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What is the process of concrete harding called after the initial setting process is over?
Wiki User
∙ 13y ago
The process that occurs after initial set is commonly referred to as Curing! What actually happens is "Hydration" , which is the reaction that takes place within the concrete matrix between the chemicals and the water in the mix.
Very important that mix water be retained inside for complete hydration to take place. Of late, engineers an design professionals are placing much more emphasis on "Internal Curing" than ever before!
Wiki User
∙ 13y ago
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What is initial and final setting time in cement according to ASTM?
Using a Vicat needle, the ASTM determined time for initial concrete setting is equal to or greater than 45 minutes. They set the final setting time is equal to or greter than 375 minutes.
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 is the setting and hardening of cement?
Setting of cement is the initial solidifying of the cement. I presume you will not be using a cement material by itself, but by mixing in aggregates and fines to create 'concrete' I will continue this answer talking about concrete but much still applied to a simple cement mortar also. Depending on temperature (warm fast, cold slow) initial set will be between 2 and 24 hours. This will result in a concrete material that can easily be marked with a fingernail. Once the concrete has set, the concrete goes through a process called curing or 'hardening' where the pozzolanic constituents of the concrete 'hydrate' (react with the water) to create a hard material. This will continue for the life of the concrete but the most significant strength gains will be noticed within the first 28 days and this is the strength normally taken as the design strength of the concrete. It can be expected in ideal conditions with warm air and a light breeze in the air, for the concrete to achieve 30% of it's 28 day strength in 1 day 60-80% in 3 days 80-100% in 7 days and 100-% in 28 days Many factors will affect this. temperature will have a large impact. additives such as retarders and accelerators can be added to slow and speed up the hardening process respectively.
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".
What is vicat apparatus used for?
vicats apparatus is used for initial setting time of cement.
How does the fineness affect the time of setting?
Setting begins to occur after the concrete is mixed and even before pouring. The cement in the concrete begins to stiffen after mixed with water. The concrete is beginning to change from liquid form to solid form. During the setting process, the concrete does gain strength, which is the beginning of the hardening process. When the water ingredient is added to the concrete mix, the concrete is still pliable and flexible, sort of a paste. There is two stages of setting: initial and final setting. Initial setting is when the concrete loses it flexibility and begins to harden. Final setting is when the concrete can sustain some load, but still has some moisture within the mixture. Hardening
How ican extend initial setting time of concrete?
Initial Setting time can be extended by adding retarders during mixing of concrete. Sugar solution is the easily available retarder.
The difference between setting and hardening in cement?
SettingSetting begins to occur after the concrete is mixed and even before pouring. The cement in the concrete begins to stiffen after mixed with water. The concrete is beginning to change from liquid form to solid form. During the setting process, the concrete does gain strength, which is the beginning of the hardening process. When the water ingredient is added to the concrete mix, the concrete is still pliable and flexible, sort of a paste. There is two stages of setting: initial and final setting. Initial setting is when the concrete loses it flexibility and begins to harden. Final setting is when the concrete can sustain some load, but still has some moisture within the mixture.HardeningHardening of the concrete is the stage when the mixture gains strength. The cement ingredient begins to attach itself to the aggregate as the water dries off the mixture. The hydration of water is what starts the hardening process. It generally takes five to seven days for the concrete to complete the hardening process. The easiest way to increase the strength of concrete is to add cement to the mixture. The more water used in the mixture, the weaker the concrete and it will also delay the hardening process. Once the concrete has hydrated all the water from the mixture, the hardening process is complete and the concrete is as strong as it will get.
Definition of fresh concrete and Hardened Concrete?
before plcement in any mold with out compction is the fresh concrete. or just after plceing the concrete before initial setting is the fresh concrete.
What is initial and final setting time in cement according to ASTM?
Using a Vicat needle, the ASTM determined time for initial concrete setting is equal to or greater than 45 minutes. They set the final setting time is equal to or greter than 375 minutes.
What is the purpose of adding a curing compound to the concrete?
Curing is necessary for freshly cast concrete in order to maintain the moisture as the chemical constituents in cement react with water and heat evolves continuously until the setting process completes. The heat evolved during the setting of concrete is called heat of hydration, and this heat causes the water to evaporate. Proper and complete setting process is the most important phenomenon that imparts the desired strength to the concrete. If the freshly cast concrete is not cured, it develops cracks and also the chemical reactions will cease resulting in bad concrete.
What is initial setting time of cement?
It's the time from which cement starts the setting process after water is added.. Usually it is 30 min.. It can be delayed or advanced using chemicals..
What is setting of Portland cement?
In normal usage, allowing the concrete to "set" is the same same as allowing the concrete to "cure". This process starts soon after you mix the cement and aggregate with water, and is a result of the water in the mix chemically binding with cement components. As the concrete sets or cures, the mixture gets harder. Depending on the proportions of the materials in the concrete, after a few hours the concrete will be hard enough to support the weight of the workers as they perform finishing operations (trowelling). After a couple of days, the concrete will typically be hard enough to remove formwork, as long as no loads are imparted to the concrete in doing so. Concrete in the US is typically specified as the compressive strength reached after 28 days. The term "initial set" is used informally to represent the time, after about 4 or 5 hours, where the concrete materials are beginning to bond chemically, and at which point the concrete must be undisturbed or irreparable damage to the structure will occur. All consolidation, compaction and initial floating (levelling) needs to be complete well before the concrete begins its initial set.
What does alternate setting mean?
An alternate setting is one that is used when the initial setting is not in use or not available. The preferredis the initial but sometimes an alternate is used in its place.
What is the intial setting time for cement?
The initial setting time of cement is 30 minutesThe final setting time of the cement is 10 hours.The initial and final setting time of the cement can be found by using the Vicat's apparatus.
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 is the setting and hardening of cement?
Setting of cement is the initial solidifying of the cement. I presume you will not be using a cement material by itself, but by mixing in aggregates and fines to create 'concrete' I will continue this answer talking about concrete but much still applied to a simple cement mortar also. Depending on temperature (warm fast, cold slow) initial set will be between 2 and 24 hours. This will result in a concrete material that can easily be marked with a fingernail. Once the concrete has set, the concrete goes through a process called curing or 'hardening' where the pozzolanic constituents of the concrete 'hydrate' (react with the water) to create a hard material. This will continue for the life of the concrete but the most significant strength gains will be noticed within the first 28 days and this is the strength normally taken as the design strength of the concrete. It can be expected in ideal conditions with warm air and a light breeze in the air, for the concrete to achieve 30% of it's 28 day strength in 1 day 60-80% in 3 days 80-100% in 7 days and 100-% in 28 days Many factors will affect this. temperature will have a large impact. additives such as retarders and accelerators can be added to slow and speed up the hardening process respectively.
