The Effect of Activated Qatari Attapulgite Clay Admixture on The Mechanical Properties and Hydration Kinetics of Ordinary Portland Cement

摘要

In the Arabian Gulf countries, Concrete durability is currently of major concern as even recent concrete construction (10 to 15 years) has shown an alarming degree of deterioration. The Gulf environment is extremely aggressive and is characterized by severe geomorphic climatic conditions, severe ground and ambient salinity, and high temperature-humidity regimes. Coupled with these difficult natural conditions are the problems of aggregates, inadequate specifications, inappropriate construction practices and lack of skilled manpower. The deterioration in the Gulf region is of an accumulative nature and due to that the total over all deterioration is said to be in a complex way. Qatar is one of the Arabian Gulf countries, therefore it is effected by the formidable problem of concrete durability. This paper provides an effective practical attempt to deal with the problem. The author produced mixes of blended cement using an original Qatari artificial pozzolana. The pozzolana was made by firing Attapulgite clay at 800 C. Portland cement/artificial pozzolana pastes were made using an initial water/solid ratio of 0.40 and hydrated at room temperature for various time intervals. The hydration characteristics of the hardened pastes were studied and related to their load bearing (compressive strength) values, combined water and free lime contents. The results could be useful as a prediction of the performance characteristics of the mixes.