Blended cement

Advantage of ternary blended cement

The binary cement, e.g. Portland cement blends with slag or fly ash or limestone, has gained great popularity in many countries. However, each kind of binary cement has its own shortfalls, e.g. the addition limestone can reduce the later strength due to its dilution effect, while the reaction of slag is relatively slow in the early ages.

To utilize materials more effectively and reduce the cost in construction industry, ternary cement that made with Portland clinkers and other two admixtures may be a better option because it presents several advantages over binary cements. With the development of separate grinding and mixing technology in cement industry, it is becoming more convenient to produce these so-called market-oriented or tailor-made cements.

The combination of limestone and slag with Portland cement can help to produce a new cement-based material which has advantage over binary blended cement. An obvious advantage is that limestone contributes to the early strength while slag increases the long-term strength, this leads to an adequate development of strength compared with either slag cement or limestone cement.

To find the strength development of ternary cement with limestone filler and blast-furnace slag, Menendez et al. tested mortar prisms in which Portland cement was replaced by up to 20% limestone and 35% blast-furnace slag. The test at 1, 3, 7, 28 and 90 days shows that the contribution of limestone to the hydration degree of Portland cement at 1 and 3 days increases the early strength of ternary system containing about 5-15% limestone and 0-20% blast-furnace slag. The later hydration of blast-furnace slag is very effective in producing ternary cements with similar or higher compressive strength than Portland cement at the ages of 28 days and 90 days.

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