When a wall is constructed with brick or a block, they are all finished with a coat of plaster which is called internal plastering. Traditionally “Internal Plastering” was done using a mixture of sand and cement plaster which is then finished with a POP punning. This is a two stage process and involves multiple compounds like sand, cement and water which is mixed onsite. This form of plastering is replaced by a direct single coat application of Gypsum plaster. Whytal Plaster produced as a result of calcinations of the raw gypsum in an automatic kettle under controlled temperature reduces the whole plastering process into single yet simple process which saves time and manpower.
For years we are only taught to dress our internal walls and ceilings only by the traditional way of plastering and fixing as the external works. What if one can replace these with the best benefits and more innovation? Gypsum was that magical product. It is basically a soft sulfate mineral composed of Calcium sulfate dihydrate (CaSO4:2H20) and widely used as a fertilized, in sculptures, and as plaster material. In recent years, the construction sector has witnessed a number of new innovations across applications, all aimed at making construction faster and delivering higher performance.
Gypsum Plaster can be applied directly on any brick, solid or hollow blocks, AAC blocks, and plasterboards. Gypsum plaster has good insulation properties, fire-resistant, and impact are resistant. Also, gypsum saves a lot of time during construction and has a superior finish. These properties have clearly drawn the attention of real estate builders and contractors towards choosing gypsum plaster over traditional cement plaster.
However, these all things are the advantages of Gypsum without any further clarifications but, there are cheap gypsum providers who are decreasing the quality of the construction. And we must beware of them. But In Whytal Tech we are converting SatinsPar And Salinite which are raw gypsum grades Containing High-Quality Natural Fiber To Plaster Grade. As Fibre Is The Base Material, It Is Less Likely To have Crack.
(CaSo4) 2 H2O + 3H2O-> 2 (CaSo4 + un reacted (CaSo4) 2.1 / 2H2O + heat hemihydrate water-> Dihydrate + un reacted hemihydrate + heat (exothermic reaction)
Gypsum plaster setting time, catalysts for controlMaterials for reducing the setting time of gypsum are called accelerators . Eg: Tera alba, sodium sulfate, potassium sulfate, sodium chloride (low concentration)The material used to increase the setting time is called RETARDER. Eg: Borax, sodium chloride, sodium sulfates, (high concentration) glue, agar, coagulated blood All these are added according to the weather only if necessary.
There are 3 theories for the setting quality (crystallization) of the Gypsum product.
1. Colloidal theory
2. Hydration theory
3. Dissolution precipitation theory
Dissolution, Suspension, Saturation, Super saturation, Nuclear formation, Growth of nuclei, Crystallization, Spherulite formation. This is important if you want the plaster to get the right quality
1. Loss of gloss method
2. Exothermic reaction
3. Penetration tests
The methods for measuring setting time are described. This is an area that needs to be explained a little more technically. It will be explained in the coming days. The exothermic reaction is the reaction of water to gypsum powder. The exothermic heat is the heat generated when water is poured into the gypsum powder.
|Parameter Values||Whytal Gypsum Plaster|
|Coverage||25 to 30 square feet 50 Kg bag(10-12mm thickness)|
|Compressive||55-60 Kg./Sq Cm|
|Flexural Strength||30 -35 Kg./Sq Cm|
|Bulk Density||0.85 – 0.9 GMS/CU-CMS|
|Moduluse of Ration (Kg. Per CM2)||40 Kg./ SQ CMS|
|Consistency (Water : Plater Ratio)||(65 Ml – 70 Ml)100/GM|
|Calcium Oxide (CaO)||IS-1288||31.03%|
|Magnesium Oxide (MgO)||IS-2547||0.21%|
|Sodium Oxide (Na2O)||ICP||0.062%|
|Loss on Ignationat 300C||IS-2547||5.50%|
|Residue on 1.18mm IS Sieve||IS-1607||Nil|
Product/Parameters – 20 – 25 minutes
Setting time – 700 – 800 kg / m3
Dry bulk density – 1200 – 1300 kg / m3
Dry set density – 5 – 7 N/mm2
Compressive strength – 5 – 7 N/mm2
Water plaster ratio – 40 – 45 %