Civil Engineering Reference
In-Depth Information
10.4.10 Abrasion durability
The abrasion durability of concrete with GGBFS increases by applying
suitable and sufficient cure. While insufficient cure conditions decrease
the abrasion durability to a large extent, slag concrete is affected by that
more than concrete with opC. In their study on abrasion durability and its
mechanical features, Fernandez and Malhotra (1990) reported that the strength
development of slag concrete indicates the partial usage of GGBFS instead
of cement in concrete; however, the abrasion durability of slag concrete
is lower than that of control concrete without slag. provided that suitable
and sufficient cure is applied, the use of GGBFS in concrete provides some
advantage in abrasion durability (Newman and Choo, 2003).
For 28 days and above, to add 50-60% GGBFS to concrete results in higher
resistance, whereas to add GGBFS over 80% results in lower resistance. It is
understood that to obtain the maximum resistance, the optimum GGBFS rate
is 40-60%. The more vitreous content, fineness and alkali content of GGBFS
and greater fineness and alkali content of opC used together will improve the
strength development. using GGBFS up to 80% can increase the resistance
to 28 Mpa. Therefore, it will be useful to prepare specifications for mixture
design and regulations concentrated on the factory operating requirements
for high-volume GGBFS and real expectations from the concrete. Hence,
more qualified concrete will be obtained regarding workability, resistance
and strength, as well as more economic concrete by waste reduction. At the
same time air pollution could be reduced.
10.5 Future trends
The following are the types of concrete that are expected to be used in the
concrete production applications of today and in the future, as the results
of the studies described above:
∑
Self-compacting concrete
: Self-compacting concrete (SCC), which is
developed especially to be used in structures with dense reinforcement
at the end of the 1980s in Japan, has a perfect workability and high
resistance to segregation. SCC can easily furnish itself to the dense
reinforced areas without using any vibration. The fresh SSC can be
defined as a concrete which has the ability to fill the moulding and
hold the reinforcement by means of its own weight, while maintaining
homogeneity. There are positive effects of GGBFS used instead of
cement on cost, and hydration will improve the strength feature of the
concrete (Yalçınkaya and Yazıcı, 2010).
∑
Roller compacted concrete
: Roller compacted concrete (RCC) is a low-
viscosity concrete which is laid in plates before hardening. It is able to
carry at least 5 tonnes of roller in order to be compacted. RCC is economic
