porosity and the high compressive strength in comparing with the
previous works [2–4,31,33–35]. Indeed, the variation of the
permeability of pervious concrete is inversely proportional to
the compressive strength and proportional to the porosity. A
difference in the permeability coefficient obtained by two methods
(at variable load and constant) was observed, in accordance with
the previous work [4].
Freeze/thaw resistance:
In agreement with Table 7, pervious concrete present weak
durability to freeze/thaw attacks compared to the ordinary concrete.
The mass loss of concrete after 25 cycles of freeze/thaw is
0.3% and concrete is the off state after 88 cycles. Specimens subjected
to freeze/thaw cycles are kept saturated whilst in reality,
the pervious concrete are rarely seen in saturation capacity of
drainage. Indeed, in a sufficiently saturated specimen, pervious
concrete degradation is mainly due to the hydraulic pressure. An
increase of 9% in volume from the transformation of the water into
ice [36] leads to a great force on the walls of the pores.
Abrasion strength:
According to Table 7, the length of abrasion of pervious concrete
is 28.9 mm. Others authors show similar results with lengths varying
from 29.2 mm to 34.7 mm [1]. Indeed, because of the specific
texture of pervious concrete, the cement paste and the aggregates
are easily loosened from the surface of concrete and the length of
abrasion of pervious concrete is greater than that required
(20.0 mm) for traditional concrete paving block [27].
Skip strength:
There are few studies on the slip resistance of pervious concrete.
It can be seen that the concrete studied has a very good skid
resistance. The slip resistance value in the wet state (averaged over
the total surface of 5 measurements) is 89. This value is greater
than 40, critical value to ensure adequate resistance to slipperiness
for city traffic at 50 km/h. In addition, slip resistance value of the
order of 90 indicate that there is no risk of slip in wet weather [37].
5. Conclusion
In this paper, the theory of the excess paste was used to determine
the thickness of the paste coating each aggregate with a given
diameter of constituting granular skeleton, then generalized to
determine total amount of paste to the coating property of the
gravel grains avoiding clog the inter-granular pores between the
grains of the granular skeleton. One scaling factor ‘‘k’’ which can
be similar for different size of concrete aggregates is introduced.
The concrete mix design for draining characteristics thus passes
first by determining the amount sufficient of gravel and an adequate
amount of cement paste assuming that the amount of the
compact paste is zero. Then, with a volume of cement paste
determined, it is necessary to determine the w/c ratio for cement
paste not too liquid to avoid the flow of the cement paste due to
vibration or compaction. The binder drainage test proposed
protocol is simple and gives very good results.
The mix design method presented in this paper is interesting as
it is based on study mixed: theoretical–experimental. The superiority
of our methods compared to older methods is:
– It applies to any type and size of gravel.
– It shows the method of determining the ratio w/c.
– It takes into account for the effect of compaction.
The properties of concrete made from this method are very consistent
with data in literature. In addition, this is a concrete with a
good strength. The small gap between the targeted porosity and
the porosity obtained confirms the accuracy of this method.
The proposed methodology, interesting to compose a pervious
concrete, must be confirmed with other experimental field studied
and different types of materials.