Virtual Labs

Chemical composition of cement

Which oxide primarily contributes to early strength development in cement?

a: Fe₂O₃ Explanation

Explanation

b: C₃A Explanation

Explanation

c: MgO Explanation

Explanation

d: CaO Explanation

Explanation

What is the function of gypsum in cement?

a: Increases strength Explanation

Explanation

b: Prevents flash setting Explanation

Explanation

c: Reduces heat of hydration Explanation

Explanation

d: Improves workability Explanation

Explanation

Why is silica (SiO₂) important in cement composition?

a: Enhances early strength Explanation

Explanation

b: Reduces setting time Explanation

Explanation

c: Improves long-term strength and durability Explanation

Explanation

d: Prevents sulfate attack Explanation

Explanation

What is the impact of excessive alkalis in cement?

a: Increases durability Explanation

Explanation

b: Causes alkali-silica reaction (ASR) leading to cracking Explanation

Explanation

c: Enhances setting time Explanation

Explanation

d: Reduces workability Explanation

Explanation

What is the approximate percentage of CaO in cement?

a: 20-30% Explanation

Explanation

b: 50-60% Explanation

Explanation

c: 70-80% Explanation

Explanation

d: 10-20% Explanation

Explanation

What is the role of Fe₂O₃ in cement?

a: Enhances workability and color Explanation

Explanation

b: Increases early strength Explanation

Explanation

c: Reduces setting time Explanation

Explanation

d: Prevents sulfate attack Explanation

Explanation

What is the significance of controlling SO₃ content in cement?

a: Prevents flash setting and sulfate attack Explanation

Explanation

b: Enhances early strength Explanation

Explanation

c: Reduces hydration rate Explanation

Explanation

d: Improves color Explanation

Explanation

What method is used to determine MgO content in cement?

a: Volumetric titration Explanation

Explanation

b: Precipitation as magnesium ammonium phosphate Explanation

Explanation

c: Gravimetric analysis Explanation

Explanation

d: Atomic absorption spectroscopy Explanation

Explanation

What is the ideal temperature range for cement hydration?

a: 20-30°C Explanation

Explanation

b: 50-60°C Explanation

Explanation

c: 10-20°C Explanation

Explanation

d: 40-50°C Explanation

Explanation

Which oxide in cement helps prevent sulfate attack?

a: Fe₂O₃ Explanation

Explanation

b: Al₂O₃ Explanation

Explanation

c: CaO Explanation

Explanation

d: SiO₂ Explanation

Explanation

Which test is commonly used to determine cement fineness?

a: Soundness test Explanation

Explanation

b: Blaine air permeability test Explanation

Explanation

c: Vicat needle test Explanation

Explanation

d: Le Chatelier test Explanation

Explanation

What is the typical range of SO₃ content in cement?

a: 0-1% Explanation

Explanation

b: 2-4% Explanation

Explanation

c: 5-6% Explanation

Explanation

d: 7-9% Explanation

Explanation

What is the main reason for using sulfate-resistant cement in marine structures?

a: High Al₂O₃ content Explanation

Explanation

b: Low C₃A content Explanation

Explanation

c: High Fe₂O₃ content Explanation

Explanation

d: Low MgO content Explanation

Explanation

What happens if the cement hydration heat is too high?

a: Increases durability Explanation

Explanation

b: Reduces sulfate resistance Explanation

Explanation

c: Causes thermal cracking Explanation

Explanation

d: Improves strength Explanation

Explanation

What is the preferred method for analyzing cement composition in modern laboratories?

a: X-ray fluorescence (XRF) Explanation

Explanation

b: Colorimetric analysis Explanation

Explanation

c: Atomic absorption spectroscopy Explanation

Explanation

d: Titration Explanation

Explanation