2. Read the following sentences and divide them into three groups ‘The Choice of Materials for Any Work of Construction’, ‘The Properties of High Alumina Cement’ and ‘The Composition of Concrete’.

1. Another important class of cement is high alumina cement.

2. Such a material may be considered an artificial conglomerate of crushed stone or gravel with a mortar.

3. The civil engineer must consider many factors when selecting the material for construction.

4. This kind of cement is very resistant to chemical attack.

5. The principal object in proportioning concrete is the production of a durable

material of adequate strength and water tightness.

6. The factors that condition the selection of materials for construction include availability, cost and physical properties.

7. This material has an extremely high rate of strength increase.

8. Timber, steel and concrete vary over considerable ranges in the properties desired by the engineer and the latter should take them into consideration in selecting the materials.

9. The most accurate method of measuring proportions for concrete is to weigh the required quantities of each material.