Sugar in Concrete | Effect of Sugar on Concrete Strength | Sugar as a Concrete Surface Retarder | Addition of Sugar in Concrete Results in Setting Time
Sugar in Concrete:
What does sugar do to concrete? Cement and Concrete, especially when considering sugar and concrete, are the foremost paramount engineering materials.
Tyrannical weather conditions play indispensable roles in the traits of concrete. Hence, admixtures are required to sustain standard conditions. Continuous change in weather conditions results in a change of initial setting time of concrete.
Hence, Retarders and Accelerators are required to increase and diminish the initial setting time of concrete respectively. e.g. Retarder- sugar and gypsum etc. & Accelerator- salt (cacl2) etc.
Retarders are admixtures which stretch the ‘Hydration Induction Period’.
What does sugar do to cement? Sugar delays the setting of cement at the construction site & it’s affordable and promptly obtainable. This is a common query when discussing sugar in cement.
Concrete is basically a blend of aggregates (gravel & stone dust) and paste (water & portland cement). Concrete gets brawny as it grows older over time.
Cement comprises from 10-15 % of the concrete blend, by volume.
The Sugar concrete retarder recipe or the sugar-concrete blend endorsed for this procedure is 1:1.2 & 2:2.78 with a water-cement ratio of 0.45.
All the specimens are watered for 28 days.
The compressive strength specimens are of dimension 150 x 150 x 150 mm.
After 28 days the maximum compressive strength for 0.06% of sugar and water-cement ratio is 0.36, 0.45, 0.50 are 48.88 N/mm2, 44.44 N/mm2, 40.14 N/mm2 respectively.
What Is Going to Happen If We Add Sugar in Concrete?
Sugar delays the setting time of cement (near about 1.33 hours at a dosage of 0.06% by weight of cement). On account of its action with concrete, sugar is rather considered as a delayed accelerator in lieu of a retarder.
Use of sugar as an admixture doesn’t affect the workability (Durability, Absorption & Shrinkage properties) in concrete.
Sugar is ought to be utilized as a retarder but if it's employed in imprudent quantity, it reverses its properties.
The quantity of the sugar must be precisely measured during the production process. Sugar content of 0.06% by weight of cement can ameliorate the compressive strength of concrete (by 3.23% at 28 days) and delay initial setting time by 1.33 hours (80 minutes).
The time delay of 3 & 7 days, in case of addition of sugar, safe-guards cold joints, by diminishing early setting of cement in tyrannical weather conditions.
The addition of OPC (Ordinary Portland Cement) offers retardation of 4hrs. Even some sorts of salts act an identical purpose.
In the process of setting concrete water requires to react with cement but, sugar-concrete combination inhibits this reaction by forming a canopy around the cement particles.
On incorporation of sugar to concrete by this procedure, the concentration of Al & Ca gets diminished, as sugar forms complexes with these elements. Therefore, the reaction between Al, Ca, and water is inhibited.
Since the surface of sugar has robust polarity it ends up in solid-liquid adsorption thus it hinders the crystal contact and tri-calcium silicate hydrate reaction.
To Adjust the Setting Time of Cement Which Product Is Added with Cement?
Gypsum may be a mineral and is hydrated salt in chemical form.
Gypsum plays an awfully vital role in manipulating the solidification of the cement.
Gypsum is incorporated to regulate the “setting of cement”. Otherwise, the cement will set instantly after mixing of water leaving barely any time for concreting process.
Final Time is the time span between the blending of the water & the time when the needle just makes the impression on the surface of the cement (but do not penetrate into it). Usually the final setting time of cement is 10-12 hrs.
Why Gypsum Is Added in Cement for Sugar in Concrete?
Tri-calcium aluminate (C3A), is the usually most reactive among the four minerals available(which are responsible for coagulation) in cement.
The increase of C3A can act as a positive catalyst in the setting and coagulation rate of cement, a huge amount of heat is radiated. Hence, the reaction of C3A with water occurs rapidly and is manipulated by adding gypsum during the production procedure.
Gypsum (crystallized CaSO4) is incorporated into cement along with water to manipulate the setting process. Gypsum content of cement is usually expressed in terms of its sulfate content.
When cement is hydrated, gypsum reacts with C3A quickly to come up with calcium sulfoaluminate hydrate which precipitates and forms a film on the cement particles which hinders the hydration of C3