SSC · Building Materials practice

Correct answer: B

C3S hydrates quickly and gives most of the strength in the first 7 to 28 days. C2S hydrates slowly and adds strength later.

Correct answer: D

Initial setting time must be at least 30 minutes so the mix can be transported and placed. Final setting time must not exceed 600 minutes.

Correct answer: A

Standard consistency is the water content (as a percentage of cement) at which the 10 mm plunger penetrates the paste and stops 5 to 7 mm from the bottom of the 40 mm deep mould.

Correct answer: C

The modular brick is 190 × 90 × 90 mm actual and 200 × 100 × 100 mm nominal, which includes 10 mm of mortar joint.

Correct answer: D

First class bricks are limited to about 20 percent absorption. Second and third class bricks are allowed a little more.

Correct answer: D

Quick lime is made by burning limestone. Slaking it with water gives calcium hydroxide.

Correct answer: A

A thin water film around the grains pushes them apart, so volume increases up to about 20 to 30 percent at roughly 4 to 6 percent moisture. Fully dry or fully saturated sand does not bulk.

Correct answer: A

Seasoning dries the timber to a safe moisture level, which reduces warping, shrinkage and attack by fungi.

Correct answer: B

Granite forms from cooled magma. Sandstone is sedimentary, while marble and slate are metamorphic.

Correct answer: C

Linseed oil absorbs oxygen from air and forms a hard, tough film, so it is the common drying oil in paints.

Correct answer: D

Hydraulic lime is made from limestone containing 5 to 30 percent clay. It can set under water, unlike fat lime.

Correct answer: C

Soda-lime glass is cheap and easy to make, so it is used for windows and bottles.

Correct answer: A

Soluble sulphates of sodium, calcium and magnesium dissolve in moisture, travel to the surface and crystallise as water evaporates.

Correct answer: A

The 70.6 mm cube has a face area of about 5000 mm² (50 cm²), which makes the stress calculation easy.

Correct answer: B

The Blaine apparatus measures the time for a fixed volume of air to pass through a cement bed, which gives specific surface in m²/kg.

Correct answer: C

Unsound cement expands after setting because of free lime or magnesia. The Le Chatelier test measures this expansion, limited to 10 mm.

Correct answer: B

IS 1489 (Part 1) allows 15 to 35 percent fly ash by mass. PPC gains strength slowly but gives lower heat of hydration.

Correct answer: B

Zone I is coarse sand and Zone IV is the finest.

Correct answer: D

Sands normally have a fineness modulus of 2.2 to 3.2. Coarse aggregate has values of about 5.5 to 8.

Correct answer: A

The limit is 30 percent for wearing surfaces and 45 percent for other concrete.