GB2134556A

GB2134556A - Concrete structures

Info

Publication number: GB2134556A
Application number: GB08234909A
Authority: GB
Inventors: Qusai Abdul Latif Alani
Original assignee: Individual
Current assignee: Individual
Priority date: 1982-12-07
Filing date: 1982-12-07
Publication date: 1984-08-15

Abstract

A concrete structure especially for shell or bomb resistance has walls and/or a roof at least 50 mm thick and made from concrete or mortar including glass and/or plastics fibre reinforcing material.The walls and/or roof may also include steel reinforcement.

Description

SPECIFICATION Concrete structures The present invention relates to concrete structures and, more particularly, to structures such as shelters, bunkers and protective walls for both military and civil purposes, which are designed to provide protection againstshelIin,bombing (whether by conventional or nuclearbornbs)and explosions.

Glassfíbre reireforced mortar, such as may be preparedfrom thagiassfibre containing cement marketed undertheregístered trade mark CEMFIL, is well known. Hitherta"ít has been employed solely for manufacturing panelsofthe order of 10-15 mm thick for the purposes of cladding and decorative and finishing panels and as a replacement for asbestos sheets. Underthecodeofpracticecovering its use, it is not permitted to be used forstructural building elements.It is considered unsuitable for such elements because the glass frbre reinforcement, even the special alkali resistantglassfibre utilised, degrades with age sothatthe strength of the elements is reduced and they may become unsafe. Moreover, it is incompatible with steel reinforcement In any event, known glass fibre reinforced cements areto expensive for normal building constructions and cheaperand more longer lasting materials are available.

The present invention consists in a concretestructure comprising a structural wall, rooforother element, preferably, at least 50 mm thick, constructed from concrete or mortar including glass and/or plastics fibre reinforcing material. The structural element may also include steel reinforcement. Walls, rooves, runways, shelters and other buildings constructed according to the invention have increased resistance to penetration and damage by shells, bombs and explosions whether as a result of a direct hit or otherwise.

With the present invention,the watl thickness of the structural element, which determines its ability to withstand the impactofshellsetc., alleviates any strength loss owing to any degradation of the fibre reinforcement. The mix'of grass and'our plastics fibres in the concrete or mortarchangesthe characteristics of normal concrete or ntcrtarfrom a brittle frangible material to a ductile material and this, in turn, increases several folitheability ofthe material to absorb the kinetic energy ofshell or bomb impact or shock, especially, whet used in thicknesses in excess of 50 mm, for example, 1-5 m.

Increase in fibre content increases the resistance of the structural elementto impact and explosion in a linear manner and the higherthe fibre content, the more the resistance, up to an amount in which the fibre is present in the concrete or mortar by about 10% oftheweightofthe latter,whereafter little advantage is achieved by increasing the fibre content. Hence, the concrete mortar utilised in the present invention should have a fibre content not exceeding 10% by weight of the weight of the concrete or mortar and, preferably, in the range from 5-10% by weight of the weight of concrete or mortar. For the higherfibre contents, it may be necessary to add a plasticiserto the mix.

Moreover, the invention enablesthewall thicknesses of structures intended to withstand shelling, bombing etc., to be reduced compared with conventional structures, whilst giving the same resistantnce to shells, bombs and explosions, thereby achieving savings in weight which, in turn, provides savings in the amount of steel reinforcementwhich maybe required and the strength offoundations. This achieves an overall saving in cost or, alternatively, enablestheerection of buildings orotherconstruc tionswhichwillwithstand larger impacts or explosionsthan hitherto known structures.The invention may enable a reduction in wall thickness of 50% or more, depending on the mix and fibre content, whilst providing the same protection as conventional constructions, and may not require steel reinforcement to achieve this improvement.

The plastics fibre used in the invention may be polypropylenefibre. The type offibre has an important effect of the behaviour ofthe material. It has been found that alkali resistance glassfibreand polypropy lene fibre of different diameters and lengths are suitable for different uses within the field of this invention. Furthermore, the use of concrete employing an aggregate in the mix givesthe structural elementadditional resistance to the penetration of shells and bombs and it has been found that different ratios ofcement, water, sand and aggregate may be used to provide different results and different resistancesto different types of shells and bombs.

As mentioned above, the structure according to the invention may include steel reinforcement. However, the invention enables satisfactory shelters for sensitive electronic installations to be constructed without steel reinforcement, thereby alleviating the effect on such installations of steel reinforcements used in conventional concrete shelters.

In a modification, the invention may be employed as a linerforthe inside of conventional concrete structures. Such liners offer added protection to installations and personnel within the shelter as the liner has a less tendency to shatterthan conventional concrete.

In one embodimentofthe invention,the mortar has a composition of 1 partcementto 1 part sand. This makes the mortar compatible with steel reinforcement and shrinkage experienced in thethickerwall structures produced with this invention. In another embodiment, the composition ofthe concrete is 1 part sand, 1 part cement and 1 part aggregate. In either case, the mortar or concrete, together with the required proportion of fibre, may be mixed in a conventional cement mixing plant.

Whilst particular embodiments have been described, it will be understood that modifications can be madewithout departing fromthe scope of the invention.

CLAIMS (filed on 7112/82) 1. A concrete structure comprising a structural wall, roof or other element at least 50 mmthickand made from concrete or mortar including glass and/or plastics fibre reinforcing material.

2. A structure as claimed in claim 1, in which the structural element also includes steel reinforcement.

3. Astructureasclaimedinclaim 1 or2, in which the structural element is from 1 to 5 mm thick.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Concrete structures The present invention relates to concrete structures and, more particularly, to structures such as shelters, bunkers and protective walls for both military and civil purposes, which are designed to provide protection againstshelIin,bombing (whether by conventional or nuclearbornbs)and explosions. Glassfíbre reireforced mortar, such as may be preparedfrom thagiassfibre containing cement marketed undertheregístered trade mark CEMFIL, is well known. Hitherta"ít has been employed solely for manufacturing panelsofthe order of 10-15 mm thick for the purposes of cladding and decorative and finishing panels and as a replacement for asbestos sheets. Underthecodeofpracticecovering its use, it is not permitted to be used forstructural building elements.It is considered unsuitable for such elements because the glass frbre reinforcement, even the special alkali resistantglassfibre utilised, degrades with age sothatthe strength of the elements is reduced and they may become unsafe. Moreover, it is incompatible with steel reinforcement In any event, known glass fibre reinforced cements areto expensive for normal building constructions and cheaperand more longer lasting materials are available. The present invention consists in a concretestructure comprising a structural wall, rooforother element, preferably, at least 50 mm thick, constructed from concrete or mortar including glass and/or plastics fibre reinforcing material. The structural element may also include steel reinforcement. Walls, rooves, runways, shelters and other buildings constructed according to the invention have increased resistance to penetration and damage by shells, bombs and explosions whether as a result of a direct hit or otherwise. With the present invention,the watl thickness of the structural element, which determines its ability to withstand the impactofshellsetc., alleviates any strength loss owing to any degradation of the fibre reinforcement. The mix'of grass and'our plastics fibres in the concrete or mortarchangesthe characteristics of normal concrete or ntcrtarfrom a brittle frangible material to a ductile material and this, in turn, increases several folitheability ofthe material to absorb the kinetic energy ofshell or bomb impact or shock, especially, whet used in thicknesses in excess of 50 mm, for example, 1-5 m. Increase in fibre content increases the resistance of the structural elementto impact and explosion in a linear manner and the higherthe fibre content, the more the resistance, up to an amount in which the fibre is present in the concrete or mortar by about 10% oftheweightofthe latter,whereafter little advantage is achieved by increasing the fibre content. Hence, the concrete mortar utilised in the present invention should have a fibre content not exceeding 10% by weight of the weight of the concrete or mortar and, preferably, in the range from 5-10% by weight of the weight of concrete or mortar. For the higherfibre contents, it may be necessary to add a plasticiserto the mix. Moreover, the invention enablesthewall thicknesses of structures intended to withstand shelling, bombing etc., to be reduced compared with conventional structures, whilst giving the same resistantnce to shells, bombs and explosions, thereby achieving savings in weight which, in turn, provides savings in the amount of steel reinforcementwhich maybe required and the strength offoundations. This achieves an overall saving in cost or, alternatively, enablestheerection of buildings orotherconstruc tionswhichwillwithstand larger impacts or explosionsthan hitherto known structures.The invention may enable a reduction in wall thickness of 50% or more, depending on the mix and fibre content, whilst providing the same protection as conventional constructions, and may not require steel reinforcement to achieve this improvement. The plastics fibre used in the invention may be polypropylenefibre. The type offibre has an important effect of the behaviour ofthe material. It has been found that alkali resistance glassfibreand polypropy lene fibre of different diameters and lengths are suitable for different uses within the field of this invention. Furthermore, the use of concrete employing an aggregate in the mix givesthe structural elementadditional resistance to the penetration of shells and bombs and it has been found that different ratios ofcement, water, sand and aggregate may be used to provide different results and different resistancesto different types of shells and bombs. As mentioned above, the structure according to the invention may include steel reinforcement. However, the invention enables satisfactory shelters for sensitive electronic installations to be constructed without steel reinforcement, thereby alleviating the effect on such installations of steel reinforcements used in conventional concrete shelters. In a modification, the invention may be employed as a linerforthe inside of conventional concrete structures. Such liners offer added protection to installations and personnel within the shelter as the liner has a less tendency to shatterthan conventional concrete. In one embodimentofthe invention,the mortar has a composition of 1 partcementto 1 part sand. This makes the mortar compatible with steel reinforcement and shrinkage experienced in thethickerwall structures produced with this invention. In another embodiment, the composition ofthe concrete is 1 part sand, 1 part cement and 1 part aggregate. In either case, the mortar or concrete, together with the required proportion of fibre, may be mixed in a conventional cement mixing plant. Whilst particular embodiments have been described, it will be understood that modifications can be madewithout departing fromthe scope of the invention. CLAIMS (filed on 7112/82)

1. A concrete structure comprising a structural wall, roof or other element at least 50 mmthickand made from concrete or mortar including glass and/or plastics fibre reinforcing material.

4. Astructure as claimed in claim 1,2 or 3, in which the fibre reinforcing material is present in the concrete or mortar by an amount not exceeding 10% by weight of the weight of the latter.

5. Astructureasclaimed in claim4, in which the fibre reinforcing material is present in the concrete or mortar in the range of from 5-10% byweightofthe weight ofthe concrete or mortar.

6. Astructure as claimed in any one of the preceding claims, in which the concrete or mortar mix also includes a plasticiser.

7. A structure as claimed in any one ofthe preceding claims, in which the fibre reinforcing material isanalkali resistantglassfibreand/or polypropylene fibre.

8. A structure as claimed in any one of the preceding claims, in which the mortar has a composition of about 1 part cement to about 1 part sand.

9. Astructure as claimed in any one of the preceding claims 1 to 7, in which the concrete has a composition of about 1 part sand, about 1 part cement and about 1 part aggregate.

10. Astructure as claimed in any one of the preceding claims, in which the structural element comprises a liner constructed on the inside of a conventional concrete structure.

11. A concrete structure substantially as hereinbefore described.