Increasing the Reactivity of Silica Fume Particles Using .... Abstract - Nowadays, Nano silica (SN)...

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Increasing the Reactivity of Silica Fume Particles Using Indirect

Sonication: Effect of Process Parameters

M. M. Hashem1, M. I. Serag2, Hala El-Kady3, Muhammad El-Feky4 1Textile Research Division, National Research Center, Giza, Egypt,

2Department of Structural Engineering, Faculty of Engineering, Cairo University, Giza, Egypt. 3Department of Civil Engineering, National Research Center, Giza, Egypt. 4Department of Civil Engineering, National Research Center, Giza, Egypt.

1. Abstract- Nowadays, Nano silica (SN) appears to be one of the most attractive cement additives.

Its incorporation improves the mechanical and physical properties of concrete. The aim of the current

research is to develop a new method for preparation of nano silica fume particles using indirect

sonication. The effects of the process parameters on the particles size have been investigated. These

parameters include sonication power, sonication frequency, homogenizer speed, sonication time, and

liquid/solid ratio. The prepared samples were monitored for particle size distribution, and level of

dispersion using transmission electron microscope (TEM). The effect of the prepared nano silica fume

on the ultimate properties of the concrete mixtures has been determined and compared with the original

silica fume. Results obtained showed that, the proposed technique yield NS particles with average size

of 57 nm and about 91% from the total particles having particle size less than 100 nm. Application of

NS as cement additives (substitution) enhanced the reactivity of the produced nano silica fume, as its

cement substitution by 1% resulted in compressive strength equivalent to that reached with 10% of the

original silica fume substitution.

Keywords-Cement, Indirect sonication, Nano silica, Zeta potential

2. INTRODUCTION

Concrete is by far the most widely used construction material worldwide. Recently, various

efforts were done to improve the environmental impact of concrete to make it suitable as a green

building material. The most successful achievements in this regard are the use of suitable substitutes

for Portland cement. Pozzolanic materials have been used for partial substitution of Portland cement

in concrete in order to achieve economical or technical benefits. Among these materials, silica fume

has found wide spread application in improving the durability and mechanical properties of cement

composites.

Nanotechnology has attracted considerable scientific interest due to the new potential uses of

particles in nanometer scale. Thus, industries may be able to re-engineer many existing products that

function at unprecedented levels. Due to these developments in nano science and technology, various forms

of nano-sized amorphous silica have become available. As these materials have higher specific surface area

compared to silica fume, a considerable research effort has been attracted to investigate the influence of

nano silica on the properties of cement based materials.

The main characteristics of silica, such as particle size distribution, specific density, specific

surface area, and reactivity (surface silanol groups), depend on the production method used [13, 14].

The main types of nanosilica materials, which have been used in cementitious systems by various

researchers include, pyrogenic nanosilicas (fumed nanosilicas), precipitated nanosilicas, nanosilica

gels and nanosilica hydrosols. Undoubtedly, each method produces a material with properties different

from other types of nano silicas. For instance, pyrogenic and precipitated nano silicas and nano silica

gels are generally in the form of relatively large agglomerates of spherical particles, the dispersion of

which in water is a difficult task, while nano silica hydrosols are mono-dispersed particles in water,

International Journal of Modern Trends in Engineering and Research (IJMTER) Volume 02, Issue 07, [July – 2015] ISSN (Online):2349–9745 ; ISSN (Print):2393-8161


with a particle size of 10– 100 nm, which are small enough to remain suspended in a fluid medium

without settling [5].

It is believed that the mono-dispersed silica nano-particles can act as filler sand seeds much

more effectively than those by using powder or dispersion [9]. However, the colloidal silica sol will

gel or coagulate immediately while mixing with cement [12], because the cement particles will hydrate

and show very high ionic strength on the surface once they contact water [13]. As a result, whether by

using nano-silica powder, dispersion, or colloidal sol, it is the behavior of the final agglomerates, rather

than that of the individual nano-particles, which controls the pozzolanic, the filling and the seeding

effects [36].

The dispersion behavior of silica fume and the parameters that influencing its properties were

investigated [4, 14, 21]. However, and to the authors knowledge, no work in the literature depict the

effect of dispersion characteristic of commercial nano silica, on properties of concrete and cement

based materials. As most nano materials are still fairly expensive, several studies should be done to

produce stable well dispersed nano structured silica particles using simple and easy techniques.

Ultrasound is used in a wide range of physical, chemical and biological processes.

Homogenizing, emulsifying, and dispersing are examples for physical processes. Most of the

applications of high-intensity ultrasound are based on cavitational effects. The physical effects of

cavitations are being used in a top-down generation of nano-particles. Here, particles are reduced in

size by the forces of cavitations. This includes the breaking of agglomerates and aggregates [REF].

Ultrasound treatment has been successfully used to break and disperse the silica fume agglomerates

in order to obtain a more reactive material with a particle size distribution lower than 1 µm [24–26]. The

use of this sonicated silica fume (SSF) as a mineral admixture in mortar mixes has a higher effectiveness

on the mechanical strength and permeability compared with mixes made with densified silica fume (DSF)

without any dispersion treatment. Longer sonication times and higher sonication power improved the

reactivity of silica fume and leads to higher consumption of calcium hydroxide by pozzolanic reaction [26,

27].

The aim of the current research is to develop a new method for preparation of nano silica fume

particles using indirect sonication. The effect of the process parameters is to be investigated. These

parameters include sonication power, sonication frequency, homogenizer speed, sonication time, and

liquid/solid ratio. The prepared samples were monitored for particle size distribution, using

transmission electron microscope (TEM). The effect of the prepared nano silica fume on the ultimate

properties of the concrete mixtures will be determined.

3. EXPERIMENTAL

3.1 Materials:

Ordinary Portland Cement (OPC) conforming to ASTM C150 standard was used as received.

Chemical and physical properties of the cement are shown in Table I. Silica fume micro particles with

particle size ranging from 625 nm to 48 nm were used for the proposed study. The properties of SiO2 micro

particles are set up in Table II. Transmission electron micrographs (TEM) and powder X-ray diffraction

(XRD) diagrams of SiO2 particles are shown in Figs. 1 and 2 respectively.

For concrete production; crushed limestone aggregates, as well as sand free of alkali-reactive materials

were used to insure producing durable Concretes; the aggregates were mixed by percentages of 65%

for coarse aggregate, and 35% for fines by volume. A polycarboxylate with a polyethylene condensate

de-foaming agent based admixture (Glenium C315 SCC) was used. Table III shows some of the

physical and chemical properties of polycarboxylate admixture used in this study.

3.2 Equipments:

A modern ultra sonication bath and a rotor-stator homogenizer were used to perform the

proposed study. Sonicator bath is produced by FALC instruments, Italy, and has the properties, and

specifications mentioned in Table IV.



In indirect sonication application, the ultrasonic wave needs first to cross the liquid inside the

ultrasonic device and then to cross the wall of the sample container. Therefore, ultrasonication intensity

inside the sample container is lower than expected, consequently, in order to overcome the mentioned

problem, a mechanical (rotor-stator) homogenizer was used in addition to the modern bath sonicator to

perform the study plan. The homogenizer type is YELLOWLINE DI 25 basic, manufactured by IKA,

and having the specifications in Table V.

3.3 Specimens preparation

Three main parameters are taken into consideration when dealing with sonication; the temperature

control, the reaction container shape, material and solvent properties. Most ultrasonic bath applications are

performed for longer than 30 min and, as consequence of continuous ultra sonication, the bulk liquid warms

up, this problem can be solved by acquiring an ultrasonic bath with heater. However, before performing an

ultrasonic treatment, it is recommended to wait until the working temperature is achieved. The working

temperature in the proposed study was set to 40 C in order to avoid the evaporation of the solution

subjected to sonication.

The shape of the reaction vessel is critical for the correct application of indirect ultrasonication [28,

29]. This is because, as with any other wave, when the ultrasonic wave impinges against any solid surface

some energy is reflected. If the base of the container is flat, such as in a conical flask, the reflected

ultrasound waves is a minimum. Conversely, when the base of the container is spherical the ultrasonic

wave hits the container at an angle, and a huge proportion of the ultrasonic wave is reflected away.

The intensity of ultrasound is attenuated as it progress through a medium. The extent of

attenuation is inversely related to the frequency. Therefore, the wall thickness of the vessel should be

kept to minimum to avoid intense attenuation. According to the above mentioned considerations, a flat

bottom glass beaker was chosen for performing the current study.

100 g of original silica fume was introduced in 600 ml water in a beaker glass, and then stirred

with a glass rod then the beaker was introduced into the sonicator bath, and the homogenizer was

installed above the beaker.

To investigate the effect of process parameters, thirteen samples were chosen for the study and

classified in sets. Each set consists of four samples and directed to investigate one parameter keeping

the other parameters constant as shown in Table VI. These experimental conditions have been chosen

according to the findings of previous studies [30, 26, 27].

The sonication power was set to 70 watts, while the chosen frequency was set to 59 KHz. The

second four samples were chosen to study the effect of the liquid/powder ratio, and all other parameters

were set to the same constant values except the homogenizer that was set to the optimum value from step

one which was 24000 rpm. The third step investigated the influence of the sonication power by comparing

two different values which were 70 watts (50% power), and 135 watts (100% power) while keeping other

parameters at constant. The fourth step was dedicated to determine the influence of sonication frequency

on the proposed process. Finally, the time effect was investigated by changing the process duration from 7

min to 150 min, while keeping other parameters set to constant values.

3.3.1. Legends:

The samples were designated by 5 numbers; the first stands for the homogenizer speed * 10-2, the

second for the liquid to solid ratio, the third for the sonication power, the fourth for the sonication

frequency, and last for the process time.

3.4 Testing, analysis, and characterization:

3.4.1 Transmission Electron Microscope (TEM):

The particle size distribution of the samples were determined by transmission electron

microscope (TEM) type JEM-1230 from JEOL CO, Japan, with energy of 120 KV. Line Resolution

of 0.2nm, and maximum magnification of 600 Kx. Sample preparations for TEM analysis was done

by taking one drop of the prepared solution after being diluted, then put on carbon support film on 3



mm copper grid. Image analysis on the silica particles was carried out on several TEM images. The

processing of the image files was performed using image analysis Software Revolution v 1.60.

3.4.2 Zeta-Sizer

Zeta potential is a property related to the electrical potential around a particle on the slip surface

within a double layer formed in the stationary layer of fluid attached to the dispersed particle [33]. The

liquid layer surrounding the particle is constituted in two sections: the stern layer where the ions are strongly

bounded to the particle and an outer or diffusive layer where they are less strongly attached. Zeta potential

is an indicator of the stability of a colloidal system. If the suspension has a large negative or positive zeta

potential, particles will tend to repel each other and there will be no tendency for the particles to come

together or to agglomerate. However, if the particles have low zeta potential values there will be no force

to prevent the particles coming together. The magnitude of the zeta potential is predictive of the colloidal

stability. Nano particles with zeta potential values greater than +25 mV or less than -25 mV typically have

high degrees of stability. Dispersions with a low zeta potential value will eventually aggregate due to Van

Der Waal inter-particle attractions.

After optimizing the process parameters, a sample based on the suggested optimum conditions

was prepared, and zeta potential was measured by electrophoresis apparatus through Malvern

Instruments Zeta-sizer 2000 as compared to the original silica fume particles, and the data reported

corresponded to an average of three measurements. The sonicated suspension used in zeta potential

test was previously diluted with distilled water and then injected into an electrophoresis cell.

Finally, the most desirable sample was chosen to be used as a cement substitute, and five concrete

mixtures were conducted to compare the effect of the treated silica fume on the compressive strength of

concrete. The first concrete mix CO was made without any cement replacements, the second mix MD1

was conducted using the most desirable prepared silica as a cement substitute of 1%, while the other

mixtures are SF1, SF5, and SF10 were prepared using untreated silica fume as a cement replacement of 1,

5, and 10% respectively, concrete mixtures constituents are shown in table 3.7.

4. RESULTS AND DISCUSSION

Typically, the calculated sizes are expressed as the diameter of a sphere that has the same

projected area as the projected image of the particle. Manual or automatic techniques are used for

particle size analysis. Manual technique is usually based on the use of a marking device moved along

the particle to obtain a linear dimensional measure of the particle added up and divided by the number

of particles to get a mean result [32]. TEM images can also be used to judge whether good dispersion

has been achieved or whether agglomeration is present in the system.

4.1 The effect of homogenizer speed variation on process efficiency:

The mechanical (rotor-stator) homogenizer has in common with ultrasonication, that both

methods generate and use to some degree cavitation, although, in mechanical homogenizing (rotor-

stator) the blade (rotor) is being moved through the liquid at a high rate of speed generating cavitation.

As it can be seen from figures 2, 3, and table 4.1, as the homogenizer speed increases, the

percentage of sub-nano metric particles increased to 61% of the samples particles, compared to only 22%

for the silica fume before treatment. Also, the range of the particles size decreased from 392 nm to 198

nm, and the D50 reached 78 nm on using homogenizer speed at 24000 rpm.

This can be attributed to the function of the homogenizer, large sized silica fume particles were

drawn up into the apparatus by a rapidly rotating rotor (blade) positioned within a static head or tube (stator)

containing slots or holes. The silica fume particles were centrifugally thrown outward in a pump like

fashion to exit through the slots or holes. Because the rotor (blade) turns at a very high rpm, the particles

were rapidly reduced in size by combination of extreme turbulence, cavitation and scissor like mechanical

shearing occurring within the narrow gap between the rotor and the stator. Since rotor-stator homogenizers

have an open configuration, the product is repeatedly recirculated, and reduced again, and again through

the process duration.



4.2. Effect of Liquid/Powder ratio on the particle size:

As it can be concluded from figure 4, 5 and table 4.2, the decrease in the liquid to powder ratio

helped in increasing the sub-nano metric particles to reach 61% at a ratio of 6, but by decreasing the

ratio lower than 6 a decrease in the sub-nano metric percentage was found, this can be attributed to the

fact that at constant volume, higher particle concentrations result in an increased particle collision

frequency. In principle, an increased collision frequency can enhance particle breakage due to an

increase in particle-particle impact events. However, at ratios less than 6 where sufficient local

activation and sintering energies were achieved, increased collision frequencies induced agglomerates

or aggregate formation as particles collide and coalesce; this can also explains the range, and D50

results that increased again by decreasing the liquid/powder ratio lower than 6.

4.3. The effect of sonication power, and frequency

From the results presented in figure 6,7 and table 4.3, we can conclude that the change in

sonication power level from 50% to 100% increased slightly the sub-nano metric particles to reach

65% at 100% power instead of 61% at 50% power, while for the D50, and mean results; a significant

decrease in particle size value was noticed.

As for the effect of changing sonication frequency from 59 KHz to 40 KHz, the results showed

as in figure 4.6, a decrease in the average particle size for the sample subjected to 40 KHz than the 59

KHz by about 10%, in addition to that the range decreased significantly for the same samples, The

physical explanation for this lies in the fact that, by increasing frequency, the cycle of compression

and decompression caused by the ultrasonic waves becomes shorter, and as a result not all of the

liquid molecules can be separated to form voids and, so cavitations effect will be decreased.

4.4. The effect of duration

The total amount of energy (E) delivered to a suspension not only depends on the applied power

(P) but also on the total amount of time (t) that the suspension is subject to the ultrasonic treatment: E

= P x t. Consequently, two suspensions treated at the same power for different times can show

significantly different dispersion states, this was the case with the samples of the proposed

investigation as seen in figure 8, 9 and table 4.4, as the time increased the sub-nanometric particle

content increased to reach an optimum value of 81% at 60 min duration, in addition to that, the increase

in time helped in a significant decrease in D50 value to reach 38 nm, with average particle size of 66

nm for the same sample, while by increasing the duration to reach 150 min, a significant reduction in

sub-nanometric particle percentage has been observed, this behavior might be attributed to a reduction

in electrostatic forces, which promotes the particle agglomeration and reduces dispersion [34].

Finally the optimum of each parameter was chosen, and a new sample (S240/6/135/40/60) was

prepared with the following conditions:

Parameter studied value

Homogenizer speed 24000 rpm,

Liquid/Solid ratio 6

Sonication Power 135 Watt

Sonication Frequency 40 KHz

And Process Time 60 min

The particle size distribution of the optimum conditions is presented in figure 10, as compared to the

untreated silica fume. While figure 11, and table 4.5 represents the increase in subnanometric

percentage to reach 90%, as well as the significant reduction in range to reach 169 instead of 392.



4.5. Zeta potential results

Zeta potential is an indicator of the stability of a colloidal system. If the suspension has a large negative

or positive zeta potential, particles will tend to repel each other and there will be no tendency for the

particles to come together or to agglomerate as shown in figure 12. However, if the particles have low

zeta potential values there will be no force to prevent the particles coming together. The magnitude of

the zeta potential is predictive of the colloidal stability. Nano particles with Zeta Potential values

greater than +25 mV or less than -25 mV typically have high degrees of stability. Dispersions with a

low zeta potential value will eventually aggregate due to Van Der Waal inter-particle attractions.

Results in figure 13, showed that the zeta potential increased significantly as the zeta potential

reached -28 mV, and conductivity of 0.0525 (mS/cm) for the prepared sample (240/6/70/59/15) after

15 min duration, while the optimum sample (240/6/135/40/60) after 60 min duration, the prepared

nano silica fume particles had zeta potential value of -35 mV, and Conductivity of 0.228 (mS/cm), as

compared to the as received silica fume which had a zeta potential value of -23, such result indicates

a high degree of stability in the prepared solution.

4.6. TEM results

Figure 14 shows the TEM images of the original untreated silica fume, while figure 15, 16 are

the micrographs corresponding to the 15 min sonicated silica fume sample, and optimally sonicated

sample respectively.

Agglomerates of more than l0 µm in size with an irregular shape silica fume can be seen in Figure 14.

The energy applied by the sonication breaks the weak bond between individual silica fume particles

as shown in Figure 15, and 16. The mean diameter measured by image analysis of the individual silica

fume sphere particles via TEM was 211nm, while for the optimum sample the mean size reached only

57nm with nano-metric percentage of about 90% of well dispersed mono nano silica fume particles as

it can be seen in figure 16.

4.8 Compressive strength results

Five concrete mixtures were conducted for the compressive strength analysis; The first is mix

MD1 (prepared with the MD nano silica fume) with cement replacement of 1%, while mixes SF1, SF5,

SF10 were prepared with the addition of silica fume as cement replacement of 1, 5, 10 % respectively,

and finally a control mix without any cement replacements added CO.

As it can be seen from figure 17, substitution of 1 % from the cement with nano silica (mix

MD1) enhance the gain in strength in both early (17%), and late strengths (20%) as compared to the

control mix CO, and almost the same compressive strength as mix SF10, this indicates the efficiency

of the proposed treatment in enhancing the reactivity of silica fume by increasing the nano metric

particles to more than 90%, and so the gain in strength can be attributed to the previously mentioned

effect of sonication in de-agglomerating, and dispersing of nano particles where higher number of

surface atoms in the nano particles translates into a larger number of free and unsaturated atomic bonds

on the surface of the nano particles, which makes them thermodynamically unstable and leads to an

increase in the appropriate surface area for chemical reactions [35]. The presence of higher number

of unsaturated atomic bonds of ≡Si- and ≡Si-O- on the surface of the nano particles, leads to higher

reactivity of the silica nano particles with Ca(OH)2 as summarized in the following scheme.

≡Si-O- + H-OH→ ≡Si-OH ……………….Eq. (A.1)

≡Si- +OH→ ≡Si-OH ……………………..Eq. (A.2)

≡Si-OH +Ca(OH)2 → C-S-H≡ [1] ……….Eq. (A.3)

, also nano silica can produce more nucleation sites for the hydration products, and has higher

pozzolanic activity that results in increasing the early strength as well as the late strength. While for

the as received silica fume 1% addition caused a significant loss in both early and late strengths, which



can be attributed to the agglomeration of silica fume particles that could not be broke down by only

being mixed with water, and consequently decreasing its reactivity.

5. CONCLUSIONS

All of the process parameters studied showed a significant influence on the decrease of silica fume

mean particle size except for the liquid/solid ratio. The proposed sonication process helped in increasing

the amount of nano metric particles to reach 90% of the sample for the optimum sample as compared to

only 22% of the original silica fume. The proposed sonication process increased the reactivity of silica

fume not only by decreasing its mean size to reach 57 nm, but also increase its dispersability, which was

confirmed by the TEM micrographs as well as the zeta potential values. Zeta potential values for the

optimum sample reached -35 mv with a significant increase as compared to the original silica fume (-

23mv). The results also depict that, significant increased in compressive strength in cement mix (about

20%) upon addition of 1% nano-silica fume prepared by the aforementioned method. Whereas a

comparable results are obtained addition of original silica fume by 10% .

The most desirable sample of prepared nano silica fume enhanced the concrete compressive strength

significantly, as by only 1% of cement substitution a gain equivalent to 10% of original silica fume was

reached (20% gain) as compared to control mix without any cement replacements.

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LIST OF FIGURES

(a) (b)

Figure 1: (a) TEM micrograph of untreated SiO2 particles, (b) XRD analysis of untreated SiO2 particles.



Figure 2: The effect of homogenizer speed on the particle size distribution.

Figure 3: The effect of homogenizer speed on the increase in nano particles percentage.



Figure 4: The effect of Liquid/Powder ratio on particle size distribution.

Figure 5: The effect of Liquid/Powder ratio on the increase in nano particles' percentage.



Figure 6: The effect of Sonication power on the increase in nano particles' percentage.

Figure 7: the effect of Sonication frequency on the increase in nano particles' percentage.



Figure 8: The effect of process duration time on the cumulative particle size distribution.

Figure 9: The effect of process duration time on the percentage of sub-nano-metric particles.



Figure 10: particle size distribution of optimum sample as compared with silica fume.

Figure 11: the Optimum sample's percentage of sub-nano-metric particles as compared

to original Silica fume particles.



Figure 12: TEM micrograph representing zeta charges around sonicated nano silica fume.

A) as received Silica fume zeta potential result

50 nm



B) (240/6/70/59/15) zeta potential result (15 min sonication)

C) (240/6/135/59/60) Optimum zeta potential result

Figure 13: zeta potential for A) as received silica fume, B) 15 min sonication sample (240/6/70/59/15), C) Optimum

(240/6/135/59/60) 60 min sonication.

Figure 14: TEM micrographs of original silica fume.

Figure 15: TEM micrograph of 15 min Sonicated silica fume.



Figure 16: TEM micrograph of optimally prepared nano silica fume.

Figure 17: Compressive strength results of 1% MD mix (most desirably prepared silica fume)

as compared with mixes of as received silica fume.

List of Tables

Table1: Properties of Portland cement (wt%).

Element SiO2 Al2O3 Fe2O3 CaO MgO SO3 Na2O K2O L.O.I

Cement 20.13 5.32 3.61 61.63 2.39 2.87 0.37 0.13 1.96

Table3.2: Chemical composition of micro SiO2 (wt %).

Element SiO2 Fe2O3 Al2O3 MgO CaO Na2O P2O5

NS 99.17 0.06 0.13 0.11 0.14 0.40 0.01

Table3.3: Physical and chemical characteristics of the polycarboxylate admixture.

Appearance Off white opaque liquid

Specific gravity @ 20°C 1.095 ± 0.02 g/cm3

pH-value 6.5 ± 1

Alkali content (%) ≤ 2.00

Chloride content (%) ≤ 0.10

280 276 295318 328

0

-12.9

7.9 20.5 20.2

-20

0

20

40

60

80

100

0

100

200

300

400

500

COD SF1 SF5 SF10 MD1

7DAYS 28DAYS % 28 Days Gain



Table 3.4: bath sonicator properties and specifications:

Capacity 4.5 litres

Drain with valve No

External dimension 320x170x230

Frequency KHz 40 o 59

Heating °C 20-80

Internal tank dimension 300x150x100

Peak Power 150 W

Absorbed Power 135 W

Power regulation 40-100 %

Timer 1-199 min

Weight 3.4 kg

Table 3.5: Rotor-stator homogenizer properties:

Speed range (rpm) 8000 – 24000

Speed variation on load scale (%) < 1

Power consumption (Watt) 600

Power output (Watt) 350

Frequency (Hz) 50/60

Dimensions (drive) WxHxD (mm) 77x66x221

Dimensions (boom) (mm) Ø13/L160

Weight (Kg) 1.6

Perm. Ambient Temp (oC) 5 – 40

Perm. Humidity (%) 80

Perm. On time (drive unit) (%) 100



Table 3.6: constituents of prepared samples:

Sample Homogenizer

Speed (Rpm) Liquid/Powder

Sonication

Power (watt)

Frequency

(kHz) Time (min) Parameter

000/6/70/59/15 0 6 70 watt 59 15 Homogenizer




240/1.5/70/59/15 24000 1.5 70 watt 59 15 Liquid/Powder

240/2.4/70/59/15 24000 2.4 70 watt 59 15 Liquid/Powder

240/10/70/59/15 24000 10 70 watt 59 15 Liquid/Powder

240/12/70/59/15 24000 12 70 watt 59 15 Liquid/Powder

240/6/135/59/15 24000 6 135 watt 59 15 Sonication power

240/6/135/40/15 24000 6 135 watt 40 15 Frequency

240/6/70/59/07 24000 6 70 watt 59 7 Time

240/6/70/59/60 24000 6 70 watt 59 60 Time

240/6/70/59/150 24000 6 70 watt 59 150 Time



Table 3.7: concrete mixtures composition by weight (kg) per 1 m3.

Mix Cement Aggregate

Water S.P. N.S. Mixing Notes Coarse Fine

Cod 480 1109 597 192 2 0 Control

Md1 475.2 1109 597 192 2 4.8 Prepared Silica Fume

Sf1 475.2 1109 597 192 2 4.8 As Received Silica Fume

Sf5 456 1109 597 192 2 24 As Received Silica Fume

Sf10 432 1109 597 192 2 48 As Received Silica Fume

Table 4.1: the effect of homogenizer speed on major statistical parameters:

Statistical

Factor

Silica

Fume 000/6/70/59/15 095/6/70/59/15 135/6/70/59/15 240/6/70/59/15

Mean 211 121 104 100 93

Range 392 333 255 240 198

D50 178 112 105 85 78

D80 325 197 182 170 155

D20 91 48 47 31 27

Nano

Size % 22 48 46 56 61



Table 4.2: The effect of Liquid/Powder ratio on major statistical parameters:

Statistical Factor Silica

Fume S240/1.5/70/59/15 S240/2.4/70/59/15 S240/6/70/59/15 S240/10/70/59/15 S240/12/70/59/15

MEAN 211 102 96 93 92 93

RANGE 392 262 261 198 260 244

D50 178 120 85 78 79 92

D80 325 182 168 155 165 173

D20 91 66 30 27 28 35

Nano Size % 24 42 57 61 60 54

International Journal of Modern Trends in Engineering and Research (IJMTER) Volume 02, Issue 08, [August– 2015] ISSN (Online):2349–9745 ; ISSN (Print):2393-8161


Table 4.3: the effect of sonication power, and frequency on major statistical parameters:

Statistical Factor Silica Fume 240/6/70/59/15 240/6/135/59/15 240/6/135/40/15

MEAN 211 93 82 75

RANGE 392 198 261 157

D50 178 78 64 70

D80 325 155 155 156

D20 91 27 22 24

Nano Size% 24 61 65 64

Table 4.4: the effect of process duration time on major statistical parameters:

Statistical

Factor

Silica

Fume S240/6/70/59/07 S240/6/70/59/15 S240/6/70/59/60 S240/6/70/59/150

Mean 211 99 93 66 86

Range 392 226 198 200 290

D50 178 98 78 38 119

D80 325 176 155 98 185

D20 91 41 27 17 64

Nano Size % 24 51 61 81 42

Table 4.5: the effect of process duration time on major statistical parameters:

Statistical Factor Silica Fume S240/6/135/40/60

MEAN 211 57

RANGE 392 169

D50 178 38

D80 325 80

D20 91 17

Nano Size % 24 90

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