orphology that is different to other pozzolanic materials. It is the
unique particle morphology to make it have the ability
reducing water, which other pozzolanic materials do not
have [3–6]. It influences not only the rheological property
of fresh mortar but also the initial structure of hardened
cement stone. In the end of 1970s, Jan de Zeeuw and
Abersch [7] put forward that the role of fly ash, which its
particle size is less than 30 Am, may be similar to that of the
microparticle of unhydrated cement in cement stone. In
1981, Danshen and Yinji [8] and Danshen [9] summarized
the previous research results and put forward the hypothesis
of ‘‘fly ash effects.’’ They considered that fly ash has three
effects in concrete, i.e., morphological, activated and microaggregate effects. The three effects are relative each other.
This shows that the morphological effect is the important
aspect of fly ash effects. In this paper, it will be discussed
emphatically. The activated and microaggregate effects will
be analyzed in other papers.
The morphological effect means that in concrete, mineral-powdered materials produce the effect due to the
morphology, structure and surface property of the particle
and the particle size distribution. From the influence of fly
ash on the properties of cement-based materials, the morphology effect includes three aspects: filling, lubricating
and well distributing. These roles depend on the shape, size
distribution, etc., of fly ash and influence many properties
of concrete