Understanding how to evaluate the quality of cement is crucial before incorporating it into your construction. Cement is a fundamental construction material globally, serving as a binding agent for concrete and mortar. Let's delve into the process of checking cement quality and its importance.

Understanding cement composition

Cement, commonly found in grey powdery form within sturdy paper bags, is a composition of various materials. Primary components include limestone, sand, iron ore, and bauxite. Additional elements like chalk, clay, and slate can also be part of its composition. These raw materials undergo processing and are subjected to high temperatures around 1500 degrees celsius. The resulting fine grey powder is then packaged and sold in the market.

The significance of cement quality check

Checking cement quality is a pivotal step for builders and masons to ensure the structural integrity of constructions. While these checks might not encompass all cement properties, they offer insights into its strength and overall quality. Fortunately, you don't need to be an expert to conduct these tests. Here are some straightforward field tests that anyone can perform to ascertain cement quality:

1. Manufacturing date check:
Inspect the manufacturing date printed on the cement bag, typically located on the back or side. It's crucial to use cement within 90 days from its manufacturing date. Cement's strength can diminish over time due to moisture absorption. Freshly produced cement has a high affinity for moisture in the air, which accelerates its chemical reaction called "Hydration." using older cement can result in reduced binding effectiveness and overall structural strength.

• 3 months: The strength of cement can typically decrease by around 20% to 30% from its initial strength during the first three months of its manufacturing date.

• 6 months: By the six-month mark, the strength reduction becomes more pronounced, ranging from 30% to 40% of its original strength.

• 12 months: After a year, the ageing process further affects the cement's strength, leading to a reduction of approximately 40% to 50% from its initial strength.
  

2. Colour examination:
Quality cement possesses a uniform grey colour with a faint greenish tint. This colour is an indicator of the burning process and composition. Dark greenish shades could suggest an excessive amount of lime or clay, affecting the cement's performance and setting characteristics. A consistent, light grey hue is generally an indication of well-processed and high-quality cement.

3. Lumps inspection:
Upon opening the cement bag, carefully examine its contents for any lumps. The presence of lumps suggests that the cement has come into contact with moisture. A bag with lumps should be rejected, as it might compromise the construction's integrity.

4. Cement float test:
Take a handful of cement and gently release it into a bucket of water. Good-quality cement will initially float on the water's surface before eventually sinking. Impure or low-quality cement, on the other hand, will rapidly sink due to the presence of heavy impurities. This test assesses the density and impurity level of the cement.

5. Adulteration test:
Rub a small amount of cement between your fingers. Quality cement should feel smooth and fine to the touch. If you feel grittiness or roughness, it could indicate adulteration with excessive amounts of sand or other impurities. A smooth texture suggests that the cement is well-processed and has a consistent composition.

6. Cement temperature test:
Insert your clean and dry hand into the cement bag, and touch the cement powder. If it feels cool to the touch, it suggests that the cement hasn't undergone hydration due to moisture exposure. However, if the cement feels warm, it indicates that hydration has started, which may lead to reduced strength and performance. Opt for cement that feels cool, indicating its freshness and quality.

7. Cement strength test:
For this test, create a cement block measuring 25mm x 25mm x 200mm and immerse it in water for seven days. After the immersion period, place the block on supports about 15 cm apart and apply a weight of around 34 kg on top of the block. A good-quality cement block should remain intact and show no signs of cracks or failure under this load, indicating its strength and durability.

8. Cement odour test:
While being cautious, smell the cement to detect any unusual odours. Quality cement should be odourless. If you detect an earthy smell, it could be an indication of excess clay and sand in the cement composition. An abnormal odour might imply a compromised mixture, affecting the final construction quality.

9. Cement setting test:
Prepare a thick paste of cement and water, resembling a cake-like structure, and place it on a glass plate. Submerge the glass plate in water for 24 hours. After this period, examine the cement cake for cracks or deformities. A well-structured, crack-free cake signifies that the cement has a consistent setting quality and will perform well in construction.

10. Consistency test:
In this test, mix cement with water to form a thick paste. Spread the paste onto a glass plate to create a uniform, flat shape. After 24 hours, observe the consistency and shape of the cement. A uniform and consistent shape indicates that the cement maintains its desired properties during the setting process, ensuring a high-quality construction outcome.

Final word

Checking cement quality on-site during preliminary inspection is essential. While these tests provide a rough idea of cement quality, not all engineering properties can be assessed through them. Remember, the proper quality of cement contributes to the durability and strength of your construction project. Whether you're building your dream home or embarking on a renovation journey, these simple field tests can empower you to make informed decisions about the cement you use, ensuring your project stands the test of time.