Properties of Cement - Free MCQ Practice Test with solutions, GATE Civil

Natural cement sets very quickly after the addition of water and hence it is not quite workable. Artificial cement is preferred over this.

Different temperature range for a cement kiln are as follows:

Additional Information
Raw material ingredients used for manufacturing of Portland Cement are as follows:
Calcareous Materials: 

• Calcareous Materials are compounds of calcium and magnesium. Limestones are common calcareous material used in manufacturing cement. Chalk and shells are also used as calcareous material.

Argillaceous Materials: 

• Argillaceous Materials are mainly silica, alumina and oxides of iron. Clay and shale are common argillaceous material used as cement ingredient in the process of manufacturing cement.

Natural cement sets very quickly after the addition of water and hence it is not quite workable. Artificial cement is preferred over this.

Joseph Aspdin, an English bricklayer and builder, patented the basic process for making Portland cement in 1824. Aspdin's process involved heating limestone and clay until it calcined, grinding it, and then mixing it with water. 

The following are the effects of Fly Ash on the properties of cement concrete:

• Reduction in water Demand: The replacement of cement by fly ash reduces the water demand for a given slump. When fly ash is 20 percent of the total cementitious material then water demand is reduced by approximately 10 percent.
• Reduced permeability. The decrease in water content and filling of voids in cement with fly ash material reduces the pore interconnectivity of concrete, thus decreasing permeability.
• Improves resistance of concrete against the sulfate attack: Fly ash induces three phenomena that improve sulfate resistance. These are:
  • Fly ash consumes the free lime making it unavailable to react with sulfate
  • The reduced permeability prevents sulfate penetration into the concrete
  • Replacement of cement reduces the number of reactive aluminates available
• Reduction in Heat of Hydration: Reduces heat of hydration in concrete such that substitution of 30% fly ash results in the reduction of 50-60% of the heat of hydration. This reduction in the heat of hydration does not sacrifice long-term strength gain or durability.
• Improve Alkali aggregate reaction: Fly ash reacts with available alkali in the concrete, which makes them less available to react with certain silica minerals contained in the aggregates and hence, improve the resistance against alkali-aggregate reaction.
• Increase the ultimate strength: The fly ash reacts with available lime and alkali in concrete, producing additional cementitious compounds and thereby increasing the ultimate strength.
• Resistance against corrosion: The reduced permeability prevents chloride penetration from outside into the concrete and hence, reduces the chance of corrosion. 

Joseph Aspdin patented Portland cement in 1824. William Aspdin, his son is regarded as the inventor of modern Portland cement due to his developments in 1840s.

Approximately 95% of cement particles are smaller than 45 microns and the average particle size is 15 microns.

• IS 8041 : 10900 → Specifications for raid hardening portland cement.
• IS 6452 : 1939 → High Alumina Cement
• IS 8043 : 1991 → Specifications for Hydrophobic portland cement
• IS 6909 : 1990 → Specifications for super sulphated cement

Approximately 95% of cement particles are smaller than 45 microns and the average particle size is 15 microns.

When cement paste hardens and sets, it should not undergo any volume change. Soundness ensures this and is tested using Autoclave expansion test.