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8 Factors Affecting Setting & Hardening Of Cement

Cement is one of the most vital components used in the construction of the structure. Using high-quality cement is essential for improving quality of construction, durability, and reliability. Setting and hardening of cement are important to provide high strength and provide resistance from sulfate attacks. Top construction companies in Pune and India have been considering following factors that affect setting and hardening of the cement:

1. Cement composition

The mineral composition and its ration have a major effect on setting and hardening of cement. Different mineral components react in different ways with water. If the amount of C3A is increased, then setting and hardening rate is accelerated. Moreover, if mixed materials are put into cement linker, then anti-erosion properties will increase and early strength & heat of hydration will reduce.

2. The amount of gypsum mixed

Gypsum is one of the most vital components of cement and used as a retarding agent to regulate setting time of cement. If gypsum is not added, the C3A can dissolve in water immediately and generate a clotting agent which will make cement useless. When cement is hydrated, gypsum reacts with C3A to form a protection film on cement particles and restrict hydration of C3A along with delaying the setting time. If too little gypsum is mixed, the retardation effect will not take place. If too much gypsum is added, it will speed up setting. The content of gypsum to be added depends on the amount of C3A in cement. Moreover, it depends on fineness in cement and content of SO3 in the linker. The amount of gypsum mixed should be around 3%–5% of the mass of cement.

3. Cement fineness

The size of cement particles has an enormous effect on hydration, strength, and setting & hardening. If cement particles are finer, the total surface area will be larger. Consequently, the area in contact with water will be bigger. So, hydration will be rapid and setting & hardening will speed up. If the size of cement particles is too small, it will easily react with water. The carbon dioxide from the air will damage the cement. If cement is very fine, it shrinkage will be large in the process of hardening.

4. Curing conditions

The curing conditions are essential in early stages of development of strength in cement. Sufficient temperature and moisture will affect setting and hardening of cement. If moisture is very dry, the water from cement evaporates and hardening process is ceased due to insufficient hydration. As the temperature rises during the curing process, hydration of cement and development of early strength accelerates. If the temperature falls below 0 °C, hydration of cement will be ceased and strength will not be developed. Moreover, the structure of cement will be destroyed. Steam curing and autoclave curing are used to accelerate setting and hardening process.

5. Curing age

The setting and hardening of cement is a continuous process. As the hydrating degree of clinker minerals in cement particles increases, gels will escalate and capillary porosities will reduce. Consequently, the strength of cement rises as the curing age increases. The cement is developed quickly in 28 days and development process is slowed after that.

6. Mixing of water content

If mixing water contents are increased, the amount of capillary porosities will rise, the strength of cement paste will reduce, and setting time will increase. The water-cement ratio should be maintained even if the amount of water and cement in the mixture is changed.

7. Admixture impact

The setting and hardening of cement depend on C3S,C3A. Admixtures that affect the hydration of C3S,C3A can affect setting and hardening of cement. If accelerator agents are used, hardening speed can be improved. On the other hand, if retarding agents are used, hardening of cement can be delayed.

8. Storage conditions

 Unfavorable storage conditions expose cement to moisture. The setting and hardening will be decelerated with the presence of moisture. Avoiding exposure to moisture is important.

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