FIREPROOF ELEMENT AND ITS FABRICATION

Abstract: The invention is concerned with a method for fabricating a fireproof lined wall, such as a tunnel tube for traffic, e.g. car or train traffic, with the aid of a mould, wherein the at least initially castable fireproof lining is formed to the mould side and/or to the fill side and wherein possibly the specific weight of the fireproof layer is lower than that of the wall. The invention is also concerned with a wall obtained by said method.

Description: , Fireproof element and its fabrication. Description Typical concrete has a poor fire- or heat resistance with e.g. prolonged and hot fires. In the following, "fire-resistance" is also used for "heat-resistance" . It is common to protect concrete elements with fire proof lining, that is either applied after the pooring and curing of the concrete, e.g. as prefabricated, rigid panels or fluid by virtue of spraying, or before as so called lost formwork as rigid panels onto which the concrete is poured and subsequently cured. It is found out that by this the fire-resistance does not meet the toughest requirements, such as those according to the so called RWS- curve, also called calamity curve. The RWS-curve is e.g. shown in fig. 6 of TNO-report 97-CVB-R0710 "FIRE PROTECTION of TUNNELS-fire test procedure", Juni 1997, ing. P.W. van de Haar, TNO Building and Construction Research, Rijswijk and its description is roughly as follows: Initially the temperature rises virtually linear from approximately 20°C to approximate- ly 1140°C within about 5 minutes, subsequently rising asymptotically to approximately 1350°C within about 45 minutes, subsequently falling almost linear to approximately 1200°C during about 60 minutes. Compared with other standard fire curves, such as the hydrocarbon curve or the ISO curve (NEN 6069), the R S curve requires a temperature of more than 1200 °C during about 90 minutes, a temperature of more than 1250 °C during about 70 minutes and a temperature of more than 1300°C during about 60 minutes. The object of the invention is to make improvements to one or more properties, such as fire-resistance or fire toughness of fire-resistant lined elements, in particular of concrete or other cured material that initially can be poored out. In particular the object is provision of adequate protection at loading according to the RWS curve or a requirement derived therefrom that is tougher compared to the other above indicated curves. It is proposed to fabricate according to the invention a fire proof lined wall, such as of a tunnel or tunnel segment, with a formwork or mould wherein said fire proof lining is applied to the mould side and/or to the fill side. After fabrication, the mould or formwork and the wall are preferably seperated. Preferably the lining is brought in the mould in a condition wherein the material of said linging can be cast. The term "to the mould side" here means the side of the mould that makes the wall side that will be facing the inner wall of the tunnel, which inner wall will eventually be exposed to the fire. The term "to the fill side" here means the open side of the mould, wherefrom the material is brought into the mould. The term "castable" here means a pourable or sprayable or castable property, such as fluid or granular or paste-like. The term "curing" here means loosing the "castable" property, e.g. by growing of a chemical bond between compounds, or e.g. by disappearance of a solvent. During introduction into the mould, the lining material has preferably a so called "zet"- value of approximately 150, although it is expected that the flow property of this lining material may vary within the range of the "zet" value between about 20 and about 200, in particular between about 130 and about 180. The value given here for the "zet" value are mm. measured mean values determined according to the method indicated in NEN 5956, "zet" value and NEN 5957, "schud" value. Preferably, the tunnel is made with a tunnel bore technique. The tunnel wall is prefera- bly build from prefabricated segments. It is surprisingly found out that the requirements of fire-resistance can be met in this way. It is surprisingly found out that the permeability of the fireproof lining can be such that suction caps can engage thereon, e.g. to lift a prefabricated segment. It is surprisingly found out that the porosity of the fireproof lining can be such that a prefered sound absorption is obtained. The specific weight of the fire-resistant layer can be smaller than that of the substrate. The specific weight of the fire- proof lining is preferably at least 10%, more preferably at least about 25%, most preferably at least about 50% lower than that of the substrate. Preferably, the fireproof layer is at least substantially free of sand. Preferably, the substrate and the fireproof lining are worked "wet in wet" . It is preferred to bring the substrate and the fireproof lining in mutual contact at the moment that the fireproof lining is still not or not yet completely cured. The term "not yet completely cured" here means a condition, wherein it is still possible to obtain an intimite adhesion or embedment of both materials (lining and substrate). Possibly, a technical upper limit is a degree of hardness wherein it is impossible, to make an impression of a thumb into the materail with hand force which can be detected with the naked eye. The proposal according to the invention is based on the recognition that in this way a very intimite or homogeneous bond between the substrate and the lining is obtained, such that the lining gets sufficient strength to be exposed to great heat for an extended period of time without collapsing, e.g. to withstand the temperature curve according to the RWS curve. It is also possible to obtain a shortening of the process and/or a decrease of the number of operations to be carried out. Preferably, the lining is applied with a thickness of approximately 40 mm, although different thicknessess are also feasible, e.g. within the range between from about 20 to about 60 mm. , depending from the nature of the applied lining material, the nature of the substrate and the expected temperature load. Compared to the prior art, it is found out that with the invention it is also possible to use thinner layer thicknessess or different lining materials (e.g. lower specific weight) to meet the same requirements of fire-resistance, such as e.g. according to NEN 6069 or the hydrocarbon curve or a temperature of about 700°C to a minimum, such that savings, e.g. to material quantities, material costs or processing costs can be obtained. The fire-resistant material is preferably based on cement, such as aluminium cement. The fire-resistant lining preferably contains at least 5 vol%, more preferably at least approximately 10 vol% aluminium cement. Preferably, the lining contains microsilica, e.g. in an amount 2 wt%. To improve properties, mineral or organic fibres are preferably added, e.g. in an amount of 10 vol%. The lining preferably contains several types of cement, among which e.g. aluminium cement. The cement is present in an amount sufficient to obtain the required heat resistance (e.g. to meet the requirements according to the RWS curve) of the lining. The skilled man will have no difficulty to experimentally determine the amount of cement and the mixing ratio of the several cement types for the above mentioned object. The lining preferably contains a large number of, preferably closed, cavities or cells. Said cells are prefera- bly mixed through the material as homogeniously as possible. On the one hand it is preferred that the dimensions of said cells are as homogenious as possible, e.g. approximately spherical with a diameter between about 0.5 and 5 mm, e.g. about 3 mm. , wherein all fractions are preferably present in about equal proportions. Those cells are conveniently obtained by adding preferably expanded granules of e.g. plastics, such as polystyrene, or any other convenient material. Alternatively such cells can be obtained with e.g. a foaming agent, such as known as such from the art of cellular concrete. If the cells are filled with granules, preferably said granules must have a better heat insulating property than the lining material surrounding the granules, and therefor contain e.g. a large proportion of air or another gas, e.g. at least 70 vol% gas, such as is the case with expanded granules. The cells prefera- bly have a volume proportion of at least about 10%, more preferably at least about 30%, most preferably at least about 50%. All above mentioned materials together make a lining that meets the above indicated objects in the best way. Proportions of cement, microsilica, fibres, cells are each such that the contribution of each to the aimed properties is substantial. Application of equivalents for one or more of the above mentioned compounds known to the skilled man is also possible. The substrate is preferably concrete, such as structural concrete, possibly provided with a convenient reinforce- ment . In combination with the lining, a unique combination of structural building in concrete is obtained by the fireproof properties and the compression strength. However, it is feasible to apply the lining according to the invention onto anot- her substrate, e.g. steel or wood. Fabrication of prefabricated elements with integrated fireproof lining is most preferred. For that, the fireproof lining is applied in the formwork or mould first, followed by the possible reinforcement and then the substrate. After sufficient curing, the segment is removed from the mould and brought to the remote tunnel construction area and added to the tunnel tube. In this way, tunnel elements provided with a fireproof layer can be fabricated previously in a well inspectable and reproducible manner. It is found out that for a proper result of the invention, inspectability and controllability are of decisive importance. During the present method one can e.g. allow some curing time for the lining applied into the mould before the substrate is added. Naturally it is feasible that one pours the still fluid or castable fireproof lining material in the mould, and then first spreads it in a uniform layer. Alternatively, the lining material can be applied in the mould by e.g. spraying. After applying the fireproof layer in the mould, it is also feasible to position in the mould a preformed tunnel segment to be lined with fireproof material, such that it is adhered to the fireproof material within the mould. For lining e.g. a rock wall it is convenient to locate a formwork at some distance from said wall such that a gap with a thickness according to the desired thickness of the fireproof lining is made, whereafter said gap is filled up with the fireproof material, e.g. with the aid of a convenient injection technique. It is also possible to first apply the fireproof material, e.g. by spraying, and than to position the mould, wherein an excess amount of applied fireproof material is pressed away. The lining can e.g. be provided with a cover layer, e.g. to give it a convenient colour or to make it e.g. dirtrepellant . By way of example, in a lying mould, i.e. wherein the monodi- rectional curved mould wall (radius 10 m.; which however also can be e.g. 6 or 11 m.) determining a part of the inner wall of the tunnel provides the bottom of the mould that bulges upward, which mould is treated with a convenient releasing agent, fireproof material (mixture of cement, comprising aluminium cement, water, polystyrene granules, mineral fibres, microsilica in a mixing ratio conveniently experimentally determined by the skilled man on the basis of the above description and his knowledge to obtain a specific weight of about 1000 kg/m ) is poured and spread out equally over the bottom in a thickness of about 40 mm. Subsequently a reinforcement, known as such, of a space structure of steel rods is located in the mould, whereafter the common structural concrete is poured. Apart from application to a wall of a traffic tunnel, different applications are feasible, e.g. in a wall for an oven or a container for molten material.

Claims: CLAIMS 1. Method for fabricating a fireproof lined wall, such as of a tunnel tube for traffic, e.g. car or train traffic, with the aid of a mould, wherein the at least initially castable fireproof lining is formed to the mould side and/or to the fill side and wherein possibly the specific weight of the fireproof layer is lower than that of the wall. 2. Method according to claim 1, wherein the wall is constructed from one or more prefabricated segments, that are preferably previously provided with the fireproof lining. 3. Method according to claim 1 or 2 , wherein the wall and the fireproof lining are worked "wet in wet" in the mould. 4. Method according to any of claims 1-3, wherein fire proof material to make the fireproof lining with a specific weigth of about 1000 kg/πr is poured onto the bottom of the mould and thereafter, before the lining is cured, structural concrete as the substrate is poured on top of the lining within the mould. 5. Method according to any of the preceeding claims, wherein the fireproof lining offers protection against a temperature of at least about 700°C, perferably meets at least the temperature time curve according to NEN 6069, more preferably the RWS temperature time curve. 6. Method according to any of the preceeding claims wherein provisions are made that the material of the fireproof lining has a "zet" measure within the range from about 20 to 200, preferably from about 130 to about 180 and most preferably about 150. 7. Wall with fireproof lining, obtained with the method according to any of the preceeding claims. 8. Wall with fireproof lining according to claim 7, wherein the fireproof lining contains at least one of the following substances: microsilica, cement, aluminium cement, expanded granules like polystyrene granules. 9. Wall with fireproof lining according to claim 7 or 8 , wherein the thickness of the fireproof layer ranges between about 20 and about 60 mm., preferably measures about 40 mm, and/or wherein the wall is made of structural concrete and preferably determines a segment for a tunnel tube. 10. Method for making a tunnel, wherein a tunnel channel is formed, particularly bored, underground, while the walls are obtained by the method according to any of the preceeding claims 1-6. SUB S TITUTE SHEET (RULE 2 β ,

Inventors: FRERIKS ED, GRAVESTEIJN NICOLAAS DIRK, FRERIKS, ED, GRAVESTEIJN, NICOLAAS, DIRK
Applicants: BALLAST NEDAM BETON WATER, FRERIKS ED, GRAVESTEIJN NICOLAAS DIRK, HANDELSMAATSCHAPPIJ DE KEERKRI, HATTUM & BLANKEVOORT BV, BALLAST NEDAM BETON EN WATERBOUW B.V., FRERIKS, ED, GRAVESTEIJN, NICOLAAS, DIRK, HANDELSMAATSCHAPPIJ DE KEERKRING B.V., VAN HATTUM EN BLANKEVOORT B.V.
Application year: 1998
Main classification: E21D11
IPC codes: C04B28, E21D11