What Are the Pros and Cons of Fly Ash Cement?

Fly ash Portland cement refers to Portland cement clinker and fly ash, mixed with an appropriate amount of gypsum and ground, and is coded as PF. All hydraulic cementitious materials made of Portland cement clinker, fly ash and appropriate amount of gypsum are called fly ash portland cement, code PF. The participation amount of fly ash in cement is 20% to 40% in terms of mass percentage. The strength grade and strength requirements of all ages are the same as those of slag portland cement.

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The unique properties of fly ash portland cement are as follows:
(1) Early strength is low and strength enhancement is large in the later stage: fly ash cement has low strength in the early stage, and the strength of the early stage decreases with the increase in the amount of fly ash. Because the vitreous body in fly ash is extremely stable, the rate of erosion and destruction of fly ash particles by Ca (OH) 2 is very slow during the hydration of fly ash cement, so the strength development of fly ash cement is mainly reflected in the later stage , Its late strength enhancement rate is large, and can even exceed the corresponding

Hydraulic cementitious materials made of calcium silicate-based portland cement clinker, limestone or granulated blast furnace slag of less than 5%, and appropriate amount of gypsum, are collectively called Portland cement, Internationally collectively referred to as Portland cement. ^[2]

Portland cement is divided into two types. The type without Portland cement is called Type Portland cement, code P · ; the limestone or granulated blast furnace slag mixed material with no more than 5% of cement mass is called II. Portland cement, code P · II.

The main mineral composition of Portland cement is: tricalcium silicate, dicalcium silicate, tricalcium aluminate, and tetracalcium iron aluminate. Tricalcium silicate determines the strength of portland cement within four weeks; dicalcium silicate does not exert its strength until four weeks, and reaches the strength of tricalcium silicate for four weeks in about one year; strength of tricalcium aluminate Faster performance, but low strength, it has a certain effect on the strength of Portland cement in 1 to 3 days or a little longer time; Tetracalcium iron aluminate also has a faster strength, but it has a lower strength The strength contribution of salt cement is small.