, and alumina in an amount ranging from 10 to 20 wt.-%, based on the total weight of the perlite.

[0019] In one embodiment of any one of the aspects of the present invention, the crude perlite comprises sodium oxide in an amount ranging from 3 to 5 wt.-%, based on the total weight of the perlite, and / or potassium oxide in an amount ranging from 4 to 5 wt.-%, based on the total weight of the perlite, and / or iron(lll) oxide in an amount ranging from 0.5 to 2 wt.-%, based on the total weight of the perlite, and / or calcium oxide in an amount ranging from 0.5 to 1 wt.-%, based on the total weight of the perlite.

[0020] In another embodiment of any one of the aspects of the present invention, the crude perlite comprises an amorphous fraction as determined by X-Ray Diffraction of > 70 wt.-%, preferably from 75 to 99 wt.-%, more preferably from 80 to 99 wt.-% and most preferably from 90 to 99 wt.-%, based on the total weight of the perlite.

[0021] In yet another embodiment of any one of the aspects of the present invention, the crude perlite is unexpanded.

[0022] In one embodiment of any one of the aspects of the present invention, the material consists of the crude perlite.

[0023] In one embodiment of the product of the present invention, the product comprises the supplementary cementitious material in an amount ranging from 0.5 to 20 wt.-%, based on the total weight of the product, preferably from 1 to 20 wt.-%, more preferably from 1 to 15 wt.-% and most preferably from 1 to 10 wt.-%.

[0024] In another embodiment of the product of the present invention, the product further comprising water, sand, aggregate(s), filler(s), chemical admixture(s) such as superplasticizer(s), retardant(s) or accelerator(s), and the like, optionally further comprising one or more of fibers, pigments, lightweight fillers and the like.

[0025] In one embodiment of the use of the present invention, the concrete or mortar including the crude perlite provides a water demand that is comparable to the same concrete or mortar being free of the crude perlite and / or a superplasticizer demand that is below the same concrete or mortar comprising metakaolin or silica fume instead of crude perlite as supplementary cementitious material and / or the crude perlite provides a pozzolanic reactivity index of at least 82 %.

[0026] Where an indefinite or definite article is used when referring to a singular noun, e.g., “a”, “an” or “the”, this includes a plural of that noun unless anything else is specifically stated.

[0027] Where the term “comprising” is used in the present description and claims, it does not exclude other elements. For the purposes of the present invention, the term “consisting of’ is considered to be a preferred embodiment of the term “comprising”. If hereinafter a group is defined to comprise at least a certain number of embodiments, this is also to be understood to disclose a group, which preferably consists only of these embodiments.

[0028] Whenever the terms “including” or “having” are used, these terms are meant to be equivalent to “comprising” as defined hereinabove.

[0029] Terms like “obtainable” or “definable” and “obtained” or “defined” are used interchangeably. This, for example, means that, unless the context clearly dictates otherwise, the term “obtained” does not mean to indicate that, for example, an embodiment must be obtained by, for example, the sequence of steps following the term “obtained” though such a limited understanding is always included by the terms “obtained” or “defined” as a preferred embodiment.

[0030] When in the following reference is made to embodiments or technical details of the inventive paper filler, it is to be understood that these embodiments or technical details also refer to the inventive product, article and method as well as the inventive use.

[0031] The supplementary cementitious material

[0032] The inventive supplementary cementitious material comprises crude perlite. The crude perlite has a volume median particle size cfeo of < 6 pm, as determined by laser diffraction, and a BET specific surface area of > 1 .4 m2 / g, measured using nitrogen and the BET method according to ISO 9277:2010.

[0033] It is appreciated that the perlite is crude perlite and thus is unexpanded.

[0034] It is preferred that the crude perlite is a ground crude perlite. The crude perlite, i.e. the ground crude perlite, can be prepared by methods well known in the art. Furthermore, the skilled person is well aware of methods and techniques for adjusting the particle size distribution and BET specific surface area according to his specific needs. For example, the perlite, i.e. the ground crude perlite, can be prepared by milling the crude perlite to the desired particle size distribution. Such milling can be carried out in any equipment known to the skilled person, e.g. including ball mills, stirred media mills, jet mills, and roller mills. The milling can be carried out in form of a dry or wet milling. The milling of the crude perlite may be carried out in conjunction with a classification in order to obtain the claimed ground crude perlite.

[0035] It is appreciated that a sufficient pozzolanic reactivity is observed for crude perlite having a volume median particle size cfeo of < 7 pm, and especially < 6 pm. Thus, the crude perlite has a volume median particle size cfeo of < 6 pm, even more preferably of < 4 pm and most preferably of < 3 pm, as determined by laser diffraction.

[0036] Furthermore, it is appreciated that a sufficient pozzolanic reactivity is observed for crude perlite having a volume median particle size cfeo of > 0.1 pm. In one embodiment, the crude perlite has a volume median particle size cko of > 0.1 pm, more preferably of > 0.5 pm, even more preferably of > 1 pm and most preferably of > 2 pm, as determined by laser diffraction.

[0037] It is thus preferred that the crude perlite has a volume median particle size cfeo in the range from 0.1 to 6 pm, more preferably in the range from 0.5 to 6 pm, even more preferably in the range from 1 to 4 pm and most preferably in the range from 2 to 3 pm, as determined by the laser diffraction. For example, the crude perlite preferably has a volume median particle size cfeo in the range from 0.1 to 6 pm, more preferably in the range from 0.5 to 6 pm, even more preferably in the range from 1 to 6 pm and most preferably in the range from 2 to 6 pm, as determined by the laser diffraction. Alternatively, the crude perlite has a volume median particle size cfeo in the range from 0.1 to 4 pm, more preferably in the range from 0.5 to 4 pm, even more preferably in the range from 1 to 4 pm and most preferably in the range from 2 to 4 pm, as determined by the laser diffraction. Alternatively, the crude perlite has a volume median particle size cfeo in the range from 0.1 to 3 pm, more preferably in the range from 0.5 to 3 pm, even more preferably in the range from 1 to 3 pm and most preferably in the range from 2 to 3 pm, as determined by the laser diffraction.

[0038] In this regard, US2018251403 A1 refers to a method for well cementing, the method comprising: supplying a settable composition comprising a cement composition and water into a well bore; and allowing the settable composition to set to form hardened concrete, wherein the cement composition comprises a hydraulic cement and natural glass, and wherein the hardened concrete has a strength activity index of at least 125%. Unexpanded perlite having a doo of 10.64 pm is used in sample 1 of the examples as natural glass. Thus, good pozzolanic reactivity as for the present invention cannot be observed with such an unexpanded perlite.

[0039] Additionally or alternatively, the crude perlite has a BET specific surface area of > 2.0 m2 / g, preferably > 2.5 m2 / g and most preferably > 3.0 m2 / g, measured using nitrogen and the BET method according to ISO 9277:2010.

[0040] In one embodiment, the crude perlite has a BET specific surface area of < 20.0 m2 / g, preferably < 10.0 m2 / g and most preferably < 5.0 m2 / g, measured using nitrogen and the BET method according to ISO 9277:2010.

[0041] It is thus preferred that the crude perlite has a BET specific surface area in the range from 2.0 to 20.0 m2 / g, preferably in the range from 2.5 to 10.0 m2 / g and most preferably in the range from 3.0 to 5.0 m2 / g, measured using nitrogen and the BET method according to ISO 9277:2010.

[0042] For example, the crude perlite has a a volume median particle size cfeo of < 6 pm, preferably < 4 pm, more preferably < 3 pm and most preferably in the range from 2 to 3 pm, as determined by laser diffraction, and a BET specific surface area of > 2.0 m2 / g, preferably > 2.5 m2 / g and most preferably in the range from 3 to 5 m2 / g, measured using nitrogen and the BET method according to ISO 9277:2010.

[0043] It is appreciated that the specific combination of the volume median particle size cfeo and the BET specific surface area of the crude perlite results in a supplementary cementitious material providing a water demand that is comparable to the same concrete or mortar being free of the crude perlite and / or a superplasticizer demand that is below the same concrete or mortar comprising metakaolin or silica fume instead of crude perlite as supplementary cementitious material . Furthermore, the specific combination of the volume median particle size cko and the BET specific surface area of the crude perlite results in a supplementary cementitious material providing a pozzolanic reactivity index of at least 82 %.

[0044] In one embodiment, the crude perlite has a top cut particle size daa of < 250 pm as determined by laser diffraction.

[0045] Thus, it is appreciated that the crude perlite of the present invention preferably has a volume median particle size dso of < 6 pm, as determined by laser diffraction, a BET specific surface area of > 1 .4 m2 / g, measured using nitrogen and the BET method according to ISO 9277:2010, and a top cut particle size daa of < 250 pm as determined by laser diffraction.

[0046] It is further preferred that the crude perlite has a top cut particle size daa of < 250 pm, preferably < 200 pm and more preferably < 150 pm, as determined by laser diffraction. For example, the crude perlite has a top cut particle size daa of < 125 pm, as determined by laser diffraction.

[0047] It is preferred that the crude perlite is a relatively fine material. Thus, it is preferred that the crude perlite has a top cut particle size daa of > 4 pm, preferably > 8 pm and more preferably > 12 pm, as determined by laser diffraction.

[0048] In one embodiment, the crude perlite thus has a top cut particle size daa in the range from 4 to 250 pm, preferably in the range from 8 to 200 pm and more preferably in the range from 12 to 150 pm, as determined by the laser diffraction. For example, the crude perlite has a top cut particle size daa in the range from 20 to 125 pm, as determined by laser diffraction.

[0049] In view of the above, the crude perlite preferably has a a volume median particle size dso of < 6 pm, preferably < 4 pm, more preferably < 3 pm and most preferably in the range from 2 to 3 pm, as determined by laser diffraction, and a BET specific surface area of > 2.0 m2 / g, preferably > 2.5 m2 / g and most preferably in the range from 3 to 5 m2 / g, measured using nitrogen and the BET method according to ISO 9277:2010, and a top cut particle size daa of < 250 pm, preferably < 200 pm, more preferably

[0050] < 150 pm, and most preferably < 125 pm, as determined by laser diffraction.

[0051] In one embodiment, it may be advantageous to provide a crude perlite having a specific particle size cho value as this may affect the viscosity of the product to be prepared. For example, the crude perlite has a particle size cho of < 3 pm, preferably < 2 pm, more preferably < 1 pm, and most preferably in the range from 0.2 to 1 pm, as determined by laser diffraction.

[0052] Additionally or alternatively, the crude perlite may have a specific ratio of volume median particle size dso to particle size cho [cfeo / c / 10]. For example, the ratio of volume median particle size dso to particle size cho [cfeo / c / 10] of the crude perlite ranges from 1 to 12, preferably from 1 .5 to 10 and most preferably from 2 to 9.

[0053] Throughout the present document, the “particle size” of crude perlite is described by its distribution of particle sizes on a volume base. Volume determined median grain diameter dso (or cfeo(vol)), the particle size cho (or dio(vol)) and the top cut particle size daa (or cfo8(vol)) was evaluated using a Malvern Panalytical Mastersizer 3000 with particle dispersion in air with the Aero S accessory. The cfeo(vol), dio(vol) or cfo8(vol) value indicates a diameter value such that 50 %, 10 % or 98 % by volume, respectively, of the particles have a diameter of less than this value. The methods and instruments are known to the skilled person and are commonly used to determine particle size distributions of fillers and pigments. It is appreciated that the crude perlite is considered a “natural amorphous aluminosilicate”, more preferably a “volcanic glass”, and most preferably a “hydrated volcanic glass”.

[0054] Crude perlite is typically formed by rapid cooling of siliceous magma or lava and is distinguished from other volcanic glasses by its relative high amount of water ranging up to 10 wt.-%, based on the total weight of the crude perlite.

[0055] The crude perlite of the present invention preferably comprises a high amount of silica and alumina. The total amount of silica and alumina in the crude perlite is preferably ranging from 60 to 95 wt.-%, based on the total weight of the perlite. For example, the total amount of silica and alumina in the crude perlite is ranging from 70 to 95 wt.-%, preferably from 75 to 90 wt.-% and most preferably ranging from 80 to 90 wt.-%, based on the total weight of the perlite.

[0056] It is appreciated that the amount of silica is higher than the amount of alumina in the crude perlite. For example, the ratio of the amount of silica to the amount of alumina in the crude perlite [silica(wt.-%) / alumina(wt.-%)] is from 2:1 to 10:1 , preferably from 3:1 to 9:1 , more preferably from 4:1 to 8:1 , even more preferably from 4:1 to 7:1 and most preferably from 5:1 to 6:1 .

[0057] In one embodiment, the crude perlite comprises silica in an amount ranging from 50 to 75 wt.-%, based on the total weight of the perlite. For example, the crude perlite comprises silica in an amount ranging from 55 to 75 wt.-%, preferably from 60 to 75 wt.-%, more preferably from 65 to 75 wt.-% and most preferably from 70 to 75 wt.-%, based on the total weight of the perlite.

[0058] In addition thereto, the crude perlite comprises alumina in an amount ranging from 10 to 20 wt.-%, based on the total weight of the perlite. For example, the crude perlite comprises alumina in an amount ranging from 10 to 18 wt.-%, preferably from 10 to 16 wt.-%, more preferably from 12 to 16 wt.-% and most preferably from 12 to 15 wt.-%, based on the total weight of the perlite.

[0059] Thus, the crude perlite preferably comprises silica in an amount ranging from 50 to 75 wt.-%, based on the total weight of the perlite, and alumina in an amount ranging from 10 to 20 wt.-%, based on the total weight of the perlite.

[0060] For example, the crude perlite comprises silica in an amount ranging from 55 to 75 wt.-%, preferably from 60 to 75 wt.-%, more preferably from 65 to 75 wt.-% and most preferably from 70 to 75 wt.-%, based on the total weight of the perlite, and alumina in an amount ranging from 10 to 18 wt.-%, preferably from 10 to 16 wt.-%, more preferably from 12 to 16 wt.-% and most preferably from 12 to 15 wt.-%, based on the total weight of the perlite.

[0061] In one embodiment, the crude perlite comprises silica in an amount ranging from 70 to 75 wt.- %, based on the total weight of the perlite, and alumina in an amount ranging from 12 to 15 wt.-%, based on the total weight of the perlite.

[0062] The crude perlite preferably further comprises minor amounts of other components. For example, the crude perlite may comprise minor amounts of sodium oxide, potassium oxide, iron(lll) oxide, calcium oxide and mixtures thereof. In one embodiment, the crude perlite further comprises sodium oxide, preferably in an amount ranging from 3 to 5 wt.-%, based on the total weight of the perlite.

[0063] In this embodiment, the crude perlite comprises silica in an amount ranging from 50 to 75 wt.-%, based on the total weight of the perlite, alumina in an amount ranging from 10 to 20 wt.-%, based on the total weight of the perlite, and sodium oxide in an amount ranging from 3 to 5 wt.-%, based on the total weight of the perlite.

[0064] In one embodiment, the crude perlite further comprises potassium oxide, preferably in an amount ranging from 4 to 5 wt.-%, based on the total weight of the perlite.

[0065] In this embodiment, the crude perlite comprises silica in an amount ranging from 50 to 75 wt.-%, based on the total weight of the perlite, alumina in an amount ranging from 10 to 20 wt.-%, based on the total weight of the perlite, and potassium oxide in an amount ranging from 4 to 5 wt.-%, based on the total weight of the perlite.

[0066] In another embodiment, the crude perlite further comprises sodium oxide and potassium oxide.

[0067] In this embodiment, the crude perlite comprises silica in an amount ranging from 50 to 75 wt.-%, based on the total weight of the perlite, alumina in an amount ranging from 10 to 20 wt.-%, based on the total weight of the perlite, sodium oxide in an amount ranging from 3 to 5 wt.-%, based on the total weight of the perlite, and potassium oxide in an amount ranging from 4 to 5 wt.-%, based on the total weight of the perlite.

[0068] Additionally or alternatively, the crude perlite further comprises iron(lll) oxide, preferably in an amount ranging from 0.5 to 2 wt.-%, based on the total weight of the perlite.

[0069] In this embodiment, the crude perlite comprises silica in an amount ranging from 50 to 75 wt.-%, based on the total weight of the perlite, alumina in an amount ranging from 10 to 20 wt.-%, based on the total weight of the perlite, and iron(lll) oxide in an amount ranging from 0.5 to 2 wt.-%, based on the total weight of the perlite.

[0070] In another embodiment, the crude perlite further comprises sodium oxide and iron(lll) oxide.

[0071] In this embodiment, the crude perlite comprises silica in an amount ranging from 50 to 75 wt.-%, based on the total weight of the perlite, alumina in an amount ranging from 10 to 20 wt.-%, based on the total weight of the perlite, iron(lll) oxide in an amount ranging from 0.5 to 2 wt.-%, based on the total weight of the perlite, and sodium oxide in an amount ranging from 3 to 5 wt.-%, based on the total weight of the perlite.

[0072] In another embodiment, the crude perlite further comprises potassium oxide and iron(lll) oxide.

[0073] In this embodiment, the crude perlite comprises silica in an amount ranging from 50 to 75 wt.-%, based on the total weight of the perlite, alumina in an amount ranging from 10 to 20 wt.-%, based on the total weight of the perlite, iron(lll) oxide in an amount ranging from 0.5 to 2 wt.-%, based on the total weight of the perlite, and potassium oxide in an amount ranging from 4 to 5 wt.-%, based on the total weight of the perlite.

[0074] In another embodiment, the crude perlite further comprises, sodium oxide, potassium oxide and iron(lll) oxide.

[0075] In this embodiment, the crude perlite comprises silica in an amount ranging from 50 to 75 wt.-%, based on the total weight of the perlite, alumina in an amount ranging from 10 to 20 wt.-%, based on the total weight of the perlite, iron(lll) oxide in an amount ranging from 0.5 to 2 wt.-%, based on the total weight of the perlite, sodium oxide in an amount ranging from 3 to 5 wt.-%, based on the total weight of the perlite, and potassium oxide in an amount ranging from 4 to 5 wt.-%, based on the total weight of the perlite.

[0076] Additionally or alternatively, the crude perlite further comprises calcium oxide, preferably in an amount ranging from 0.5 to 1 wt.-%, based on the total weight of the perlite.

[0077] In this embodiment, the crude perlite comprises silica in an amount ranging from 50 to 75 wt.-%, based on the total weight of the perlite, alumina in an amount ranging from 10 to 20 wt.-%, based on the total weight of the perlite, and calcium oxide in an amount ranging from 0.5 to 1 wt.-%, based on the total weight of the perlite. In another embodiment, the crude perlite further comprises sodium oxide and calcium oxide. In this embodiment, the crude perlite comprises silica in an amount ranging from 50 to 75 wt.-%, based on the total weight of the perlite, alumina in an amount ranging from 10 to 20 wt.-%, based on the total weight of the perlite, calcium oxide in an amount ranging from 0.5 to 1 wt.-%, based on the total weight of the perlite, and sodium oxide in an amount ranging from 3 to 5 wt.-%, based on the total weight of the perlite.

[0078] In another embodiment, the crude perlite further comprises potassium oxide and calcium oxide.

[0079] In this embodiment, the crude perlite comprises silica in an amount ranging from 50 to 75 wt.-%, based on the total weight of the perlite, alumina in an amount ranging from 10 to 20 wt.-%, based on the total weight of the perlite, calcium oxide in an amount ranging from 0.5 to 1 wt.-%, based on the total weight of the perlite, and potassium oxide in an amount ranging from 4 to 5 wt.-%, based on the total weight of the perlite.

[0080] In another embodiment, the crude perlite further comprises iron(lll) oxide and calcium oxide.

[0081] In this embodiment, the crude perlite comprises silica in an amount ranging from 50 to 75 wt.-%, based on the total weight of the perlite, alumina in an amount ranging from 10 to 20 wt.-%, based on the total weight of the perlite, calcium oxide in an amount ranging from 0.5 to 1 wt.-%, based on the total weight of the perlite, and iron(lll) oxide in an amount ranging from 0.5 to 2 wt.-%, based on the total weight of the perlite.

[0082] In another embodiment, the crude perlite further comprises sodium oxide, potassium oxide and calcium oxide.

[0083] In this embodiment, the crude perlite comprises silica in an amount ranging from 50 to 75 wt.-%, based on the total weight of the perlite, alumina in an amount ranging from 10 to 20 wt.-%, based on the total weight of the perlite, calcium oxide in an amount ranging from 0.5 to 1 wt.-%, based on the total weight of the perlite, sodium oxide in an amount ranging from 3 to 5 wt.-%, based on the total weight of the perlite, and potassium oxide in an amount ranging from 4 to 5 wt.-%, based on the total weight of the perlite.

[0084] In another embodiment, the crude perlite further comprises sodium oxide, iron(lll) oxide and calcium oxide.

[0085] In this embodiment, the crude perlite comprises silica in an amount ranging from 50 to 75 wt.-%, based on the total weight of the perlite, alumina in an amount ranging from 10 to 20 wt.-%, based on the total weight of the perlite, calcium oxide in an amount ranging from 0.5 to 1 wt.-%, based on the total weight of the perlite, sodium oxide in an amount ranging from 3 to 5 wt.-%, based on the total weight of the perlite, and iron(lll) oxide in an amount ranging from 0.5 to 2 wt.-%, based on the total weight of the perlite.

[0086] In another embodiment, the crude perlite further comprises potassium oxide, iron(lll) oxide and calcium oxide.

[0087] In this embodiment, the crude perlite comprises silica in an amount ranging from 50 to 75 wt.-%, based on the total weight of the perlite, alumina in an amount ranging from 10 to 20 wt.-%, based on the total weight of the perlite, calcium oxide in an amount ranging from 0.5 to 1 wt.-%, based on the total weight of the perlite, potassium oxide in an amount ranging from 4 to 5 wt.-%, based on the total weight of the perlite, and iron(lll) oxide in an amount ranging from 0.5 to 2 wt.-%, based on the total weight of the perlite.

[0088] In another embodiment, the crude perlite further comprises potassium oxide, iron(lll) oxide and sodium oxide.

[0089] In this embodiment, the crude perlite comprises silica in an amount ranging from 50 to 75 wt.-%, based on the total weight of the perlite, alumina in an amount ranging from 10 to 20 wt.-%, based on the total weight of the perlite, calcium oxide in an amount ranging from 0.5 to 1 wt.-%, based on the total weight of the perlite, potassium oxide in an amount ranging from 4 to 5 wt.-%, based on the total weight of the perlite, and sodium oxide in an amount ranging from 3 to 5 wt.-%, based on the total weight of the perlite.

[0090] Preferably, the crude perlite further comprises, sodium oxide, potassium oxide, calcium oxide and iron(lll) oxide.

[0091] In this embodiment, the crude perlite comprises silica in an amount ranging from 50 to 75 wt.-%, based on the total weight of the perlite, alumina in an amount ranging from 10 to 20 wt.-%, based on the total weight of the perlite, iron(lll) oxide in an amount ranging from 0.5 to 2 wt.-%, based on the total weight of the perlite, sodium oxide in an amount ranging from 3 to 5 wt.-%, based on the total weight of the perlite, potassium oxide in an amount ranging from 4 to 5 wt.-%, based on the total weight of the perlite, and calcium oxide in an amount ranging from 0.5 to 1 wt.-%, based on the total weight of the perlite.

[0092] It is appreciated that the crude perlite comprises an amorphous fraction as determined by X-Ray Diffraction of > 70 wt.-%, based on the total weight of the perlite.

[0093] The term “amorphous” fraction of the crude perlite shall mean that this fraction does not show a crystalline morphology when analysed by known means of investigating a material's morphological state. For instance, the crude perlite is considered to be amorphous if it does not show any X-ray pattern upon X-ray analysis and shows only one refractive index upon subjecting the material to refractive index analysis.

[0094] For example, the crude perlite comprises an amorphous fraction as determined by X-Ray Diffraction 75 to 99 wt.-%, more preferably from 80 to 99 wt.-% and most preferably from 90 to 99 wt.-%, based on the total weight of the perlite.

[0095] It is appreciated that the supplementary cementitious material comprises the crude perlite in high amounts. For example, the supplementary cementitious material comprises the crude perlite in an amount of > 80 wt.-%, based on the total weight of the supplementary cementitious material. It is preferred that the supplementary cementitious material comprises the crude perlite in an amount of

[0096] > 85 wt.-%, more preferably of > 90 wt.-%, even more preferably of > 95 wt.-%, and most preferably of

[0097] > 98 wt.-%, based on the total weight of the supplementary cementitious material. Preferably, the supplementary cementitious material comprises the crude perlite in an amount from 80 to 100 wt.-%, preferably from 85 to 100 wt.-%, more preferably from 90 to 100 wt.-%, even more preferably from 95 to 100 wt.-%, and most preferably from 98 to 100 wt.-%, based on the total weight of the supplementary cementitious material.

[0098] In one embodiment, the supplementary cementitious material consists of the crude perlite.

[0099] In other words, the crude perlite of the present invention is a supplementary cementitious material. Products and methods

[0100] According to another aspect of the present invention, a product comprising the supplementary cementitious material in an amount of > 0.5 wt.-%, based on the total weight of the product, is provided.

[0101] With regard to the definition of the supplementary cementitious material, the crude perlite and preferred embodiments thereof, reference is made to the statements provided above when discussing the technical details of the supplementary cementitious material of the present invention.

[0102] The product may be any kind of product which is typically formed by using a supplementary cementitious material. Preferably, the product comprising the supplementary cementitious material is a concrete or mortar. For example, the product comprising the supplementary cementitious material is a concrete. A preferred embodiment is concrete comprising said supplementary cementitious material.

[0103] It is preferred that the product comprises the supplementary cementitious material in an amount ranging from 0.5 to 20 wt.-%, based on the total weight of the product, preferably from 1 to 20 wt.-%, more preferably from 1 to 15 wt.-% and most preferably from 1 to 10 wt.-%.

[0104] In view of this, the product to be prepared preferably further comprises additives and admixtures typically used in the products to be prepared. It is to be noted that the additives and admixtures are used in amounts typically used in the products to be prepared. For example, the product further comprises water, sand, aggregate(s), filler(s), chemical admixture(s) such as superplasticizer(s), retardant(s) or accelerator(s), and the like.

[0105] Optionally, the product further comprises one or more of fibers, pigments, lightweight fillers and the like.

[0106] It is appreciated that the product can be hardened into an article. Thus, the product of the present invention is an unhardened product. In view of this, the product preferably comprises water. In particular, the product comprises water in order to provide a sufficient viscosity such that the product can be hardened to prepare a corresponding hardened article.

[0107] For example, the product comprises water in an amount ranging from 3 to 50 wt.-%, preferably from 5 to 40 wt.-%, more preferably from 8 to 30 wt.-% and most preferably from 8 to 20 wt.-%, based on the total weight of the product.

[0108] It is further preferred that the product comprises chemical admixtures such as superplasticizer(s), retardant(s) or accelerators), and the like.

[0109] Such chemical admixtures are preferably present in the product in a total amount ranging from 0 to 10 wt.-%, preferably from 0 to 8 wt.-%, more preferably from 0.1 to 6 wt.-% and most preferably from 0.5 to 5 wt.-%, based on the total weight of the cementitious binder.

[0110] It is to be noted that the term “cementitious binder” refers to the mixture of supplementary cementitious material, i.e. the crude perlite, and cement.

[0111] Preferably, the product comprises a superplasticizer which helps to provide a sufficient viscosity such that the product can be hardened to prepare a corresponding hardened article.

[0112] For example, the product comprises a superplasticizer in an amount ranging from 0 up to 10 wt.-%, based on the total weight of the cementitious binder.

[0113] In one embodiment, the product comprises sand. For example, the product comprises sand in an amount ranging from 40 to 75 wt.-%, preferably from 50 to 70 wt.-%, more preferably from 55 to 70 wt.-% and most preferably from 60 to 70 wt.-%, based on the total weight of the cementitious binder.

[0114] It is preferred that the product of the present invention may comprise aggregate(s). The aggregate(s) may be natural, artificial, recycled or a mixture thereof, e.g. crushed stone.

[0115] In one embodiment, the product of the present invention comprises filler(s). The filler(s) may be natural, artificial, recycled or a mixture thereof, e.g. calcium carbonate.

[0116] It is further appreciated that the product is a cementitious or composition, which may be formed into concrete or mortar.

[0117] In one embodiment, it is preferred that the supplementary cementitious material replaces or supplements cement and / or cementitious binders and / or other supplementary cementitious materials (i.e. differing from the present supplementary cementitious material) in the product in an amount ranging from 1 to 40 wt.-%, based on the total weight of the product, preferably from 2 to 35 wt.-%, more preferably from 5 to 30 wt.-% and most preferably from 10 to 25 wt.-%.

[0118] According to a further aspect of the present invention, a hardened article prepared from the product defined herein is provided.

[0119] The hardened article is thus an article typically made from concrete or mortar.

[0120] Furthermore, the article comprises water in an amount below the amount of water in the product from which it is prepared.

[0121] For example, the water content of the article is > 20 wt.-%, preferably > 40 wt.-%, more preferably > 60 wt.-% and most preferably > 80 wt.-%, based on the total weight of the article, below the water content of the product from which it is prepared.

[0122] It is further preferred that the hardened article comprises less water than the product from which the article is prepared.

[0123] According to another aspect of the present invention, a method of preparing the hardened article is provided. The method comprises the steps of a) mixing the supplementary cementitious material as defined herein with cement, and water, and b) hardening the product obtained in step a) to form the hardened article.

[0124] With regard to the definition of the supplementary cementitious material, the crude perlite and preferred embodiments thereof, reference is made to the statements provided above when discussing the technical details of the supplementary cementitious material of the present invention.

[0125] According to a preferred embodiment, the mixing in method step a) is performed by mechanical stirring. Suitable process equipment for mixing (or agitation or stirring) is known to the skilled person.

[0126] It is appreciated that step a) can further include the addition of one or more of aggregate(s), filler(s), chemical admixture(s) such as superplasticizer(s), retardant(s) or accelerator(s), and the like, as defined herein. For example, step a) further includes the addition of one or more of aggregate(s), filler(s), chemical admixture(s) such as superplasticizer(s), retardant(s) or accelerator(s), and the like, in the amounts as defined herein.

[0127] In this embodiment, the method comprises the steps of a) mixing the supplementary cementitious material as defined herein with cement, water and one or more of aggregate(s), filler(s), chemical admixture(s) such as superplasticizer(s), retardant(s) or accelerator(s), and the like, and b) hardening the product obtained in step a) to form the hardened article.

[0128] The mixing of the supplementary cementitious material with cement, water and, if present, the one or more of aggregate(s), filler(s), chemical admixture(s) such as superplasticizer(s), retardant(s) and accelerator(s), and the like, can be carried in any order. It is to be noted that the skilled person generally knows how to prepare the product (and the article) to be prepared such that there is no need to describe this / these steps in more detail.

[0129] The hardening of the product in method step b) can be performed by any method known to the skilled person. For example, the hardening of the product in method step b) includes pouring, spraying, 3D-printing or towel throwing the product. Preferably, the hardening of the product in method step b) includes pouring, spraying or 3D-printing the product.

[0130] According to another aspect of the present invention, the use of crude perlite as supplementary cementitious material in cement, concrete or mortar is provided. The crude perlite has a volume median particle size cfeo of < 6 pm, as determined by laser diffraction, an a BET specific surface area of > 1 .4 m2 / g, measured using nitrogen and the BET method according to ISO 9277:2010.

[0131] With regard to the definition of the supplementary cementitious material, the crude perlite and preferred embodiments thereof, reference is made to the statements provided above when discussing the technical details of the supplementary cementitious material of the present invention.

[0132] It is appreciated that the concrete or mortar including the crude perlite of the present invention provides advantageous properties compared to concrete or mortar including a supplementary cementitious material differing from the crude perlite of the present invention.

[0133] In particular, the concrete or mortar including the crude perlite provides a water demand that is comparable to the same concrete or mortar being free of the crude perlite. The water demand is determined according to ASTM C311 .

[0134] Additionally or alternatively, the concrete or mortar including the crude perlite provides a superplasticizer demand that is below the same concrete or mortar comprising metakaolin or silica fume instead of crude perlite as supplementary cementitious material. The superplasticizer demand is determined according to ASTM C311 .

[0135] Additionally or alternatively, the crude perlite in concrete or mortar provides a pozzolanic reactivity index of at least 82 %. For example, the crude perlite in concrete or mortar provides a pozzolanic reactivity index of at least 85 %. Preferably, the crude perlite concrete or mortar provides a pozzolanic reactivity index of at least 88 %, e.g. in the range from 82 to 99 %, preferably from 85 to 99 % and most preferably from 88 to 99 %. The pozzolanic reactivity index is determined according to ASTM C311 .

[0136] In one embodiment, the concrete or mortar including the crude perlite provides a water demand that is comparable to the same concrete or mortar being free of the crude perlite, and a superplasticizer demand that is below the same concrete or mortar comprising metakaolin or silica fume instead of crude perlite as supplementary cementitious material. In another embodiment, the concrete or mortar including the crude perlite provides a water demand that is comparable to the same concrete or mortar being free of the crude perlite, and a superplasticizer demand that is below the same concrete or mortar comprising metakaolin or silica fume instead of crude perlite as supplementary cementitious material, and the crude perlite in the concrete or mortar provides a pozzolanic reactivity index of at least 82 %.

[0137] Brief description of the Figures

[0138] Fig 1 : Water demand according to ASTM C311 of mortars containing various mineral additions.

[0139] Fig 2: Reactivity index of perlites as function of fineness. The scope and interest of the invention will be better understood based on the following examples which are intended to illustrate certain embodiments of the present invention and are non- limitative.

[0140] Experimental part

[0141] Methods:

[0142] X-Ray Diffraction (XRD) measurements

[0143] XRD is a versatile, non destructive analytical technique that’s sensitive to the atomic structure of matter. XRD enables phase identification and quantification. Samples were split using a rifle splitter to reduce the samples to a suitable quantity for the analysis. The samples were then dried at 105 °C, overnight. Afterwards, the samples were ground using a Retsch RS200 mill at a speed of 1100 rpm for 90 seconds. 5 drops of isopropanol were used as grinding aid. The samples were homogenized in a glass bottle.

[0144] All samples were analyzed with a Bruker D8 Advance powder diffractometer obeying Bragg’s law. This diffractometer consists of a 1 kW X-ray tube, a sample holder, a 9-9 goniometer, and a LYNXEYE XE-T detector. The profiles were collected using a scan speed of 0.02° per second in 29. The resulting powder diffraction pattern is qualitatively analyzed using the DIFFRACsuite software packages EVA, based on reference patterns of the International Centre for Diffraction Data (ICDD) database.

[0145] Quantitative analysis of the diffraction data refers to the determination of amounts of different phases (minerals and amorphous) in a multi-phase sample and was performed using the DIFFRAC suite software package TOPAS. In detail, quantitative analysis allows to determine structural characteristics and phase (mineral) proportions with quantifiable numerical precision from the experimental data itself. This involves modelling the full diffraction pattern (Rietveld approach) such that the calculated pattern(s) duplicates the experimental one. The Rietveld and PONKCS methods were combined to quantify both the crystalline (minerals) and amorphous phases. This requires knowledge of the approximate crystal structure of all phases (minerals) of interest in the pattern.

[0146] X-Ray Fluorescence (XRF) measurements

[0147] XRF is a non-destructive analytical technique used to determine the elemental composition of materials. Samples were prepared as fused beads with a loss on ignition (LOI)-free ratio flux: sample of 9:0.9 (g of fluxed material / g of sample). Lithium Tetraborate (66:34%) : Lithium Metaborate (99.98%) + 0.20% Lithium bromide was used as fluxed material. LOI was obtained via annealing the samples at 1000 °C either in the furnace or by thermogravimetric analysis. The prepared fused beads were measured by XRF using the Perform’X sequential X-Ray florescence Spectrometer device from Thermo Fisher Scientific and quantified against an external calibration. The result represents the average of two measurements. The individual measurement is valid if its relative standard deviation is not higher than 10%.

[0148] Particle size distribution

[0149] Particle size distribution (PSD) data was obtained by laser diffraction, specifically with a Malvern Panalytical Mastersizer 3000 with particle dispersion in air with the Aero S accessory. A pressure of 2 bars was used for particle dispersion using a standard venturi disperser. The angular scattering pattern of red laser light (633 nm) was recorded for 10 s on both background and sample measurements. The Fraunhofer Approximation model was used to fit a PSD to this scattering pattern. Three independent measurements were recorded for each sample; the PSD reported here represents the average.

[0150] The processes and instruments are known to the skilled person and are commonly used to determine the particle size of fillers and pigments.

[0151] Specific surface area (BET)

[0152] Specific surface area (SSA) data was measured with gas adsorption following the Brunauer- Emmett-Teller (BET) theory using a Micromeritics TriStar II Plus device. A sample mass of 0.3-0.8 g was added to an empty 3 / 8-inch tube of known weight and dried at 100 °C for 30 minutes under flowing N2. The sample tube was then weighed again to determine the mass of the dried and degassed sample. N2 gas adsorption was then measured in five points over the BET range from 0.05 to 0.3 p / pO.

[0153] ASTM C311

[0154] Impact on water demand and strength development of SCM in substitution of cement.

[0155] Reference formulation: 1375 g sand, 500 g cement, 242 g water.

[0156] SCM testing: 20% replacement of cement (400 g cement + 100 g SCM), water adjusted to reach 180- 220 mm flow.

[0157] Omya LG27 - Method to determine superplasticzer demand and compressive strength at 1 and 28 days

[0158] Self-leveling mortar with the following reference composition: 1350 g sand, 415 g CEM I, 260 g Betocarb HP-OG, 230 g mixing water, 1.8 g superplasticizer. w / c=0.55

[0159] To investigate the performance of the SCM (supplementary cementitious material), it was added in replacement of sand:

[0160] 1250 g sand, 415 g CEM I, 260 g Betocarb HP-OG, 100 g SCM, 230 g mixing water, superplasticizer dosage adjusted to 390-430 mm flow. w / b (water / cement + perlite): 0.40

[0161] Materials

[0162] Perlite samples from 3 locations were used for in this study:

[0163] • Crude perlite from Nieves Mine, Termolita, Mexico

[0164] • Crude perlite from Puebla Mine, Termolita, Mexico

[0165] • Crude perlite from Ozkaymak, Turkey

[0166] For comparing the performance of the crude perlites, other types of supplementary cementitious materials were investigated in this study:

[0167] • Metakaolin: Optipozz from Burgess

[0168] • Silica fume from RW Silicium GmbH

[0169] • Ground Calcium Carbonate: Betocarb F-OM , Betocarb UF-GU from Omya Cement: CEM I 52.5 available from e.g. Heidelberg Materials Sand: CEN standard sand (EN 196-1)

[0170] Superplasticizer: polycarboxylate ether type, available from e.g. Chryso

[0171] Crude perlite characterization

[0172] The chemical and mineralogical analysis of the crude perlites tested are given in the following tables 1 and 2.

[0173] Table 1: Chemical analysis (XRF)

[0174] Table 2: Mineralogical analysis (quantitative XRD)

[0175] The crude perlite samples were ground using a laboratory pin mill. For the crude perlites from Nieves and Puebla, samples with different fineness’s were collected by milling and classifying as can be gathered from the following table 3. Table 3: Fineness parameters and specific surface area (BET).

[0176] Results

[0177] Water demand and strength development (ASTM C311) • The water demand of mortar mixes with a cement replacement of 20% ground perlite does not increase compared to 100% CEM I (see table 4 and Fig.1). This is a surprising effect and unexpected for a natural pozzolan.

[0178] • Even perlite samples ground to a very high finesses (dso about 2-3 pm) do not increase the water demand and are comparable to a ground calcium carbonate (Betocarb F-OM). • Other SCM like metakaolin or silica fume show a much higher water demand (135-145%), demonstrating the surprising property of fine ground perlite.

[0179] • For a good pozzolanic reactivity of perlite a high finesses is needed: below about 7 pm (dso) we can observe a good correlation between finesses and reactivity index (see Fig. 2). Above 7 pm the reactivity index is around 80%, indicating that no contribution to strength development is present (20% cement replacement with something “not reactive” yields to about 80% strength). Such a good pozzolanic reactivity cannot be observed when using crude perlite having a dso of above 7 pm such as described in US2018251403 A1.

[0180] Table 4: Results of ASTM C311 mortar testing.

[0181] Superplasticizer need (Omya LG27)

[0182] • unlike with typical SCM such as metakaolin or silica fume, ground perlite has a very moderate impact on the need of superplasticizer. In most cases the need is about 120-130% which is in the same range as ultrafine ground GCC (Betocarb UF). Only the very fine ground crude perlite (2 pm) shows a slightly higher need of 147% (see table 5).

[0183] • Other SCM like metakaolin or silica fume show a clearly higher superplasticizer need (168-191 %).

[0184] Table 5: Results of Omya LG27 testing.

Claims

Claims1 . Supplementary cementitious material comprising crude perlite, the crude perlite having a volume median particle size cfeo of < 6 pm, as determined by laser diffraction, and a BET specific surface area of > 1 .4 m2 / g, measured using nitrogen and the BET method according to ISO 9277:2010.

2. The supplementary cementitious material of claim 1 , wherein the crude perlite has a a volume median particle size cfeo of < 4 pm, preferably < 3 pm and most preferably in the range from 2 to 3 pm, as determined by laser diffraction, and a BET specific surface area of > 2.0 m2 / g, preferably > 2.5 m2 / g and most preferably in the range from 3 to 5 m2 / g, measured using nitrogen and the BET method according to ISO 9277:2010.

3. The supplementary cementitious material according to claim 1 or 2, wherein the crude perlite has a top cut particle size da of < 250 pm, preferably < 200 pm, more preferably < 150 pm, and most preferably < 125 pm, as determined by laser diffraction.

4. The supplementary cementitious material according to any one of claims 1 to 3, wherein the crude perlite comprises silica in an amount ranging from 50 to 75 wt.-%, based on the total weight of the perlite, and alumina in an amount ranging from 10 to 20 wt.-%, based on the total weight of the perlite.

5. The supplementary cementitious material according to any one of claims 1 to 4, wherein the crude perlite comprises sodium oxide in an amount ranging from 3 to 5 wt.-%, based on the total weight of the perlite, and / or potassium oxide in an amount ranging from 4 to 5 wt.-%, based on the total weight of the perlite, and / or iron(lll) oxide in an amount ranging from 0.5 to 2 wt.-%, based on the total weight of the perlite, and / or calcium oxide in an amount ranging from 0.5 to 1 wt.-%, based on the total weight of the perlite.

6. The supplementary cementitious material according to any one of claims 1 to 5, wherein the crude perlite comprises an amorphous fraction as determined by X-Ray Diffraction of> 70 wt.-%, preferably from 75 to 99 wt.-%, more preferably from 80 to 99 wt.-% and most preferably from 90 to 99 wt.-%, based on the total weight of the perlite.

7. The supplementary cementitious material according to any one of claims 1 to 6, wherein the crude perlite is unexpanded.

8. The supplementary cementitious material according to any one of claims 1 to 7, wherein the material consists of the crude perlite.

9. A product, preferably a concrete or mortar, comprising the supplementary cementitious material according to any one of claims 1 to 8 in an amount of > 0.5 wt.-%, based on the total weight of the product.

10. The product of claim 9, wherein the product comprises the supplementary cementitious material in an amount ranging from 0.5 to 20 wt.-%, based on the total weight of the product, preferably from 1 to 20 wt.-%, more preferably from 1 to 15 wt.-% and most preferably from 1 to 10 wt.-%.11 . The product according to any of claims 9 and 10, further comprising water, sand, aggregate(s), filler(s), chemical admixture(s) such as superplasticizer(s), retardant(s) or accelerator(s), and the like, optionally further comprising one or more of fibers, pigments, lightweight fillers and the like.

12. A hardened article prepared from the product according to any of claims 9 to 11 .

13. A method of preparing the hardened article according to claim 12, wherein the method comprises the steps of a) mixing a supplementary cementitious material according to any one of claims 1 to 8 with cement and water, and b) hardening the product obtained in step a) to form the hardened article.

14. Use of a crude perlite as supplementary cementitious material in concrete or mortar, wherein the crude perlite has a volume median particle size cfeo of < 6 pm, as determined by laser diffraction, and a BET specific surface area of > 1 .4 m2 / g, measured using nitrogen and the BET method according to ISO 9277:2010.

15. The use according to claim 14, wherein the concrete or mortar including the crude perlite provides a water demand that is comparable to the same concrete or mortar being free of the crude perlite and / or a superplasticizer demand that is below the same concrete or mortar comprising metakaolin or silica fume instead of crude perlite as supplementary cementitious material and / or the crude perlite provides a pozzolanic reactivity index of at least 82 %.

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