Luận văn thạc sĩ VNU ULIS experimental study on strength and permeability of pervious concrete pavement containing fly ash, blast furnace slag and silica fume

VIETNAM NATIONAL UNIVERSITY, HANOI
VIETNAM JAPAN UNIVERSITY

TRAN THANH TUAN

EXPERIMENTAL STUDY ON STRENGTH
AND PERMEABILITY OF PERVIOUS
CONCRETE PAVEMENT USING FLY ASH,
BLAST FURNACE SLAG AND SILICAFUME

MASTER’S THESIS

Hanoi, 2019

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VIETNAM NATIONAL UNIVERSITY, HANOI
VIETNAM JAPAN UNIVERSITY

TRAN THANH TUAN

EXPERIMENTAL STUDY ON STRENGTH
AND PERMEABILITY OF PERVIOUS
CONCRETE PAVEMENT USING FLY ASH,
BLAST FURNACE SLAG AND SILICAFUME
MAJOR: MASTER IN INFRASTRUCTURE ENGINEERING
CODE:

RESEARCH SUPERVISOR:
Associate Prof. Dr. KOHEI NAGAI

Dr. DUONG QUANG HUNG

Hanoi, 2019

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CONTENTS
Acknowledgment ....................................................................................................... 6
Abstract ...................................................................................................................... 7
LIST OF FIGURE .................................................................................................... 3
LIST OF TABLE ...................................................................................................... 4
LIST OF ABBREVIATIONS .................................................................................. 5
CHAPTER 1: INTRODUCTION ............................................................................ 6
1.1.

Background of Pervious Concrete Pavement ........................................... 8

1.2.

Scope and Objective .................................................................................... 9

CHAPTER 2: LITTERATURE REVIEW ........................................................... 10
2.1.

Introduction of the development of pervious concrete .......................... 10

2.2.

Overview of pervious concrete uses Fly ash and BFS additives ........... 12

CHAPTER 3: METHODOLOGY AND EXPERIMENT ................................... 15
3.1.

Methodology ............................................................................................... 15

3.2.

Experimental procedure ........................................................................... 15

3.2.1.

Compressive and flexural strength test. ................................................... 15

3.2.2.

Void ratio test. .......................................................................................... 15

3.3.

Matertial preparation ............................................................................... 17

3.4.

Mixing Proportions and Casting Specimen ............................................ 24

3.4.1.

Proportion ................................................................................................. 24

3.4.2.

Casting Specimen ..................................................................................... 25

CHAPTER 4: RESULTS AND DISCUSSION .................................................... 28
4.1.

RESULTS ................................................................................................... 28

4.1.1.

Compressive Strength of PCPC ............................................................... 28

4.1.2.

Permeability of PCPC: ............................................................................. 31

4.2.
4.2.1.

Discussion ................................................................................................... 33
Combine slag in slurry to make porous concrete ..................................... 33
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4.2.2.
4.2.3.

Mortar with BFS and SF produces strength pervious concrete ................ 34

Fly ash particle did not significantly enhance strength of porous concrete
35

CHAPTER 5: CONCLUSION AND RECOMMENDATION ........................... 37
5.1.

Conclusion .................................................................................................. 37

5.2.

Recommendation ....................................................................................... 38

Reference.................................................................................................................. 39

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LIST OF FIGURE
Figure 3.1: Mixing PCPC with concrete mixer ................................................... 25
Figure 3.2: Casting specimen at Lab .................................................................... 25
Figure 3.4: Curing PCPC specimen at Lab ......................................................... 27
Figure 4.1: Testing PCPC at Lab .......................................................................... 28
Figure 4.2: The PCPC sample is destroyed after compression .......................... 29
Figure 4.3: Crack of PCPC after compression .................................................... 29
Figure 4.4: Compressive strength development with time ................................. 30
Figure 4.5: Testing permeability of PCPC ........................................................... 31

Figure 4.6: Void ratio (%) of PCPC Specimen.........Error! Bookmark not defined.
Figure 4.7: Coefficient of Permeability (mm/s) ................................................... 33
Figure 4.8: Hydrated Cement Paste ..................................................................... 34
Figure 4.9: Cement Hydration Reaction .............................................................. 34
Figure 4.10: Pozzolanic Reaction .......................................................................... 35
Figure 5.1: solution for designing PCPC road structure layers......................... 38

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LIST OF TABLE
Table 2.1: Summary of the research results on PCPC ....................................... 10
Table 2.2: Typical mix design and properties of existing PCPC in the US (reported
by Nation Ready Mix Concrete Association – NRMCA, 2004) ......................... 11
Table 3.1. Physical and chemical properties of OPC and GGBS ...................... 17
Table 3.2: Mix Proportion of specimens in trial experiment ............................. 24
Table 4.1: Compressive strength of PCPC .......................................................... 30
Table 4.2: Void ratio of PCPC .............................................................................. 29
Table 4.3: Permeability of PCPC .......................................................................... 29

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LIST OF ABBREVIATIONS
PCPC

: Portland cement Pervious Concrete

PCP

: Pervious Concrete Pavement

NRMACA

: National Mixing Concrete Association

SP

: Super plasticizer

SF

: Silica Fume

FA

: Fly Ash

BFS

: Blast Furnace Slag

GGBFS

: Ground Granulated Blast Furnace Slag

CSH

: Calcium Silicate Hydrate

AASHTO

: American Association of State Highway and Transportation Officials

ACI

: American Concrete Institute

ASTM

: American Society for Testing and Materials

FHWA
: Federal Highway Administration - United States Department of
Transportation
ACPA

: American Concrete Pavement Association

NRMCA

: Nation Ready Mix Concrete Association

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Acknowledgment
My master thesis was started from my internship at The University of Tokyo in September
2018. It was really a memorable and lucky time in my life. Experimental activities at
Komaba Campus – The University of Tokyo are very interesting and useful during the
internship in Japan under the supervision of Associate Professor Kohei Nagai - University
of Tokyo, Japan and Dr. Duong Quang Hung - Hanoi Architectural University. From the
bottom of my heart, I would like to express my gratitude to Associate Professor Kohei
Nagai, Dr. Duong Quang Hung for giving me helpful advice and dedicated guidance and
valuable lectures for conducting research.
It is difficult to express my gratitude to two talented and respectable professors Professor
Nguyen Dinh Duc - Vietnam National University in Hanoi and Professor Hironori Kato –
University of Tokyo. Two co-directors of the Master in Infrastructure Engineering program
- VJU gave me useful advice and orientation in the right direction.
Also, I would like to send many thanks to Dr. Phan Le Binh, lecturer, JICA long term expert
who always encouraged me and Dr. Tien Dung Nguyen Dung at VJU for his devoted and
valuable support. Their support is extremely precious and always inspires me to complete
the thesis.
Also, without the help of my friends studying at Komaba Campus - University of Tokyo, I
would not have accomplished my thesis. Therefore, I would like to thank for their help.
The last, I would like to give special thanks to MIE02-VJU classmates and students from
the same course at Vietnam Japan University for supporting and accompanying me
throughout my great time at Vietnam Japan University.
My master thesis is also a gift for my whole family, for my parents, my wife and my lovely
children because they were always beside me during the whole time I studied at VJU.
Sincerely,

Tran Thanh Tuan
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ABSTRACT
About 30 years ago, Porous Concrete (PC) was studied for use in the United Kingdom and
the United States in some traffic works. In Europe and Japan, to reduce noise and improve
skid resistance, PC is also used as a very effective application material.
Research and application development of Blast Furnace Slag (BFS) are widely used in
Portland Cement Pervious Concrete (PCPC).Fly ash (FA) is very important because it not
only increases the surface drainage capacity of transport works but also contributes to
reducing pollution as a material of environmental friendliness.
According to a study in Belgium, for some PC mixtures, the 28-day compressive strength
also reaches 31.7 MPa. However, the permeability of this mixture has not been specifically
reported.
Therefore, research on PCPC strength and permeability with the use of BFS, FA to replace
part of cement and to achieve proper permeability is very promising and essential in the
future.
PCPC is a kind of concrete mixture made from coarse aggregate, small sand content (0-20%
by weight of aggregate or no sand, water from 27-43% and binder. Pervious concrete with
void ratio of 14-30% and rough textured surface.
In this study, the author has found some mixing proportion of porous concrete using BFS
and FA to replace part of cement and reduce the amount of sand used.
The author carried out the design of various mixing proportion used for PC such as ash,
flying ash combined with silica fume. The experimental process at the Komaba Lab - Tokyo
University finds the results and compares the effect of each of these materials on the
strength and permeability of PC.
When using BFS in combination with silica fume, the mixed concrete resulted in a strength
of porous concrete of 29.42 MPa with a permeability of 1,747 mm / s. It can be considered
for application in a number of projects using porous concrete that can drain in reality such

as parking lots, sidewalks, etc.

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CHAPTER 1: INTRODUCTION
1.1.

Background of Pervious Concrete Pavement

Today, along with the development of modern construction technologies, advanced and
environmentally friendly materials are also focused on sustainable development.
Concrete is a common construction material in the construction industry in general and
technical infrastructure in particular.
In particular, Portland Cement Pervious Concrete (PCPC) or Pervious Concrete Pavement
(PCP) is a material that has been researched and applied in recently as an environmentally
friendly material.
According to the National Mixing Concrete Association (NRMCA), porous concrete is a
high porosity concrete used for flat surface concrete applications that allows water from rain
and other sources to flow through. This will reduce the flow from one location and reload
the groundwater level. These are also called non-fines concrete and are made of Portland
cement, coarse aggregates, water, with little or no sand and additives.
The draining water PCP has many merits, such as good safety driving in rainy days,
reducing noise, high anti-slippery performance of the pavement and no accumulated water,
no splash and spray in rainy days, increasing the driving safety in rainy days greatly. The
draining water bituminous pavement obtains widespread applications in Western Europe,
US and Japan and so on.
Porous concrete is used for pavement materials, it can penetrate rainwater at the source,

contributing to improved driving safety, noise while reducing traffic, road heat effects in the
capital. Marketing is also overcome and contributes to sustainable development.
Evaluating the environmental impact of porous concrete with non-porous or conventional
concrete also gives different results. Porous pavement makes air, water and temperature
penetrate into different parts of the environment, from which they undergo different storage,
handling and flow processes. Therefore, porous concrete is an environmentally friendly
material.

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Research on using fly ash and Blast Furnace Slag also contributes to reducing
environmental pollution because Blast Furnace Slag pollutes water and air when left in
nature.
1.2. Scope and Objective
Objectives:
The study on strength and permeability of PC containing fly ash, slag and silica fume is
to achieve the following goals:
- To investigate the effect of fly ash and Blast furnace slag, silica fume on strength and
permeability of PCPC
- To achieve PCPC mixture design that has necessary compressive strength and
permeability suitable for practical road applications.
Scope:
Pervious concrete pavement has important indicators as strength, permeability, abrasion,
surface texture and some other indicators. Within the scope of this thesis, the author
focuses on two main indicators: strength and permeability of Pervious Concrete
Pavement (PCP).
The super plasticizer used in this study is a common polycarboxylate-based SP8P

admixture in Japan, which increases the workability, slump for concrete and extends the
setting time of cement and concrete.
Experimental process of making PCP samples at Komaba Lab, the study carried out the
design, tested the compressive strength of concrete according to ACI 522 standard and
determined the permeability of PCP according to Park and Tia’s Equation (2004).
By using materials to replace a part of cement such as Blast Furnace Slag (BFS), Fly
Ash (FA) with additives such as Super plasticizer (SP) and Silica Fume (SF) to find the
optimal mixture. PCPC has enough strength and permeability to be applied in practice.
Structure of thesis:
Chapter 1: Introduction
Chapter 2: Literature review
Chapter 3: Methodology and Experiment
Chapter 4: Result and discussion.
Chapter 5: Recommendation and conclusion.

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CHAPTER 2: LITTERATURE REVIEW
2.1.

Introduction of the development of pervious concrete

Leading institutes and associations in the field of concrete pavement in the world:
 United States Department of Transportation – Federal Highway
Administration (FHWA)
 American Concrete Pavement Association (ACPA)
 American Association of State Highway and Transportation Officials

(AASHTO)
 ACI Committee 522 – Pervious Concrete
 Center for Transportation Research and Education, Iowa State University
The issues around PCPC have been investigated as the following table:
Table 2.1 Summary of the research results on PCPC
No

Issues

1

Construction Materials

2

PCPC Material Properties

3

Researcher
Tennis (2004); Tamai (2003); Kajio (1998).

Strength

Kaijo (1998); Beeldens (2003); Tennis (2004);
Elsayed (2011)

Porosity and permeability

Ferguson(2005); Tennis (2004); Yang (2003)

Tanaka (1998)

Surface Characteristics
Noise reduction

Olek (2003); Tamai (2003)

4

Pervious Pavement Design

Kosmatra (2002); Young (2005); Ramadhansyah
(2014)

5

Construction

Husain (2015), Darshna shar (2013),

6

Maintenance

Olek (2003)

7

Environment
PCP using waste material

Durability of Porous Concrete

Sukamal (2015)

Tamai (2003)
An Experimental study on the
water-purification properties Park, Tia (2004)
of porous concrete

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According to research, author Nguyen Van Chanh pointed out that: Pervious Concrete is
a type of concrete with continuous pore structure, magnetic porosity (15-35%) having the
same composition as normal concrete, however coarse aggregates are used with the same
grain size and contain very little or no sand. (Nguyen Van Chanh et al., 2005).
When using synthetic stone gravel with smaller size, it increases compressive strength,
while increasing porosity in concrete structure and thus increasing the drainage capacity of
porous concrete.
However, the drainage capacity of porous concrete is not merely secondary to porosity,
but is still dependent to many other factors such as continuous counting, winding, pore
surface
Water (W) and cement (C): The W/C ratio is determined to be from 0.25 to 0.45. Unlike
conventional concrete, the amount of cement in porous concrete is lower than the amount of
pore between aggregate particles.
When the strength of cement mortar increases, it will lead to an increase in the overall
strength of porous concrete. Therefore, it is necessary to control the amount of water closely.
Using the right amount of water will make the concrete mixture get the desired

properties, no mortar phenomenon will flow to the bottom of the bottom layer to fill the
pores, causing the drainage of porous concrete.
Pervious concrete mix designs in the US include cement, coarse aggregates with a size
between 2.54 cm and No. 4 sieves and are classified according to the ratio of water/cement
(W / C) within from 0.25 to 0.43.
28-day compressive strength of porous concrete ranged from 7 MPa – 24 MPa, with the
rate of voids from 14% to 31% and the range of velocity permeability (2-6 cm/min).
Compared to conventional concrete, compressive strength ranges from 3,500 to 4,000psi (28
MPa – 32 MPa), lower than 3,000 psi.
Table 2.2 Typical mix design and properties of existing PCPC in the US (reported by Nation
Ready Mix Concrete Association – NRMCA, 2004)
Property

Specification

Cement content

300 to 600 lbs/yd3

Coarse aggregate content

2,400

to

180 to 360 kg/m3

2,700 1,440 to 1,620 kg/m3
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Fine aggregate content

lbs/yd3

0 kg/m3

Water-cement ratio

0 lbs/yd3

0.27 to 0.43

Aggregate to cement ratio

0.27 to 0.43

4 to 4.5/1 by mass

Slump

0 to 1 inch

0 to 2.54 cm

28-day
strength

compressive 800 to 3,000 psi

1 to 3.8 MPa

Flexural strength
Void ratio
Permeability (flow rate)

7 to 24 MPa

14% to 31% by volume
36
to
inches/hour

864 2 to 36 cm/min (120 to 320
L/m2/min)

Density (unit weight)

1600 to 2000 kg/m3

Shrinkage

200x10-6

Strength and permeability
The Strength of concrete pavement is lower than that of conventional concrete.
Therefore, the application of PCPC is limited to low-intensity structures such as parking lots,
shoulder lanes, light traffic areas, or roads but not highways.

For a wider application, a long-term plan for the study of porous concrete pavements is
needed to determine the optimal porous concrete mixing ratio to enhance the strength with
suitable permeability to be used highway or highway surface.
Nader Ghafoori and Shivaji Dutta reported that both sealed- and wet-curing conditions
have shown similar effects on strength development. Moreover, the gain in strength, under
both curing types, is unaffected by the increase in compaction energy. It is found the
strength of no-fine concrete increase with rise in compaction energy.
The movement of water will be more convenient when the interconnected voids are
present in the structure of the permeable concrete. When the porosity is higher, the texture is
lower in strength and when the porosity is lower, the strength of the porous concrete will be
higher (Ferguson, 2005).
2.2.

Overview of pervious concrete uses Fly ash and BFS additives

Pervious Concrete: ''The new era for rural road sidewalks'' has said:

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The objective of the study is to evaluate the cost effectiveness of porous concrete compared
to conventional concrete. In that study, conventional concrete was used according to the
design of the IS Class M20, including 59.25 kg of cement (300 rs/50 kg), 88.88 kg of fine
aggregate (600 rs/1 ton) and a total of 177.8 kg (1000 rs/1 ton) (Darshna et al., 2013).
Pervious concrete is used in accordance with the NRMCA guidelines, which are composed
of 46.5 kg of cement (300rs / 50kg) and concrete of course (1000rs /1 ton). The conclusion
indicates that Porous concrete reduces the flow of rainwater to increase the amount of
groundwater to eliminate costly storms for water management practices. And that is

significant savings in the amount of about 29 rs/m3 or 18 rs/ft2.
A study named: “Effect of Aggregate Grading and Cement By-Product on Performance of
Pervious Concrete” also indicates that:
Replacing part of cement with industrial by-products such as fly ash, GGBS has been
successfully used as an additional cement material as the target of this study.
The author used type 53 cement (specific weight 3.15), coarse aggregate (transmitted
through 20 mm and left sieve on 10 mm sieve) together with using GGBS (specific gravity
2.88), fly ash and water (Husain et al., 2015).
Through the research article named: "Evaluation of performance of absorbent concrete
using waste materials”, the use of furnace slag, rice husk ash and silica fume and solid waste
(glass powder, ceramic waste, bottom ash) and its effect on strong compressive strength and
permeability are as per below:
Usage: Fly ash (2-50%), RHA (10-30%), GGBS (35-70), Silica fume (8-12%), Rubber
waste, Glass powder (20-40%) is used to replace part of cement.
Research shows that the compressive strength and permeability when using materials have
different effects as below:
Fly ash gives long-term compressive strength when increasing but then decreases
compressive strength.
Rice husk ash reduces more than 10-12% of compressive strength, permeability and
durability.

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GGBFS gives higher strength but lower permeability. Silica fume increases compressive
strength but does not affect permeability. Glass powder strengthens durability and
workability and Ceramic powder improves durability (Sukamal et al., 2015).
Author A.Elsayed in the research paper: "Influence of Silica Fume, Fly Ash, Super Pozz and

high slag on water permeability and strength of concrete" said that:
Can improve the properties of concrete, such as increasing resistance and reducing
permeability by using mineral additives such as fly ash, BFS and silica fume. (Elsayed,
2011).

Conclusion
In previous studies, increasing the strength of porous concrete will lead to reduce
permeability and vice versa. In the data sheet you can see, the PCPC strength is about 7-31
MPa. That is the limit to expand the application of porous concrete in practice. Limitations
on strength & durability prevent widespread application of Porous Concrete.

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CHAPTER 3: METHODOLOGY
3.1.

Methodology

Topics using experimental methods to research. The steps for conducting the study
include:
The calculation of grading using cement, coarse aggregates, fine aggregates with FA,
BFS replaces part of cement, SP and SF as additives based on ACI 522 standard and inherits
pervious research results. After that, casting samples and testing the strength and
permeability of PCPC are conducted.
3.2.

Experimental procedure

Experiment method: There are four types of tests to characterize properties of pervious
concrete mix in this research, including unconfined compressive strength, flexural strength,
void ratio and permeability. The characterization of tests methods and formulas used for the
experiment are indicated as following:
3.2.1. Compressive and flexural strength test.
Slump of the fresh concrete is measured following ASTM C143 by a standard cone test.
Compressive strength is determined according to ASTM C39, and flexural strength is
conducted in accordance with ASTM C78 (using simple beam with third-point loading).
The cylinder specimens with 10cm in diameter and 20cm in length are used for testing
compressive strength. The prismatic samples 10x10x40cm are for testing flexural strength.
Testing machine to test the compressive strength of samples with a capacity of 100 tons
is used, cylindrical test samples are aged at 7, 28, 56, 91 days since casting. Loading speed
is 14 N /mm2/minute.
3.2.2. Void ratio test.
The void ratio of pervious concrete is determined by measuring the weight difference
between dry samples and water saturated samples.
When using the equation of Park and Tia (2004), cylindrical samples with a diameter of
10cm and a length of 20 cm were constructed to check the void ratio:

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  W  W1 
100(%)
Vr  1   2
   wVol 

where,

(1)

Vr: total void ratio, %
W1: weight under water, kg
W2: oven dry weight, kg
Vol: volume of sample, cm3
 w: density of water, kg/cm3

Permeability test
The samples are wrapped in rubber and surrounded by adjustable tube clamps.
Cylindrical sample for experiments has a diameter of 10cm and a height of 20 cm. The
average permeability coefficient (k) is determined as follows according to Das equation
(1998):
k

aL  h0 
ln  
At  ht 

where,

(2)

k: coefficient of permeability, cm/sec
a: area of standpipe, cm2
L: height of sample, cm
A: area of sample, cm2
t: time for water to drop from h0 to ht, sec

h0: height of water in burette at initial time (t = 0), cm
ht: height of water in burette at final time (t = t), cm

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3.3.

Material preparation

Material:
Ordinary Portland cement (C), Fly Ash (FA) ash, blast furnace slag (BFS) and silica
fume (SF) are used in this study.
Crushed gravel with the largest size Dmax 15mm used as a raw aggregate, washed with
water before use (G)
Super-plasticizer (SP, a sulfoanated naphthalene formaldehyde condensate of Japanese
origin, a dark brown aqueous solution with 42% solids and a density of 1.2) is employed to
aid the dispersion of Nano-particles and silica in binder and achieve good workability of
concrete.
20% sand to coarse aggregate by mass is used, which is expected to enhance strength of
pervious concrete.
Cement
Ordinary Portland cement (OPC) follows JIS R5210 standard, used in this study. The
physical properties and chemical properties as well as the limit value are specified by JIS
R5210.
Ground Granulated Blast Furnace Slag (GGBFS) or Blast Furnace Slag (BFS)
Blast furnace slag (GGBS) or blast furnace slag (BFS), is used instead of OPC in this
study. Blast furnace slag conforms to JIS A6206 and the criteria listed in Table 3.1.

Table 3.1 Physical and chemical properties of OPC and GGBS
OPC
Material

JIS
R5210

Physical
properties

Density,
cm3
Fineness,

g/

GGBS4

OPC

JIS
A6202

GGBS

-

3.15

< 2.80

2.91

> 2500

3470

3000-

4070
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cm2/g

5000

LOI

< 3.0

0.77

< 0.3

-

SiO2

-

20.84

-

-

Al2O3

-

5.95

-

-

Fe2O3

-

2.62

-

-

CaO

-

63.63

-

-

MgO

< 5.0

1.79

< 10.0

5.46

SO3

< 3.0

1.97

-

0.04

Na2O

-

0.18

< 4.0

-

K2O

-

0.33

-

-

TiO2

-

0.34

-

-

P2O5

-

0.08

-

-

MnO

-

0.1

-

-

CI

< 0.02

ND

< 0.02

0.005

Chemical

properties

Note: “-“: not be specified, “ND”: not be determined
Fly ash
In the process of burning coal in power plants with by-products produced, it is fly ash.
Helmuth (Mindes and Young) has shown a summary of the properties and chemical
composition of different fly ash.
Based on the chemical composition, it is classified as fly ash type F or type C. In type F
there is a lower amount of High, hence less cement properties and vice versa, C has higher
CaO content, so it has more cement properties and less toxic than F-type fly ash (Elsayed,
2011).

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The fly ash particles are spherical, and the main chemical components include SiO2,
Al2O3 and Fe2O3. The process of using fly ash for concrete mixtures can bring benefits
such as improved workability, lower hydration.
Besides, when mixing fly ash replaces a part of cement, it also helps concrete with lower
cost and improves resistance to sulfate attack.
The strength of concrete will also increase with lower porosity in the long term, while
improving waterproofing ability.
Specimen fabrication
Concrete containing BFS, FA, and SF is manufactured according to the following
process:
First water and super-plasticizer are poured into the stirrer and then they are added to stir
at high speed for 3 minutes.
Then, Cement, fly ash or slag, coarse aggregate and sand are rotated for 30 seconds by

mixing dry in the mixer and then the water, SP, SF mixture is poured slowly and mixed for
1 minute, Hold for 1 minute before final mixing for 1 minute.
When porous concrete mixing consists of silica fume, cement powder, fly ash or slag,
and silica fume, the mixture is mixed under dry conditions in the planetary mixer before 3
minutes.
Then the raw aggregate and sand are added to the rotary drum mixer before adding the
above mixture and dry mixing for 30 seconds. After that, the liquid mixture of additives are
poured slowly and mixed for 1 minute, stopping for 1 minute before mixing the last 1
minute.
The final fresh concrete is poured into cylindrical molds and prisms prepared for each
type of test. All cylinders are compacted with 25-fold pokes with skewers 10 mm in
diameter and in three layers. The outer surface of the mold is lightly tapped 15 times with a
mallet after each layer to avoid the concrete sample being pitted around.
For a prismatic beam pattern (10x10x40cm), concrete is added to the mold, which is
flexed 30 times using a round head with a diameter of 16mm (once for each 14 cm2 of the
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upper surface area of the mold), Then, apply external vibration to the four corners of the
mold using the hard shaft vibrator for about 3 seconds for each corner.
All samples are finished with a steel flight machine after casting. Then, to prevent
evaporation, plastic sheets used to cover the samples were used.
After 24 hours, the samples will then be removed from the molds and soaked in water at
a laboratory temperature of about 20-23 degrees C for maintenance in 7, 28, 56 and 91 days
until the time of testing. Specimens are maintained in the same condition.
For a prismatic beam pattern (two samples are placed into a mold made of steel
formwork), two layers of concrete are added to the mold with 30 clamps for each layer of
each sample and outside the mold, 10 seconds of use. Use the vibrator for each of the eight

corners after each class.
To prevent evaporation, plastic sheets are used to cover the samples. After that, the
sample will be removed from the mold after 24 hours and soaked in water at 20 ° C for
curing until the test time is 7 days, 28 days and 56 days.
When conducting compression testing, the compressor used is with ASTM 400 kips
compression testing machine. To ensure that the samples are loaded with axes, the cylinders
are covered with sulfur. The loading speed is 200 psi (1,4MPa) per minute until the sample
is failure.
Sample test for compressive strength test is performed at each test age: 7, 28 days.
To avoid the loss of additives, plasticizers are washed off the mixing tank to avoid loss
of additives because the amount of super-plasticizer mixed in the concrete mixture is small.
The amount of super-plasticizers into concrete mixes is based on the weight of Portland
cement. Super-plasticity seems to be able to remove additional particles or change its spatial
arrangement around high-grade particles.
Apparatus required in experiment of pervious concrete:
Cylindrical mold 15x30 cm (experiment of tensile strength - ASTM C496)
Prismatic mold 15x15x50 cm (experiment of flexural strength – ASTM C78)

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Supplementary devices for testing tensile strength
Permeability-meter:
- A Glass (plastic) testing tube with outside diameter of 10 cm and height of 60 cm
- A rubber sleeve with inside diameter of 9.8 cm and height of 10 cm
- Adjustable hose clamps
- A flexible sealing gum
- An oven to dry sample

- A high speed stir machine (to evenly disperse Nano-particle in water and superplasticizer)
- A vibrating table with amplitudes of 0.127 mm
- A planetary mixer to mix cement, fly ash, slag, silica fume
The coarse aggregate is about 9.5mm in diameter (all pass through 1/2 inch sieves and is
retained entirely on 3/8 inch sieves)
The strength of porous concrete with an aggregate size of 5 to 10 mm will increase from
1.8 to 2.0 times compare to porous concrete with an aggregate size of 10 to 20 mm.
When the contact surface between aggregate and cement concrete of porous concrete
containing 5 to 10 mm aggregates compared to porous concrete with an aggregate size of 10
to 20 mm has a greater capacity, the calf strength cardboard rose (Park & Tia, 2004).
When mixing porous concrete mixtures with additives, the compressive strength will
increase from 10% to 15% for porous concrete containing 5 to 10 mm aggregates and 10 to
20 mm for the silica fume mixing ratio of 10%.
When the ratio of mixing with fly ash is 20%, the strength of porous concrete will be
reduced by 5.2% to 10% for aggregates from 5 to 10 mm and by 3 to 12% for all types of
aggregates whether the aggregate size is 10 to 20 mm. Researching the sound absorption of
porous concrete shows that the noise reduction coefficient is optimal when the porous ratio
is about 25%.
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Silica fume
Silica fume was first used in Norway in the 1970s as an additive in concrete. They have
specific gravity of about 2.2 and high bulk density from 200-300kg / m3 (0.2-0.3g / cm3).
The fineness of silica fume can reduce the flow and porosity of concrete.
The properties of silica fume are enhanced when used in conjunction with super
plasticizing additives in concrete mixtures.
When fly ash is used as an additive in Portland cement mixtures, fly ash often has a low

reaction rate. After 28 days, the amount of fly ash reacted by fly ash is just over 10%. And
after 90 days, only about 20% of fly ash reacts.
The reason for the low fly ash activity is because at the temperature in the experiment,
the pH of the solution is 10, while the pH requirement of fly ash is about 13.3.
The reaction of BFS is different from fly ash because slag is more dependent on
temperature. The initial hydration time of fly ash goes through two processes.
The process of nucleation and growth of hydration stages takes place first. These
compounds are then converted into CSH gel. Next is the interaction that occurs between the
phase of the reaction or the reaction that occurs between the old and new compounds
formed after the reaction.
When implementing the design, the important parameter for concrete structure is
compressive strength. Because, the compressive strength can affect the project cost and
promote the design process.
Concrete costs can be reduced through the use of construction materials and some
mineral additives.
It also enhances the properties and strength of mortar or concrete. The increase in
strength can occur late or early depending on different conditions.
The 8% silica fume content by weight when added to concrete mixtures is the optimal
content to create the strength growth of concrete. It is the conversion of surface calcium
hydroxide of particles into silicate calcium hydrates.

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It can be explained that the addition of silica fume as an additive enhances the strength
of the concrete, which may be due to the improvement of the link between the matrix of
hydrated cement particles and aggregate particles.
However, the compressive strength of porous concrete begins to decrease when

increasing the amount of silica fume to the concrete mixture to more than 10%. The cause
of this decrease in strength may be the result of insufficient water in the mixture because the
moisture absorption of the test sample may occur.
At that time, pozzolanic reaction will be limited and thus reduce the strength of concrete.
EI Hadj Kadri and Roger Duval, “Effect of Ultrafine Particle on Heat of Hydration of
Cement Mortar”, ACI Materials Journal, Technical paper, no.99-M11
Silica Fume particles has active participation in the process of hydration of cement in the
early stage. Then, the reduction of free calcium ions will stimulate the dissolution of cement
particles. Pozzolanic reaction will reduce the amount of calcium hydroxide after hydration
of cement in concrete (Kadri and Duval, 2002).
Cement particles are gradually coated with silica fume and hydro silicate gel to form a
barrier that interferes with the contact with the alternating solution and inhibits the
hydration rate.
Super-plasticizer
The mixing, pumping, pouring and placing of the powder is easy or the workability of
the concrete mixture is easier due to the higher Superplastic concentration. The appearance
of Super-plastic increases its adsorption capacity on the particle surface and particle-particle
interaction.
When cement is mixed with the BFS and FA mixture is mixed with water, the first
clinker mineral will react to hydrate and produce calcium hydroxide. Mixing water will be
saturated by calcium hydroxide. And glass phase bonds when BFS and FA react with alkali,
Silicdioxyte Si - O - Si, and Aluminum Dioxides Al - O - Al, etc.
The reaction will degrade the substance to create SiO42-, AlO45-, Ca2 +, etc., digging
into the solution and creating new calcium silicate hydration and calcium aluminate
hydration.
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