Frost resistance

Bricks are classified into one of the three categories, F2, F1 and F0 according to their frost resistance within a standardized freezing test (Table 3.2).

Table 3.2 Designation of freeze/thaw resistance and active soluble salts content for clay bricks

Durability designation	Freeze/thaw resistance
F2	masonry subjected to severe exposure
F1	masonry subjected to moderate exposure
F0	masonry subjected to passive exposure
Active soluble salts content
S2	sodium/potassium 0.06%, magnesium 0.03
S1	sodium/potassium 0.17%, magnesium 0.08
S0	no requirement

Only category F2 bricks are totally resistant to repeated freezing and thawing when in a saturated condition. Category F1bricks are durable, except when subjected to repeated freezing and thawing under saturated conditions. Therefore, category F1 bricks should not be used in highly exposed situations such as below damp-proof courses, for parapets or brick-on-edge copings, but they are suitable for external walls which are protected from saturation by appropriate detailing. Category F0 bricks must only be used where they are subject to passive exposure, as when protected by cladding or used internally.

21 Topics for projects and presentations:

1. Optimal dimension, characteristics, and strength.

2. Brick tinting.

3. World masterpieces made of brick.

4. Concrete bricks and concrete brickworks.

5. Calcium silicate bricks.

“Beauty is due more to harmonious relationships among the elements of a composition

than to the elements themselves.” Matthew Frederick (architect)

CEMENTITIOUS MATERIALS FOR CONCRETE

Unit 4

a) concrete	b) cement	c) lime

Figure 4.1

LEAD-IN  

1 a) Match the words with the pictures (more than one answer is possible):

Mixture, to harden, calcium oxide, gravel, combination of, composite construction material, Portland, to bind, burnt in kilns, aggregates.

b) Match the terms with definitions:

1. cement	a) calcium-containing inorganic materials, in which carbonates, oxides and hydroxides predominate
2. concrete	b) a powdery substance made by calcining lime and clay, mixed with water to form mortar or mixed with sand, gravel, and water to turn into a solid
3. lime	c) a mixture of cement, water, sand and gravel (stones, crushed rock)

2 Read the following information and offer your ideas of further development and usage of cement:

Современный цемент был изобретен сравнительно недавно. В 1822 году после Отечественной войны 1812 года, Москва стремительно строилась. К вновь возводимым каменным зданиям предъявлялись повышенные требования по прочности и надежности. Деревянных построек после памятного пожара, который устроили отступающие французы, старались не возводить. Русский строитель Егор Челиев (по некоторым данным Делиев), проводя эксперименты с обожженным составом извести и глины, получил сухую строительную смесь способную затвердевать в воде до состояния камня. Так был изобретен современный цемент.

3 Discuss the following:

«Concrete tsunami is wiping out Russian heritage». (From guardian.co.uk)

Clay and lime conceal much evil. (Spanish proverb)

• Write a paraphrase. • Say whether you agree or not, and why.

READING  

4 a) Transcribe the following words:

hydraulic cement, carbon dioxide, lime mortar, aqueduct, artificial pozzolanas, argillaceous, calcium carbonate, carboniferous, iron oxide, polypropylene fibres.

b) In what context do you think the following words and phrases will appear in the text?

•adhesives •mortar •volcanic ashes •kiln •decarbonisation •plastic material •shape of the mould•absorption of water •frost damage

b) Read the text and check your answers:

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