When we first heard Dr. Jorge B. Sousa,
Managing Director and owner of CONSULPAV (www.consulpav.com)
describing RARX’s performance, when properly used in SAMI, THING GAP and
GAP gradations, I have to admit that I was skeptical. The
idea of using 9.35% and 11.5% binder contents and at the same time being
virtually rutting proof took a while to become credible.
Finally, my quest to provide Indonesia
with tools to end potholes led me to believe Dr. Sousa’s research results,
and experience, and invest heavily into RARX.
Two years after using RARX, provided by
CIRTEC (www.cirtec.es) in Indonesia, where it was placed
under the most severe conditions, I have to admit that I am impressed and
converted.
We just made a survey of all the jobs made
by PJI and we come with a very profound knowledge of RARX’s capabilities.
In the table below, we have the complete
list of the projects we have done.
The
first, in Jakarta – Kapuk, was a learning
experience for the company and performed exactly like Dr. Sousa expected.
Some areas very well and other areas where we had roping in the SAMI or
existing pot holes quickly filled with pot hole mix reveled the expected
problems. From this we learned how to make proper SAMI and that Dr. Sousa
could predict failures and success. He did say that RARX-SAMI -RARX-GAP
graded combination could resist reflective cracking as we can see below (no
cracks appear in the properly constructed areas).
The
second project JORR W2 is a great success. The RARX SAMI and GAP graded have
resisted reflective cracking beyond any treatment ever used in Indonesia.
It also shows no rutting whatsoever. The sections rehabilitated just before
and after the trail sections with conventional mixes already show distress and where paved a few months after. This section
was 12 in. thick concrete and actually failed 3 years after construction.
This was reported at RAR2018 (www.rar2018.net)
in the paper “Road Pavement Preservation Trial with Reacted and Activated Rubber at
JORR W2 Toll Road- Indonesia”
The
5th, 6th and 7th project are in perfect condition despite some having very
heavy channelized traffic. NO rutting, NO cracking, NO raveling. Simply PERFECT!Below you can see a few pictures. We did
have to wait to take a picture of the pavement as the traffic was so
intense. In the last section it was simply not possible to take pictures
without traffic…
The gradations of the
RARX ThinGAP and the RARX Gap mixes are presented
below. The film thickness of the bitumen covering the aggregate and RARX
particles was 12 and 15 microns respective.
RARX Gap gradation
RARX ThinGap gradation
Now… from “failures” we learn!!!…
Projects
3rd and 4th have POTHOLES! You can see how they look.
The
purpose of this report it to present the “failures” of these two projects
and how they make us understand why the other projects are performing so
well.
The pot
holes appear only during each heavy rain and on the wheel path. Some
treated pot holes had to be re-treated and some have already become pot
holes again.
If
you notice on the table above these two projects have a conventional mix
layer placed between the RARX-GAP and the RARX-SAMI. Between the RARX-GAP
and the conventional mix an emulsion tack coat was placed.
Given
that there is no drainage in these pavements the RARX-SAMI retains ALL the water INSIDE the
mixes above it in the pavement. The pumping pressure of the tires makes the
pore pressure very high and start by debonding the interface between the
RARX-GAP and the conventional mix. The accumulation of water in that
interface is the source of the water that pumps away the binder in the
surface layer causing the pot holes. This is particular enhanced in the
cold construction joint near the center lane made in the conventional mix.
Actually, a series of circumstances led us
to pave these two sections placing the BINDER Conventional mix between the
Wearing course and the SAMI. Even before the pothole appearance George Way
told us that it was not a good design approach exactly because of what
happen.
In all
other jobs where the RARX-SAMI is placed directly below the wearing course
we do not have potholes.
This demonstrates that SAMI is indeed a
waterproofing membrane and that it has a very high debonding resistance as
no water gets between it and the wearing or bottom layer.
Based on this, our recommendations for
countries where we have heavy rains and very high levels of UV, that lead
to premature embrittlement and cracking of the wearing course, is to use
the very powerful combination of RARX-SAMI and RARX- GAP or RARX -THINGAP.
These mixes, that have very high rubber contents and very high binder
contents, do exhibit also great aging resistance.
After
these incredible observations on how these products performance we are more
convinced than ever that they are the products INDONESIA needs to cost
effectively maintain their road network.
We
are very happy that Dr. Sousa persistence to convince us of RARX benefits.
As we are now building 90 km of coal roads with a RARX double chip seal
over cement treated bases!!! In the video below the 3/4 in. RARX - SAMI is
being applied over a cement treated base.
The
constructed sections have been performing very well under really very heavy
traffic and heavy heavy (!) rains (rainfall in lowland
areas averages 180–320 cm (70–125 in) annually, increasing with elevation
to an average of 610 cm (240 in) in some mountain areas!).As presented below now we have 1000
vehicles per day with GVW of about 160 ton (the payload is 130 ton!) over
the RARX double chip seal.
Our conclusions,
from the observations made during the last survey, are:
•RARX THINGAP and RARX GAP are very rut resistant
(No ruts found even under the most intense channelized traffic!)
•RARX THINGAP and RARX GAP are very resistant to
flexural fatigue and reflective cracking failures
•RARX-SAMI provides great adhesion to concrete
pavements
•RARX-SAMI must be placed below the surface
course
Jorge Sousa
Rubberized Asphalt
Foundation Asphalt Rubber Director
