Abstract: In this study two series of self compacting concrete
mixtures were prepared with 100% coarse recycled concrete
aggregates and different percentages of 0%, 20%, 40%, 60%, 80%
and 100% fine recycled concrete aggregates. In series I and II the
water to binder ratios were 0.50 and 0.45, respectively. The cement
content was kept 350
3 m
kg for those mixtures that don't have any
Nano-Silica. To improve the compressive strength of samples, Nano-
Silica replaced with 10% of cement weight in concrete mixtures. By
doing the tests, the results showed that, adding Nano-silica to the
samples with less percentage of fine recycled concrete aggregates,
lead to more increase on the compressive strength.
Abstract: Based on statistics released by Islamic Republic of
Iran Police (IRIP), from among the total 9555 motorcycle accidents
that happened in 2007, 857 riders died and 11219 one got injured. If
we also consider the death toll and injuries of other vehicles'
accidents resulted from traffic violation by motorcycle riders, then
paying attention to the motorcycle accidents seems to be very
necessary. Therefore, in this study we tried to investigate the traits
and issues related to production, application, and training, along with
causes of motorcycle accidents from 4 perspectives of road, human,
environment and vehicle and also based on statistical and
geographical analysis of accident-sheets prepared by Iran Road
Patrol Department (IRPD). Unfamiliarity of riders with regulations
and techniques of motorcycling, disuse of safety equipments,
inefficiency of roads and design of junctions for safe trafficking of
motorcycles and finally the lack of sufficient control of responsible
organizations are among the major causes which lead to these
accidents.