Santa Clara River Trail Final Master Plan - Development Services ...

Santa Clara River Trail Plan
Figure 6. Concrete Trail Cross-Section 3
Use of Recycled Concrete Aggregate (RCA)
RCA is granular material manufactured by removing, crushing, and processing hydraulic-cement
concrete pavement for reuse with a hydraulic cementing medium to produce fresh paving concrete.
Except for removing steel, impurities, and contaminates, this process is identical to the process used to
produce aggregate from virgin stone materials. Adding RCA to concrete pavement may reduce costs,
depending on availability of RCA vs. virgin stone materials. 4
Fly Ash
Fly ash is a fine, glass-like powder recovered from gases created by coal-fired electric power generation.
U.S. power plants produce millions of tons of fly ash annually, which is usually dumped in landfills. Fly
ash is an inexpensive replacement for Portland cement used in concrete, while it improves strength,
segregation, and ease of pumping of the concrete. The techniques for working with this type of concrete
are standard for the industry and will not impact the budget of a job.
Use of Pervious Concrete
Pervious concrete allows rain to seep through the surface and percolate into the soil reducing run-off.
The water is never trapped as it is on normal concrete paving. The use of pervious pavement systems
attenuates the peak discharge of storm water into drainage systems. Pervious concrete lasts for
approximately 15 years and requires a sweep and pressure wash four times per year to maintain
percolation.
3 Note: The “c le ar” shoulde rs shown on the cross-section should be kept emp ty of buildings or fences; however, low-lying vege tation or bioswale plantings
are encouraged in these areas. Depth of subbase should be determined by a soil analysis.
4 Additional information available at: http://www.fhwa.dot.gov/pavement/t5 04037.cfm
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