WO2020144648A1

WO2020144648A1 - Superlight double-structure expanded particles and production method

Info

Publication number: WO2020144648A1
Application number: PCT/IB2020/050195
Authority: WO
Inventors: José WALLS MUYCELO
Original assignee: Tecnwm S.A. De C.V.
Priority date: 2019-01-11
Filing date: 2020-01-10
Publication date: 2020-07-16

Abstract

The present invention relates to superlight double-structure expanded particles having a density of 40-400 kg/m3 for use as construction aggregate; a method for obtaining the superlight double-structure expanded particles; and a superlight concrete comprising the superlight double-structure expanded particles as aggregate, and a binding agent, wherein the concrete has a density below 350 kg/m3, for producing any light construction element with insulating properties without losing compressive strength, owing to the rigidity of its external structure.

Description

SUPER LIGHT EXPANDED PARTICLES OF DOUBLE STRUCTURE AND PROCESS OF

OBTAINING

FIELD OF THE INVENTION

The present invention is related to superlight aggregates for construction and to the processes for obtaining such aggregates, and more particularly is related to superlight double structure expanded particles and the process to obtain them.

BACKGROUND OF THE INVENTION

The construction materials used today seek to gather all the properties necessary to comply with the standards of the matter and carry out their specific function. Although in general it is sought that these materials have a very high resistance to compression and a relatively light weight to be able to handle them safely and at low cost, many of them, depending on the use to which they will be put, seek to gather some additional properties such as they are: insulating, fireproof properties, flexibility, decorative appearance, among others.

For this reason, different aggregates have been developed in the state of the art that can give concrete various properties, thus improving its characteristics. The main property that is sought to give concrete is a greater lightness combined with a sufficiently high hardness to be able to serve as a constructive element in a building and to reduce the susceptibility to rupture or structural damage. In order to obtain a light and resistant concrete, concrete aggregates have been developed in the state of the art that are manufactured from materials with higher strengths than any aggregate and that have high amounts of closed pores that do not absorb concrete but that give resistance and lightness to the materials.

In relation to the above, ceramic particles have been developed in the state of the art to be used as construction aggregates. For example, JP2001261463 describes a process for forming porous ceramic particles in which a foaming agent is used to promote pore formation and subsequently, during a cold solidification step, the size, orientation and amount of the pores by controlled movements, but this greatly complicates the process of formation of said pores. Also, in patent documents US20060016598 and CA2475668, the production of a sintered porous ceramic particle for use as a construction aggregate is described. In the production process of said particle, it is mentioned that the base that is used is obtained through a sol-gel process, and then it must be pelletized to achieve the proper shape to be sintered and that once sintered, it must be followed molding to obtain a specific shape. The steps of molding the ceramic compound for the production of porous particles make the operation very inefficient without really giving a competitive advantage to the final product in addition to the porosity and the ability to be sintered. Another document in which they also employ a similar procedure, in the The initial material is pelletized to give it the proper shape to be sintered and then it is further molded, it is US20060162929. The materials obtained from the procedures described in these documents have not had good results since they have interconnected pores that merit the absorption of the concrete, thus losing the characteristics of lightness. It is for the same reason that it has not been detected that this type of material can weigh less than 600 kg / m ³ .

The manufacturing process of the mentioned particles consists, in most of the cases, of a ceramic particle manufacturing process followed by a sintering process to achieve its expansion and therefore, an increase in its porosity. In most ceramic aggregates, you must have special control over the geometry and dimensions of the particles, paying attention to the drying process of the base material with which it is being formed or adding stages in which the particles before being expanded. In many of these cases, it is also indicated that to ensure the desired dimensions and geometry, the particles must continue to be shaped after sintering, making the process highly inefficient and susceptible to error. Another drawback of these ceramic particles is that they have open pores, which does not make it possible to obtain high-lightness concrete with said particles, since the binder with which they mix to form the concrete fills the open pores of the particles when they are mixed for concrete formation.

On the other hand, in the state of the art, silicates are used for the production of porous particles. In the known processes of production of aggregates for construction from silicates, it has been detected that in order to be sintered and thus have a lower density, they usually require being in combination with other compounds, which do not necessarily give the final mixture properties additional, but only serve to achieve the formation of pores in the particles and their subsequent mixing with construction elements.

As an example, in patent document EP1180503 porous particles are prepared from a mixture of quartz, various clays, sodium hydroxide and an agent to promote expansion. Also, additional steps are often employed to prepare the particles before sintering as shown in EP1840084, where it is stated that the particles are obtained by a hydrolysis process using water, an organic solvent, a surfactant and a base, and which subsequently combine with sodium alumina to form the granules that will be expanded. Yet another document showing processes for expanding silicon-based particles is EP1894907, where the initial mixture is composed of silicon particles, a linker and a plasticizer, which must be extracted later, making the process very complicated and expensive. .

Also in the state of the art, lightweight concretes obtained from using low-density aggregates in their preparation have been described, however, to achieve better performance, other components such as plasticizers, linkers, gases, must be added. , blowing agents or agents to reduce compressibility. Such is the case of the developments described in documents MXPA2003000467 and FR2933091. Also, there are cases in which the light aggregate particles must have a special prior treatment to be added to the concrete mix, as is the case in EP1805114, where the porous glass particles formed must have been treated with an adherent component to improve their properties within the cement mix. Also, there are developments in which low density is obtained by expanding polymeric particles and adding them to a combination of cement, which, as in previous developments, requires other aggregates such as plasticizers and fibers such as that described in MX2007011485.

Additionally, some construction aggregates have been detected that seek to give concrete additional properties such as being insulating, or resistant to fire and high temperatures as described in document JP2003240451. However, such materials do not provide concrete with the desirable hardness properties and do not achieve the necessary lightness for the preparation of a super light concrete.

Based on the above, although it has been detected that there are currently multiple developments to obtain construction aggregates that achieve concrete that is light, that is, that it has a reduced density, without losing its properties of hardness and resistance, it was not has detected one that achieves a density of 400 kg / m ³ while maintaining a high compressibility resistance and that is resistant to chemical attacks and high temperatures. In addition, the particles described in the state of the art have the drawback of having open pores, which does not allow obtaining with said particles high lightness. Additionally, no document was detected that describes a procedure that, from any sand, can obtain a variety of aggregates with characteristic properties to be used in different construction products such as light and resistant concrete, materials resistant to flame, insulating materials, materials with a decorative appearance, insulating paints, among others.

Therefore, it is necessary to develop a process to manufacture an aggregate for different construction applications, which is capable of being bonded with organic or inorganic substances and has a density of less than 400 kg / m ³ , which allows it to be suitable for the preparation of a super light concrete and also allows it to have improved characteristics in terms of hardness, resistance to chemical attacks, or thermal insulation, among others.

OBJECTS OF THE INVENTION

Considering the problems and disadvantages of the state of the art that were previously mentioned, it is an object of the present invention to provide a process for obtaining superlight double structure expanded particles, which can start from any sand.

It is another object of the present invention to provide superlight double structure expanded particles with a density of 40 to 400 kg / m ³ , which can be used in different applications in construction.

Furthermore, another object of the present invention is to provide a super light concrete comprising double structure super light expanded particles. BRIEF DESCRIPTION OF THE INVENTION

For this purpose, a first aspect of the present invention comprises superlight double-structured expanded particles having a density of 40 to 400 kg / m ³ .

A second aspect of the present invention is a process for obtaining double-structure superlight expanded particles that comprises the following steps:

(a) mix a silicate with a reaction medium and heat to a temperature between

80 and 100 ° C;

(b) adding to the above mixture at least one property modifying agent selected from: a gas generating agent, an elasticity and surface tension enhancing agent, a hardening agent, a stabilizing agent, a porosity modifying agent, or a pH regulating agent;

(c) stirring the mixture for a period of time sufficient for the modifying agent to react;

(d) separating the reaction medium to obtain a solid;

(e) grinding the solid and screening it to obtain particles of a certain size;

(f) mixing the particles with a filler material to coat the surface of the particles; and

(g) passing the particles covered with the filler through a sintering stage at a temperature sufficient to achieve their expansion and obtain superlight double-structured expanded particles.

In a preferred embodiment of the present invention, the silicate can be obtained from any sand according to the following steps: (i) analyze a sand from any origin to determine its silica content (Si0); (ii) add silica to obtain a sand with a silica content of at least 80% by weight in case the silica content of the sand is less than 80% by weight; (iii) mixing the silica-containing sand of at least 80% by weight with a base in a weight ratio of 5 to 80% of the base with respect to the sand; and (iv) heating the mixture to a temperature of between 80 and 1800 ° C to obtain the silicate.

In another preferred embodiment of the present invention, the process may comprise an additional step of cooling the dual-structure superlight expanded particles, as well as an additional step of separating the residual filler material from the dual-structure superlight expanded particles.

A third aspect of the present invention refers to a superlight concrete that comprises the double structure superlight expanded particles as an aggregate and a binder, where said concrete has a density of less than 350 kg / m ³ . DETAILED DESCRIPTION OF THE INVENTION

It has been found that it is possible to obtain double-structure superlight expanded particles, which can be used as a construction aggregate that mixed with any binder or cementitious agent can produce superlight concrete for the manufacture of any lightweight construction element with insulating properties, but without losing strength to compression thanks to the rigidity of its external structure and even being fireproof. Said aggregate can even be mixed with resins, polymers, rubber, silicones or any binder for the manufacture of products for different applications, such as wood substitutes.

Therefore, the present invention relates in a first aspect to superlight double structured expanded particles with a density of 40 to 400 kg / m ³ .

The dual structure superlight expanded particles preferably have an average size between 0.001 to 10 mm.

Dual structure superlight expanded particles have an internal structure and an external structure.

In a preferred embodiment of the present invention, the internal structure of the double-structured superlight expanded particles comprises a porous body. Preferably, said porous body comprises closed pores, that is, pores that do not have contact with the outside and have encapsulated air inside them, which gives insulating properties to the superlight double-structured expanded particles. Therefore, the superlight double-structured expanded particles are resistant to temperatures up to 1200 ° C.

In a preferred embodiment of the present invention, the porous body that forms the internal structure of double-structure superlight expanded particles is formed by a complex silicate, a term that for the purposes of the present descriptive text should be understood as a mixture of various silicates, between which can be found sodium silicate, aluminum silicate, iron silicate, magnesium silicate, calcium silicate, among others. The precise composition of said complex silicate will depend on the silicate and property modifying agents that are used, according to the process for obtaining superlight double-structured expanded particles that will be described later, and / or the natural composition of the sand that is have used to obtain it, if applicable.

The outer structure of dual-structure superlight expanded particles is a thin rigid layer of a filler material that increases the compressive strength of the particles. In a preferred embodiment of the present invention, the filler is selected from: aluminum silicate, calcium silicate, magnesium silicate, aluminum, silica, aluminum carbonate, calcium carbonate, magnesium carbonate, cement, gypsum, fine sand, kaolins, clays or mixtures thereof. More preferably, the filler material is selected from cement, silica, aluminum silicate, calcium silicate, magnesium silicate, aluminum carbonate, calcium carbonate, magnesium carbonate, or mixtures thereof. Even more preferably, the filler is silica or cement, with Portland cement being preferred. The superlight double structure expanded particles are suitable as an aggregate for different construction applications such as concrete and mortar manufacturing, with high resistance to chemical attack and compression, with insulating properties and are fireproof.

(a) mix a silicate with a reaction medium and heat to a temperature between

80 and 100 ° C;

(d) separating the reaction medium to obtain a solid;

(e) grinding the solid and screening it to obtain particles of a certain size;

Preferably the silicate is selected from sodium silicate, aluminum silicate, iron silicate, magnesium silicate, calcium silicate, or mixtures thereof.

In a preferred embodiment of the present invention, the silicate may be obtained from any sand according to the following steps: (i) analyzing a sand from any source to determine its content of silica (S¡0 _2); (ii) add silica to obtain a sand with a silica content of at least 80% by weight in case the silica content of the sand is less than 80% by weight; (iii) mixing the silica-containing sand of at least 80% by weight with a base in a weight ratio of 5 to 80% of the base with respect to the sand; and (iv) heating the mixture to a temperature of between 80 and 1800 ° C to obtain the silicate. Preferably, the silica content of the sand should be between 80 and 99.99% by weight. Once you have a sand with a silica content of at least 80% by weight, a base is added in a weight ratio of 5 to 80% of base with respect to the sand, and said mixture is heated to a temperature between 80 and 1800 ° C to obtain the silicate. The required temperature will depend on the melting point of the sand, since it needs to be melted. In a preferred embodiment, water, at least 100% water relative to the weight of the sand, is added to the sand and base mixture. Preferably, the base may be in a solution or in a high purity state in the form of a pellet. Preferably, the base is selected from among sodium-containing bases such as sodium hydroxide, sodium carbonate, or mixtures thereof. It is desirable that the heating of the mixture in the silicate forming step is carried out under stirring conditions. In a preferred embodiment of the present invention, the reaction medium that is mixed with the silicate in step (a) is added in a ratio of between 20% and 100% by weight with respect to the mixture. Preferably the reaction medium is water.

Step (b) of the process comprises mixing the product obtained in the previous step with at least one property modifying agent. Said property modifying agent has the objective of giving the final product, which is the superlight double structure expanded particles, some special characteristic.

The property modifying agent is selected from a gas generating agent, an elasticity and surface tension enhancing agent, a hardening agent, a stabilizing agent, a porosity modifying agent, or a pH regulating agent.

In a preferred embodiment, the property modifying agent can be added in an amount of between 0.1 and 20% by weight with respect to the rest of the mixture. In an even more preferred embodiment, depending on the selected property modifier, the amount by weight thereof with respect to the rest of the mixture is selected according to Table 1.

TABLE 1

In a preferred embodiment of the present invention, the gas generating agent is selected from: ethyl acetate, acetone, urea, toluene, or organic potassium or ammonium compounds. More preferably, in an embodiment where the mixture product is intended to have a reduced cure time, the gas generating agent is ethyl acetate.

In a preferred embodiment of the present invention, the elasticity and surface tension enhancing agent is selected from: calcium carbonate, urea, and boron compounds. More preferably, in an embodiment where the particles are sought to expand further, the elasticity and surface tension enhancer is a boron compound such as sodium borate (borax). In a preferred embodiment of the present invention, the curing agent is selected from among metal oxides. More preferably, the curing agent is selected from iron oxides, titanium oxides, and magnesium oxides.

In a preferred embodiment of the present invention, the stabilizing agent is selected from: sodium carbonate, calcium carbonate and aluminum silicate. More preferably, in an embodiment in which the final product is sought to have greater hardness and resistance, the stabilizing agent is aluminum silicate, and in an embodiment in which it is sought to avoid concrete slump and increase the size of the pores. of the aggregate, the stabilizing agent is calcium carbonate.

In a preferred embodiment of the present invention, the porosity modifying agent is selected from: aluminum hydroxide and magnesium hydroxide.

In a preferred embodiment of the present invention, the pH regulator is selected from: sulfuric acid, nitric acid, and hydrochloric acid.

Process step (c) comprises stirring the mixture to increase the interaction of the property modifying agent with the mixture for a period of time sufficient for the reaction to proceed. This reaction is an exothermic reaction that must be controlled to maintain the temperature between 80 and 100 ° C. In a preferred embodiment of the present invention, the stirring time is between 4 and 6 hours.

In step (d) of the process of the present invention, once the reaction is complete, the reaction medium is removed to obtain a solid. In a preferred embodiment, the reaction medium is separated by means of drying.

As previously mentioned, superlight double-structured expanded particles can have various uses, depending on the properties given to them in the previous steps. These can be used as a construction aggregate, and in such a case it will be required that they have a certain size and that said size be homogeneous, so in step (e) of the process of the present invention grinding and screening are carried out to obtain a certain particle size. In a preferred embodiment of the present invention, the particles obtained by grinding and screening the solid have an average size between 0.000001 and 1 mm.

In stage (f) of the referred process, the particles are mixed with a filler material to coat their surface, which will form the external structure of the superlight double-structured expanded particles that give them important properties, which depend on the type of filler material. that is used. In a preferred embodiment of the present invention, the filler is selected from: aluminum silicate, calcium silicate, magnesium silicate, aluminum, silica, aluminum carbonate, calcium carbonate, magnesium carbonate, cement, gypsum, fine sand, kaolins, clays and mixtures thereof. More preferably, the filler material is selected from cement, silica, aluminum silicate, calcium silicate, magnesium silicate, aluminum carbonate, calcium carbonate, magnesium carbonate, or mixtures thereof. Even more preferably, the filler is silica or cement, with Portland cement being preferred. In step (g) of the process as described, the particles coated with the filler material are passed through a sintering step to achieve their expansion and the formation of the internal structure of the dual-structure superlight expanded particles. comprising a porous body of complex silicate.

In a preferred embodiment of the present invention, the sintering step is carried out at a temperature of between 500 and 1200 ° C to achieve expansion.

Optionally, the process comprises a further subsequent step of cooling the double-structured superlight expanded particles.

Furthermore, in a further optional embodiment, a further additional step may be carried out which comprises separating the residual filler material from the dual-structure superlight expanded particles. Preferably, this stage is carried out by means of screening.

A third aspect of the present invention refers to a superlight concrete that comprises the double structure superlight expanded particles as an aggregate and a binder, where said concrete has a density of less than 350 kg / m ³ .

In a preferred embodiment, the superlight concrete comprises from 25 to 75% by volume of double structure superlight expanded particles as aggregate in relation to the total volume of the mixture thereof and the binder.

In a preferred embodiment, the binder is selected from cement, gypsum, lime, or mixtures thereof.

In a preferred embodiment, water is added to the mixture of the superlight double-structured expanded particles and the binder to form the superlight concrete. Preferably the volume of the water that is added corresponds to 20 to 60% of the volume of the binder.

Optionally, it is possible to add polymers or copolymers to concrete to improve its stiffness or elasticity properties.

The present invention will be better understood from the following examples, which are presented for illustrative purposes only to allow a full understanding of the preferred embodiments of the present invention, without implying that there are no other non-illustrated embodiments that can be the practice based on the detailed description above.

EXAMPLE 1

A test was carried out to prepare double structure superlight expanded particles according to the principles of the present invention from a sand.

For this, an analysis of the original content of a sand was carried out, obtaining the following results:

TABLE 2

As can be seen, the silica content (S¡0) is less than 80%, so silica was added to the chosen sand until it was 98% by weight. Water and 50% by weight of NaOH were added. The mixture was heated to 1000 ° C to form the silicate. Subsequently, the temperature was lowered to 95 ° C and the following property modifiers were added:

TABLE 3

The mixture was stirred for 5 hours and the water was evaporated off. The obtained solid was ground and screened to obtain particles. These were mixed with Portland cement as a filler. The particles were then sintered at a temperature of 1200 ° C to expand them. Superlight double structure expanded particles with a size between 0.000001 and 10 mm with a weight of 122 Kg / m ^{3 were obtained} .

EXAMPLE 2

For this, an analysis of the original content of a sand was carried out, obtaining the following results: TABLE 4

As can be seen, the silica content (S¡0 ₂ ) is greater than 80%, so no silica was added to the chosen sand. Water and 50% by weight of NaOH were added. The mixture was heated to 1000 ° C to form the silicate. Subsequently, the temperature was lowered to 95 ° C and the following property modifiers were added:

TABLE 5

The mixture was stirred for 5 hours and the water was evaporated off. The obtained solid was ground and screened to obtain particles. These were mixed with Portland cement as a filler. The particles were then sintered at a temperature of 900 ° C to expand them. Superlight double structure expanded particles with a size between 0.000001 and 10 mm with a weight of 60 Kg / m ^{3 were obtained} .

EXAMPLE 3

For this, an analysis of the original content of a sand was carried out, obtaining the following results: TABLE 6

As can be seen, the silica content (S¡0) is greater than 80%, so no silica was added to the chosen sand. Water and 50% by weight of NaOH were added. The mixture was heated to 1000 ° C to form the silicate. Subsequently, the temperature was lowered to 95 ° C and the following property modifiers were added: TABLE 7

The mixture was stirred for 5 hours and the water was evaporated off. The obtained solid was ground and screened to obtain particles. These were mixed with Portland cement as a filler. The particles were then sintered at a temperature of 800 ° C to expand them. Superlight double structure expanded particles with a size between 0.000001 and 10 mm with a weight of 42 Kg / m ^{3 were obtained} .

EXAMPLE 4

TABLE 8

As can be seen, the silica content (S¡0) is less than 80%, so silica was added to the chosen sand until it reached 98.5% by weight. Water and 50% by weight of NaOH were added. The mixture was heated to 1000 ° C to form the silicate. Subsequently, the temperature was lowered to 95 ° C and the following property modifiers were added:

TABLE 9

The mixture was stirred for 5 hours and the water was evaporated off. The obtained solid was ground and screened to obtain particles. These were mixed with Portland cement as a filler. The particles were then sintered at a temperature of 700 ° C to expand them. Superlight double structure expanded particles with a size between 0.000001 and 10 mm with a weight of 85 Kg / m ^{3 were obtained} .

EXAMPLE 5 A test was carried out to prepare superlight double structured expanded particles according to the principles of the present invention from a sand.

For this, an analysis of the original content of a sand was carried out, obtaining the following results: TABLE 10

TABLE 11

The mixture was stirred for 5 hours and the water was evaporated off. The obtained solid was ground and screened to obtain particles. These were mixed with Portland cement as a filler. The particles were then sintered at a temperature of 900 ° C to expand them. Superlight double structure expanded particles with a size between 0.000001 and 10 mm with a weight of 88 Kg / m ^{3 were obtained} .

EXAMPLE 6

A test was carried out to prepare double-structure superlight expanded particles according to the principles of the present invention from sodium silicate.

75 kg of sodium silicate and 20 L of water were mixed. The mixture was heated to 95 ° C and the following property modifiers were subsequently added: TABLE 12

The mixture was stirred for 5 hours and the water was evaporated off. The obtained solid was ground and screened to obtain particles. These were mixed with Portland cement as a filler. The particles were then sintered at a temperature of 750 ° C to expand them. Superlight double structure expanded particles with a size between 0.000001 and 10 mm with a weight of 54 Kg / m ^{3 were obtained} .

EXAMPLE 7

75 kg of sodium silicate and 20 L of water were mixed. The mixture was heated to 95 ° C and the following property modifiers were subsequently added:

TABLE 13

The mixture was stirred for 5 hours and the water was evaporated off. The obtained solid was ground and screened to obtain particles. These were mixed with Portland cement as a filler. The particles were then sintered at a temperature of 650 ° C to expand them. Superlight double structure expanded particles with a size between 0.000001 and 10 mm with a weight of 72 Kg / m ^{3 were obtained} .

In accordance with what has been previously described, it will be seen that the double structure superlight expanded particles have been designed to have a very low density and to serve as a superlight aggregate that can be used to manufacture a superlight concrete, and it will be evident to any expert in the Matter that the modalities of double structure superlight expanded particles as described above are only illustrative but not limiting of the present invention, since numerous changes of consideration in their details are possible without departing from the scope of the invention.

Therefore, the present invention should not be considered as restricted except as required by the prior art and by the scope of the appended claims.

Claims

CLAIMS NOVELTY OF THE INVENTION

1. Superlight double structure expanded particles with a density of 40 to 400 kg / m ³ .

2. The superlight expanded particles according to claim 1, further characterized in that they have an average size between 0.001 to 10 mm.

3. The superlight expanded particles according to claim 1, further characterized in that they are resistant to temperatures up to 1200 ° C.

4. The superlight expanded particles according to claim 1, further characterized in that they have an internal structure and an external structure.

5. The superlight expanded particles according to claim 4, further characterized in that the internal structure comprises a porous body.

6. The superlight expanded particles according to claim 5, further characterized in that the porous body comprises closed pores.

7. The superlight expanded particles according to claim 5, further characterized in that the porous body is formed by a complex silicate.

8. The superlight expanded particles according to claim 4, further characterized in that the outer structure is a thin rigid layer of a filler material that increases the compressive strength of the particles.

9. The superlight expanded particles according to claim 8, further characterized in that the filler material is selected from among aluminum silicate, calcium silicate, magnesium silicate, aluminum, silica, aluminum carbonate, calcium carbonate, carbonate of magnesium, cement, plaster, fine sand, kaolin, clay or mixtures thereof.

10. The superlight expanded particles according to claim 1, further characterized in that they are suitable as an aggregate for different applications in construction.

11. A process for obtaining superlight double-structured expanded particles characterized in that it comprises the following stages:

(a) mix a silicate with a reaction medium and heat to a temperature between

80 and 100 ° C;

(d) separating the reaction medium to obtain a solid; (e) grinding the solid and screening it to obtain particles of a certain size;

12. The process for obtaining superlight expanded particles according to claim 11, further characterized in that the silicate is selected from sodium silicate, aluminum silicate, iron silicate, magnesium silicate, calcium silicate, or mixtures of the themselves.

13. The process for obtaining superlight expanded particles according to claim 11, further characterized in that the silicate is obtained from a sand.

14. The process for obtaining superlight expanded particles according to claim 13, further characterized in that obtaining the silicate from sand comprises the following steps: (i) analyzing a sand of any origin to determine its silica content ( Si0); (ii) add silica to obtain a sand with a silica content of at least 80% by weight in case the silica content of the sand is less than 80% by weight; (iii) mixing the silica-containing sand of at least 80% by weight with a base in a weight ratio of 5 to 80% of the base with respect to the sand; and (iv) heating the mixture to a temperature of between 80 and 1800 ° C to obtain the silicate.

15. The process for obtaining superlight expanded particles according to claim 14, further characterized in that the base can be in a solution or in a high purity state in the form of pellets.

16. The process for obtaining superlight expanded particles according to claim 14, further characterized in that the base is selected from among bases with sodium content.

17. The process for obtaining superlight expanded particles according to claim 16, further characterized in that the base is selected from sodium hydroxide, sodium carbonate, or mixtures thereof.

18. The process for obtaining superlight expanded particles according to claim 11, further characterized in that in step (a) the reaction medium is added in a ratio between 20% and 100% by weight with respect to the mixture.

19. The process for obtaining superlight expanded particles according to claim 11, further characterized in that the reaction medium is water.

20. The process for obtaining superlight expanded particles according to claim 11, further characterized in that the property modifying agent can be added in an amount of between 0.1 and 20% by weight with respect to the rest of the mixture.

21. The process for obtaining superlight expanded particles according to claim 20, further characterized in that the amount by weight with respect to the rest of the mixture is selected from 1% to 15% for gas generating agents, 0.1% to 20 % for agents elasticity and surface tension enhancers, 0.1% to 10% for hardening agents, 1% to 15% for stabilizing agents, 0.1% to 5% for porosity modifying agents, and 0.1% to 5% for pH regulating agents.

22. The process for obtaining superlight expanded particles according to claim 11, further characterized in that the gas generating agent is selected from among ethyl acetate, acetone, urea, toluene or organic compounds of potassium or ammonia.

23. The process for obtaining superlight expanded particles according to claim 11, further characterized in that the elasticity and surface tension enhancing agent is selected from calcium carbonate, urea, and boron compounds.

24. The process for obtaining superlight expanded particles according to claim 11, further characterized in that the hardening agent is selected from among metal oxides.

25. The process for obtaining superlight expanded particles according to claim 11, further characterized in that the stabilizing agent is selected from among sodium carbonate, calcium carbonate and aluminum silicate.

26. The process for obtaining superlight expanded particles according to claim 11, further characterized in that the porosity modifying agent is selected from aluminum hydroxide and magnesium hydroxide.

27. The process for obtaining superlight expanded particles according to claim 11, further characterized in that the pH regulator is selected from among sulfuric acid, nitric acid and hydrochloric acid.

28. The process for obtaining superlight expanded particles according to claim 11, further characterized in that the stirring time is between 4 and 6 hours.

29. The process for obtaining superlight expanded particles according to claim 11, further characterized in that in step (d) the reaction medium is separated by means of drying.

30. The process for obtaining superlight expanded particles according to claim 11, further characterized in that the particles obtained in step (e) have an average size between 0.000001 and 1 mm.

31. The process for obtaining superlight expanded particles according to claim 11, further characterized in that in step (f) the filler is selected from among aluminum silicate, calcium silicate, magnesium silicate, aluminum, silica , aluminum carbonate, calcium carbonate, magnesium carbonate, cement, gypsum, fine sand, kaolin, clay and mixtures thereof.

32. The process for obtaining superlight expanded particles according to claim 11, further characterized in that step (g) is carried out at a temperature of between 500 and 1200 ° C.

33. The process for obtaining superlight expanded particles according to claim 11, further characterized in that it comprises a further subsequent step of cooling the double structure superlight expanded particles.

34. The process for obtaining superlight expanded particles according to claim 11, further characterized in that it comprises a subsequent additional step of separating the residual filler material from the double-structure superlight expanded particles.

35. The process for obtaining superlight expanded particles according to claim 34, further characterized in that the subsequent additional step of separating the residual charge material from the double-structure superlight expanded particles is carried out by screening.

36. A superlight concrete characterized in that it comprises superlight double structure expanded particles as an aggregate and a binder.

37. The superlight concrete according to claim 36, further characterized in that it has a density of less than 350 kg / m ³ .

38. The superlight concrete according to claim 36, further characterized in that it comprises from 25 to 75% by volume of double structure superlight expanded particles as aggregate in relation to the total volume of the mixture of the same and the binder.

39. Superlight concrete according to claim 36, further characterized in that the binder is selected from cement, gypsum, lime, or mixtures thereof.

40. The superlight concrete according to claim 36, further characterized in that it comprises water.

41. The superlight concrete according to claim 40, further characterized in that the volume of the water corresponds to 20 to 60% of the volume of the binder.

42. The superlight concrete according to claim 40, further characterized in that it comprises polymers or copolymers that improve its stiffness or elasticity properties.