Good quality concrete starts with quality materials, cost effective designs are actually a by-product of selecting the best quality material and good construction practices. Technical knowledge is an advantage to the concrete producer, even if the concrete mix design is good but unusual or incorrect procedures are practiced, failures will occur.
Normal concrete is the combination of cement, aggregates (coarse and fine), water, admixtures. In which, cement is the most important factor influencing the characteristics of concrete. Different types of Portland cement are manufactured to meet various normal physical and chemical requirements for specific purposes. Portland cement is manufactured to meet the specifications of ASTM (American Society for Testing and Materials) C150, ASTM 1157, AASHTO (American Association of State Highway and Transportation Officials) M85
Below are important things to remember about the properties and use of cement.
1. About 30 kilograms of water are required to fully hydrate 100 kilograms of cement.
2. Hydration begins as soon as water is introduced into the cement.
3. Rule of thumb: The higher the water/cement ratio, the lower the strength, so keep the water-cement ratio as low as possible.
4. It is a good practice to order the cement in advance to lower its temperature, remember that 5 degrees
Increasing the temperature of the cement increases the temperature of the concrete by 0.5 degrees.
5. The normal temperature range of cement before batching should be 66 to 85 degrees Celsius.
6. The specific gravity range of Portland cements is 3.10 to 3.25 and that of blended cement is 2.90 to 3.15.