The water causes the hardening of concrete through a process called hydration. Hydration is a chemical reaction in which the major compounds in cement form chemical bonds with water molecules and become hydrates or hydration products. In the Non-Water state, four main types of minerals are normally present: alite, belite, aluminate (C3A) and a ferrite phase (C4AF). Also present are small amounts of clinker sulfate (sulfates of sodium, potassium and calcium) and also gypsum, which was added when the clinker was ground up to produce the familiar grey powder. When water is added, the reactions which occur are mostly exothermic, that is, the reactions generate heat. We can get an indication of the rate at which the minerals are reacting by monitoring the rate at which heat is evolved using a technique called conduction calorimetry. Three principal reactions occur: Almost immediately on adding water some of the clinker sulphates and gypsum dissolve producing an alkaline, sulfate-rich, solution. Soon after mixing, the (C3A) phase (the most reactive of the four main clinker minerals) reacts with the water to form an aluminate-rich gel (Stage I on the heat evolution curve above). The gel reacts with sulfate in solution to form small rod-like crystals of ettringite. (C3A) reaction is with water is strongly exothermic but does not last long, typically only a few minutes, and is followed by a period of a few hours of relatively low heat evolution. This is called the dormant, or induction period (Stage II). The first part of the dormant period, up to perhaps half-way through, corresponds to when concrete can be placed. As the dormant period progresses, the paste becomes too stiff to be workable. At the end of the dormant period, the alite and belite in the cement start to react, with the formation of calcium silicate hydrate and calcium hydroxide. This corresponds to the main period of hydration (Stage III), during which time concrete strengths increase. The individual grains react from the surface inwards, and the anhydrous particles become smaller. (C3A) hydration also continues, as fresh crystals become accessible to water. The period of maximum heat evolution occurs typically between about 10 and 20 hours after mixing and then gradually tails off. In a mix containing PC only, most of the strength gain has occurred within about a month. Where PC has been partly-replaced by other materials, such as fly ash, strength growth may occur more slowly and continue for several months or even a year. Ferrite reaction also starts quickly as water is added, but then slows down, probably because a layer of iron hydroxide gel forms, coating the ferrite and acting as a barrier, preventing further reaction.
7 days curing is for 50% strength gain. But for getting more strength,28 days curing is needed. So If possible it is recommended to cure for 28 days for gaining the full strength. But usually people go for 14 days curing.
කොන්ක්රීට් එකට අයිස් වතුර දැම්මාම කොන්ක්රීට් එක ගොඩක් ශක්තිනත් කියනවනේ..
ඒත් එක්කන විඩාඩි 3 ඇතුලත හයි වෙනවව ලු
මේක ගැන රිප්ලයි එකක් දෙන්න 𝙥𝙡𝙯..
මේකෙන් කරන්නෙ කොන්ක්රීට් එකේ ප්ලේසින් ටෙම්ප්රෙචර් එක අඩු අගයක තියාගන්න එක. එතකොට කොන්ක්රීට් හයි වෙනකොට අධික තාපයක් පිටවීඹ නිසා උෂ්ණත්වය වැඩි වෙලා වෙන උපරිම උෂ්ණත්වය කියන අගයත් අඩු කරගන්න පුලුවන් තරමක් දුරට. ඒකෙන් උෂ්ණත්වය නිසා වෙන ඉරිතැලීම් වලක්වාගන්න පුලුවන් යම් තාක් දුරකට.
මීට අමතරව විශාල අයිතම කොන්ක්රීට් කරනකොට ඩී.ඊ.එෆ්. කියල දෙයක් ෆෝම් වෙලා කොන්ක්රීට් එක අධික ලෙස ඉරිතැලෙන්න පුලුවන්. ඒ වගේ දේවල් වලක්වාගන්නත් කොන්ක්රීට් අයිස් සමග මිශ්‍ර කරල භාවිතා කරනවා.
Thanks you very useful
You are welcome
Tnx a lot
This is a good lession ...
Thank you Laksiri!
Konkrit Damien pasu Dina kiyak wathura danna onada
concrete mix design එකක් කරන විදිය ගැන video එකක් කරන්න පුලුවන්ද??
ඉදිරියේදී අනිවාර්යයෙන්ම කරනවා
වැදගත්
Thanks
Curing karaddi laba dena jalaya.. Hydration eka ta dayaka wena(jalaya athul wena) vidiya pehedili karanna puluwanda..
The water causes the hardening of concrete through a process called hydration. Hydration is a chemical reaction in which the major compounds in cement form chemical bonds with water molecules and become hydrates or hydration products.
In the Non-Water state, four main types of minerals are normally present: alite, belite, aluminate (C3A) and a ferrite phase (C4AF). Also present are small amounts of clinker sulfate (sulfates of sodium, potassium and calcium) and also gypsum, which was added when the clinker was ground up to produce the familiar grey powder.
When water is added, the reactions which occur are mostly exothermic, that is, the reactions generate heat. We can get an indication of the rate at which the minerals are reacting by monitoring the rate at which heat is evolved using a technique called conduction calorimetry.
Three principal reactions occur:
Almost immediately on adding water some of the clinker sulphates and gypsum dissolve producing an alkaline, sulfate-rich, solution.
Soon after mixing, the (C3A) phase (the most reactive of the four main clinker minerals) reacts with the water to form an aluminate-rich gel (Stage I on the heat evolution curve above). The gel reacts with sulfate in solution to form small rod-like crystals of ettringite. (C3A) reaction is with water is strongly exothermic but does not last long, typically only a few minutes, and is followed by a period of a few hours of relatively low heat evolution. This is called the dormant, or induction period (Stage II).
The first part of the dormant period, up to perhaps half-way through, corresponds to when concrete can be placed. As the dormant period progresses, the paste becomes too stiff to be workable.
At the end of the dormant period, the alite and belite in the cement start to react, with the formation of calcium silicate hydrate and calcium hydroxide. This corresponds to the main period of hydration (Stage III), during which time concrete strengths increase. The individual grains react from the surface inwards, and the anhydrous particles become smaller. (C3A) hydration also continues, as fresh crystals become accessible to water.
The period of maximum heat evolution occurs typically between about 10 and 20 hours after mixing and then gradually tails off. In a mix containing PC only, most of the strength gain has occurred within about a month. Where PC has been partly-replaced by other materials, such as fly ash, strength growth may occur more slowly and continue for several months or even a year.
Ferrite reaction also starts quickly as water is added, but then slows down, probably because a layer of iron hydroxide gel forms, coating the ferrite and acting as a barrier, preventing further reaction.
polawa hodata talala tiyennama onada concrete daanakota? talapu pasata udin wali tattuwak ho pas tattuwak tibunot bol wenna puluwanda?
Tnx
Thank You, Subodha!
Roof slab eka dapudavase idan dawas kiyak vithara wathura danna oneda.
Samanyayen dawas 3-7 dakwa kalayedi thamai awashya shakthiyen 50% th 70% th athara langawenne. E nisa aniwaryayenma dawas 7k wathura yediya yuthuyi.
E wagema concrete karapu dawase indan dawas 14 langa weddi thamai awashya shakthiyen 90% kata asanna pramanayak langakaraganne. E nisa dawas 14 dakwama wathura yediya hakinam wada hondayi.
Amathara danaganeema sandaha: dawas 21 dee thamai awashya shakthiyen 99% k langakaraganne.
Thank u..
You are welcome!
👍👍👍👍
👍👍👍👍
Concrete වල සිදුවන crack වර්ග සහ ඒවා අදුනගන්න විදිය ගැන වීඩියෝ එකක් කරන්න පුලුවන්ද??
ඉදිරියේදී අනිවාර්යයෙන්ම කරනවා
බොහෝම ස්තූතියි බිත්තියක් බැදලා පැය කියක් ගියට පස්සෙද වතුර දාන්න ඕනේ කිවතක් වතුර දාන්න ඕනේ ද
පැය 24 කට පස්සෙ. දවස් 7ක් වෙනකන්.
@@CivilEngineerSL thanks
සර් කොන්ක්රීට් මිශ්‍රණයේ සවිශක්තිය වැඩි කිරීමට භාවිතා කරන කෙමිකල් වර්ග මොනවද....
ඇත්තටම සවි ශක්තිය වැඩි කිරීමට කෙමිකල් නැහැ. සවි ශක්තිය වැඩිකිරීමට නම් කොන්ක්රීට් ග්රේඩ් එක වැඩි කල යුතුයි. (උදා. ග්රේඩ් 20 වෙනුවට ග්රේඩ් 25 හෝ 30 යෙදිය යුතුයි. එනම් සිමෙන්ති,වැලි,ගල් අනුපාතය වෙනස් කල යුතුයි.)
කෙමිකල් භාවිතා කරන්නේ රිටාඩර් එකක් විදියට, ඇඩ්මික්ෂර් එකක් විදියට හෝ සුපර්ප්ලාස්ටිසයිසර් එකක් විදියටයි.
එනම් කොන්ක්රීට් ඝන වීම පමාකරවාගැනීමට හෝ යොදන වතුර පුමාණය අවම කරගෙන කොන්ක්රීට් මෙලෙක් ලෙවල් එකේ තබාගැනීමටයි.
ඔය දෙකෙන් දෙවෙනි එකේදි වතුරට සිමෙන්ති අනුපාතය අඩුවන නිසා ශක්තිය වැඩැවීමක් සිදුවේ.
M15, M20, M25 ් ්‍යන කොන්ක්රීට් වර්ග වලට මිශ්‍ර කිරීමේදී ජලය යෙදිය යුතු ප්‍රමාණයන් කොපමනද?
ජලය පුරවන කොන්ක්රීට් පොකුනක ගාන්න පුලුවන් නිල් පාට තින්න තියේනවාද
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ස්තූතියි
සර් පොලව කොන්ක්රීට් කරන්න අගල් 1 මැටල් පාවිච්චි කලාට කමක් නැතිද ...
කමක් නෑ
How many days need to curin straight columns/ beams..??
7 days curing is for 50% strength gain. But for getting more strength,28 days curing is needed. So If possible it is recommended to cure for 28 days for gaining the full strength. But usually people go for 14 days curing.
සිමෙන්ති කොට්ටෙ කඩන්නෙ නැතුවත් ගල් වෙලා කිමද?
මේකෙ තියනවා
th-cam.com/video/dPYxNcK2EgE/w-d-xo.html
6375000
Ela.