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 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 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: A random copolymer corresponding to Formula I in free acid or salt form having the following types and numbers of monomer units; ##STR1## wherein A is selected from the moities (i) and (ii);--CR.sub.1 R.sub.2 --CR.sub.3 R.sub.4 -- (i)wherein R.sub.1 and R.sub.3 are selected from substituted benzene, C.sub.1-8 alkyl, C.sub.2-8 alkenyl, C.sub.2-8 alkylcarbonyl, C.sub.1-8 alkoxy, carboxyl and hydrogen, or R.sub.1 and R.sub.3 can together with R.sub.2 and/or R.sub.4 form a ring; and R.sub.2 and R.sub.4 are selected from hydrogen and C.sub.1-4 alkyl; and ##STR2## wherein R.sub.1 and R.sub.3 are as for (i) and R.sub.7, R.sub.8, R.sub.9 and R.sub.10 are individually selected from hydrogen and C.sub.1-6 alkyl, or R.sub.1 and R.sub.3 together with R.sub.7 and/or R.sub.8, R.sub.9 and R.sub.10 form a continuous C.sub.

Abstract: A random copolymer corresponding to Formula I in free acid or salt form having the following types and numbers of monomer units; ##STR1## wherein A is selected from the moieties (i) and (ii);--CR.sub.1 R.sub.2 --CR.sub.3 R.sub.4 -- (i)wherein R.sub.1 and R.sub.3 are selected from substituted benzene, C.sub.1-8 alkyl, C.sub.2-8 alkenyl, C.sub.2-8 alkylcarbonyl, C.sub.1-8 alkoxy, carboxyl and hydrogen, or R.sub.1 and R.sub.3 can together with R.sub.2 and/or R.sub.4 form a ring; and R.sub.2 and R.sub.4 are selected from hydrogen and C.sub.1-4 alkyl; and ##STR2## wherein R.sub.1 and R.sub.3 are as for (i) and R.sub.7, R.sub.8, R.sub.9 and R.sub.10 are individually selected from hydrogen and C.sub.1-6 alkyl, or R.sub.1 and R.sub.3 together with R.sub.7 and/or R.sub.8, R.sub.9 and R.sub.10 form a continuous C.sub.

Abstract: A random copolymer in free acid or salt form having the following types and numbers of monomer units; ##STR1## in which M is hydrogen or a residue of a hydrophobic polyalkylene glycol or polysiloxane,R is an C.sub.2-6 alkylene radical,R.sub.1 is a C.sub.1-20 alkyl, C.sub.6-9 cycloalkyl or phenyl group,x,y and z are numbers from 1 to 100,m is a number from 1 to 100,n is a number from 10 to 100,with the provisos, thati) the ratio of x to (y+z) is from 1:10 to 10:1 inclusive,ii) the ratio of z:y is from 5:1 to 100:1, andiii) m+n=15-100.The copolymers are useful as additives in cementitious compositions.