Lined element for pipe or tank
A magnesium-based additive in the cement mortar composition of pipe and tank elements effectively reduces metal leaching, addressing regulatory concerns and maintaining mechanical integrity.
Patent Information
- Authority / Receiving Office
- AE · AE
- Patent Type
- Applications
- Current Assignee / Owner
- SAINT-GOBAIN PAM CANALISATION
- Filing Date
- 2024-12-16
AI Technical Summary
Existing pipe and tank elements used for drinking water distribution and storage release harmful metals like chromium, vanadium, and antimony into the water, violating stringent regulatory limits.
Incorporating a magnesium-based additive into the cement mortar composition of the inner liner of these elements to reduce metal leaching, while maintaining mechanical integrity.
Substantially decreases the release of metals such as aluminum, vanadium, and antimony into the water, meeting regulatory standards and ensuring the liner's mechanical properties are retained.
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Abstract
Description
Description Title: Lined PIPE OR TANK element [1] The present invention relates to a pipe or tank element comprising a particular mineral inner liner, said element being advantageously suitable for the adduction, distribution or storage of drinking water. It also relates to a pipe or tank comprising such an element. [2] Pipe or tank elements made of ductile cast iron, steel or concrete have been used for many years for the adduction, distribution and storage of drinking water. The inner wall of these elements is generally coated with a mortar to provide protection through a passivation mechanism. When put into use, the water gradually soaks into the mortar, enriching it with alkaline elements and thus becoming non-corrosive when it reaches the wall of the pipe or tank element. [3] However, it was found that certain metals present in the mortar composition, such as chromium, vanadium, antimony and aluminum, were released into the water in contact with the mortar. Regulations are imposing increasingly stringent constraints on the metal content in water, particularly drinking water. [4] There is thus still a real need for a pipe or tank element lined with a mortar that releases fewer metals into the water. SUMMARY OF THE INVENTION [5] In this context, the inventors have demonstrated that the addition of a magnesium-based additive to the cement mortar composition used to line the inner wall of the pipe or tank element substantially reduces the levels of certain metals released into the water. The inventors found that this performance could be achieved even with low levels of magnesium-based additive. [6] Advantageously, the liner has been shown to retain good mechanical properties. [7] Thus, the present invention relates to a lined pipe or tank element, comprising:- a raw pipe or tank element made of ductile cast iron, made of steel, or made of concrete, and- an inner liner situated on an inner wall of the raw pipe or tank element, the inner liner being made from a mortar composition comprising:- a cement and- a magnesium-based additive. [8] The invention also relates to a pipe or a tank comprising one or more lined pipe or tank elements as described in the present application, the pipe or the tank preferably being intended for the adduction, distribution or storage of drinking water. FIGURES [9] [Fig 1]: Schematic cross-sectional representation of a lined pipe or tank element, in a particular embodiment of the invention. DETAILED DESCRIPTION
[10] The lined pipe or tank element according to the invention comprises:- a raw pipe or tank element made of ductile cast iron, made of steel, or made of concrete, and- an inner liner situated on an inner wall of the raw pipe or tank element.
[11] The lined pipe or tank element defines an interior space in which the liquid (typically water) in contact with the inner liner can flow.
[12] The raw pipe or tank element may, for example, be a pipe section or a branch, or form a tank.
[13] In some embodiments, the lined pipe or tank element further comprises an outer liner situated on an outer wall of the raw pipe or tank element. The outer liner is advantageously suitable for contact with the ground. The outer liner, which is well known to those skilled in the art, is advantageously configured to increase the corrosion resistance of the raw pipe or tank element. This outer liner is generally made up of a metallic protective layer, notably based on sacrificial zinc, covered with a filler paint based on an organic resin.
[14] Advantageously, the inner liner lines the entire inner wall of the raw pipe or tank element.
[15] The inner liner advantageously has a nominal thickness of 2 to 15 mm, preferably 2.5 to 9 mm.
[16] The inner liner is a mortar formed from a mortar composition comprising:- a cement and- a magnesium-based additive.
[17] More particularly, the inner liner is a mortar, typically formed by applying said mortar composition to the inner wall of the raw pipe or tank element and then curing (or setting) said mortar composition. The mortar composition can be applied by centrifuging, spraying or manual coating.
[18] Cement is a hydraulic mineral compound, meaning it sets on contact with water through hydration.
[19] Cement generally comprises clinker, and preferably one or more constituents selected from blast furnace slag, steelworks slag, fly ash, pozzolan, silica fume, limestone and calcined clay.
[20] The cement may, for example, be a Portland cement, a Portland composite cement, a blast furnace slag cement, a composite cement, a slag pozzolanic cement, a limestone and calcined clay cement, an aluminous cement, a sulfo-aluminous cement, an oversulfated cement, a prompt cement or a mixture thereof.
[21] The cement is advantageously a cement as defined by EN 197-1 standard or EN 197-5 standard. Unless otherwise indicated, the weight content given for the constituents of a cement defined by EN 197-1 standard or EN 197-5 standard are as defined by EN 197-1 standard or EN 197-5 standard, respectively.
[22] In some embodiments, the cement is a CEM I Portland cement of EN 197-1 standard. The clinker content of a CEM I Portland cement of EN 197-1 standard is at least 95% by weight.
[23] In some embodiments, the cement is a CEM II Portland composite cement of EN 197-1 standard. A CEM II Portland composite cement of EN 197-1 standard is a mixture of clinker in a quantity of at least 65% by weight and other constituents such as blast furnace slag, fly ash, pozzolans and silica fume, the total of which does not exceed 35% by weight.
[24] In some embodiments, the cement is a CEM II / A-S or CEM II / B-S Portland slag cement of EN 197-1 standard. CEM II / A-S cement comprises 80 to 94% by weight clinker and 6 to 20% by weight blast furnace slag. CEM II / B-S cement comprises 65 to 79% by weight clinker and 21 to 35% by weight blast furnace slag.
[25] In some embodiments, the cement is a CEM II / C-M Portland composite cement of EN 197-5 standard, in particular a CEM II / C-M (S-P), CEM II / C-M (S-V), CEM II / C-M (S-L), CEM II / C-M (S-LL), CEM II / C-M (P-L), CEM II / C-M (V-L), CEM II / C-M (P-LL), or CEM II / C-M (V-LL) cement of EN 197-5 standard. CEM II / C-M cement typically comprises 50 to 64% by weight clinker, and at least two other constituents selected from blast furnace slag, pozzolan, fly ash, calcined clay and limestone.
[26] In some embodiments, the cement is a CEM III / A, CEM III / B, or CEM III / C blast furnace slag cement of EN 197-1 standard. CEM III / A cement comprises 35 to 64% by weight clinker and 36 to 65% by weight blast furnace slag. CEM III / B cement comprises 20 to 34% by weight clinker and 66 to 80% by weight blast furnace slag. CEM III / C cement comprises 5 to 19% by weight clinker and 81 to 95% by weight blast furnace slag.
[27] In some embodiments, the cement is a CEM V / A or CEM V / B slag composite cement of EN 197-1 standard. CEM V / A cement comprises 40 to 64% by weight clinker, 18 to 30% by weight blast furnace slag and 18 to 30% by weight pozzolan or fly ash. CEM V / B cement comprises 20 to 38% by weight clinker, 31 to 49% by weight blast furnace slag and 31 to 49% by weight pozzolan or fly ash.
[28] In some embodiments, the cement is a CEM VI slag pozzolanic cement of EN 197-5 standard, in particular a CEM VI (S-P), CEM VI (S-V), CEM VI (S-L) cement. CEM VI (S-P, V or L) cement comprises 35 to 49% by weight clinker, 31 to 59% by weight blast furnace slag and 6 to 20% by weight pozzolans, fly ash or limestone.
[29] In some embodiments, the cement is a mixture comprising (preferably consisting of) CEM I Portland cement and blast furnace slag, the weight content of CEM I Portland cement preferably being 5 to 64% (or 20 to 50%) based on the weight of the mixture.
[30] In some embodiments, the cement is a mixture comprising (preferably consisting of) CEM I Portland cement, silica fume and blast furnace slag, the weight content of CEM I Portland cement preferably being 30 to 60% (or 40 to 60%) based on the weight of the mixture and the weight content of silica fume preferably being 5 to 35% (or 10 to 30%) based on the weight of the mixture.
[31] In some embodiments, the cement is a mixture comprising (preferably consisting of) CEM I Portland cement or CEM III / B cement, and silica fume, the weight content of CEM I Portland cement or CEM III / B cement preferably being 50 to 94% (or 60 to 80%) based on the weight of the mixture.
[32] In some embodiments, the cement is a mixture comprising:- a cement as defined by EN 197-1 standard or EN 197-5 standard (e.g. CEM I or CEM III / B cement), and- an addition having a Blaine specific surface area of at least twice the specific surface area of the cement in said mixture.
[33] The Blaine specific surface area of the addition is advantageously greater than 0.6 m2 / g, for example greater than 0.8 m2 / g, greater than 1.0 m2 / g, greater than 1.2 m2 / g, and preferably less than 5 m2 / g. The addition typically consists of inorganic particles, in particular SiO2, the inorganic particles being finer and / or less dense than the cement in said mixture. More specifically, the addition may comprise (or consist of) one or more of the following compounds: diatomite, moler, expanded perlite, andalusite, bentonite, chamotte, activated carbon, biochar, feldspar, graphite, graphene, halloysite, kaolin, mica, molochite, mullite, carbon black, talc or wollastonite.
[34] The Blaine specific surface area is determined using the Blaine method (defined by NF EN 196-6 standard).
[35] The cement used in the present invention may comprise secondary constituents in a content of less than 5% by weight. The secondary constituents are as defined in EN 197-1 or EN 197-5 standard. Specifically, these are usually compounds derived from the method for producing clinker, or blast furnace slag, fly ash, pozzolan, silica fume, limestone or calcined clay.
[36] In a preferred embodiment, the cement is a CEM III / B cement according to EN 197-1 standard.
[37] The cement may comprise magnesium in its composition, in particular magnesium oxide. When present in cement, magnesium-based components, particularly magnesium oxide, are generally amorphous (or essentially amorphous).
[38] The weight content of magnesium-based components (conventionally expressed as oxide) in cement is generally less than 20%, preferably less than 10% or less than 5%, based on the total weight of the cement.
[39] The weight content of cement (based on its dry weight) is advantageously 15 to 60%, for example 20 to 60%, preferably 25 to 50% or 25 to 45%, based on the total dry weight of the mortar composition.
[40] The mortar composition further comprises a magnesium-based additive.
[41] The cement may comprise magnesium in its composition. It is understood that said additive is distinct from the cement, and more particularly distinct from any magnesium-based components that may be present in the cement.
[42] The magnesium-based additive can be organic or inorganic.
[43] Examples of organic magnesium-based additives in particular include magnesium carboxylates, such as magnesium acetate, magnesium lactate, magnesium malate or magnesium citrate.
[44] However, it is preferred that the magnesium-based additive be inorganic.
[45] In some embodiments, the magnesium-based additive is selected from a magnesium halide (e.g. magnesium chloride, magnesium bromide), a magnesium hypohalite (e.g. magnesium hypochlorite), a magnesium perhalogenate (e.g. magnesium perchlorate), magnesium sulphate, magnesium carbonate, magnesium silicate, magnesium nitrate, magnesium phosphate, magnesium sulfonate, magnesium thiosulphate, magnesium hydroxide (e.g. hydrotalcite or Mg(OH)2), a magnesium oxide (e.g. MgO), a hydrate thereof, and a mixture of at least two of these.
[46] In a preferred embodiment, the magnesium-based additive comprises a magnesium oxide (e.g. MgO), advantageously in a weight content of greater than 50%, or greater than 60%, or greater than 70%, or greater than 80%, for example greater than 90% (based on the total weight of the magnesium-based additive).
[47] In a more preferred embodiment, the magnesium-based additive is a magnesium oxide. Better still, the magnesium-based additive is MgO.
[48] The magnesium-based additive is advantageously crystalline (or essentially crystalline). In a preferred embodiment, the magnesium-based additive is a crystalline (or essentially crystalline) magnesium oxide. Better still, the magnesium-based additive is crystalline (or essentially crystalline) MgO.
[49] Preferably, the magnesium-based additive has a reactivity to citric acid at 23°C of at most 2,000 s, in particular from 5 to 2,000 s, or from 10 s to 1,500 s, or from 20 to 1,000 s. Citric acid reactivity is measured in accordance with YB / T 4019-2020 standard (Determination of chemical activity of light calcined magnesia). Such a criterion of reactivity to citric acid advantageously contributes to optimizing the performance of the additive (i.e., optimum reduction in the levels of certain metals released into the water).
[50] The specific surface area of the magnesium-based additive is advantageously at least 1 m² / g, for example from 1 m² / g to 100 m² / g, or from 5 m² / g to 50 m² / g, as determined by the BET method (typically using dinitrogen as the adsorption gas).
[51] The weight content of magnesium-based additive (based on its dry weight) is advantageously 0.02 to 10%, for example 0.05 to 10%, 0.1 to 10%, 0.2 to 10%, 0.4 to 10%, 0.1 to 8%, 0.1 to 5%, 0.2 to 5%, or 0.4 to 3%, based on the total dry weight of the mortar composition. When said additive is a hydrate, it is understood that the reference weight for the weight content is that of the hydrate and not of the corresponding anhydrous compound.
[52] Typically, the mortar composition further comprises mineral aggregates. Preferably, the mineral aggregates are selected from fillers, sand, gravel, or a mixture of at least two of these.
[53] The term "filler" refers in particular to fines, or added fines, that is, fine aggregate.
[54] Sand and gravel are preferably of a siliceous or calcareous nature.
[55] Advantageously, at least 95% by mass of the aggregates have a diameter less than or equal to 8 mm. Such a diameter can be measured in accordance with EN 933-1 standard, using the test for determining the geometric characteristics of aggregates (Part 1: Determination of particle size distribution - Sieving method).
[56] The mass ratio of the amount of mineral aggregates to the amount of dry cement is preferably 0.5 to 5, or 1 to 4 or 1.5 to 3.
[57] Typically, the mortar composition further comprises water. The mass ratio of the amount of water to the amount of dry cement is preferably 0.2 to 1, or 0.3 to 0.6 or 0.35 to 0.5.
[58] In some embodiments, the mortar composition further comprises one or more admixtures. Admixtures can be organic or mineral. Examples include set (or hardening) accelerators, set retarders, viscosity-modifying agents and superplasticizers.
[59] The role of a superplasticizer is in particular to increase the fluidity of the mortar composition at constant water dosage, or to reduce the water content at constant fluidity. The superplasticizer can, for example, be a polycarboxylate solution with a dry extract of 10 to 50%, preferably 20 to 35%.
[60] The mass ratio of the quantity of admixture(s) to the quantity of dry cement is preferably from 0.0001 to 0.1, for example from 0.0001 to 0.05, or from 0.0005 to 0.04, or from 0.001 to 0.03.
[61] It is understood that the magnesium-based additive is not encompassed by the term "admixture" used in the present application.
[62] Figure 1 is a schematic cross-sectional representation of a lined pipe or tank element, in a particular embodiment of the invention. In this embodiment, the lined pipe or tank element 10 comprises:- a raw pipe or tank element 12 made of ductile cast iron, made of steel, or made of concrete,- an inner liner 18 situated on an inner wall 14 of the raw pipe or tank element 12, the inner liner 18 being made from a mortar composition as defined in the present application, and- advantageously, an outer liner 20 situated on an outer wall 16 of the raw pipe or tank element 12.
[63] The lined pipe or tank element 10 defines an interior space 22 in which the liquid (typically water) 5 flows in contact with the inner liner 18.
[64] The outer liner 20 is advantageously suitable for contact with the ground 24.
[65] The present invention also relates to a pipe or tank comprising one or more lined pipe or tank elements as defined in the present application.
[66] Advantageously, the pipe or tank is intended for the adduction, distribution or storage of drinking water.
[67] Examples of metals whose release can be limited by means of the inner liner of the invention in particular include those mentioned in EU directive 2020 / 2184. Examples include the following metals: antimony (Sb), arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), manganese (Mg), mercury (Hg), nickel (Ni), lead (Pb), selenium (Se), vanadium (V), zinc (Zn), aluminum (Al) and uranium (U).
[68] It further relates to a method of manufacturing a lined pipe or tank element as defined in the present application, comprising:i) applying a mortar composition to an inner wall of a raw pipe or tank element made of ductile cast iron, made of steel, or made of concrete, to form a wet inner liner, andii) curing the wet inner liner to obtain said lined pipe or tank element comprising a cured inner liner,characterized in that the mortar composition is as defined in the present application.
[69] The following examples show the present invention in a non-limiting manner. EXAMPLES
[70] Test specimens were made by lining portions of a cast iron pipe section of nominal diameter 200 mm with mortar compositions of different formulations. This mortar is processed by centrifuging at 175 G. The sand used is silica sand with a particle size of 0 to 2 mm.
[71] These test specimens were tested according to the leaching protocol of EN 14944-3 standard, which describes the implementation of three successive migrations. The levels shown in table 1 below are the levels obtained at the end of the third migration. The levels shown for the reference (i.e., without magnesium additive) are by default set at 100% and those shown for the invention (i.e., with magnesium-based additive) are calculated relative to the reference. [Table 1] AluminumVanadiumAntimonyReference CEM III / B(comparative)100%100%100%CEM III / B + 0.4%* MgO 500 s(invention)90%< 59%< 9%CEM III / B + 2%* MgO 500 s(invention)< 29%< 59%40%* weight content of MgO expressed based on the total dry weight of the mortar composition and MgO characterized by reactivity to citric acid at 23°C (measured in accordance with YB / T 4019-2020 standard).
[72] Table 1 shows that the use of a mortar formed from a composition comprising a magnesium-based additive substantially reduces the levels of aluminum, vanadium and antimony released into the water.
Claims
1.A lined pipe or tank element (10), comprising:- a raw pipe or tank element (12) made of ductile cast iron, made of steel, or made of concrete, and- an inner liner (18) situated on an inner wall (14) of the raw pipe or tank element (12), the inner liner (18) being made from a mortar composition comprising:- a cement and- a magnesium-based additive.2.The lined pipe or tank element (10) according to claim 1, characterized in that the cement is a Portland cement, a Portland composite cement, a blast furnace slag cement, a composite cement, a slag pozzolanic cement, a limestone and calcined clay cement, an aluminous cement, a sulfo-aluminous cement, an oversulfated cement, a prompt cement or a mixture thereof.3.The lined pipe or tank element (10) according to claim 1 or 2, characterized in that the cement is a CEM III / B cement according to EN 197-1 standard.4.The lined pipe or tank element (10) according to any one of claims 1 to 3, characterized in that the weight content of dry cement is 15 to 60%, for example 20 to 60%, preferably 25 to 50%, or even 25 to 45%, based on the total dry weight of the mortar composition.5.The lined pipe or tank element (10) according to any one of claims 1 to 4, characterized in that the magnesium-based additive is selected from a magnesium halide, a magnesium hypohalite, a magnesium perhalogenate, magnesium sulphate, magnesium carbonate, magnesium silicate, magnesium nitrate, magnesium phosphate, magnesium sulfonate, magnesium thiosulphate, magnesium hydroxide, a magnesium oxide, a hydrate thereof, and a mixture of at least two of these.6.The lined pipe or tank element (10) according to claim 5, characterized in that the magnesium-based additive is MgO.7.The lined pipe or tank element (10) according to any one of claims 1 to 6, characterized in that the weight content of magnesium-based additive is 0.02 to 10%, for example 0.05 to 10%, 0.1 to 10%, 0.2 to 10%, 0.4 to 10%, 0.1 to 8%, 0.1 to 5%, 0.2 to 5%, or 0.4 to 3%, based on the total dry weight of the mortar composition.8.The lined pipe or tank element (10) according to any one of claims 1 to 7, characterized in that the mortar composition further comprises mineral aggregates, wherein the mass ratio of the amount of mineral aggregates to the amount of dry cement is preferably 0.5 to 5, or 1 to 4, or even 1.5 to 3.9.The lined pipe or tank element (10) according to claim 8, characterized in that the mineral aggregates are selected from fillers, sand, gravel, or a mixture of at least two of these.10.The lined pipe or tank element (10) according to any one of claims 1 to 9, characterized in that the magnesium-based additive has a reactivity to citric acid at 23°C of at most 2,000 s, in particular from 5 to 2,000 s, or from 10 to 1,500 s, or from 20 to 1,000 s.11.A pipe or a tank comprising one or more lined pipe or tank elements as defined in any one of claims 1 to 10, the pipe or the tank preferably being intended for the adduction, distribution or storage of drinking water.