Gypsum is commonly used as retarding agent with cement to prevent it from premature hardening. It is this quality of gypsum that enables workers to pour the cement mixture into various moulds and create frames as and when required. Gypsum in cement plays a crucial role due to its chemical properties. Let’s find out how gypsum prevents early setting of cement.
What is Gypsum?
Gypsum is mostly found in sedimentary deposits. It is a sot, translucent mineral that is made up of crystallized calcium sulphate (CaSO4). It is used for a variety of purposes in the area of agriculture, construction, industrial and manufacturing sector. Gypsum is also used in the manufacture of wall boards, paper, paints, and plasters.
How is Cement Made?
Cement is produced from a chemical combination of calcium, silicon, aluminum, iron and small amounts of other ingredients that are carefully measured to get the right result. Cement has a fine texture and is often used in construction work. Cement sets due to the reaction of tricalcium aluminate with water. Gypsum in cement regulates this extreme setting reaction.
What Happens When Gypsum is Mixed With Cement?
The addition of gypsum in cement not only influences its setting time but other properties as well. Gypsum is fire resistant. It influences the strength, strength development, and volume stability of cement. Gypsum also influences the grindability of cement, which is the grinding energy required to produce cement. To get a better understanding of the importance of adding gypsum in cement, you need to understand what happens in its absence. If gypsum is not added to cement, then tricalcium aluminate reacts quickly with water. It then forms interlinking bridges of solid material between cement particles. This in turn reduces the mobility of cement particles and produces a firm structure, which results in the cement mixture setting. This phenomenon is called ‘flash set’ and is irreversible.
If you wish to know more about the usage of gypsum in cement, then get in touch with our experts at Eilers construction.