Fiber, When Is Useful? - The Issues and Discussion of Modern Concrete Science - page 83

As the author had done only 4 experiments at different construction site, so from
time, scale, data, and generalization degree, it is inevitably unilateral to draw a
different conclusion for a concrete variety which is recognized by worldwide
academia just basing on the four experiments.
However, one point can be af

rmed. By means of the four successful and
unsuccessful engineering practices, it is necessary to remind every engineer that
defects of application of fiber-reinforced concrete are obvious. If it is necessary to

adopt it, experiments must be done in advance to all

rm its all advantage and

disadvantage, and then, it can be employed cautiously.
Looking back on argument, conclusion, more serious argument after conclusion,
and final conclusion during the four experimental process, the author is so agitated

that it is different to calm down. As a result, please forgive if discourse of this
chapter may not conform to data proving and cautious mode of scienti

c research

paper.

7.2 Experimental Method and Conclusion

The first experiment was carried in 2003 at an airport in Xinjiang. We prepared to

apply steel fiber-reinforced concrete in parking apron for purpose of boosting

flexural strength drastically without increasing engineering cost especially cement
consumption. Eight experienced engineers were deployed from Xi an and Urumchi

'

to constitute an experimental group for a month.
When cement consumption of unilateral concrete was raise up to 350 kg (the
consumption had exceeded ordinary consumption of Civil Aviation under the same
condition), results of 15 groups specimens indicated that

flexural strength of con-

crete adding steel fiber had not been boosted while strengths of separate group were

even lower than ordinary concrete with no steel fiber under the same condition.

After discussion, the experimental group decided to abandon the plan because
there is no drastically improving signal of

flexural strength while engineering cost

had been increased signi cantly, as well as there is no mature construction oper-

ation experience.
The second experiment was carried out at the end of 2003 in a navy airport in
Sanya of Hainan Province. The author, together with 15 engineers, such as Han
Min-cang and Wang Zhao-yuan, had joined in this experiment. We still prepared to
apply steel

fiber-reinforced concrete in parking apron like what we done in Xinji-
ang. As the project deadline was ample and time is plenty, the experiment had
conducted nearly for one year. We made adjustments repeatedly according to
experimental results and emerged questions. At last, the discarded specimens of
experiments were taken away by two trucks.
We learned a lesson from the last experience and increased cement consumption
directly. In order to prevent phenomenon caused by exaggerated cement con-
sumption, such as false setting and cracking,

fly ash was employed when cement

consumption was over 350 kg.