In the year 2000, the International Arab Company was working on a multi-million EGP project of building the Eastern Port Said Sea Port. This project required approximately 280,000 M.cubic of concrete for building a 1200x35 meter platform going to a depth of 65 meters in a severe environment having high Sulphates and Chlorides. When the company requested a suitable type of cement from ECC, high-slag cement was specified. High-slag cement is produced by taking the high quality granulated blast furnace slag, which is a byproduct of iron blast furnace operations, and inter-grinding it up to 75% with cement clinker and gypsum. The use of high slag cement is advantageous when dealing with sulphate and chloride as it induces corrosion resistance. Its use is also very suitable in warmer climates, since it develops less heat in concrete than ordinary Portland cement. In January 2001, while using the high slag cement, the customers noticed that there was a problem with the concrete; bleeding occurred in fresh concrete, which was then followed by its segregation. According to the standard specification, there was no problem with the high slag cement, but a problem still existed in the concrete. ECC's technical service team went onsite to perform field trials with customer. After countless efforts performed onsite and in ECC's laboratory, it was discovered that the bleeding was due to a high addition of high range water reducer. This was a result of the high water demand present on the specific high slag cement used. Modifications were then carried out to decrease the water demand. This was done by improving the particle size distribution at the same specific surface area requested in the contract. Consequently, the water demand was reduced. No bleeding occurred in the concrete after this modification, and the project continued as planned. |