Porous aggregate for light-weight concrete

Claim 2

Porous aggregate for light-weight concrete, characterized in that the individual particles of the aggregate are covered at least partly by a dry additive, which, with a cement slurry, forms a gel-like protective layer scarcely permeable to water, said protective layer facilitating a bond between the aggregate and the cement, said additive being a water-soluble polyethylene oxide of high molecular weight.

Claim 3

Aggregate according to claim 1, characterised in that the additive is melted onto the aggregate.

Claim 4

A material for forming light-weight concrete comprising a porous aggregate suitable for the production of light-weight concrete and composed of a plurality of particles of aggregate, each individual particle of aggregate being at least partially covered with a dry layer of a water-soluble polyethylene oxide having a molecular weight sufficient to form a gel-like protective layer scarcely permeable to water when contacted with a cement slurry.

Claim 5

A material for forming light-weight concrete comprising a porous aggregate suitable for the production of light-weight concrete and composed of a plurality of particles of aggregate, each individual particle of aggregate being at least partially covered with a dry layer of a water-soluble polyethylene oxide having a molecular weight sufficient to form a gel-like protective layer scarcely permeable to water when contacted with a cement slurry.

Claim 6

The material of claim 3 wherein said particles of aggregate are produced by heating expanded clay, expanded shale or both.

Claim 7

The material of claim 3 wherein the thickness of the additive coating on each individual particle of aggregate is about 0.001mm.

Claim 8

The material of claim 3 wherein said particles of aggregate are formed from pumice.

Claim 9

The material of claim 3 wherein said polyethylene oxide has a melting point of about 60° to 80° C.

Claim 10

In a composition for forming a light-weight concrete comprising a mixture of a cement slurry and a porous aggregate, the improvement wherein each individual particle of said porous aggregate is at least partially covered with gel-like protective layer scarcely permeable to water formed from a water-soluble polyethylene oxide.

Claim 11

In a composition for forming a light-weight concrete comprising a mixture of a cement slurry and a porous aggregate, the improvement wherein each individual particle of said porous aggregate is at least partially covered with gel-like protective layer scarcely permeable to water formed from a water-soluble polyethylene oxide.

Claim 12

The composition of claim 8 wherein the amount of porous aggregate in said composition is sufficient so that the density of the concrete obtained when said composition dries is less than about 1.5gm/cc.

Claim 13

The composition of claim 8 wherein said porous aggregate is produced by heating expanded clay, expanded shale or both.

Claim 14

The composition of claim 8 wherein said porous aggregate is pumice.

Claim 15

The composition of claim 8 wherein the amount of gel-like protective layer on each individual particle of porous aggregate is sufficient so that the thickness of said water-soluble polyethylene oxide on each individual particle of porous aggregate when in a dry state is about 0.001mm.

Claim 16

The composition of claim 8 wherein said water-soluble polyethylene oxide has a melting point of about 60° to 80° C.

Claim 17

Composition of claim 8 wherein said composition further contains 60 to 100 grams of a segregation-preventing agent per cubic meter of said composition, said segregation-preventing agent comprising a water-soluble polyethylene oxide have a melting point between about 60° to 80° C.

Claim 18

In a process for forming a porous aggregate for use in the production of light-weight concrete in which clay, shale or both are heated to a temperature of at least about 1000° C. to form a porous aggregate and the porous aggregate is thereafter cooled to ambient, the improvement wherein said porous aggregate is coated during cooling thereof with a solution of a water-soluble polyethylene oxide.

Claim 19

In a process for forming a porous aggregate for use in the production of light-weight concrete in which clay, shale or both are heated to a temperature of at least about 1000° C. to form a porous aggregate and the porous aggregate is thereafter cooled to ambient, the improvement wherein said porous aggregate is coated during cooling thereof with a solution of a water-soluble polyethylene oxide.

Claim 20

The process of claim 15 wherein said polyethylene oxide forms a dry coating at ambient conditions, said dry coating forming on said porous aggregate a gel-like protective layer scarcely permeable to water when contacted with a cement slurry.

Claim 21

The process of claim 16 wherein said polyethylene oxide has a melting point of about 60° to 80° C.

Claim 22

The process of claim 17 wherein said porous aggregate is coated with said polyethylene oxide at a temperature above the melting point of said polyethylene oxide.

Claim 23

The process of claim 18 wherein said porous aggregate is coated with said polyethylene oxide at a temperature below the decomposition temperature thereof.

Claim 24

The process of claim 19 wherein said polyethylene oxide aggregate is applied in a form of an aqueous solution, said aqueous solution being applied to said porous aggregate at a temperature of more than 100° C.

Claim 25

The process of claim 20 wherein said aqueous solution is applied to said porous aggregate at a temperature of about 180° to 190° C.

Claim 26

The process of claim 18 wherein said polyethylene oxide is applied to said porous aggregate at a temperature of about 140° to 150° C.

Claim 27

A method for producing an additive covering for the aggregate particles according to claim 1, comprising spraying a solution of the additive onto the aggregate particles which are heated to a temperature above the boiling point of the solvent of the solution whereby the solvent is evaporated and aggregate particles individually covered at least partly by the additive are produced.

Claim 28

A method according to claim 23 further comprising mixing the aggregate particles individually covered at least partly by the additive to facilitate a uniform distribution of the additive on a surface of the individual particles.

Claim 29

Method according to claim 23, characterised in that the uncoated aggregate is produced by heating expanded clay, expanded shale or both and the additive is applied during the cooling of the expanded material.

Claim 30

Method according to claim 25, characterised in that the aggregate is mixed thoroughly after spraying.

Claim 31

Method according to claim 23 wherein said solution is an aqueous solution.

Claim 32

Porous aggregate for light-weight pumpable concrete characterized in that the individual porous particles of the aggregate are covered at least partially by an adhesive solid layer of an additive which in the presence of water converts to a gel-like layer which retards the absorption of water of a cement slurry by the porous aggregate particles under a pumping pressure, thereby facilitating pumping of the concrete by reducing the frictional resistance of the porous aggregate particles and preventing hardening of the concrete, the additive being further characterized in that when converted to the gel-like layer on the porous particle surface, the gel-like layer remains contiguous to the porous particle surface during a time of pumping of concrete containing the porous aggregate particles and forms a gel-like mass with the cement slurry facilitating secure bonding between the surface of the porous aggregate particles and the cement.

Claim 33

Porous aggregate for light-weight pumpable concrete characterized in that the individual porous particles of the aggregate are covered at least partially by an adhesive solid layer of an additive which in the presence of water converts to a gel-like layer which retards the absorption of water of a cement slurry by the porous aggregate particles under a pumping pressure, thereby facilitating pumping of the concrete by reducing the frictional resistance of the porous aggregate particles and preventing hardening of the concrete, the additive being further characterized in that when converted to the gel-like layer on the porous particle surface, the gel-like layer remains contiguous to the porous particle surface during a time of pumping of concrete containing the porous aggregate particles and forms a gel-like mass with the cement slurry facilitating secure bonding between the surface of the porous aggregate particles and the cement.

Claim 34

A material for forming a light-weight pumpable concrete comprising porous aggregate particles suitable for the production of light-weight concrete characterized in that the individual porous particles of the aggregate are covered at least partially by an adhesive solid layer of an additive which in the presence of water converts to a gel-like layer which retards the absorption of water of a cement slurry by the porous aggregate particles under a pumping pressure, thereby facilitating pumping of the concrete by reducing the frictional resistance of the porous aggregate particles and preventing hardening of the concrete, the additive being further characterized in that when converted to the gel-like layer on the porous particle surface, the gel-like layer remains contiguous to the porous particle surface during a time of pumping of concrete containing the porous aggregate particles and forms a gel-like mass with the cement slurry facilitating secure bonding between the surface of the porous aggregate particles and the cement.

Claim 35

A material for forming a light-weight pumpable concrete comprising porous aggregate particles suitable for the production of light-weight concrete characterized in that the individual porous particles of the aggregate are covered at least partially by an adhesive solid layer of an additive which in the presence of water converts to a gel-like layer which retards the absorption of water of a cement slurry by the porous aggregate particles under a pumping pressure, thereby facilitating pumping of the concrete by reducing the frictional resistance of the porous aggregate particles and preventing hardening of the concrete, the additive being further characterized in that when converted to the gel-like layer on the porous particle surface, the gel-like layer remains contiguous to the porous particle surface during a time of pumping of concrete containing the porous aggregate particles and forms a gel-like mass with the cement slurry facilitating secure bonding between the surface of the porous aggregate particles and the cement.

Claim 36

In a composition for forming a light-weight pumpable concrete comprising a mixture of a cement slurry and a light-weight aggregate, the improvement wherein the individual porous particles of the aggregate are covered at least partially by an adhesive solid layer of an additive which in the presence of water converts to a gel-like layer which retards the absorption of water of a cement slurry by the porous aggregate particles under a pumping pressure, thereby facilitating pumping of the concrete by reducing the frictional resistance of the porous aggregate particles and preventing hardening of the concrete, the additive being further characterized in that when converted to the gel-like layer on the porous particle surface, the gel-like layer remains contiguous to the porous particle surface during a time of pumping of concrete containing the porous aggregate particles and forms a gel-like mass with the cement slurry facilitating secure bonding between the surface of the porous aggregate particles and the cement.

Claim 37

In a composition for forming a light-weight pumpable concrete comprising a mixture of a cement slurry and a light-weight aggregate, the improvement wherein the individual porous particles of the aggregate are covered at least partially by an adhesive solid layer of an additive which in the presence of water converts to a gel-like layer which retards the absorption of water of a cement slurry by the porous aggregate particles under a pumping pressure, thereby facilitating pumping of the concrete by reducing the frictional resistance of the porous aggregate particles and preventing hardening of the concrete, the additive being further characterized in that when converted to the gel-like layer on the porous particle surface, the gel-like layer remains contiguous to the porous particle surface during a time of pumping of concrete containing the porous aggregate particles and forms a gel-like mass with the cement slurry facilitating secure bonding between the surface of the porous aggregate particles and the cement.