Nanotechnology in Construction Materials

This assignment delves into the application of nanotechnology in enhancing the properties and sustainability of construction materials, particularly concrete. It examines various aspects such as improved strength, durability, and energy efficiency through the incorporation of nanoparticles. The analysis also covers the environmental impact and future prospects of nanotechnology in the construction industry.

NANO SILICA INCLUSION INTO CONCRETE
Student’s Name
Class
Tutor’s Name

Nano silica
Contents
Introduction.................................................................................................................................................3
Methodology in experimentation and materials.........................................................................................4
Materials.................................................................................................................................................4
Experimenting methods..........................................................................................................................5
Reinforcement.........................................................................................................................................7
Resistivity to chloride penetration.........................................................................................................13
Electrical resistance...............................................................................................................................15
Improvements on mechanical properties..............................................................................................19
Porosity observation..........................................................................................................................19
Thermal analysis................................................................................................................................21
Morphological observation................................................................................................................22
General Observation of inclusion of nano silica.....................................................................................23
Dispersing nano silica into cement............................................................................................................24
Physical dispersion method...................................................................................................................24
Chemical dispersion method.................................................................................................................26
The best method...................................................................................................................................28
Improvements of the best method are mentioned...............................................................................28
Determination of optimum amount of nano silica required......................................................................28
Setting time experiment........................................................................................................................28
Fluidity experiment................................................................................................................................29
Nano silica Environmental and human impacts.........................................................................................29
Cost...........................................................................................................................................................30
Conclusion.................................................................................................................................................31
References.................................................................................................................................................33
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Nano silica
Nano silica affecting mechanical properties of concrete
Introduction
Lately, cement has been modified by the use of nanoparticles. The concrete being used as a
major cement composite has its major binder portion replaced by nanoparticles that include TiO2,
Fe2O, Al2O3 SiO2. In these nanoparticles, Nano silica comes out as the most researched on with
the chemical composition of C-S-H. Another reason for the popularity of Nano silica was due to
the improvement of the properties of composites of cement, Samali et al., (2012, p. 40). Both
Nano silica and the silica fume are very reactive pozzolan that can consume existing calcium
hydroxide and form a secondary C-S-H. However, a group of researchers explained that adding
Nano silica affected the existing silicate polymerization and not the formed amount of C-S-H.
The same Nano silica composition can also affect compound of concrete by the seeding effect.
An accelerated hydration in the early stages is due to the present greater number of precipitation
of the hydration products (Samali, et al., 2012). The microscopic properties of cement have been
influenced by Nano silica and studied to produce controversial data. For example, the
compressive strength of cement was affected differently with certain amounts of Nano silica
content in it, Barre, et al. (2016, p. 32). Superplasticizer addition timing affected the Nano silica
use in concrete properties. Other than compressive strength, durability is one more property
important in concrete construction in reinforced concrete. Studies relating to the durability of
concrete have been conducted in that investigation was made on the resistance to penetration by
chloride, water sorptivity, carbonation resistance and electrical resistivity, Tokyay (2016, p. 60).
It was discovered that the absorption property of water in concrete decreased with the increase of
Nano silica content. Another study led to the discovery that the water sorptivity did not get
affected by the inclusion of the nanoparticles. In a compressive analysis of strength, when Nano
silica was added to mortars there were varying results from different ratios of water-cement.
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Nano silica
Researching on chloride diffusion led to the discovery that it reduced with the addition of Nano
silica. In carbonation, some researchers produced no change in resistance to carbonation while
others produced a reduced chloride diffusion coefficient, Andrade et al., (2014, p. 48).
Methodology in experimentation and materials
Materials
Nano silica material. The concrete cast was in CEM I 42.5R (Barre, et al., 2016); limestone
aggregate was crushed and divided into various classes i.e. calc1 to calc4 and sand in
maximum 12.5 mm sizes. This combination fitted the Fuller’s Grade curve. The Saturated
Surface Dried density, the percentage of absorption and combination of the five aggregate
classes was the summarized below:
Table
Table 1 (Ashton, 2012)
The commercial Nano silica suspension of a concentration of around 10% by water’s weight in
the nominal mean size of particles of 20nm got used (beton & du, 2013). Dynamic Light
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Nano silica
Scattering technique showed the suspended dispersed Nano silica content in the water, Schutter
(2012, p. 20).
Experimenting methods
Compressive strength – this test was done in accordance to the EN-12390-3 on the moisture
cubes that were cured in curing chambers for about 7 to 28 days.
Water absorption and sorptivity – the capillary absorption of water was taken as the mass of
absorbed liquid per surface unit in cylindrical samples for a duration of t. these samples got over-
dried for a week in 40 degree Celsius so as to get the dry mass and later there surfaces were
exposed to demineralized water. The water sorptivity could then be calculated using the 24h
values, Grantham et al., (2011, p. 52);
Equation
i=S √ t Ultra-High Performance Concrete and Nanotechnology in Construction Schmidt, et al.,
(2012, p. 82)
These samples got dipped in demineralized water to get the overall water absorption Win
percentage as subtracting dry mass and saturated water with respect to the dry mass.
Resistance to chloride penetration – this test was d CEN/TS 12390-11. Samples were put in
vacuum containers of absolute pressure about 1-5 kPa for a duration of 3h. The container got
filled with a volume of demineralized water for an hour as the pump continued running then put
in a lab for about 2 to 4h for their surfaces to become dry (Grantham, et al., 2011). All these
surfaces got covered in epoxy resin except one and dipped in concentrated calcium hydroxide for
about 18h then dipped in a solution of sodium chloride of 3% mass concentration for 90 days. In
the end, these samples were crushed and the powder obtained from different levels for analysis
of sodium chloride acid in accordance with EN 14629. The percentage content of each sample
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Nano silica
was extracted, the diffusion coefficient of chloride Dapp and the surface content of chloride Cs
obtained by use of interpolation of the profile of chloride in accordance with EN 14629, beton &
du (2013, p. 70).
Electrical resistivity – this test was performed by measuring conductance across the cylindrical
samples. The surface of the mould was not ground in this test. After coring the specimen were
dipped in demineralized water immediately then maintained at 20-25 degree Celsius (Schutter,
2012). The conductance was them measured periodically for about 4 months and recorded. This
conductance was changed to electrical resistivity taking use of the geometry of the specimens.
Equation
ρ= A
lG CITATION All 16 ¿1033 (Allen∧Mayes, 2016)
With the respective meanings of A and l being the surface area and sample heights.
Resistance to carbonation – the cylindrical samples were conditioned in a lab for a duration of 14
days at 18 – 25 degree Celsius and a relative humidity of 50 – 65% the sides of the sample
surfaces covered in epoxy resin. Later, the samples were put in the accelerated chamber for
carbonation at 4% carbon dioxide concentration, about 50% relative humidity and 20 degree
Celsius. The carbonation depth was measured after the 45 and 135 days by a phenolphthalein
indicator. Each sample’s surface produced averagely 10 points of carbonation depth. This
information was interpolated with (Schmidt, et al., 2012)
Equation
x=K √ tUltra-High Performance Concrete and Nanotechnology in Construction Schmidt, et al.,
(2012, p. 82)
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Nano silica
x being the carbonation depth and t being the duration in years and the coefficient of carbon
determined.
Microstructural characterization – the calcium hydroxide content in the samples of concrete were
gotten by using X-ray diffraction, thermal analysis by differential and the analysis by the thermal
gravimetric method. The patterns of diffracted X-ray were in a range of 15 – 60 degrees with
copper radiation rube and λ = 1.5418 A with a 0.02-degree step size and 0.2deg/s scan rate.
These experiments were done with the use of isothermal analyzer o the ground concrete
aggregates with an approximate 100 mg (Shivani, 2014). Also, the experiments were done under
a flow of nitrogen, 50 mL/min. The temperature was made to rise from 25 to 900 degree Celsius
at a rate of 10 degree Celsius per min and got held constant at 105 degree Celsius for around
hours so as to evaporate water. The calcium hydroxide amount was estimated as below;
Equation
CH ( % )=WLCH (%) × MW CH
MW H CITATION And14 \l 1033 (Andrade, et al., 2014)
In that CH means the percentage of calcium hydroxide, WLCH being the percentage weight loss
due to CH decomposition and MWH and MW H is molecular weights of water and calcium
hydroxide respectively (Malhotra, 2011).
The analysis of porosity was done using the Mercury Intrusion Porosimetry and the morphology
noted using the Environmental Scanning Electron Microscope in the fragments of concrete
obtained from the broken specimens during compressive strength experiment. The specimens
from these tests were chosen in accordance to the best performing Nano silica incorporated
concrete compressive strength (Sheng & Wang, 2014).
Discussion
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Nano silica
Reinforcement
Slump values of freshly made concrete were listed as in the table 1 that was shown
previously. An inclusion of 105% of Nano silica notably reduced the slump from a value of
175 to another of 240 mm taking the reference concrete slump as w/b 0.65 and another 0.55
to the respective values 30 and 40 mm. The slump reduction in Nano silica incorporated
concrete may introduce more air being trapped in it. Values of a slump with w/b being 0.5
did not reduce if compared to reference with the inclusion of the silica content. The graph
below shows the compressive strength of cured concrete in relation to Nano silica
composition (Polshettiwar & Asefa, 2013);
Graphs
a) (Siddique. & Khan, 2011)
(Siddique. & Khan, 2011)
b) (Siddique. & Khan, 2011)
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Nano silica
(Siddique. & Khan, 2011)
c) (Siddique. & Khan, 2011)
(Siddique. & Khan, 2011)
The graphs were made from concrete with w/b ratios a, b and c as 0.65, 0.55 and 0.5
respectively. After the 7 days, the strength in the concrete’s compression improved in
accordance with the 30.3 reference value to 39.5 MPa in the 1.5% Nano silica inclusion
(Tokyay, 2016). The w/b of 0.55 form the 28 days improved from 49.1 MPa to about 53.8
MPa when added 1% of Nano silica. There was no change noted from the 28 days
observation in the w/b 0.5 concrete whereas the 7-day strength increased from 17.7 to around
51.5 MPa at 1.5% Nano silica (Ashton, 2012).
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Nano silica
Another graph comparing the use of Nano silica to influence the compressive strength is
shown below. This experiment indicated an average increase in compressive strength from
ranging to 10% in three days, 14.93% in seven days and 19% in 28 days after the inclusion of
Nano silica (Gopalakrishnan, et al., 2011).
Graph
(Ashton, 2012)
An illustration of the further analysis of the compressive strength of the influence of Nano
silica is presented in the graph that follows in that 1% of powdered Nano silica is increased
by 19 to 17% from 1 to 3 days respectively. The inclusion of 1% of colloidal Nano silica led
to an increase of 15% when compared to mixed cement mortar. A 1% strength gain in
powdered Nano silica is 26% in 28 days greater than the control. Arguably, there is an
increase in compressive strength (Ashton, 2012);
Graph
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Nano silica
(Ashton, 2012)
More brief tests were also done to investigate this type of strength and some findings were
visible in graphical features as below. The test was a 45-minute test and had features that
were consistent with the findings as before (Ashton, 2012);
Graph
(Ashton, 2012)
1.1.1 Water sorptivity.
The capillary in water sorptivity comes from the tendency of water to get absorbed into
concrete via capillary suction. An example of a typical curve of water absorption per unit
surface, represented as I, as a square root function of time with 1.5% Nano silica addition
into concrete and w/b = 0.65 is shown below;
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Nano silica
Graph
(Kelsall, et al., 2005)
This graph shows a little variation of water absorption per unit surface for a replicate of two
in each type of concrete. Water absorption after 24h was noted to be 1.91 and 2.02 Kg/M2 in
the control and a percentage of 1.5% of Nano silica. Calculations of coefficient of water
sorptivity with the changes in relation to Nano silica content are shown below (Kelsall, et al.,
2005);
Graph
(Kelsall, et al., 2005)
An addition of 0.5% of Nano silica slightly reduced water sorptivity from 0.4 Kg/M3 that s
the reference value to 0.3 Kg/m2h0.5. Using w/b = 0.55 there was a decrease the range
between 0.34 and 0.2Kg/m2h0.5 after including Nano silica (Bergna & Roberts, 2005).
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Nano silica
The average values of concrete in relation to Nano silica content produced the graph below;
Graph
(Bergna & Roberts, 2005)
Using w/b = 0.65 and adding 0.5% Nano silica slightly reduces water absorption from 3.9%
that is the reference value to 3.6%. When w/b = 0.55 is used, water absorption decreased
from 3.8% that is the reference value to 2.3% with the use of 1% Nano silica composition.
Using w/b = 0.5 produced a small variation between 2.7% and another 3.1% with inclusion
of silica particles (Shi, 2008).
Resistivity to chloride penetration.
This experiment was done to take note of the concrete’s resistivity to being penetrated by
chloride ion in the non-stationary process of diffusion. An example of chloride content in w/b
= 0.6 with a Nano silica percentage of 1.5% is compared with the reference as indicated in
the graph below;
Graph
a) (Hu, et al., 2014)
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Nano silica
(Hu, et al., 2014)
The chloride profile interpolation gave rise to the apparent coefficient of chloride diffusion,
Dapp, and the content f surface chloride, Cs, in every concrete was calculated and presented as
below (Hu, et al., 2014);
Graphs
b) (Hu, et al., 2014)
(Hu, et al., 2014)
c) (Hu, et al., 2014)
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Nano silica
(Hu, et al., 2014)
Using w/b = 0.65, the coefficient for diffusion was reduced slightly from 19.1 m2/s that is the
reference value to 15.2 × 10-2 in a 0.5% Nano silica. For 1% Nano silica, the value grew to 32
× 10-2 m2/s and later had a decrease to a value of 18.9 × 10-2 m2/s for a1.5% Nano silica. When
w/b was 0.55, the Dapp got reduced from the control value reading 18.1 × 10-12 m2/s to 10.4 ×
10-12 in a value of 0.5% Nano silica almost reaching the reference value with more addition
of Nano silica content (Harries & Sharma, 2016).
Concrete durability was also assessed in other experiments to monitor the cement mortar in
powdered Nano silica. The powdered Nano silica decreased the concentration of chloride ion
to value of 43% when compared to the usual cement mortar. Thereby, the graph below was
produced from this experiment (Bergna & Chemistry, 1994);
Graph
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Nano silica
(Bergna & Chemistry, 1994)
Electrical resistance.
Electrical resistivity is important in observing and inspecting reinforced concrete in
accordance to corrosion reinforcement. This measures the permeability of ion in the saturated
condition of the concrete. Concrete that is dense leads to reduced permeability thereby
resulting to high electrical resistivity. Taking 28 days to dip concrete in water after curing it
leads to hydration of the concrete and decreased pore connectivity and porosity (Harland &
Prud'homme, 1992). These changes increased the electrical resistivity with time. At w/b 0.65
for reference and Nano silica percentage 1.5% an example of two types of concrete are
shown below;
Graph
(Harland & Prud'homme, 1992)
The immersion day is set as zero time. There was an abrupt drop in the electrical resistivity
since they were saturated in water. The resistivity in the drop is pointed out as ρi. Resistivity
improves to the 85th-day value pointed out as ρ85. The variations of the two parameters in
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Nano silica
accordance with Nano silica content in accordance to all concrete is shown below (Popovics,
1998);
Graph
(Harland & Prud'homme, 1992)
When 0.5% of Nano silica was added, the ρi increased from 57 Ωm to a vale 67 Ωm. taking a
comparison of resistivity of 0.5 w/b concrete to the 0.65 and 0.555 gave a different
observation. The highest reading was 87 Ωm in the 1.5 Nano silica of w/b 0.5 and those of
0.55 and 0.65 did not differ from the reference.
In the gradual increase of powdered Nano silica, there was a significant increase of gel/space
ration since the particles were centers of nucleation and accelerated hydration. Such
accelerated nucleation reduced the graph below from another experiment (Hong, et al.,
2016);
Graph
(Hong, et al., 2016)
1.1.2 Resistance to carbonation.
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Nano silica
Below is a carbonation depth against duration of exposure after w/b = 0.65 with a 1.5% Nano
silica troweled surface is put in comparison with the reference;
Graph
(Hong, et al., 2016)
The depth of carbonation increased from a value of 14.1 mm reference 17.5 mm for Nano
silica percentage 1.5% after a duration of 135 exposure days (Khaya & Schutter, 2014). The
carbonation coefficient is depicted below in accordance with Nano silica composition for
mould and troweled surfaces
Graphs
a) Troweled surface (Khaya & Schutter, 2014)
(Khaya & Schutter, 2014)
b) Mould surface (Khaya & Schutter, 2014)
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Nano silica
(Khaya & Schutter, 2014)
Carbon coefficient, K, increased in content w/b 0.65 in the troweled surface from 24 to 29.3 mm/
√ year with 1% Nano silica content. K reduced from 20.8 to 16 mm/√ year in 1% Nano silica
content but did not vary in 0.5 w/b. a comparison of K values between the troweled and mould
surface showed that troweled surface produced higher values since they were influenced by
bleeding (Junior., et al., 2017).
Experiments that were performed on different w/b ratios that were categorized into various
mixes produced information that was consistent as noted above and the resulting graphical
analysis is presented as below;
Graph
(Junior., et al., 2017)
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Nano silica
Improvements on mechanical properties.
Porosity observation.
The figures a, b and c indicate pore distribution differential (dV/d log D) that relates pore
volume, V, and its pore size, D. the higher the differential pore distribution the greater the
pore volume fraction that relates to pore size in accordance with porosity volume. The
volume of cumulative intrusion (mL/g) is shown as below (Matsagar, 2014);
Graphs
a) (Matsagar, 2014)
(Matsagar, 2014)
b) (Matsagar, 2014)
(Matsagar, 2014)
c) (Matsagar, 2014)
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Nano silica
(Matsagar, 2014)
The gel pore is not contributive to permeability and strength. The overall intrusion volume,
the pore size of the median and overall porosity were not influenced in the 1.5% addition of
Nano silica when compared to the reference. In the 1.5% Nano silica composition, the
porosity of gel increased when compared to the reference. The table below shows the
reduced macro and micro-porosity with a comparison to control;
Table
(Harper-Leatherman & Solbrig, 2016)
This table indicates that overall porosity averagely reduced with respect to the reference and
such decrease was less than w/b of 0.55. Raising the gel porosity to .5% Nano silica and
comparing it to the two different w/b ratios did not make a great change (Harper-
Leatherman & Solbrig, 2016).
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Nano silica
Thermal analysis.
The figure below shows a TGA/DTA graphs. They relate to the concrete of 0.65 w/b ratio
with 1.5% Nano silica content that was compared to control. The weight loss of calcium
hydroxide and calcium carbonate and dolomite weight losses are indicated by the DTA
peaks (Siddique. & Khan, 2011);
Graph
(Siddique. & Khan, 2011)
Calculated contents of calcium hydroxide is produced in the table below too
Table
(Siddique.
& Khan, 2011)
There was a sharp decrease of calcium hydroxide content in the 0.5 w/b from 5.06% to a
value 2.71% in weight. A contrasting calcium hydroxide composition for other types of
concrete did not produce changes after addition of Nano silica.
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Nano silica
Morphological observation.
An example of a concrete’s micrograph, for reference in a 1.5% Nano silica and 0.65 w/b is
produced below;
Fig
(Popovics, 1998)
There are huge calcium hydroxide plates together with ettringite needles that are very visible
in the figure shown above being indicated by hollow and solid arrows. This is different to
the non-existing unreacted Nano silica agglomeration after a duration of 28 days as shown
below (Popovics, 1998);
Fig
(Popovics, 1998)
Hence Nano silica had fully reacted producing a granular surface when compared to plain
concrete. Also, it had more morphological uniformity with reduced visible macropores.
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Nano silica
General Observation of inclusion of nano silica.
There are some observations that have been drawn from the investigation of Nano silica
effects on the durability and compressive strength properties such as the effectiveness of
particular including silica amount on concrete’s strength. The concrete of high strength
differed from ones of low strength. An inclusion of 1.5% Anno silica into concrete w/b ratios
of 0.65, 0.55 and 0.5 made gain in strength of 41%, 6.5% and none respectively.
A high variation in the durability of the various w/b ratios came from increasing the Nano
silica composition. Certain compositions did not produce changes. Also, the variation
tendency in accordance with the w/b ratios did not get preserved with silica addition
(Han., et al., 2014).
Water absorption and sorptivity were negligible after the inclusion of Nano silica in the
0.65 and 0.5 w/b ratios. However, they reduced with the inclusion of Nano silica
composition in the 0.5 w/b ratio with an optimum of 1%.
The diffusion coefficient of chloride in concrete reduced in the 0.5% Nano silica
composition for ratios 0.65 and 0.55 but did not reduce with higher percentage addition
of Nano silica. A small reduction occurred in the 1.5% Nano silica composition in the 0.5
w/b ratio.
The electrical resistivity of the saturated sample increased after inclusion of 0.5% Nano
silica for all the ratios of w/b.
The inclusion of Nano silica was negative to the coefficient of carbonation in that in 0.65
w/b it increased from 24mm /√ year to 29.3mm/ √ year using 1% Nano silica. W/b of
0.55 reduced its coefficient from 20.4 to value 16mm/ √ year using the same composition
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Nano silica
of Nano silica content. Also calcium hydroxide only decreased in w/b ratio of 0.5 (Provis
& Deventer, 2013).
Using Nano silica improved the microstructure porosity in the ratio w/b 0.55 and 1%
Nano silica inclusion if compared to the reference. However, there was a limited
improvement in macroporosity when using 1.5% Nano silica inclusion in w/b of 0.5. The
gel porosity of 0.65 w/b increased with 1.5% Nano silica inclusion.
Dispersing nano silica into cement.
Physical dispersion method.
This type of dispersion is inclusively about ultrasonic and mechanical dispersion. In
mechanical dispersion, there is a full dispersion of Nano silica in a medium with
assistance from mechanical energy. Mechanical energy includes shear force and impact
force. Majorly the method involves, general ball milling, grinding and many others.
Ultrasonic waves used are featured by a short length in a wave, easy focus, and
propagation in a straight line.
Mechanical dispersion majorly comprises of direct mixing, ultrasonic dispersion, and
mechanical pre-mixing. Indirect mixing, the Nano silica, and cement are set at a specific
speed and stirred for 5 min with the use of cement mortar mixer. In mechanical pre-
mixing, a mixture is mixed for 5 minutes with the use of a mixer. Some small steel balls
are added into the mixer so as to increase the impact force that yields greater mechanical
force. This evenly disperses the Nano silica. In ultrasonic dispersion, the contents are
mixed for 5 minutes with the use of ultrasonic cleaners (Hellmich, et al., 2015).
Mechanical dispersion manages to disperse 3% of Nano silica together with 97% cement
after the mixing. In ultrasonic dispersion, Nano silica is mixed with 80% of water
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Nano silica
beforehand then mixing takes only 5 minutes which when exceeded would lead to
heating up. Proportions of mixing in physical dispersion is as follows;
Table
(Hellmich, et al., 2015)
There are different compressive strengths that arise from the proportion in physical
mixing as shown below;
Graph
(Hellmich, et al., 2015)
Chemical dispersion method.
The physical dispersion method solves Nano silica dispersion in water or other media but
once it has been stopped, the Nano silica comes together due to the existence of Van
Edward forces. The chemical method, therefore, comes in to be absorbed on Nano silica
particles and change their property surface. This, in turn, changes interaction that existed
between the Nano silica particles or between the Nano silica and the media they are in.
the Particles then possess strong repulsion between them. There will be durable slurry
flocculation inhibition (Barros, et al., 2017).
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Nano silica
Several chemicals are used as dispersing agents. They include polymers, surfactants, and
other low molecular inorganic electrolytes. The commonly used methods are the
surfactants and polymers. Surfactants use water reducer in the cement. The water agent
used as a reducer is in polycarboxylic series of water PSW-1, naphthalene powdered
water series reducer, and powdered polycarboxylic water series reducer. Adjusting the
amount of Nano silica content is important since there are various reducing agents used.
Nano Silica is replaced for 2% wt. of cement, reducing agent of water used is 0.6%, and
the ratio of water-binder was 0.5 and the cement to the sand ratio of 1:3. The table below
indicates the proportion of mixing the chemical dispersion method.
Table
(Barros, et al., 2017)
Polymers used can be divided into non-ionic and ionic groups. Non-ionic stabilizes the
slurry through space position. A polyethylene glycol molecular weight of 2000 and 400 is
used in this method. An addition of Nano silica, water, and polyethylene glycol with an
ultrasonic dispersion for about 5 minutes is done to cement. Nano silica replaced 3% wt
of cement, a water-binder of ratio 0.5 and the cement-sand ratio of 1:3. The proportion of
mixing is shown in the table below (Allen & Mayes, 2016)
Table
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Nano silica
(Barros, et al., 2017)
Performing the chemical method of dispersion produces various graphs when the two
methods were chosen are used. For the surfactant, the graph below is observed;
Graph
(Barros, et al., 2017)
Graph;
(Barros, et al., 2017)
The best method.
Taking note of the physical methods of dispersion leads to the conclusion that ultrasonic
dispersion is the better method due to the low compressive strength and the percentage of
9.11%. If the chemical method of dispersion is used, then an addition of naphthalene
water reducing agent proves best. This is due to the increased percentage of compressive
strength by 6.68% on the 28-day analysis.
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Nano silica
Improvements of the best method are mentioned.
Both methods, chemical and physical methods having best ways in each need to improve
on the efficiency of dispersion. With the improvement of dispersion, comes the
development of optimization of durability, microstructure uniformity and mechanical
improvement in an ultimate and extensive construction of application-specific building
materials.
Determination of optimum amount of nano silica
required.
Setting time experiment.
Setting of mortar has provided some variation in the setting time as shown in the table
below;
Fig;
(Andrade, et al., 2014)
The setting time was proven to be reduced to values of 19 to 16 minutes in concrete with
Nano silica content when compared to concrete without. Final and initial setting times
were notably decreased by 47 and 51 minutes respectively.
Fluidity experiment.
The addition of Nano silica to cement mortar showed a reduction in the fluidity. Taking
Nano silica content of 0.5% wt., there was a sharp fluidity of mortar decrease. If a 4.0 %
29

Nano silica
wt. of Nano silica was used then the fluidity got decreased to 8.0% (Andrade, et al., 2014).
The Nano silica mixing procedure was done in a beaker. Hence, the feature present in this
study focuses on the difficulty on the dispersion of Nano silica in the process of stirring.
Smaller sized particles meant larger surface area and poor uniformity in the dispersion.
The difficulty in the dispersion of Nano silica meant that they were existing in forms of
agglomerates. Latter stages of adding Nano silica influenced a reduction of slurry water
that resisted flocculation. Significantly decreasing the fluidity (Andrade, et al., 2014).
Nano silica Environmental and human impacts.
There are fewer studies done on the effect of Nano silica on their effect on the
environment. Nano silica has proved difficult to remove from water during its cleansing.
This is so because uncoated Nano silica sieves through during wastewater treatment.
However, elements of coated Nano silica can be seen in such sieves. Some studies have
proved hat Nano silica can be used in negative control in studies of toxicity due to the
less effect to microorganisms. There is a contradicting study indicating that Nano silica is
more toxic than they seem even in small quantities. Diversity of Nano silica effects on the
environment is difficult to put down. However, most information exist in the concerns
relating to aquatic environment where living organism living in it are exposed to its
effects. Silica particles leak into oceans, lakes and seas getting into the edible organism
that when consumed them lead transfer silica into the human and animal bodies. This ahs
been proven by use analytic tools that validate models explaining the transfer of silica
into aquatic environment and to humans.
It is proven that amorphous silica is safer than Nano silica. There is a chronic
inflammatory response that is observable after inhalation of Nano silica. This is in
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Nano silica
contrast to only high doses of amorphous silica. Amorphous silica can, however, be
contaminated by Nano silica during its production. There are well-documentation of
pneumoconiosis that affects earth-workers. The limit in documented data does not
exclude the risks existing that may lead to chronic obstruction of the bronchitis. Also,
COPD and emphysema are some of the health diseases that may occur. If amorphous
silica in inhaled, there are possibilities of experiencing pulmonary inflammation response
that can be a long-term effect. That is not the end of diseases brought by silica as fibrotic
lung disease might develop and progress due to lung reaction to silica particles.
Cost
The use of Nano silica in concrete is influential in the mechanical properties of the construction of
durable concrete. With the development of better concrete properties comes the increased cost in the
production of these building material. Take for example the inclusion of Nano silica. Addition of
constituents of building material means added purchasing price in construction. Hence the control
components of concrete turn out to be cheaper than concrete made of Nano silica. Also in the
dispersion of Nano silica, more manpower is required both in skilled and semiskilled qualities for
sufficient dispersion of Nano silica in concrete mix. An added measure also needs to be determined in
that research for the required proportions are to be made to develop the desired mechanical properties
of concrete mix. There is no set standard for mixing Nano silica proportions. All these included activities
lead to included expenses unlike the expense incurred in purchasing the control mix of concrete.
Overall, the inclusion of Nano silica has proven to be more expensive in the initial cost when compared
to the control concrete mix. However, the durability of the developed Nano silica concrete mix makes it
far more cheaper in long run since control concrete mix have an added expense in maintenance.
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Conclusion
There are existing gasp in the study of Nano silica particles in that data to be sued is far much
less to use for proper technological development. Specific data on the various Nano particles are
missing if not adequate together with the information pertaining the use of such data of the
products in discussion. More to the gaps present is the need to increase the understanding of
science on Nano particles and their toxicological effects that would facilitate a step towards
generalization and any abstraction. Discovery is not the end of the road in Nano particles
technology but further monitoring and assessment of emerging developments is the step forward.
The use of Nano silica technology has made a potential breakthrough in the materials
technology. Nano silica has been used in mortar, paste, and concrete to enhance individual
material properties. An observation on the optimum amount of Nano silica that should be utilized
is contradictory since the researcher is the one to choose the best. This distinct feature is
important as it will enable construction of specific use and construction of building materials.
The latest development in Nanotechnology and concrete modification have been invented but
there need to be solutions to the exiting challenges before the best use of such technology is
utilized vastly. Challenges in cement material compatibility and best dispersion methods need to
be stated. In conclusion, the property improvement of Nano silica is notable in water sorptivity
of concrete with the Nanoparticle increasing the amount of water is absorbed. Also, the
compressive strengths of concrete increases with the inclusion of Nano silica. Improvement is
the general notification on the inclusion of Nano silica in the concrete mix. It is however prudent
that more research needs to be done on the mechanical and permeability features of concrete and
not just on cement mortar and paste.
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References
Allen & Mayes, 2016. Dynamics of Coupled Structures, Volume 4: Proceedings of the 34th IMAC, A
Conference and Exposition on Structural Dynamics 2016. illustrated ed. Darwin: Springer.
Andrade, Gulikers & Polder, 2014. Durability of Reinforced Concrete from Composition to Protection:
Selected Papers of the 6th International RILEM PhD Workshop held in Delft, The Netherlands. illustrated
ed. Darwin: Springer.
Ashton, 2012. Issues in Engineering Research and Application: 2011 Edition. 1 ed. Port Macquarie:
ScholarlyEditions.
Ashton, 2012. Issues in Materials and Manufacturing Research: 2011 Edition. 1 ed. Sydney:
ScholarlyEditions.
Ashton, 2012. Issues in Mechanical Engineering: 2011 Edition. 1 ed. Darwin: ScholarlyEditions.
Barre, Bisch, Chauvel & Coste, 2016. Control of Cracking in Reinforced Concrete Structures. illustrated ed.
Geelong: John Wiley & Sons.
Barros, Ferrara & Martinelli, 2017. Recent Advances on Green Concrete for Structural Purposes: The
contribution of the EU-FP7 Project EnCoRe. 1 ed. Shepparton–Mooroopna: Springer.
Bergna & Chemistry, A. C. S. D. o. C. a. S., 1994. The Colloid Chemistry of Silica. [Online]
Available at: http://pubs.acs.org/doi/abs/10.1021/ba-1994-0234.ch001
[Accessed 5 Otcober 2016].
Bergna & Roberts, 2005. Colloidal Silica: Fundamentals and Applications. Illustrated ed. Sydney: CRC
Press.
beton & du, f. -. f. i., 2013. fib Model Code for Concrete Structures 2010. 1 ed. Darwin: John Wiley &
Sons.
Gopalakrishnan, Birgisson, Taylor & Attoh-Okine, 2011. Nanotechnology in Civil Infrastructure: A
Paradigm Shift. illustrated ed. Sydney: Springer Science & Business Media.
Grantham, Mechtcherine & Schneck, 2011. Concrete Solutions 2011. illustrated ed. Wollongong: CRC
Press.
Han., Yu & Ou, 2014. Self-Sensing Concrete in Smart Structures. 1 ed. Sydney: Elsevier Science.
Harland & Prud'homme, 1992. Polyelectrolyte gels: properties, preparation, and applications. [Online]
Available at:
https://www.researchgate.net/publication/236404306_Polyelectrolyte_Gels_Properties_Preparation_a
nd_Applications
[Accessed 5 October 2016].
Harper-Leatherman & Solbrig, 2016. The Science and Function of Nanomaterials: From Synthesis to
Application. [Online]
34

Nano silica
Available at: http://pubs.acs.org/isbn/9780841230163
[Accessed 5 October 2016].
Harries & Sharma, 2016. Nonconventional and Vernacular Construction Materials: Characterisation,
Properties and Applications. 1 ed. Tamworth: Elsevier Science.
Hellmich, Pichle & Kollegger, 2015. CONCREEP 10: Mechanics and Physics of Creep, Shrinkage, and
Durability of Concrete and Concrete Structures : Proceedings of the 10th International Conference on
Creep, Shrinkage, and Durability of Concrete and Concrete Structures, September 21-23, 2015 Vi. 1 ed.
Darwin: Engineering Mechanics Institute.
Hong, Seo & Moon, 2016. Advanced Materials, Mechanical and Structural Engineering. [Online]
Available at: http://www.crcnetbase.com/isbn/978-1-138-02908-8
[Accessed 5 October 2016].
Hu, Burghaus & Qiao, 2014. Nanotechnology for Sustainable Energy. [Online]
Available at: http://pubs.acs.org/isbn/9780841228139
[Accessed 5 October 2016].
Junior., Fiorelli & Santos, 2017. Sustainable and Nonconventional Construction Materials using Inorganic
Bonded Fiber Composites. 1 ed. Port Macquarie: Elsevier Science.
Kelsall, Hamley & Geoghegan, 2005. Nanoscale Science and Technology. 1 ed. Darwin: John Wiley &
Sons.
Khaya & Schutter, 2014. Mechanical Properties of Self-Compacting Concrete: State-of-the-Art Report of
the RILEM Technical Committee 228-MPS on Mechanical Properties of Self-Compacting Concrete.
[Online]
Available at: https://www.goodreads.com/author/show/4332007.Kamal_Khayat
[Accessed 5 October 2016].
Malhotra, 2011. Ionic Liquid Applications: Pharmaceuticals, Therapeutics, and Biotechnology. illustrated
ed. Newcastle–Maitland: OUP USA.
Matsagar, 2014. Advances in Structural Engineering: Materials, Volume Three. 1 ed. Ellenbrook: pringer.
Polshettiwar & Asefa, 2013. Nanocatalysis: Synthesis and Applications. 1 ed. Launceston: John Wiley &
Sons.
Popovics, 1998. Strength and Related Properties of Concrete: A Quantitative Approach. illustrated ed.
Ellenbrook: John Wiley & Sons.
Popovics, 1998. Strength and Related Properties of Concrete: A Quantitative Approach. illustrated ed.
Darwin: John Wiley & Sons.
Provis & Deventer, 2013. Alkali Activated Materials: State-of-the-Art Report, RILEM TC 224-AAM. 1 ed.
Darwin: Springer Science & Business Media.
Samali, Attard & Song, 2012. From Materials to Structures: Advancement through Innovation. 1 ed.
Cairns: CRC Press.
35

Nano silica
Schmidt, et al., 2012. Proceedings of Hipermat 2012. 3rd International Symposium on UHPC and
Nanotechnology for High Performance Construction Materials. Ultra-High Performance Concrete and
Nanotechnology in Construction, 1(19), pp. 850-970.
Schutter, 2012. Damage to Concrete Structures. 1 ed. Adelaide: CRC Press.
Sheng & Wang, 2014. Manufacturing and Engineering Technology (ICMET 2014): Proceedings of the
2014 International Conference on Manufacturing and Engineering Technology. 1 ed. Melbourne: CRC
Press.
Shi, 2008. High-performance Construction Materials: Science and Applications. 1 ed. Geraldton: World
Scientific.
Shivani, 2014. Handbook of Research on Diverse Applications of Nanotechnology in Biomedicine,
Chemistry, and Engineering. 1 ed. Darwin: IGI Global.
Siddique. & Khan, 2011. Supplementary Cementing Materials. 1 ed. Sydney: Springer.
Tokyay, 2016. Cement and Concrete Mineral Admixtures. illustrated ed. Darwin: CRC Press.
36