enhancement of thermal efficiency published.pdf

8/16/2019 Enhancement of thermal efficiency PUBLISHED.pdf

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[SYLWAN., 160(1)]. ISI Indexed 251

Enhancement of thermal efficiency: the effect of polymer microspheres embedded in

mortar for saving energy

Jesús Hernández-Frías1, Rodrigo Velázquez-Castillo2 and Miguel Galván-Ruiz3*

1 Faculty of Engineering, Autonomous University of Queretaro. C.U. Cerro de las Campanas

76010, Querétaro. México. Email: [email protected]


76010, Querétaro. México. Email: [email protected]


76010, Querétaro. México; CETIS 105-SEP. Km 3.5 Carretera Tlacote 76138, Querétaro.México. *Corresponding author, Email: [email protected]

Abstract

The aim of this paper is to investigate key aspects related to the thermal conductivity of sand-

cement mortar mixed with polymethylmethacrylate (PMMA) microspheres. The assessment

was done with tests, following ASTM guidelines. Previously, cement particles were bond

permanently to the surface during PMMA microspheres synthesis. The embellishments of

PMMA microspheres increases the resistance of thermal conductivity of the mortar, shown by

this pioneering method substantially.

Keywords: Mortar, PMMA microspheres, saving energy.

1. I ntroduction

Currently, many people noticed the effect on climate change as a result of greenhouse gasses

emissions (Lashof & Ahuja, 1990). A sustainable development satisfies the requirements of

people without committing the capacity of future generations, conserving the environmental

resources using energy, water, and raw materials efficiently (Bruntland, 1987). As a priority,

the generation of new materials increases the productivity of resources and offer a more

efficient use of them (Velázquez-Castillo, Galván-Ruiz and Rivera-Muñoz 2010). Nowadays

is more noticeable the development of a sustainable technology committed to developing new

construction materials. The enhancement of thermal properties offers some advantages for the

common users, such as important savings on the cost of energy consumption. Wellbeing is


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essential in buildings and homes where people spend considerable time (Yeladaqui, 2010).

Comfort in construction depends on factors such as proper lighting, ventilation, and a pleasant

thermal environment. This last one depends primarily on construction materials and

intelligent systems being used (Galván-Ruiz et al. 2009).

The appropriate use of thermal insulation in buildings contributes to reducing energy costs

(Al-Homoud, 2005). The magnitude of saving energy using thermal insulation varies

according to the type of building, climate conditions, building location and insulation

materials (Budaiwi & Abdou, 2013). In general, energy saving has a boundless impact on

environmental quality, use of resources, and human comfort. Hence, the thinking in the

building industry is no longer about should insulation be used or in what way and how much, but to look ahead to new building material for energy saving (Galván-Ruiz and Zaleta, 2013).

Research emphasizes thermal analysis to study various types of inorganic and organic

construction materials (Velázquez-Castillo et al. 2012), more extensively in the examination

of inorganic materials (Ramachandran, Paroli, Beaudoin, & Delgado, 2002).

Alternatively, mortars are broadly construction materials used by a huge number of cultures

disseminated worldwide. With the accelerated technological development, mortars have

evolved until obtaining a well-documented mix by their applicability and physical properties

(Galvan-Ruiz & Velázquez-Castillo, 2011). These spread over for building works as a lining

and final additions to walls (Ohama, 1995). Formerly, development of polymer-modified

mortars resulted in supplies currently used in the construction industry (Afridi, Ohama and

Iqbal 2003). Several studies on different materials were examined for improvement on walls

with compounds containing polymers (MacMullen et al. 2011; Bhutta, Ohama and Tsuruta

2011; Kong et al. 2013), as well for reducing water absorption and improving thermal

insulation saving energy (Saikia & de Brito, 2012). Several polymer additives modify the

properties of mortars (Lanzón and García-Ruiz, 2008; Gadea et al. 2010), or decrease the

density and modify the hydrophobic properties (Zhao et al., 2011; Afridi et al., 1995;

Frattolillo et al., 2005). This research then will be looking at the thermal efficiency – by

studying the effect of polymer microspheres embedded in mortar for saving energy.

2. Materials and M ethods

This research agrees with ASTM guidelines:


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ASTM C-778 Standard Specification for Standard Sand.

ASTM C109/C109M-08 Standard Test Method for Compressive Strength of

Hydraulic Cement Mortars.

ASTM C 1437 Standard Test Method for Flow of Hydraulic Cement Mortar.

ASTM C191-08 Standard Test Methods for Time of Setting of Hydraulic Cement by

Vicat Needle

ASTM C266-08 Standard Test Method for Time of Setting of Hydraulic-Cement Paste

by Gillmore Needles.

ASTM C1403 Standard Test Method for Rate of Water Absorption in Masonry

Mortars.

Workability Test by Abram’s cone.

ASTM C177-10 Standard Test Method for Steady-State Heat Flux Measurements and

Thermal Transmission Properties using the Guarded Hot Plate Apparatus.

2.1 Mortar formulation

The formulation of fresh mortars was 1:2.75 parts of cement CPC 40 and sand according to

ASTM C-778. There is an inclusion of PMMA microspheres from 0% to 40% by volume.

This limit of 40% by volume is about the workability of the mortar because a higher content

produces an inappropriate consistency, and it became unworkable as a layer. Mortar

preparation assures that the aggregate is uniformly mixed, bonding the material and the other

comparatively heavier ingredients of the mortar mix.

Table 1. Percentages of Sand + Cement + PMMA according to the total addition of the

mixture.

PMMA

microspheres

Proportion (m3) volume (m3) weight (kg)

Cement SandPMM

ACement Sand PMMA

Cem

entSand

PMM

A

0% 1 2.750 0.000 0.000850 0.002338 0.000000 2.55 6.194 0.000

10% 1 2.475 0.275 0.000850 0.002104 0.000234 2.55 5.575 0.028

20% 1 2.200 0.550 0.000850 0.001870 0.000468 2.55 4.956 0.056

30% 1 1.925 0.825 0.000850 0.001636 0.000701 2.55 4.337 0.084

40% 1 1.650 1.100 0.000850 0.001403 0.000935 2.55 3.717 0.112


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2.2 Character ization

2.2.1 Scanning Electron Microscopy (SEM)

The morphology and topology of samples were analyzed by scanning electron microscopy

using a JEOL JSM 5600, accelerating voltage 20 kV, and secondary electron images

recorded. A very fine layer of gold was placed on the sample surface, to prevent electrostatic

charge accumulation.

2.2.2 Compressive Strength Test

Standard Test Method for Compressive Strength of Hydraulic Cement Mortars ASTM C109

/C109M-08. This test method agrees with the measurement of the compressive strength ofhydraulic cement mortars using 50 mm cube specimens.

2.2.3 Water Absorption of Masonry Mortars

Standard Test Method for Rate of Water Absorption if Masonry Mortars ASTM C1403. This

test method provides a standardized laboratory procedure for determining the relative water

absorption by capillary uptake (wicking) characteristics of masonry mortars.

2.2.4 Flow of fresh mortar

Standard Test Method for Flow of Hydraulic Cement Mortar ASTM C 1437. This test method

determines the flow of hydraulic cement mortars, and of mortars containing cemented

materials other than hydraulic cement.

2.2.5 Time of setting by Vicat apparatus method

Standard Test Methods for Time of Setting of Hydraulic Cement by Vicat Needle ASTM

C191-08. The test method used in this research is the manually operated standard Vicat

apparatus.

2.2.6 Time of setting by Gillmore Needles method

Standard Test Method for Time of Setting of Hydraulic-Cement Paste by Gillmore Needles

ASTM C266-08. This test method covers the determination of the time of setting of hydraulic

cement paste using the Gillmore needles.

2.2.7 Thermal conductivity

Standard Test Method for Steady-State Heat Flux Measurements and Thermal Transmission

Properties using the Guarded Hot Plate Apparatus ASTM C177-10. This test method

contributes to the general design requirements necessary to construct and operate a suitable


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Figure 1. SEM Micrographs from PMMA microspheres with cement particles.

Figure 2 shows the mortar matrix appearance obtained after the compression test of the

samples; some microspheres looked broken and deflated and hence collapsed due to this test.

The spreading of the microspheres of various diameters is heterogeneous, contributing to a

more efficient development of the mixture. Dispersion of microspheres is significant

depending on the volume of the sand-cement mixture thus improving the mortar thermal

properties, including air inside.


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Figure 2. Mortar bulk after the compressive test.

3.2 Compressive Strength Test

Samples were prepared according to the established regulation in Standard Test Method for

Compressive Strength of Hydraulic Cement Mortars ASTM C109/C109M-08. PMMA

microspheres added in different percentages from 0% through 40% by volume according to

ASTM compressive strength parameters and using a proportion 1:2.75 of silica sand according

to ASTM C778. Key information about the quality come from the compression tests shown in

Figure 3. The main contribution of this research is the formulation of lightweight mortar

improved by PMMA microspheres with better thermal insulation properties, lengthwise with

the lowest decrement in compressive strength.


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Figure 3. Compression experiment on the test cubes according to guideline ASTM C109,

including PMMA microspheres from 0 to 40%, test age 7 and 28 days.

The results show an inversely proportional relation between the percentage of added

microspheres and the magnitude of the compression strength, for which the final effect will be

the maximum percentage of added PMMA that will allow an appropriate workability and, at

least, the minimum compression strength specified by ASTM directive. The optimal ratio

results at 40% content of PMMA microspheres and 8 Mpa compression strength, at 28 day's

test.

3.3 Water absorption

Water absorption according to regulation ASTM C1403 Standard Test Method for Rate of

Water Absorption in Masonry Mortars.

Water absorption in mortars provides an approximate prediction as to how the material will

respond as mortar. Water absorbing capacity will affect the structure and in some cases the

resistance of the masonry. The results of the absorption tests showed a relation inversely

proportional to PMMA content and water absorption showing in Figure 4. It turned out that the

PMMA microspheres produce certain hydrophobic properties to the mortar. Furthermore, the

water absorption shows an almost linear propensity at small percentages of microspheres, then


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decreasing due to the increment in the fluidity properties, originated by the water reduction

effect of growing of PMMA microspheres content.

Figure 4. Water absorption in mortar samples.

3.4 Flow of f resh mortar

The fluency test analyzes the property that allows mixtures to flow and fill gaps; they can

become self-leveling without the need of vibrating equipment. This material is a new option

for others to fill porosity. A good flow is obtained when no significant segregation occurs,

and the material extends at least 200 mm in diameter. Filling fluids must not have

segregations, exudates or volume shrinkage. When the fresh mixture flows, some have a

slight expansion after hardened. The laboratory data appears in Table 2 and Figure 5. Small

proportions of microspheres increase the flow while decreasing at higher rates.


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Table 2. The flow of fresh mortar by percentage of polymeric microspheres aggregated.

PMMA microspheres

%

Diameter

(flow test) cm

00 20.620

10 22.250

20 24.550

30 23.050

40 22.250

50 19.920

60 18.025

Figure 5. Test flow of fresh mortar mixture according to ASTM C 1437.

3.5 Time of setting by Vicat apparatus method

The assessment consists of preparing a mixture with a previously calculated water content.

The mortar is placed into the mold and using a probe that falls by gravity, the setting time is

then calculated. Curing time may vary depending on the temperature and humidity of the

external environment. The results are shown in Table 3.


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Table 3. Time of setting by Vicat apparatus.

PMMA microspheres

%

Setting time

(minutes)

0 269

10 251

20 244

30 239

40 233

50 228

60 215

3.6 Setting time by Gillmore Needles method

Under the conditions of work, the workability or installation time is shorter than the setting

time obtained in laboratories because it cannot be controlled under environmental conditions.

Indeed, this essay is about finding the time in minutes during which the mortar is pliable

before hardening to a level that makes placing too difficult or impossible. Gillmore needles

support the results obtained using the Vicat apparatus to the final setting time; moreover, the

data also get initial setting time. The results are shown in Table 4.

Table 4. The setting time by Gillmore needles method.

PMMA microspheres

%

Initial setting time

(minutes)

Final setting time

(minutes)

0 140 260

10 130 255

20 130 250

30 125 240

40 125 220

50 120 215

60 120 215


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3.7 Thermal conductivity and thermal resistance

The thermal conductivity accomplished according to ASTM C177 - 10 Standard Test Method

for Steady-State Heat Flux Measurements and Thermal Transmission Properties using the

Guarded Hot Plate Apparatus. Results in Table 5 show an increment of the thermal resistance

of the material. The greatest thermal resistance increment was off about 50% compared to a

material with no PMMA microspheres added. This increment in the thermal resistance is the

key result of this research, and will have a direct impact on the sustainability of construction

where this type of materials is used since this material could contribute to energy saving and a

reduction of 'greenhouse' gas emissions as a cost-effective strategy against the global

warming. Table 5. Thermal measurements.

Results thermal conductivity and thermal resistance

PMMA microspheres % 0 10 20 30 40

Apparent thermal conductivity W/K m 0.580 0.522 0.476 0.415 0.365

Thermal resistance K m2/W 0.033 0.037 0.041 0.045 0.047

Expanded uncertainty (k=2) % 5 5 5 5 5

4. Conclusions

The increase of PMMA microspheres transforms the mortar by decreasing its density while

modifying its mechanical properties, workability, and air content. The material is comparable

to lightweight mortars prepared with other traditional materials. The results obtained by

mixing cement with different ratio of aggregate and PMMA microspheres show noticeable

good thermal properties. On the other hand, decreasing compressive strength of the optimal

formulation proposed to agree with ASTM guidelines that unlock a valuable compatibility in

this research. The microspheres also provide a hydrophobic property to the mortar. The

linkage of cement particles to the surface during microspheres synthesis is a significant aspect

of adhesion to the mortar bulk. The microspheres decrease the density by the inclusion of micro-air

bubbles in the mortar bulk. Therefore, the air inclusion reduces significantly the thermal conductivity

increasing thermal insulation. The enhancement of thermal efficiency by the effect of PMMA


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microspheres embedded in this innovative lightweight mortar maintain more stable room

temperatures and save energy.

Acknowledgements

The authors acknowledge to PROINSA for support this work and to Mr. Rene Plaza for

proofreading.

References

Afridi, M., Ohama, Y. D., & Iqbal, M. (2003). Development of polymer films by thecoalescence of polymer particles in powdered and aqueous polymer-modified mortars.

Cement and Concrete Research, 33(11), 1715-1721. http://dx.doi.org/10.1016/S0008-

8846(02)01094-3.

Afridi, M., Ohama, Y., Iqbal, M., & Demura, K. (1995). Water retention and adhesion of

powdered and aqueous polymer-modified mortars. Cement and Concrete

Composites(17), 113 – 118. http://dx.doi.org/10.1016/0958-9465(95)00007-Y.

Al-Homoud, M. (2005). Performance characteristics and practical applications of common

building thermal insulation materials. Building and Environment (40), 353-366.

http://dx.doi.org/10.1016/j.buildenv.2004.05.013.

Bhutta, M., Ohama, Y., & Tsuruta, K. (2011). Strength properties of polymer mortar panels

using methyl methacrylate solution of waste expanded polystyrene as a binder.

Construction and Building Materials, 25(2), 779-784.

http://dx.doi.org/10.1016/j.conbuildmat.2010.07.006.

Bruntland, G. (1987). Closing Ceremony. Eighth and Final Meeting of the World Commission

on Environment and Development. Tokyo: World Commission on Environment and

Development. http://www.un-documents.net/our-common-future.pdf. Retrieved from

http://www.un-documents.net/our-common-future.pdf

Budaiwi, I., & Abdou, A. (2013). The impact of thermal conductivity change of moist fibrous

insulation on the energy performance of buildings under hot – humid conditions.

Energy and Buildings, 60, 388-399. http://dx.doi.org/10.1016/j.enbuild.2013.01.035.

doi:http://dx.doi.org/10.1016/j.enbuild.2013.01.035.


14/15


Frattolillo, A., Giovinco, G., Mascolo, M., & Vitale, A. (2005). Effects of hydrophobic

treatment on thermophysical properties of lightweight mortars. Experimental Thermal

and Fluid Science(29), 733 – 741.

http://dx.doi.org/10.1016/j.expthermflusci.2004.12.002.

Gadea, J., Rodríguez, A., Campos, P., Garabito, J., & Calderón, V. (2010). Lightweight

mortar made with recycled polyurethane foam. Cement and Concrete Composites, 32,

9, 672-677. http://dx.doi.org/10.1016/j.cemconcomp.2010.07.017.

Galvan-Ruiz, M., & Velázquez-Castillo, R. (2011). Lime, an Ancient Material as a Renewed

Option for Construction. Ingeniería Investigación y Tecnología, XII (1), 93-102.

http://revistas.unam.mx/index.php/ingenieria/article/view/24120.Galván-Ruiz, M., & Zaleta, M. (2013). Study High-Performance Thermal Properties of

Natural Pumice-Based Bricks. British Journal of Applied Science & Technology, 3(4),

1022-1034.

http://www.sciencedomain.org/abstract.php?iid=226&id=5&aid=1632#sthash.MHrJZi

vA.dpuf. Retrieved from

http://www.sciencedomain.org/abstract.php?iid=226&id=5&aid=1632#sthash.MHrJZi

vA.dpuf

Galván-Ruiz, M., Hernández, J., Baños, L., Noriega, J., & Rodríguez, M. (2009).

Characterization of Calcium Carbonate, Calcium Oxide, and Calcium Hydroxide as

Starting Point to the Improvement of Lime for Their Use in Construction. Journal of

Materials in Civil Engineering , 694-698. DOI: 10.1061/(ASCE)0899-

1561(2009)21:11(694).

Kong, X., Wu, C., Zhang, Y., & Li, J. (2013). Polymer-modified mortar with a gradient

polymer distribution: Preparation, permeability, and mechanical behavior.

Construction and Building Materials(38), 195-203.


Lanzón, M., & García-Ruiz, A. (2008). Lightweightcementmortars: Advantages and

inconveniences of expanded perlite and its influence on fresh and hardened state and

durability. Construction and Building Materials, 22, 1798 – 1806.



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