Method for encasing underground electrical cables

Patent metadata

Field	Value
Publication number	US-11078116-B2
Application number	US-201916441714-A
Country	US
Kind code	B2
Filing date	Jun 14, 2019
Priority date	Jun 15, 2018
Publication date	Aug 3, 2021
Grant date	Aug 3, 2021

Abstract

A method for encasing underground electrical cables, includes (a) providing a fresh concrete composition including a paste that includes a hydraulic binder, a mineral addition and water, the paste being present in a mixture with sand and aggregates, whereby the paste is present in the concrete composition in a volume of <320 L/m3 and/or the solid volume fraction of said paste is >50 vol.-% and (b) placing the fresh concrete composition so as to encase the underground cables therewith.

First claim

The invention claimed is:

1. A method for encasing underground electrical cables, comprising:
(a) providing a fresh concrete composition comprising a paste that comprises a hydraulic binder, a mineral addition and water, said paste being in a mixture with sand and aggregates, whereby the solid volume fraction of said paste is >50 vol.-%, and
(b) placing said fresh concrete composition so as to encase the underground cables therewith,
wherein the paste is present in the fresh concrete composition in a volume of <300 L/m 3 ,
wherein the fresh concrete, after having been placed, is allowed to harden and dry, wherein the thermal resistivity of the concrete once hardened and dried is <0.7 m·K/W, and
wherein the concrete composition is free from a material having a thermal conductivity of >10 W/m·K.

2. The method according to claim 1 , wherein the solid volume fraction of said paste is >55 vol.-%.

3. The method according to claim 1 , wherein water is present in the fresh concrete composition in a volume of <170 L/m 3 .

4. The method according to claim 1 , wherein the fresh concrete composition comprises 1.5 to 12 kg per m 3 of a water reducer, a plasticizer or a superplasticizer.

5. The method according to claim 1 , wherein Portland cement is used as said hydraulic binder.

6. The method according to claim 1 , wherein the hydraulic binder is present in the fresh concrete composition in an amount of 15-40 kg/m 3 .

7. The method according to claim 1 , wherein the hydraulic binder is present in the fresh concrete composition in an amount of 150-500 kg/m 3 .

8. The method according to claim 1 , wherein a limestone filler or a siliceous filler, or a mixture of limestone filler and a siliceous filler is used as said mineral addition.

9. The method according to claim 8 , wherein the mineral addition has a particle size distribution that is characterised by a D50 of ≤10 μm and/or a D98 of ≤100 μm.

10. The method according to claim 1 , wherein a hematite filler is used as said mineral addition.

11. The method according to claim 1 , wherein said sand includes a magnetite sand and/or said aggregates include magnetite aggregate.

12. The method according to claim 1 , wherein a skeleton packing density of the aggregate is selected to be >0.69.

13. The method according to claim 1 , wherein the fresh concrete composition comprises a super-plasticiser.

14. The method according to claim 1 , wherein the 28d compressive strength of the concrete is 1.0-5.0 MPa.

15. The method according to claim 1 , wherein the 28d compressive strength of the concrete is >20 MPa.

16. The method according to claim 1 , wherein the concrete composition is free from a material having a thermal conductivity of >20 W/m·K.

17. The method according to claim 8 , wherein the siliceous filler is fine quartz and/or silica flour.

18. The method according to claim 1 , wherein the fresh concrete composition is free of metals.

Assignees

• Holcim Technology Ltd

Inventors

• Zhang Qing
• Peuchlestrade Anthony
• Creyx Antoine
• Toussaint Fabrice
• Wise Jody
• Levy Christophe

Classifications

• C04B2111/00051

  Mortar or concrete mixtures with an unusual low cement content, e.g. for foundations · CPC title

• H02G9/10

  in cable chambers, e.g. in manhole or in handhole · CPC title

• C04B14/04

  Silica-rich materials; Silicates · CPC title

• H02G9/025

  Coverings therefor, e.g. tile · CPC title

• C04B28/04 Primary

  Portland cements · CPC title