Decide whether the following statements are true or false according to the text.

1) Gravity dams use its own dead weight to resist the vertical force of the water.

2) The shape of the gravity dam resembles a triangle.

3) The shallower the water, the more horizontal pressure it exerts on the dam.

4) At the surface of the reservoir, the water is exerting maximum pressure.

5) At the bottom of the reservoir, the water is exerting no pressure.

6) For gravity dams, good pervious foundations are essential.

7) The solid form of the gravity dam is more widely used.

8) The hollow dam is less economical to construct.

9) The construction works on a gravity dam may be divided into two stages.

10) The foundation must be excavated to solid rock before any concrete will be poured.

11) After excavation cavities or faults in the foundation are sealed with concrete or grout.

12) A grout curtain is placed near the top of the dam to increase seepage and uplift.

13) The maximum width of a block is usually about 50 ft and maximum height of a single block is usually about 5 ft on medium-height dams.

14) Block are sprinkled with water and so protected from the drying.

15) The lateral surfaces of each block are painted with an asphaltic emulsion to prevent adherence of adjoining sections.

16) Metal water stops are also placed in the vertical construction joints near the downstream face to prevent leakage.

17) Inspection galleries are formed after the concrete has been placed.

18) Water never seeps into the dam.

19) To avoid cracks, special low-heat cement may be used.

20) For obtaining best results the temperature of the concrete mix should be between 10⁰ and 26.6⁰ C.