Abstract: The present invention relates to mixtures, preferably sealing pastes, particularly preferably shield tail sealing pastes, and the use of the mixtures according to the invention for sealing construction elements and/or construction machines, in particular for preferably temporary sealing of the transition between shield tail of a tunnel boring machine and the pipe lining or tubbing lining of the tunnel securing means.

Abstract: A method of reducing wear in a cutting head of a tunnel boring machine, by means of the addition at the cutting head of a foamed aqueous liquid composition, which comprises a foaming agent and a lubricant, the lubricant being selected from the group consisting of high molecular weight polyethylene oxides and bentonite. Preferred foaming agents are anionic and nonionic surfactants. Wear rates of cutting elements of TBMs boring in hard rock are considerably reduced. A wear-reducing foamable concentrate is also described.

Abstract: A method of boring a tunnel by means of an earth pressure balance tunnel boring machine, comprising the injection at the cutting head of a foamed aqueous solution and an aqueous solution of a water-soluble acrylic acid-based polymer. The method allows easier tunnel boring in soft, sticky soils.

Abstract: The surface of rock or soil, newly-exposed, for example, by tunnelling, and having the tendency to become friable on exposure to the atmosphere, can be protected by forming thereon a film by the process of combining on the surface at least one coagulable material and a coagulating agent therefor. The preferred coagulable material is an aqueous polymer dispersion, preferably one which has some degree of elastomeric properties, and preferably one which additionally is anionically stabilized.

Abstract: The surface of rock or soil, newly-exposed, for example, by tunnelling, and having the tendency to become friable on exposure to the atmosphere, can be protected by forming thereon a film by the process of combining on the surface at least one coagulable material and a coagulating agent therefor. The preferred coagulable material is an aqueous polymer dispersion, preferably one which has some degree of elastomeric properties, and preferably one which additionally is anionically stabilised.

Abstract: A method of boring a tunnel by means of an earth pressure balance tunnel boring machine, comprising the injection at the cutting head of a foamed aqueous solution and an aqueous solution of a water-soluble acrylic acid-based polymer. The method allows easier tunnel boring in soft, sticky soils.

Abstract: A method of reducing wear in a cutting head of a tunnel boring machine, by means of the addition at the cutting head of a foamed aqueous liquid composition, which comprises a foaming agent and a lubricant, the lubricant being selected from the group consisting of high molecular weight polyethylene oxides and bentonite. Preferred foaming agents are anionic and nonionic surfactants. Wear rates of cutting elements of TBMs boring in hard rock are considerably reduced. A wear-reducing foamable concentrate is also described.

Abstract: A process of boring a tunnel using an earth-pressure balance shield boring tunnelling machine having a cutting head, an excavation chamber for soil removed by boring and conveying means for removal of said soil from the excavation chamber; wherein there is injected into a stratum being bored at the cutting head a foamed aqueous solution, characterized in that (a) the aqueous solution contains two essential components which are (i) a sulphate- or sulphonate-containing anionic susfactant, and (ii) &bgr;-naphthalene sulphonate-formaldehyde condensate; and in that (b) there is applied to the soil removed by boring in at least one of the excavation chamber and the conveyor a second aqueous solution containing essentially a high molecular weight polyethylene oxide and optionally a sulphate- or sulphonate-containing anionic surfactant. The process allows easy removal of soil from the cutting head to the excavation chamber and from the excavation chamber out of the machine.

Abstract: A method of boring a tunnel through a stratum utilizing a shield tunneling apparatus, the process comprising the injection into the stratum at the cutting face of an aqueous material comprising (a) from 0.005-0.05% by weight of a polyethylene oxide of weight-average molecular weight from 2,000,000 to 8,000,000 (b) from 0.05-0.5% by weight of a sulphate-containing anionic surfactant. The method is effective even in difficult soils.

Abstract: An admixture for use in cementitious compostions which are to be applied in consecutive layers consists essentially of a water-soluble polyalkylene oxide and a superabsorbent material. Optionally (and preferably) also present is a plasticiser or superplasticiser, preferably a polyalkylene oxide-modified styrene-maleic anhydride copolymer.

Abstract: A storable cement-mortar dry mix, which comprises the components cement, aggregate, reaction resin and hardener in a single mixture, wherein the hardener is present as the reaction product of the hardener with an organic acid or a functional derivative thereof.

Abstract: A storage stable dry mixture for resin containing cement compositions is produced by contacting the resin and the hardener with a finely divided, solid adsorbent having a surface area of at least 0.2 m.sup.2 /g which is of an amorphous nature and is produced by a pyrogenic method, before mixing these components with cement.

Abstract: An apparatus and a process for mixing water from a pressurized source and an additive or admixture for a cementitious composition in a mixing chamber comprising introducing, in the form of a jet, water under a first pressure, which is above atmospheric pressure, and introducing the additive under a second pressure between atmospheric pressure and the first pressure, the amount of the additive that is introduced to the mixing chamber being controlled by means regulated by the pressure of water.