116) The main reason to use lime in the cement slurry during the plastering in the top coat, is

• (a) to make the surface bright
• (b) to harden the cement
• (c) to make the plaster non-shrinkable
• (d) to improve the workability of plaster

117) The hydraulicity of the hydraulic lime is mainly due to

• (a) calcium oxide
• (b) clay
• (c) sulphur
• (d) water

118) The constituent in lime which retard the slaking action and increase the rapidity of setting, is

• (a) silica
• (b) sulphate
• (c) alkalies
• (d) alumina

119) The main constituent of a Portland cement is

• (a) lime
• (b) alumina
• (c) iron oxide
• (d) alkalies

120) The silica (SiO2) in Portland cement should be

• (a) 10 to 20%
• (b) 20 to 25%
• (c) 25 to 40%
• (d) 40 to 60%