III. Now say which material:

1. is made from a combination of aggregate and binder?

2. was historically used for building in its unprocessed form?

3. can be made in the course of the stiff mud process?

4. was used to build the Aztec pyramids?

IV. Answer the questions:

1. What are basic building materials?

2. Do you think the list of building materials used for costruction today is complete? If not, what other materials would you add to the list?

3. How would you describe the properties of the most widely used building materials?

4. What building materials do you think will be used in 100 years' time?

V. Match building materials to their descriptions:

	A		B
1	concrete	A	hard vulcanized rubber
2	Portland cement	B	powder made from alumina, silica, lime, iron oxide, and magnesia burned together in a kiln and finely pulverized
3	vulcanite	C	gray, brown or black quartz
4	marble	D	a hard strong bilding material made by mixing a cementing material (commonly Portland cement) and a mineral aggregate
5	flint	E	artificial stone of crushed granite and cement
6	cement	F	a mixture of limestone and clay, burned in a furnace and then pulverized. Impervious to water, it actually becomes stronger if submerged after it hardens
7	granolith	G	limestone crystallized in varying degrees by metamorphism ranging from granular to compact in texture, usually white or veined or tinted or mottled

VI. Now look at this table:

	Density kg/m3	Melting point 0°C	Typical tensile strength N/mm2	Relative cost
Glass	2520	1500	60	12
Concrete	2300	-	4	1
Softwood (pine) Hardwood (oak)	5500 8800	- -	40 100	6 15
Mild steel	7850	1900	450	9
Aluminium	2640	660	90	35
Copper Zinc	8950 7100	1083 420	340 110	25 20

a) Identify these materials from the table:

a) This material has a slightly lower density than aluminium.

b) This material has a much higher melting point than glass.

c) This material has a tensile strength much higher than concrete, but slightly lower than zinc.

d) This material is slightly lighter than oak but is much stronger in tension.

e) This material has a considerably higher melting point than copper but a much lower tensile strength.

f) This material has a tensile strength approximately twice that of pine.

g) The melting point of this material is approximately 11/2 times as high as that of copper. h) The density of this material is approximately half that of pine.

i) This material is ten times as strong as concrete in tension.

j) These two materials have very nearly the same tensile strength.

b) In pairs, compare some materials as in the following way:

e.g. Oak is considerably heavier than pine, has a much higher tensile strength and costs 2,5 times more per kilogramme.

a) glass and concrete

b) aluminium and mild steel

c) copper and zinc

d) pine and mild steel