Abstract: A spray nozzle of the type adapted to feed a liquid to a material being sprayed therefrom comprises a tubular spray conduit around which is arranged an annular feed port, this feed port being closed in a liquid-tight manner by resilient material openable by liquid pressure and whose degree of opening, and therefore the quantity of liquid fed to the material, rises linearly with increasing liquid pressure. Preferably, the resilient material is provided by a membrane ring (7) which is a flat ring with inwardly-tapering radial ridges (8b) raised thereon, the gaps between the ridges being filled with an elastomeric material, such that a series of resilient segments (9) is created. Under liquid pressure, the segments are compressed equally, giving a nearly completely annular flow of liquid into the material. The nozzle is particularly useful for the spraying of concrete, especially by the dry method.

Abstract: The invention relates to a random styrene-maleic anhydride (SMA) copolymer in free acid or salt form wherein the copolymer has the following types and numbers of monomer units ##STR1## in which M is selected from hydrogen, a cation and a residue of a hydrophobic polyalkylene glycol or polysiloxane, R is the residue of methylpoly(ethylene)glycol of molecular weight (weight-average) 900-2000, x=0.35-0.75 and y=0.25-0.65. These copolymers are particularly useful as superplasticizers in cementitious compositions such as concretes and mortars.

Abstract: An admixture dispensing and concrete mixer monitoring system which determines the correct amount of admixture, such as a stabilizer, to dispense in a load of unused concrete or for washing out a concrete mixer includes an admixture dispensing unit linked to a computer system. The computer system includes a processor which controls and monitors the operation of the dispensing unit which includes an admixture piping system and a water piping system. The processor is linked to various pumps, meters and valves in the admixture and water piping systems to control the flow of admixture and water into the concrete mixer. Additionally, the computer system provides questions and prompts to the user to assist in accurately and quickly determining the correct amount of admixture to deposit in the concrete mixer. The computer system also allows the tracking of multiple delivery or mixing trucks and their content status at multiple mixing plants to assist in the scheduling thereof.

Abstract: An admixture dispensing and concrete mixer monitoring system which determines the correct amount of admixture, such as a stabilizer, to dispense in a load of unused concrete or for washing out a concrete mixer includes an admixture dispensing unit linked to a computer system. The computer system includes a processor which controls and monitors the operation of the dispensing unit which includes an admixture piping system and a water piping system. The processor is linked to various pumps, meters and valves in the admixture and water piping systems to control the flow of admixture and water into the concrete mixer. Additionally, the computer system provides questions and prompts to the user to assist in accurately and quickly determining the correct amount of admixture to deposit in the concrete mixer. The computer system also allows the tracking of multiple delivery or mixing trucks and their content status at multiple mixing plants to assist in the scheduling thereof.

Abstract: A cementitious mixture comprises a hydraulic cement; greater than about 10% by weight of a pozzolanic cement replacement selected from fly ash, slag, natural pozzolans, and mixtures thereof, based on the weight of said hydraulic cement and cement replacement; and a compatabilizing admixture, wherein the compatabilizing admixture comprises a compatabilizing polycarboxylate polymer dispersant capable of acting as a water reducer, in combination with an accelerator.

Abstract: A cement clinker grinding aid which comprises a styrene-maleic anhydride copolymer (SMA) superplasticiser. The SMA is preferably a type with polyoxyalkylene-based side chains. Use of the grinding aid renders the grinding process more efficient and improves the performance of cementitous compositions in which the cement thus ground is used.

Abstract: An accelerating admixture for use with spraying cementitious compositions such as shotcrete comprises (a) a compound selected from aluminium hydroxide, aluminium hydroxysulphate and mixtures thereof, and (b) an acidic substance which essentially does not react with the compound. The preferred acid substances are organic acids.

Abstract: An accelerating admixture for use with sprayable cementitious compositions such as shotcrete comprises a mixture of (a) amorphous aluminium hydroxide and/or aluminium hydroxysulphate, and (b) at least one amine, preferably an alkanolamine. In a preferred embodiment, the admixture also comprises an aqueous dispersion of at least one polymer which comprises pendant carboxylic moieties.

Abstract: An accelerating admixture for use with cementitious compositions, especially shotcrete, comprises aluminium sulphate and at least one alkanolamine. The admixture also preferably comprises an stabilising agent, which is preferably selected from aqueous stable polymeric dispersions and sepiolite magnesium silicate.

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 method for coating a substrate with a cementitious composition by spraying, comprising the addition to the initial cementitious mix one of a .beta.-naphthalene sulphonate-formaldehyde condensate and a water-soluble poly(alkylene oxide) of molecular weight from 100,000-8,000,000, the other being added at the spraying nozzle, there being additionally added at the nozzle (preferably as a single component with the other nozzle-added material) an accelerator selected from aluminium sulphate, aluminium hydroxide and aluminium hydroxysulphate. In a preferred embodiment, the material added at the nozzle also contains a superplasticiser.

Abstract: Polysuccinimide and/or polyaspartate, copolymers of succinimide and aspartate and the polymers cross-linked with a diamine are demonstrated to be enhancement agents for the preparation of cementitious materials. The agents may be added to the dry cementitious mixture or the water which is added to form the cementitious material upon hardening. The enhancement agents improve the workability of the wet cementitious mixture, reduce slump loss during mixing, transport, and placement of the wet cementious mixture; and may provide extra strength upon hardening of the cementitious material.

Abstract: Rapid setting cementitious compositions comprise hydraulic cement and at least 4% by weight based on the weight of the cement of a water-soluble malate or citramalate such as an alkali metal malate or alkali metal citramalate.

Abstract: An admixture for decreasing the water demand of cementitious compositions such as concrete consists of(a) from 75-25% by weight of a water-reducing agent whose major component is a polycarboxylate; and(b) from 25-75% by weight of at least one saccharide component selected from hydrogenated saccharides and polyhydric alcohol adducts of saccharides.The saccaride component is preferably a hydrogenated polysaccharide with a molecular weight distribution as follows:(i) 70-30% by weight (on total weight of hydrogenated saccharides) have molecular weights in the range 180-300;(ii) 30-70% by weight have molecular weights of from 300 up to 4,000; and(iii) 30% by weight maximum have molecular weights of 4,000 and over.

Abstract: Cement admixtures contain an alkali metal carbonate as component (a) and a mono- or di-carboxylate acid or alkali metal salt thereof or an alkali metal salt of a tricarboxylic acid as component (b).

Abstract: A cement setting and hardening accelerator having the formulaAl(OH).sub.x (R).sub.ywherein R is a basic anion which is not sulphate, and x+y=3. The anion is preferably derived from an acid RH.sub.n which is preferably an organic acid. The accelerator gives excellent performance in shotcrete and is alkali-free.

Abstract: Storing, transporting and dispensing of silica fume containing pozzolanic compositions can be improved by mixing an amount of water in the range of 2 to 25% with the silica fume containing composition so that a uniform humidified powder is obtained. The treated silica fume containing composition has higher bulk gravity and better flow characteristics.

Abstract: The fluidity characteristics of cementitious compositions may be rapidly altered by the addition thereto of an aqueous dispersion of at least one comb polymer which comprises carboxylic moieties. The invention works especially well when the polymer is combined with an accelerator which is at least one of aluminium hydroxide or aluminium hydroxysulphate.

Abstract: An additive for concrete, mortar or grout comprises at least one admixture material in a compacted unit of selected amount, the unit having strength sufficient to maintain structural integrity during handling and storage, but having sufficient solubility or friability upon mechanical agitation within a wet mixing environment of a cementitious composition mixture to dissolve or fragment for uniform dispersal throughout the cementitious composition mixture.

Abstract: A cement pumpability-enhancing additive which comprises polyethylene glycol and diethylene glycol monobutyl ether and/or a derivative thereof, and optionally polysaccharide. The additive is especially useful for high-strength, high-flow concretes for use in construction.