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Why is gypsum added to Portland cement?
Gypsum is added to portland cement to retard C3A hydration
What are the components of concrete?
cement fine aggregates and course aggregates and water for the hydration of cement are the main component of plain cement concrete. and for RCC M-S bars are used with these component.
When does hydration in concrete start?
As soon as the Cement comes into contact with water. This will start as soon as the cement and aggregates come into contact unless the aggregates have been dried of all surface water.
How would you describe the process of concrete setting?
Concrete setting is initiated by a process called hydration. Rather than the concrete just 'drying out', the hydration process involves the water added to the materials (stone, sand & cement) reacting with the cement. The water reacts with calcium in the cement to form an alkali paste which bonds the materials together. Adding too little water means not enough cement hydrates to set properly, but too much will cause separation of the materials.
What are the factors affecting the initial setting time of cement?
When cement is mixed with water, it forms slurry which gradually becomes less plastic with the passage of time & finally a hard mass is obtained. In this process, at a certain stage when the cement paste is sufficiently rigid to withstand a definite amount of Pressure, it is said to have set & the time required to reach this stage is termed as "setting time".
When cement is allowed to set why does it give off heat?
The hydration of cement is an exothermic reaction. Three exothermic reactions are important: - hydration of gypsum and tricalciumaluminate - hydration of dicalciumsilicate - hydration of tricalciumsilicate
Meaning of hydration in concrete?
Hydration in concrete provides the means with which to mix Portland cement and the aggregates.
What happens when you mix water with cement?
Cement reacts with water (this reaction is known as hydration).
Why is gypsum added to Portland cement?
Gypsum is added to portland cement to retard C3A hydration
What is the cement hydration?
Hydration process is a chemical reaction takes place between cement and water.Heat of evolution takes place.C3A > C3S > C4AF > C2SC3S + H2O ------> Ca(OH)2On account of hydration certain products are formed which have adhesive and cementing value.
What does the fineness of the cement indicate?
That indicates higher hydration rate of the cement , thus faster to achieve the desired resistance.
What are the components of concrete?
cement fine aggregates and course aggregates and water for the hydration of cement are the main component of plain cement concrete. and for RCC M-S bars are used with these component.
Fine grained material used in cement?
The fineness of cement has an important bearing on the rate of hydration and hence onthe rate of gain of strength and also on the rate of evolution of heat. Finer cement offers agreater surface area for hydration and hence faster the development of strength.
When does hydration in concrete start?
As soon as the Cement comes into contact with water. This will start as soon as the cement and aggregates come into contact unless the aggregates have been dried of all surface water.
What are the bogues compounds in cement?
Tricalcium silicate(C3S) ALITE (gives early strength to cement....heat of hydration is 120 cal/gm) Dicalcium silicate(C2S) BELITE (gives later strength ie after 7 days...less heat of hydration) Tricalcium aluminate(C3A) CELITE (gives INITIAL strength...high heat of hydration ...320 cal/g) Tetracalcium alumino ferrite(C4AF), FELITE (very high heat of hydration) - K @ $ ! civil engineering... GITAM UNIVERSITY
How would you describe the process of concrete setting?
Concrete setting is initiated by a process called hydration. Rather than the concrete just 'drying out', the hydration process involves the water added to the materials (stone, sand & cement) reacting with the cement. The water reacts with calcium in the cement to form an alkali paste which bonds the materials together. Adding too little water means not enough cement hydrates to set properly, but too much will cause separation of the materials.
Does cement have hydrogen in it?
No,it does not haveAt the time of hydration hydroxyl particles are formed.Major componenets i.e., Bogue's componenets does not have any hydrogen particles.
