LABORATORY STUDIES ON PERFORMANCE OF POROUS CONCRETE
Rita Moura Fortes
Department of Civil Engineering, Mackenzie Presbyterian University, Brazil
João Virgílio Merighi
Department of Civil Engineering, Mackenzie Presbyterian University, Brazil
Alex Alves Bandeira
Department of Civil Engineering, Mackenzie Presbyterian University, Brazil
The skid resistance of any surface is an important characteristic for the driving safety point of view.
The rain affects the traffic security, because there are splash and sprays effects caused by the
truck wheel. This fact contributes to the dynamic hydroplaning effect.
In recent years many agencies research’s has been studied the porous concrete as material to
server a sacrifice layer however with skid-resistant increase.
The purpose of this study was to determiner the mechanical and hydraulic characteristics of the
porous concrete with higher percent of air void to be used as drainage layer of pavement to obtain
better development in terms of skid resistance. Also is important to add some information
regarding the bond of the porous concrete to the sub layer, because the thickness is around 6 to
10 cm and thus being, these materials must work as a composite pavement to guarantee a
significant reduction of bending stresses on the concrete slab. In this way the bond strength
between both materials is essential for the performance of the thin porous concrete overlay
creating itself thus a composed structure of pavement.
It was made tests in specimens to obtain compressive and flexural strength and permeability.
STATIC STRENGTH SHEAR TEST / POROUS CONCRETE / SKID-RESISTANT /
COMPRESSIVE STRENGTH / PERMEABILITY/ PERVIOUS CONCRETE.
Dynamic hydroplaning occurs when standing water on a wet runway is not displaced from under
the tires fast enough to allow the tire to make pavement contact over its total footprint area. This
effect occurs because part of the tire surface rides on a wedge of water. The importance of surface
texture characteristics to roadway safety has been studied since 1940. It is important to mention
that because of the traffic increases volumes and vehicle speeds during these years it’s resulted
also in increases of wet weather crashes and fatalities.
When the superficial layer is very porous and permeable, we can observer a decrease of
accidents. Naturally, the water excess enters in the pavement surface drains because of the macro
texture with high voids, occurring facilitate to drainage this water. So, many agencies have been
including an extensive program to obtain a surface condition that reduces the accidents.
Until the present time the problem caused by wet skidding accidents on streets and highways are a
continuing concern of officials, highway engineers and contributing, in a lot of causes, with the lost
life and increase of the accidents.
Naturally, the principal causes of these accidents include variables such as reduced pavement
friction, in some cases associated with poor drainage properties of the surface, and driver
The philosophy of the open graded friction course (OGFC) as a tool to prevent wet skidding
accidents was preconized, according to literature, in USA since 1950 (Fortes and Merighi, 2004;
Merighi and Fortes, 2005). In according to these authors, the experience of United States with
open graded friction asphalt course has been widely varied. They affirm that many transportation
agencies have reported good performance while others have stooped using this kind of mix
regarding of poor performance with asphalt mix materials.
The production of porous concrete has been used in building construction. However, since 1990
we can find references in the literature about the porous concrete experiences in pavements.
Porous concrete also referred as Portland cement pervious pavement or pervious pavement is an
open-graded material consisting of Portland cement, coarse aggregate and water. These materials
produce a pavement layer with a void structure of 15% to 25%.
It is a concrete mix that has high void content, being thus a skeleton of uniform aggregate size and
a minimum of fines.
The elevated void content associated with a crushed stone makes possible the formation of good
macro texture and consequently good frictional characteristics and the drainage of water occurs
between the tire and the pavement interface. The combination of theses effects permits the
reduction of the potential for hydroplaning and a minor tire spray. A listing of the desirable
properties has been related by Onstenk et al. (1993): noise reduction, acceptable strength and
stiffness, adequate surface properties with respect to traffic safety – skid resistance, evenness,
sufficient service life - bonding to underlying dense concrete and costs comparable to conventional
2. RESEARCH SIGNIFICANCE
The research reported in this paper is a part of ongoing research at Mackenzie Presbyterian
University to investigate the friction course in airports pavements. The proposal of this research is
to find a concrete mix, which has, in the same time, a good performance in terms of mechanical
resistance and increase of surface frictional resistance when used as pavements. Data is
presented on compressive, flexural strengths, also permeability values and analyzed on aspects to
contribute for development of new materials that attend the condition of reduction of risk of
Regarding the thickness of the slab, it is around 6 to 10 cm. These materials must work as a
composite pavement to guarantee a significant reduction of bending stresses on the concrete slab.
In this way the bond strength between both materials is essential for the performance of the thin
porous concrete overlay creating itself thus a composed structure of pavement (Fortes, 1999 e
Fortes; Balbo, 2000).
There are many tests used to study the phenomenon of adherence between an underlying and an
overlay layer as: pull-off test method; slant shear test; Grzybowska test; impacto-echo method;
Wedge Splitting Test; pure tension; test collar (Iowa 406 Method); Ancona Shear Testing.
Some limitations of these tests used in this case are to mold the specimens to the pull-off test,
slant shear test, Ancona shear testing and the result do not represent the real behavior in the pull-
off test, impact-echo method, Ancona shear testing. Also, here in Brazil the impact-echo method,
wedge splitting test equipments are not available (Fortes, 1999, 2001).
Considering these difficulties, Fortes (1999, 2001) proposed a simple test that was used in this
3. POROUS CONCRETE
Porous concrete, Portland cement pervious concrete or simplify pervious concrete is an open-
graded friction course made with cement Portland, coarse aggregate, and water.
For porous pavement to perform effectively with respect to reduce road spray and hydroplaning, it
has been recommended that 15-25% interconnected porosity is required. Hoerner et. al. (2003)
relates that the principle of this technique is to create voids in the concrete (e.g., 20 percent by
volume of concrete) so that water can quickly drain from the surface. The same authors affirm that
the initial experience in Belgium with this surface type showed poor durability in freezing weather;
however, the durability of these mixtures has been improved with the addition of polymers and the
use of higher cement content.
The conception of porous concrete is represented in the Figure 1 where it can observer the high
porosity concrete system. In terms of superficial drainage the Figure 2 shows the different behavior
under water conditions between the normal concrete and porous concrete.
Figure 1 - Schematic representation (left) and a Porous Concrete (right)
Figure 2 - Schematic representation of drainage behavior of dense-graded and open-graded
In Figure 3 it’s possible to observer the high permeability of this kind of mix.
Figure 3 - The high porosity of the specimen milled from the plaque
The technology of porous concrete has been utilized in low-traffic areas such as the following
types of applications (Georgia Stormwater management Manual, 2006):
Parking pads in parking lots;
Overflow parking areas;
Residential street parking lanes;
Golf cart and pedestrian paths;
Emergency vehicle and fire access lanes.
The same manual affirm that its use o porous concrete is limited because:
Presents traditionally high failure rate and short life span;
High maintenance requirements;
Special attention to design and construction needed;
Should not be used in areas of soils with low permeability, wellhead protection zones, or
recharges areas of water supply aquifer recharges areas;
Presents restrictions on use by heavy vehicles;
Intended for low volume auto traffic areas or for overflow parking applications.
KUENNEN (2003) affirm that pervious concrete pavements are not appropriate for full-scale use
on high-volume roadways, but it is conditioned in low-volume roads applications and explain that
this technology improve road safety due to prompt drainage of rain.
The Georgia Stormwater management Manual (2006) recommend a typical cross-section of
porous concrete pavement as shown in Figure 4. Observe that the porous concrete layer is over a
POROUS CONCRETE SLAB ~5 cm
filter course while the present research proposal a different philosophy and the porous layer is an
overlay of an impermeably layer. So, the water should flow to the shoulder, similar the asphalt
Figure 4 - Porous Concrete System Section (Modified From: LAC 2000) (Georgia Stormwater
management Manual, 2006)
For them, the porous concrete layer consists of an open-graded concrete mixture usually ranging
from 5 to 10 centimetres of thickness, depending on required bearing strength and pavement
design requirements. Porous concrete can be assumed to contain approximately 20 percent voids
for design purposes. The porosity of the porous pavement is provided by the absence of the fine
aggregate. To provide a smooth riding surface and to enhance handling and placement is
recommended a coarse aggregate of 9.5 mm maximum size (Georgia Stormwater management
Filter layer is used over and under the stone reservoir layer. Top layer consists of a 12,5 mm
diameter crushed stone to about 5 cm of thickness and the surface of the sub grade should be an
15 cm (6 inches) layer of sand or 5 cm thick layer of 12,5 mm (0,5”) crushed stone.
The stone reservoir layer consists of washed bank-run gravel, 38 to 62.5 mm in diameter with a
void space about 40%. The thickness of this layer is function of the soil infiltration rate and void
spaces, but a minimum thickness of 23 cm (9 inches).
Filter Fabric has a very important function by inhibiting soil from migrating into the reservoir layer
and reducing storage capacity.
They recommend some test boring to determine the soil classification, seasonal high ground water
table elevation and impervious substrata, and initial estimate permeability.
The porous concrete shows three advantages when compared with traditional concrete: ground
water recharging, reduced hydroplaning and noise reduction. This manual recommends Porous
concrete to be used on the runway of airports, primarily for its better drainage capacities.
In the authors’ point of view, this paper considered that there is a lot of research in this theme and
certainly the material porous concrete has potential to be used as sacrifice layer upper the
concrete layer, in road (R), urban street (U) and airport (A) pavement for the follow propose:
i) Hydroplaning reduction (R and A),
ii) Spray tire reduction (R and U),
iii) Noise reduction (U, R),
iv) Balance between storm water runoff and the local ecosystem of wetlands (Urban area).
Naturally, even if the idea of porous concrete is very simple, it shows a large spectrum of
utilization. Its application, according in to the literature, is restrict or recommended only to parking
and low-traffic places. In terms of philosophy this material has a potential to be used as porous
layer in roads, in particular in places with elevated number of accidents, and in runway.
4. EXPERIMENTAL PROGRAM
This research was developed in two parts. The first was related a study of the porous concrete mix
and the second was a study of the bond strength between this superficial layer and the concrete
4.1 Porous concrete mixes
Preliminary was made some studies using gradation similar recommended in the open-graded mix
asphalt projects looking for a high porosity, but was verified low mechanical resistance. It is
important to mention that some of they attend the Stone Matrix Asphalt (SMA) conception in terms
of stone-on-stone contact (Brown and Haddock, 1997; Brown and Mallick,1994). So, were selected
four gradations: A, B, C and D. Mixes A and B with a little variation of the cement content, mix C
presenting a lower porosity than the others and mix D with was the best to attend the OGFC
The Figure 5 shows the distribution of the four gradations curves studied compared to an open
graded friction course (OGFC) gradation presented by Merighi and Fortes (2005).
Table 1 presents the details of the composition and some of the fresh concrete properties of the
four concrete mixes used in the testing programs. The mixes are referred to as A, B, C and D.
In the mix C was used micro silica. Due to the low water-cement ratios of the mixes was used
super plasticizer to obtain good workability. Crushed granite were used from a local quarry, with
maximum aggregates sizes of 12.5 mm to coarse aggregate, 9.5 mm to small shower of crushed.
The Los Angeles Abrasion was 25.1%. River sand having a fineness modulus of 2.08, was used in
the four mixes.
The Portland cement used in this research was CP III 40, from Votoran plan in according to the
Brazilian cement Portland specification (NBR5732/1991). The principal characteristics are
presented in Table 1.
Table 1 – Principal characteristics of the Portland cement
The density of the mixes was low due to higher porosity and porous size. The values are
presented in Table 2.
Table 2 – Composition and some properties of the concrete mixes
A B C D
Cement (kN/m3) 2.22 2.71 3.01 2.41
sand 2.22 2.38 2.65 1.49
Micro silica 0 0 3.65 0
Small shower (kN/m3) 1.33 1.35 3.65 1.12
Coarse aggregates (kg/m3) 12.88 13.13 7.32 13.31
Total water (l/m3) 0.65 0.70 0.87 0.62
Water-cement ratio 0.292 0.257 0.289 0.257
Superplasticizer (kN/m3) 0.050 0.040 0.044 0.360
Slump (mm) 182 169 175 161
Air content (%) 17.3 14.6 10.1 19.8
Density (kN/m3) 19.59 20.56 21.49 19.22
They were molded 100 x 200 mm concrete cylinder and a concrete slab as shown in Figure 6. The
cylindrical specimens from representative samples of fresh concrete attended the standard
requirements for making, curing, protecting and transporting concrete test specimens. These
specimens were cured in Moist Room, kept in a relative humidity of 80 percent and an average
temperature of 20ºC, as recommended by NBR 5738/2003.
CHARACTERISTICS STANDARD RESULTS
1. NORMAL CONSISTÊNCE NBR NM 43 24.2 %
2. MATERIAL PASSING # 200 NBR 11579 2.1 %
BEGINNING 3:25 HOURS
ENDING 6:15 HOURS
3. SETTING TIME NBR NM 65 COLD 0.0 mm
HOT 0.5 mm HOT < 5mm
4 LE CHATELIER EXPANSIBILITY NBR 11582 COLD 0.0 mm COLD <
5. SPECIFIC AREA (BLAINE METHOD) NBR NM 76 4040 cm²/g
(MPa) STANDARD DEVIATION
6. COMPRESSIVE STRENGTH NBR 7215
7. SPECIFIC GRAVITY NBR NM 23 3.02 g/cm³
Figure 5 - Gradation of mixes that were studied
Figure 6 - Slab Concrete
4.2 Bond strength between Portland cement concrete and porous concrete
A test plan was developed considering two proceedings: overlaying a plaque of Portland cement
concrete of 350 x 350 x 70 mm dimensions with porous concrete, applying in the interface a
textural superficial treatment (see Figure 7 (a) and (b)) and moulded 100 x 200 mm concrete
cylinder as showed in Figure 8.
The test was done as recommended by Fortes et al (1999, 2006) and showed in Figure 9 for both
0,1 1 10 100
Sieve Si ze (mm)
Percent Passing (%)
D - OGF
Figure 7 – (a) Plaque molded (b) epoxi resin bond
Figure 8 - Cylindrical specimens molded (a) specimen before the epoxi resin bond (b)
Figure 9 - Static strength shear test using: (a) cylindrical specimen (b) specimen cut from the
5. EXPERIMENTAL RESULTS
The results are presents in two parts: concerning to porous concrete mix and to the bond strength
between this superficial layer and the concrete sub layer.
5.1 Porous concrete mixes results
The strength of porous concrete depends on the grain size distribution, accessible porosity and the
type and amount of additive used.
A test plan was developed considering two proceedings of four specimen’s mixes, using cylindrical
and milled from plaques specimens.
The determination of the compressive and flexural strength of concrete was made as
recommended by 5739/1994 and NBR12142/1991, respectively. The compressive strength was
determined to 7, 14 and 28 days age and the flexural strength to 28 days age.
The Determining Pervious PCC Permeability with a Simple Triaxial Flexible-Wall Constant Head
Permeameter followed the Florida DOT falling-head laboratory permeability test as recommended
by Kandhal and Mallick (1997, 1998). Permeability testing was performed using a constant-head
permeameter. The hydrostatic head remains constant, with the quantity of water flowing through
the concrete sample for any period of time measured by means of a graduate.
The pervious samples were mounted into the cell pressure and the space between the sample and
the cells was completed with Bentonite clay. A photograph of the apparatus is shown in Figure 8.
Figure 8 – Permeameter used in the permeability determinations
In table 2 is presented the results of compressive, flexural strength and permeability properties.
Table 2 - Results of compressive, flexural strength and permeability properties
Compressive strengths (MPa) - days
7 14 28
A1 8.3 21.5 29.5 5.1 x 10-3 2.5
A2 6.6 20.4 27.4 6.0 x 10-3 2.3
B1 9.7 19.8 25.2 4.3 x 10-3 2.2
B2 8.3 17.4 23.3 2.7 x 10-3 2.4
C1 12.2 24.6 32.1 8.3 x 10-5 3.1
C2 10.2 22.4 31.2 4.3 x 10-6 2.9
D1 5.4 16.9 22.1 6.6 x 10-3 1.8
D2 6.3 15.4 20.4 8,9 x 10-2 1.7
5.2 Interface bond strength
The average results of Static strength shear was 10.11 MPa.
6. CONCLUSIONS AND RECOMMENDATIONS
The following conclusions and recommendations can be obtained from this research:
1) In terms of literature review it is possible to observer that porous concrete material is
recommended using in low traffic pavements conditions, parking, urban areas and under the point
of view of environmental considerations because permits the water infiltrations.
2) More than a filter to permit the water percolation, porous concrete present a good potential
to use under high traffic if used as superficial layer because it promote a reduction of the potential
for hydroplaning and a minor tire spray.
3) After many mixes tested, it was possible to find compressive strength to the 28 days of age
above 20 MPa associated a coefficient of permeability of the 10-3 cm/s,
4) The mixtures A and B, had presented values of compressive strength of the 28 and 25 MPa,
respectively and a porosity such that allowed to get compatible values of permeability as found in
the layers type OGFC. The flexural value was not raised however, these two mixtures have
potential to increase the resistance because the cement content was low, about 2.22 and
5) The mix C, the most density, presented the highest cement content (3.0 kN/m3) and
obviously, the low porosity. As expected the strength increase but the decrease of the permability
do not advises its use as a drainage layer.
6) Finally, the mix D, though attends the OGFC and SMA concept considering the stone-on-
stone contact. Its permeability performance was the best but the strength presented the poorest
7) The static strength shear was about 50% of the compressive strength of the porous
concrete. The authors intend to realize numerical simulations using 3D Finite Elements
8) The authors intend to improve their research doing more tests studying, others gradations
and also the bond between Portland cement concrete slab and a porous concrete thin overlay for
promoting a reduction of the potential for hydroplaning and a minor tire spray.
The authors would like to thank the Mackenzie Presbyterian University for his assistance in tests,
in special to Mr. José Carlos Sobrinho and Mr. Osmar Alves.
ASSOCIAÇÃO BRASILEIRA DE NORMAS TÉCNICAS. NBR 5738/2003 – moldagem e cura de
corpos de prova cilíndricos e prismáticos, ABNT, Rio de Janeiro, 2003.
ASSOCIAÇÃO BRASILEIRA DE NORMAS TÉCNICAS. NBR 5739/1994 – Concreto – ensaio de
compressão de corpos-de-prova cilíndricos, ABNT, Rio de Janeiro, 1994.
ASSOCIAÇÃO BRASILEIRA DE NORMAS TÉCNICAS. NBR NM 248/2003 – Determinação da
composição granulométrica. ABNT, Rio de Janeiro, 2003.
ASSOCIAÇÃO BRASILEIRA DE NORMAS TÉCNICAS. NBR12142/1991 - Concreto -
Determinação da resistência à tração na flexão em corpos-de-prova prismáticos, ABNT, Rio de
ASSOCIAÇÃO BRASILEIRA DE NORMAS TÉCNICAS. NBR5732/1991 – Cimento Portland
Comum, ABNT, Rio de Janeiro, 1991.
ASSOCIAÇÃO BRASILEIRA DE NORMAS TÉCNICAS. NBR NM 43/2002 - Cimento Portland -
Determinação da pasta de consistência normal. ABNT, Rio de Janeiro, 2002.
ASSOCIAÇÃO BRASILEIRA DE NORMAS TÉCNICAS. NBR 11579/91 – Cimento Portland –
Determinação da finura por meio da peneira 75 mm. ABNT, Rio de Janeiro, 1991.
ASSOCIAÇÃO BRASILEIRA DE NORMAS TÉCNICAS. NM65/2002 - Cimento Portland -
Determinação do tempo de pega. ABNT, Rio de Janeiro, 2002.
ASSOCIAÇÃO BRASILEIRA DE NORMAS TÉCNICAS. NBR 11582/91 – Cimento Portland –
Determinação da expansibilidade de Le Chatelier. ABNT, Rio de Janeiro, 1991.
ASSOCIAÇÃO BRASILEIRA DE NORMAS TÉCNICAS. NBR NM 76/98 - Cimento Portland -
Determinação da finura pelo método de permeabilidade ao ar (Método de Blaine). ABNT, Rio de
ASSOCIAÇÃO BRASILEIRA DE NORMAS TÉCNICAS. NBR NM 23/2001 - Cimento Portland e
outros materiais em pó – Determinação de massa específica. ABNT, Rio de Janeiro, 2001.
ASSOCIAÇÃO BRASILEIRA DE NORMAS TÉCNICAS. NBR 7215/96 (MB 1) Cimento Portland -
Determinação da resistência à compressão. ABNT, Rio de Janeiro, 1996.
BROWN, E. R. & HADDOCK, J. E.., 1997 A Method to Ensure Stone-on-stone Contact in Stone
Matrix Asphalt Paving Mixtures. NCAT Report No. 97-2. 20 p.
BROWN, E. R. & MALLICK, R. B.., 1994 Stone Matrix Asphalt-Properties Related to Mixture
Design. NCAT Report No. 94-2. 83 p.
FORTES, R.M. - Estudo da aderência entre placas de concreto de cimento Portland e concretos
asfálticos para fins de reforços ultradelgados de pavimentos, São Paulo, 1999. 335p. Tese
(Doutorado) - Escola Politécnica, Universidade de São Paulo.
FORTES, Rita Moura & BALBO, José Tadeu Estudo da aderência entre o concreto de cimento
Portland e concretos asfálticos com a finalidade de utilização em pavimentos de Whitetopping
Ultradelgado - 1º Simpósio Internacional de Manutenção e Restauração de Pavimentos e Controle
Tecnológico, São Paulo, Brasil, maio de 2000.
FORTES, Rita Moura Proposta de ensaio de resistência ao cisalhamento direto para
determinação da aderência entre duas camadas. 33ª Reunião Anual de Pavimentação, ABPv -
Associação Brasileira de Pavimentação, Florianópolis - SC, Brasil, 2001.
FORTES, Rita Moura & MERIGHI, João Virgilio, 2004. OPEN-GRADED HMAC CONSIDERING
THE STONE-ON-STONE CONTACT. International Symposium on Design and Construction of
Long Lasting Asphalt Pavements, Auburn, Alabama, EUA.
FORTES, Rita Moura & MERIGHI, João Virgilio, Bandeira, Alex. ESTUDO DA RESISTÊNCIA AO
CISALHAMENTO NA INTERFACE DA PLACA DE CONCRETO DE CIMENTO PORTLAND E
PLACA DE CONCRETO POROSO UTILIZADAS EM PAVIMENTAÇÃO (STUDY OF THE BOND
STRENGTH BETWEEN PORTLAND CEMENT CONCRETE AND POROUS CONCRETE USING
IN PAVEMENTS). 48º Congresso Brasileiro do Concreto CBC 2006, Rio de Janeiro, RJ, Brasil,
setembro de 2006.
Georgia Stormwater Management Manual - Volume 2 / Section 3.3.7 >
http://www.georgiastormwater.com/vol2/3-3-7.pdf < Accessed in February, 25th, 2006.
KANDHAL, P.S. and MALLICK, R.B. Design of new-generation open-graded fiction courses. NCAT
Report No. 97-2, January 1997.
KANDHAL, P.S. and MALLICK, R.B., 1998. Open Graded Asphalt Friction: State of the Practice.
NCAT Report No. 98-7.
KUENNEN, Tom. Voids Add Value To Pervious Concrete. Better Roads. August 2003, Road
Science. Articles > http://www.betterroads.com/articles/aug03a.htm< Acessed in February, 25th,
MERIGHI, João Virgilio; FORTES, Rita Moura. STUDY OF LABORATORY PROPERTIES OF
OGFC CONSIDERING STONE-ON-STONE CONTACT. SOUTHERN AFRICAN TRANSPORT
CONFERENCE (SATC 2005). 11to 15 July 2005, Pretoria, South Africa.
ONSTENK, E., AGUADO, A., EICKSCHEN, E., and JOSA A., “Laboratory study of porous
concrete for its use as top layer of concrete pavements”, Proceeding of the Fifth International
Conference on Concrete Pavement and Rehabilitation, Purdue University, Indiana, 1993, Vol.2,