Minerals - The Ecology of Building Materials - page 98

Table 6.5: Additives in cement and concrete

Additive Contents

Anti-freeze Alcohol, glycol, inorganic salts

Expander Iron powder, sulphur-aluminate cement

Water repellent Stearic acid, oleic acid, fats, butyl stearate, wax emulsions, calcium

stearate, aluminium stearate, bitumen, silicone, artificial resins

Permeability reducer Bentonite clay, lime, fossil meal

To improve pumping Alginates, polyethylene oxides, cellulose ethers

To reduce reactions with Lithium- and barium salts, pozzolanas

alkali-silica compounds

To reduce corrosion Sulphites, nitrites, benzoates

Fungicide Copper salts, dieldrin, polyhalogenized compounds

To reduce foaming Polyphosphates, polyphthalates, silicones, alcohol

Aerating Hydrogen peroxide, aluminium powder, magnesium, zinc, maleic

acid-anhydride

To increase adhesion Silicones, artificial resins such as PVA, PVP and acryl, epoxy,

polyurethane, styrene and butiadiene compounds

To mix in air Natural timber resins, fatty acids and oils, lignosulphonates, alkyl

sulphonates or sulphates (e.g. ethylene ether sulphate, sodium
dodecyl sulphate, tetradecyl sulphate, cetyl sulphate, oleoyl
sulphate, phenol etoxylates, sulphonated naphthalenes) tensides,
plastic pellets

To reduce the amount of water Ligno sulphonates, polyhyroxy-carboxyl-acids and salts,

polyethylene glycol, melamine formaldehyde sulphonates,
naphthalene formaldehyde sulphonates, aliphatic amines, sodium
silicate, sodium carbonate

Accelerators Calcium chloride, other calcium salts (e.g. bromide, iodine, formiate,

nitrite, nitrate, sulphate, oxolate, hydroxide, fluate), the equivalent
salts of sodium, potassium, lithium and ammonium,
triethanolamine, sodium silicate (waterglass), sodium carbonate
(soda), aluminates

Retardants Carbohydrates (sugar, starch), heptonates, phosphates, borates,

silicon fluoride, lead and zinc salts, hydroxy-carboxyl acids and
salts (e.g. gluconates), calcium sulphate dihydrate (gypsum)

(Source: U. Kjær et al , 1982)

for other production methods that use fossil fuel. The temperatures in the firing
zones are so high, around 2000°C, that it must be assumed that nitrogen oxides
are also emitted. This is not removed from the effluent today, although the