10 Fill in the gaps with derivatives of the words in capitals:

MASONRY CEMENTS Portland cement mortar is 1) _____ strong and concentrates any differential movement within brickwork or blockwork into a few large cracks, which are unsightly and may increase the risk of rain 2) _____. Masonry cement produces a weaker mortar, which accommodates some differential movement and ensures a 3) _____ of hairline cracks within joints, thus 4) _____ the integrity of the bricks and blocks. Masonry cements contain water-retaining mineral fillers, usually ground limestone, and air-entraining agents to give a 5) _____ workability than unblended Portland cement. They should not normally be blended with further admixtures but 6) _____ with building sand in ratios between 1:4 and 1:6½ depending upon the degree of 7) _____ of the brick or blockwork. The air entrained during mixing increases the durability and frost resistance of the 8) _____ mortar. Masonry cement is also appropriate for use in renderings but not for floor screeds or concreting. It is therefore 9) _____ used as an alternative to Portland cement with hydrated lime or plasticiser. 10) _____ pigments, except those containing carbon black, may be incorporated for visual effect. (From “Materials for Architects and Builders”)

UNNECESSARY PENETRATE DISTRIBUTE PRESERVE HIGH MIX EXPOSE HARDEN GENERAL ORGANIC

11 Fill in the gaps in the following passage with a suitable preposition given below: properties of cement

• Not permeable. Creates a sealed surface that does not allow vapour passage.

• Rigid. Requires expansion joints to allow 1) _____ natural earth movement without cracking.

• Hard. A great property 2) _____ the right place but often cement is too strong for the materials it is used with.

• Waterproof. Completely seals mortar joints or walls.

• Susceptible 3)_____ frost. Will crack in very cold conditions and therefore if used in foundations, needs to be in deep trenches that make contact with the warmth 4) _____ the earth to avoid problems associated with frost heave.

• Attracts moisture. Other materials around cement need to be protected 5) _____ it as it holds water and can cause rot to develop.

• Does not deal 6) _____ moisture. Can cause condensation problems in bathrooms, kitchens, bedrooms as it does not regulate moisture.

• Does not have a long history. It was invented in the mid 19th century and began to be used extensively 7) _____ 1930 onwards. We are seeing some major damp and durability problems now, caused 8) _____ the inappropriate use of cement from 50 or so years ago e.g. collapse of cob walls re-plastered with cement, the need to re-inforce some motorway bridges, excessive cracking in town houses leading 9) _____ difficulty in re-selling.

• Causes green house gas effect. The manufacture of cement is one of the major causes of the green house gas effect globally as it releases tonnes of carbon dioxide 10) _____ the atmosphere, none of which is re-absorbed by cement plaster.

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