What is the advantage of using GGBS as replacement of cement in concrete?

From structural point of view, GGBS replacement enhances lower heat of hydration, higher durability and higher resistance to sulphate and chloride attack when compared with normal ordinary concrete. On the other hand, it also contributes to environmental protection because it minimizes the use of cement during the production of concrete.

However, it is identified that there are still some hindrances that prevent the prevalence of its usage in local market. Technically speaking, GGBS concrete suffers from lower rate of strength development which is highly sensitive to curing conditions. In this connection, certain site measures have to be introduced to the construction industry to ensure better quality of curing process in order to secure high quality of GGBS concrete. On the other hand, designers have to be cautious of the potential bleeding problem of GGBS concrete.

Another major hurdle of extensive use of GGBS concrete lies in the little source of supply of GGBS. As Hong Kong is not a major producer of steel, GGBS as a by-product of steel has to be imported overseas and this introduces higher material cost due to transportation and the supply of GGBS is unstable and unsteady.

This question is taken from book named – A Self Learning Manual – Mastering Different Fields of Civil Engineering Works (VC-Q-A-Method) by Vincent T. H. CHU.