1

THERMAL INSULATION CHARACTERISTICS OF STRUCTURAL LIGHTWEIGHT AND NORMAL WEIGHT CONCRETES PRODUCED WITH DIFFERENT TYPES OF

AGGREGATES

Alexandre Daniel Antunes Almeida da Silva

Abstract

The present paper aims at evaluating the thermal characteristics of structural lightweight aggregate concrete (LWAC) produced using different w/c ratios and several types of lightweight aggregates, with distinct porosities. In order to perform this study, an experimental campaign was conducted, involving physical, mechanic and thermal tests of the produced specimens.

The mixtures produced involved 4 types of lightweight aggregate and 1 type of normal weight aggregate; 4 different w/c ratios (0.35, 0.45, 0.55 and 0.65), which have various levels of mortar compactness, covering a vast range of LWAC.

Thermal conductivity was measured and analysed using both a transient and a stationary method. Depending on the type of aggregate, a thermal conductivity coefficient reduction from 30 to 60% was obtained in LWAC, compared to reference NWC of equal composition.

1 Introduction

Nowadays, reinforced concrete is the most commonly used structural material in the construction industry. However, growing concerns with energetic efficiency lead to a search for alternative solutions. In that perspective, and despite higher initial costs, lightweight aggregate concretes (LWAC) have a very high potential of use, not only for their reduced density, which allows for better structural performance, but also for their thermal properties, which give these materials great advantages.

With the increase of regulation demands regarding the thermal insulation of buildings and in face of the new properties attained by the latest generation LWAC, its application in structural solutions is becoming more and more appealing, contrary of what happened in the past, when lightweight concretes were mainly used for non-structural purposes (Bogas 2011; Newman 1993). Furthermore, the use of LWAC in alternative to conventional concretes may contribute to the reduction of thermal bridge effects in structural elements, reducing the levels of energy consumption or reducing the amount of correction systems necessary to comply with regulations (Bogas 2011).

LWAC can be produced using different techniques, from the introduction of voids in the cement matrix to the incorporation of natural or artificial lightweight aggregates (Bogas 2011). However, it is only possible to produce LWAC with structural capabilities using certain types of lightweight aggregates (for example made from expanded clay, fly ash and some types of natural aggregates (Holm e Bremner 2000).

The thermal conductivity of concrete depends mainly of its density and moisture content, being also affected by the size and distribution of the pores, chemical composition, crystallinity of the solid components and temperature (FIP 1983; Holm e Bremner 2000). The reduced thermal conductivity of the air present in lightweight aggregates’ pores is the main reason for the higher insulation capacity of LWAC, compared to NWC.

Regarding the contribution of the cement matrix, thermal conductivity tends to decrease with increments of the w/c ratio of the mixtures (Ashworth e Ashworth 1991; FIP 1978; Uysal 2004). According to Bessenouci (2011), thermal conductivity is inversely proportionate to porosity. In turn, the variation of porosity is directly related to the density, which is once again emphasizing the main influences this characteristic has on the thermal conductivity of concrete, being suggested an exponential relation between these two quantities (Newman 1993; Uysal 2004; Valore 1980; ACI213R 2003).

Thermal conductivity is greatly influenced by the moisture content, increasing 6 to 9% for each 1% increment (by weight), according to (ACI213R 2003). Also, (FIP 1983) suggests a 2 to 6% increase in thermal conductivity per 1% increase in water content (by volume).

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Several authors refer thermal conductivity values of lightweight concrete. Some of these values are shown in this figure, although it should be noted that some of the values given refer to concretes without structural application and that there are significant variations in composition, moisture content and test methods adopted.

Another important property for the thermal study is the specific heat, which indicates the amount of energy required to raise the temperature of a unit mass of material in 1ºC (Holm e Bremner 2000). The specific heat tends to increase with temperature and with decreasing density, being little affected by the mineralogical composition of the aggregates. Typically, concrete in the dry state have values of around 860 J/kgºC. In samples with moisture the specific heat increases due to water in the pores (for values that are around 4200 J/kgºC) (Neville 1995).

This work’s objective is to characterize the thermal properties of LWAC with different types of lightweight aggregates and w/c relations, involving a wide range of densities and strengths, aiming to address the most commonly used structural concrete. The influence on thermal conductivity of aggregate type, w/c ratio and moisture content, using two different test methods is also studied.

2 Experimental program

The experimental campaign began by choosing the appropriate materials and formulating the needed mixtures. Once produced, several physical and mechanical tests were performed, both in fresh and dry states, on the different concretes. Finally, thermal characterization tests were performed, using two distinct methods.

2.1 Materials

The mixtures produced for this study used four types of coarse lightweight aggregates: two expanded clay aggregates (Leca and Argex), both produced in Portugal; one expanded slate aggregate (Stalite), produced in the USA; one sintered fly ash aggregate (Lytag) from the United Kingdom. There were also two normal weight limestone aggregates, of different sizes, used for the reference normal weight concrete (NWC), named fine and coarse gravel. These aggregates’ properties are listed in Table 1.

Fine aggregates included coarse (70%) and fine sand (30%), whose properties are also listed in Table 1, for all mixtures. The cement used was of type I 42.5R and a polycarboxylate based superplasticizer was added in mixtures with low w/c ratio.

Table 1 Aggregate properties

Normal weight aggregates Lightweight aggregates

Properties Fine sand

Coarse sand

Fine gravel

Coarse gravel

Leca Lytag Stalite Argex

2-4 Argex 3-8F

Absorption at 24h (%) 0.19 0.26 0.73 0.35 15.81 17.92 3.57 21.38 19.28

Dry density (kg/m3) 2605 2617 2646 2683 1076 1338 1483 669 597

Staurated density with dry surface (kg/m3)

2610 2606 2665 2693 1246 1577 1535 814 712

Dry bulk density (kg/m3) 1569 1708 1309 1346 624 750 760 377 330

Granulometric fraction (di/Di)

4/11.2 4/8 4/11.2 4/11.2 8/16 0/8 4/11.2 0/1 0/4

2.2 Mixture compositions and production

In order to cover a wide range of strength and density classes, various compositions containing the 5 different types of aggregate and with 4 different w/c ratios were chosen (0.35, 0.45, 0.55 and 0.65), according to EN 197-1.

The compositions studied are detailed in table A1 (in annex). All concretes were produced using a vertical shaft mixer with bottom discharge. The lightweight aggregates (except Argex) were previously

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soaked in water for 24 hour and later surface dried with absorbent towels, in order to control workability and effective water content of the final mixture. The mixture process started by adding the coarse and fine aggregates and 50% of the total water volume. After two minutes of mixing, the contents were left to rest for one minute before slowly adding the binder and the rest of water. The superplasticizer (when needed), was added after one minute with 10% of the water. The total mixing time was seven minutes.

2.3 Specimens and test methods

In each mixture were produced: two 10 cm cubic specimens, used in dry density tests, according to EN 12390-7 ; four 15 cm cubic specimens, used for compressive strength tests (28 days), according to EN

12390-3; one cylindrical specimen (10.5x25 cm), later cut into three (10.5x5 cm specimens, used in thermal conductivity tests. All specimens were demoulded 24 hours after mixing and cured in water until 28 days of age.

Later in the experimental campaign, 10 more specimens (slabs) were produced for each w/c ratio, using the same compositions as before (without w/c ratio of 0.65), and cast into wooden 30x30x8 cm moulds, half of which (one of each type of aggregate) had 3 type T thermocouples inside, at equal lengths across their thickness (at 2, 4 and 6 cm). These specimens produced, demoulded and cured using the same procedure as the others.

The first part of the thermal conductivity tests were performed using the Isomet 2114 equipment, from Applied Precision company. This device uses a surface measurement probe, which uses a transient

method to determine thermal conductivity (λ), volumetric specific heat (cρ) and average test temperature (Tm). This type of method, although with a different shape of probe, is described in ASTM D 5334-14 and ASTM D 5930-09). The manufacturer reports accuracy values of 10% for λ (ranging from 0.3 to 6 W/mºC), 15% for cpρ and 1ºC for Tm. The thermal conductivity was measured on the three specimens of each composition, for four different water contents (saturated, dry, and two intermediate water contents).

The second part of the thermal conductivity tests used an adapted stationary method (fluximetric method). Eight slab specimens of each w/c ratios, with thermocouples and flux meters, and one Polyurethane slab (for seal quality control) were mounted on a wall and sealed using Polyurethane foam. On one side of the wall was a climatic chamber set to a continuous temperature of 40ºC and on the other side the temperature was the ambient temperature of the laboratory. Thermal conductivity was determined using the heat flux values passing the slabs and the temperatures measures in different parts of the slabs and climatic chamber (interior, exterior, slab interior surface and exterior surface). Each of the 3 tests took approximately 6-7 days and was performed on dry specimens.

All values of λ obtained with either method were later converted to a reference temperature of 10ºC, according to ISO/FDIS 10456.

3 Results and discussion

The results obtained from the performed tests, regarding dry density, compressive strength, dry thermal conductivity (using both methods), thermal conductivity with different moisture contents, specific heat values and Ks (which represents the increment, in percentage, of thermal conductivity with 1% increase in moisture content), are represented in table A1, in annex.

The dry density of LWAC produced ranged from 1484 to 1851 kg/m3. The compressive strengths achieved varied from 19.8 to 66.8 MPa. These concretes fall between the LC20/22 and LC60/66 resistance classes, and are suitable for structural use.

It is worth noting that concretes using Stalite achieved compressive strength values almost as high as the reference NWC, leading to higher structural efficiency values, considering equal compositions. On the other hand, Argex was found to be more adequate for lower resistance concretes, though providing increased weight reduction.

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3.1 Thermal properties – Transient method

3.1.1 Thermal conductivity

For the compositions produced and tested, results show conductivity coefficients between 0.87 and 1.36 W/mºC in LWAC and 1.86 to 2.00 W/mºC in NWC, measured in the cylindrical specimens, which means a reduction of 32 to 53% of thermal conductivity, depending on the composition.

Figure 1 Thermal conductivity vs. dry density

Figure 1 shows the results obtained using the transient method on the cylindrical specimens. A great influence of density in the thermal conductivity is confirmed, which climbs exponentially as the density increases. A high exponential correlation between these two properties is apparent, with a correlation coefficient above 0.9. However, other properties may have an influence in the thermal conductivity of concretes, such as the type of aggregate, w/c ratio and moisture content.

Figure 2 Thermal conductivity with type of

aggregate

Figure 3 Thermal conductivity with w/c ratio

The influence of the type of aggregate, as shown in Figure 2, appears to be of little importance. Thermal conductivity increases slightly as the aggregates’ density climbs, which should be caused by the reduction of porosity. Differences in thermal conductivity are less than 20% for concretes with the same composition and different aggregates. For a given density, the thermal conductivity is higher on concretes with more porous aggregates, which indicates that thermal conductivity is not only affected by density but also by the composition of its phases.

Figure 3 shows the results divided by w/c ratios. The tendency lines for each type of w/c ratio are approximately parallel. For a given density, thermal conductivity decreases as the w/c increases. This is caused by the resulting increment of porosity in the cement’s paste, leaving more voids, and increasing the insulation capacity of the concrete. The porosity and density of the cement matrix appears to have a more significant impact on thermal conductivity, compared to the aggregates’ porosity and density.

y = 0,1888e0,001x

R² = 0,9089

0,00

0,50

1,00

1,50

2,00

2,50

1400 1600 1800 2000 2200 2400

λ (W

/mºC

)

ρdry (kg/m3)

0,70

0,90

1,10

1,30

1,50

1,70

1,90

2,10

1400 1600 1800 2000 2200 2400

λ(W

/mºC

)

ρdry (kg/m3)

Leca

Stalite

A.N.

Lytag

Argex

0,70

0,90

1,10

1,30

1,50

1,70

1,90

2,10

2,30

1400 1600 1800 2000 2200 2400

λ(W

/mºC

)

ρdry (kg/m3)

a/c = 0.35

a/c = 0.45

a/c = 0.55

a/c = 0.65

5

Figure 4 Ks with w/c ratio

Figure 5 Ks with type of aggregate

The influence of the moisture content on the thermal conductivity of concretes is easier to identify via the analysis of the Ks value. This parameter indicates the increment of thermal conductivity (in percentage), for every 1% raise in moisture content of the sample, and can be calculated by analysing the thermal conductivity results for a given sample measures with different moisture contents. All specimens tested showed a linear variation of thermal conductivity with moisture content. Depending on the composition of the concrete, Ks results varied from 4.7 to 9.1%. These values are similar to the ones suggested by other authors. (ACI213 et al. (2003) suggests a range between 6 and 9% for low to moderate strength concrete). Figure 4 shows that the values of Ks for a given w/c ratio stay approximately constant as the density varies, and the Ks values decrease as the w/c ratio decreases. In Figure 5 the values of Ks are divided by the type of aggregate. This indicates that this parameter is not significantly influenced by the aggregates, showing the same results across the range.

3.1.2 Specific heat

The specific heat values obtained from the tests on the cylindrical specimens, using the Isomet 2114 device are represented in Figure 6. The average values measured for the different types of aggregate are represented in Table A1. It was found in both cases that specific heat decreases with concrete density. This is the expected result, as denser concretes are more conductive of heat and therefore need less energy to increase internal temperature. These results and tendency are in line with other authors (FIP 1983; Neville 1995; Van Geem e Fiorato 1983).

Figure 6 Specific heat on cylindrical specimens

3.1.3 Other termal properties

In this paper, other thermal properties were measured and analysed, although not as extensively, such as thermal diffusivity and thermal inertia.

Thermal diffusivity (α), measures the ability of a material to conduct thermal energy relative to its ability to store thermal energy, and is measured in m2/s. it is the result of the quotient between thermal conductivity and the volumetric specific heat. The results for the LWAC specimens (Table A1) showed a reduction between 41.5 and 49.9% of thermal diffusivity when compared with NWC specimens.

0,000

0,020

0,040

0,060

0,080

0,100

1400 1500 1600 1700 1800 1900

Ks

ρ (Kg/m3)

a/c 0.35

a/c 0.45

a/c 0.55

a/c 0.65

0,000

0,020

0,040

0,060

0,080

0,100

1400 1500 1600 1700 1800 1900

Ks

ρ (Kg/m3)

Leca

Stalite

Lytag

Argex

500

600

700

800

900

1000

1100

1200

1300

1350 1850 2350

Specific

heat

(J/k

gºC

)

Density (kg/m3)

Cylindricalspecimens

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Thermal inertia (Ti), measures the capacity of the material to store thermal energy and is measured in J.m-2.ºC-1.s-1/2. Materials with high thermal inertia offer more resistance to temperature changes and can conserve heat for longer. Results showed a decrease in thermal inertia as the density increases, with a reduction from 25.2 to 33.4% for LWAC, compared to NWC.

3.2 Thermal properties – Fluximetric method

Each test using the fluximetric method lasted for 6-7 days. During this time, temperatures and heat fluxes were measured in the slab specimens every minute and the average values calculated and registered every 10 minutes. When the temperatures and heat transfer stabilized (a few hours after the start of the test), results showed that the concretes with the highest density also had the highest energy flux, while the lowest density concretes showed the opposite.

Figure 7 Section of a slab during fluximeter test – temperatures (w/c =0.45)

Figure 7 shows the temperatures along the section of a slab (w/c ratio of 0.35) during the test, for the various types of aggregate, after reaching equilibrium heat flux. The temperature decreases linearly along the thickness of the slab (which confirms that the test has reached the equilibrium state) and the angle of descent is increases as the density (and thermal conductivity) decreases.

Figure 8 Termograph of the exterior slab during test: a)LWAC with Leca; b) Reference NWC

During the assembly of the slab specimens it was important to guarantee that the heat fluxes were uniform and that there were no heat losses through the surrounding area of the slabs. Figure 8 shows two thermograms taken during the test. It is clear that the temperature is constant in the exposed area of the slabs, which confirms that the heat flux was uniform in the center (where the flux meter was placed).

24

26

28

30

32

34

36

38

40

-1 4 9 14

Tem

pera

ture

(ºC

)

Distance (cm)

Reference

Stalite

Lytag

Leca

Argex

Linear (Reference)

Linear (Stalite)

Linear (Lytag)

Linear (Leca)

Linear (Argex)

b) a)

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3.2.1 Thermal conductivity

Using the data from the fluximetric test, thermal conductivity was calculated (for every slab specimen), using (1), where q is the heat flux (W/m2), e is the slab thickness (m), Tsi is the interior superficial temperature of the slab (ºC) and Tse was the exterior superficial temperature (ºC).

𝜆 =𝑞. 𝑒

𝑇𝑠𝑖 − 𝑇𝑠𝑒

(𝑊/𝑚º𝐶) (1)

Each slab specimen was also tested previously with the transient method. Both results are presented in Table A1, in annex. Thermal conductivity values from 0.88 to 1.57 W/mºC and 2.04 to 2.55 W/mºC were obtained for LWAC and NWC, respectively. This meant an average reduction of 40, 43.1, 48.9 and 57.8% for concretes with Stalite, Lytag, Leca and Argex, respectively, compared to NWC. These percentages were slightly higher than the ones calculated for the transient method. The difference in the results of the two methods was below 5% for all tested samples, which is below the transient method equipment’s manufacturer recommended error margin (10%). The influences of type of aggregate and w/c ratio found were basically the same as before.

3.2.2 Specific heat

Results obtained for the slab specimens are presented in Table A1 and organized in Figure 9 and 10 according to type of aggregate and w/c ratio. It was again found that specific heat decreases with increases of concrete density. The porosity of the aggregates has a significant influence on this parameter, mainly because of the effect it has on the overall density of the specimens. There was no particular influence of w/c ratio found.

Figure 9 Specific heat of slabs – type of

aggregate

Figure 10 Specific heat of slabs – w/c ratio

500

600

700

800

900

1000

1100

1200

1300

1350 1850 2350

Specific

heat

(J/k

gºC

)

Density (kg/m3)

Leca

Lytag

Stalite

Argex

reference

500

600

700

800

900

1000

1100

1200

1300

1350 1850 2350

Specific

heat

(J/k

gºC

)

Density (kg/m3)

w/c = 0.35

w/c = 0.45

w/c = 0.55

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3.3 Comparison of test methods and specimen types

After performing the thermal evaluation tests on all compositions, it is now important to compare the two test methods used. Figure 11 shows the results of thermal conductivity for all compositions, using both methods.

Figure 11 Comparison of thermal conductivity results

It is shown in Figure 11 that results from both methods were very consistent. The differences are minor for LWAC specimens, although is it visible a slight increase for the reference samples. Overall difference between methods was below 15%. However, In LWAC, that value falls to less than 4%, depending on the composition.

These differences may depend on the error margins of the test methods, mainly for the higher density reference samples, as the transient method’s measuring error tends to increase with density, but also because of the physical characteristics of the two types of specimens. The cylindrical specimens are obtained by sectioning larger cylinders. The transient method’s probe is therefore placed directly over a mixture of paste and sectioned aggregates. As for the slabs, the same probe is placed over the thin layer of cement paste resulting from moulding. The aggregates are, in this case, a few millimetres below the surface of the slab. The higher thermal conductivity coefficient of the cement paste explains the slightly higher values obtained in the slab specimens, using the transient method.

Figure 12 shows the direct comparison of the two tests. It is confirmed that the difference between them is less than 10% (the manufacturer reported error).

Figure 12 Thermal conductivity – Different

methods

Figure 13 specific heat – different specimens

The comparison of the specific heat results measured on the two types of specimens is presented in Figure 13. Considering the tendency lines, the results showed an increase of around 10% from cylindrical to slab specimens.

0,5

0,7

0,9

1,1

1,3

1,5

1,7

1,9

2,1

2,3

2,5

1400 1600 1800 2000 2200 2400

Th

erm

al co

ncu

ctivity(W

/mºC

)

Density (Kg/m3)

Leca slabs isomet

Stalite slabs isomet

Reference slabs isomet

Lytag slabs isomet

Argex slabs isomet

Leca slabs flux meter

Stalite slabs flux meter

Reference slabs flux meter

Lytag slabs flux meter

Argex slabs flux meter

Leca cyl. spec. isomet

Stalite cyl. spec. isomet

Reference cyl. spec. isomet

Lytag cyl. spec. isomet

Argex cyl. spec. isomet

Exponencial (general slabsisomet)Exponencial (general cyl. Spec.isomet)Exponencial (general slabs fluxmeter)

y = 1.24x - 0.26

0,5

1,0

1,5

2,0

2,5

3,0

0,5 1,5 2,5 3,5

λflu

xím

etr

os (

W/m

ºC)

λ isomet (W/mºC)

500

600

700

800

900

1000

1100

1200

1300

1350 1850 2350

Specific

heat (J

/kgºC

)

Density (kg/m3)

Cylindricalspecimens

Slabs

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3.4 Application of LWAC in plane thermal bridge areas

After the analysis of the thermal properties of the LWAC, it is important to understand their thermal behaviour when applied to structural elements. A brief study was conducted, applying the concretes’ thermal conductivity values to a standard solution of construction (building exterior wall with a pillar in the middle) and calculating the thickness of insulating material (XPS and a thermal mortar) necessary to comply with the regulation (REH 2013). The concrete pillar measured 0.25x0.25 (m) and the surrounding wall is a standard solution two plane clay brick with insulation layer (XPS) in the middle.

The results for the required extra insulation thickness on the pillar using both materials are presented in Table A2. It was determined that a reduction between 8 and 27% in the insulating material’s thickness was possible using the various types of lightweight aggregate concretes studied, compared to the NWC samples.

4 Conclusions

The focus of this study was to characterize the thermal properties of lightweight aggregate concretes, using different compositions and types of aggregates, as well as two different thermal test methods. The main conclusions reached are presented below.

- It was possible to produce high strength concretes, using Stalite aggregate, with higher structural efficiency than NWC of equal composition.

- A thermal conductivity coefficient reduction from 30 to 50% was achieved in LWAC, depending on the type of aggregate, compared to NWC.

- The most influencing properties on the thermal conductivity of concretes are density and moisture content, although an influence of the characteristics of the concrete’s phases was found as well.

- A high correlation was found between aggregate porosity and thermal conductivity. Also, an increment of w/c ratio reduces the thermal conductivity coefficient.

- Thermal conductivity increases linearly with moisture content (4.8 to 9.1% per 1% moisture content increment).

- Specific heat of concrete decreases linearly with the increase of density. Differences found between test methods were less than 10%, for each composition.

- LWAC’s diffusivity and thermal inertia values were reduced between 40-50% and 25-35%, respectively, when compared to NWC.

- Differences found between test methods of thermal conductivity were less than 10%, for the same type of specimens.

- Analysing the thermal performance of the studied mixtures, when applied in a standard use structural solution (pillar and surrounding two pane clay brick wall), it was found, depending on the type of lightweight aggregate, that it was possible to reduce the insulation material’s thickness necessary to comply with regulations, in 10 to 30%.

5 References

ACI213R. 2003. "Guide for Structural Lightweight-Aggregate Concrete." Concrete Institute.

Ashworth, T., e E. Ashworth. 1991. "Insulation Materials: Testing and Applications." R.S. Graves, D.C. Wysocki ASTM Special Technical Publication 1116: 415–29.

Bessenouci, M.Z. et al. 2011. "The apparent thermal conductivity of pozzolana concrete." Physics procedia 21: 59–66.

Bogas, J. A. 2011. "Caracterização de betões estruturais com agregados leves de argila expandida." Universidade Técnica de Lisboa, Instituto Superior Técnico.

FIP. 1978. "State of Art Report, Principles of Thermal Insulation with Respect to Lightweight Concrete." FIP/8/1, C and CA, Slought, England.

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FIP. 1983. "FIP Manual of lightweight aggregate concrete." Editado por Fédération internationale de la Précontrainte. 2.a ed. Surrey University press.

Holm, Thomas A., e Theodore W. Bremner. 2000. "State-of-the-art report on high-strength, high-durability structural low-density concrete for applications in severe marine environments." Washington, DC.

Neville, A. M. 1995. "Properties of concrete." Editado por Longman Group. 4.a ed. UK Limited.

Newman, J.B. 1993. "Properties of structural lightweight aggregate concrete." Em Structural lightweight aggregate concrete, 19–44. Chapman & Hall.

Uysal, H. 2004. "The effects of different cement dosages, slumps, and pumice aggregate ratios on the thermal conductivity and density of concrete." Cement and Concrete Research 34: 845–48.

Valore, R.C. 1980. "Calculation of U-values of hollow concrete masonry." Concrete International 2 (2): 40–63.

Van Geem, M.G., e A.E. Fiorato. 1983. "Thermal properties of masonry materials for passive solar design – A state-of-the-art review." Construction Technology Laboratories, Portland Cement Association. Skokie, Ill.

ASTM D 5334-14. “Standard Test Method for Determination of Thermal Conductivity of Soil and Soft Rock by Thermal Needle Probe Procedure”. ASTM International, West Conshohocken, PA, 2014.

ASTM D 5930-09. “Standard Test Method for Thermal Conductivity of Plastics by Means of a Transient Line-Source Technique”. ASTM International, West Conshohocken, PA, 2009.

EN197-1. “Cement – Part 1: Composition, specifications and conformity criteria for common cements”. European Committee for standardization CEN, english version, 2011, 38p.

ISO/FDIS 10456 “Building materials and products — Hygrothermal properties — Tabulated design values and procedures for determining declared and design thermal values”. 2007. 27p.

NP EN 12390-3. “Ensaios do betão endurecido. Parte 3: Resistência à compressão dos provetes de ensaio.” Versão portuguesa da EN 12390-3:2003, Instituto português da Qualidade, 2001.

NP EN 12390-7. “ Ensaios do betão endurecido. Parte 7: Massa volúmica do betão endurecido.” Versão portuguesa da EN 12390-7:2003, Instituto Português da Qualidade, 2000.

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Anexos

Table A1 Physical, mechanical and thermal results

Aggregate type

Mixture

General Cylindrical Specimens Slab Specimens

Mbinder (kg/m3)

Vcoarse aggregate

(l/m3)

Vsand (l/m3)

Vwater (l/m3)

w/c Slump (cm)

ρ fresh

(kg/m3)

ρ dry

(kg/m3)

Fcm (MPa)

Structural efficiency

(fc/ps) (x103 m)

ρdry aparent (kg/m3)

λdry (W/mºC)

λsat (W/mºC)

Ks cisomet

(J/kgºC)

α (x10-

6m2/s)

IT(J.m-2.ºC-1 .s-1/2)

ρdry aparent (kg/m3)

λdry isomet(W/

mºC)

λdry flux meter(W/

mºC)

cisomet

lajetas (J/kgºC)

Reference CEM I

450 350 314 157.5 0.35 13.6 2390 2324 76.3 3.28 2324 2 2.05 - - - - 2339 2.1 2.37 767

400 350 310 180.0 0.45 13.3 2367 2248 57.7 2.57 2248 1.98 2.22 - 741 1.19 1816.1 2229 1.98 2.22 787

350 350 315 192.5 0.55 9.7 2353 2245 47.8 2.13 2245 1.86 2.04 - 739 1.12 1756.7 2231 1.96 2.16 832

300 350 328 195.0 0.65 4.0 2304 - 37 - - - - - - - - - - - -

Leca CEM I

450 350 314 157.5 0.35 13.3 1900 1685 43.3 2.57 1685 1.16 1.7 0.048 980 0.7 1384 1755 1.21 1.27 1034

400 350 310 180.0 0.45 13.8 1887 1659 37.6 2.27 1659 1.06 1.67 0.056 945 0.68 1289.1 1695 1.16 1.14 1079

350 350 315 192.5 0.55 13.3 1844 1631 32.6 2.00 1631 0.94 1.65 0.062 971 0.59 1220.1 1638 1.1 1.04 1014

300 350 328 195.0 0.65 14.1 1836 1620 28.4 1.75 1620 1.01 1.81 0.069 970 0.64 1259.8 - - - -

Stalite CEM I

450 350 314 157.5 0.35 21.5 1989 1851 66.8 2.16 1851 1.36 1.91 0.059 913 0.8 1516 1892 1.52 1.55 1000

400 350 310 180.0 0.45 11.5 1961 1811 49.9 2.76 1811 1.21 1.79 0.059 932 0.72 1429.1 1843 1.36 1.3 1006

350 350 315 192.5 0.55 10 1959 1796 41.5 2.31 1796 0.99 1.49 0.057 870 0.63 1243.7 1799 1.19 1.2 962

300 350 328 195.0 0.65 6.2 1893 1770 31.9 1.80 1770 1.12 1.89 0.091 860 0.74 1305.7 - - - -

Lytag CEM I

450 350 314 157.5 0.35 17.2 2010 1767 47.8 2.70 1767 1.2 1.77 0.048 910 0.75 1389.1 1842 1.32 1.35 986

400 350 310 180.0 0.45 13 1997 1739 41.2 2.37 1739 1.14 1.82 0.058 951 0.69 1373.1 1773 1.15 1.25 1000

350 350 315 192.5 0.55 9.5 1978 1725 37.3 2.16 1725 0.93 1.65 0.053 911 0.59 1208.9 1739 1.02 1.25 980

300 350 328 195.0 0.65 5.5 1949 1694 30.6 1.81 1694 0.94 1.8 0.087 895 0.62 1193.8 - - - -

Argex CEM I

450 350 314 157.5 0.35 12.7 1676 1644 28.5 1.73 1644 1.1 1.39 0.049 958 0.7 1316.2 1552 1.13 1.02 1131

400 350 310 180.0 0.45 15.3 1636 1541 26.1 1.69 1541 0.94 1.53 0.057 1002 0.61 1204.8 1474 1.01 0.95 1168

350 350 315 192.5 0.55 18.2 1642 1484 22.5 1.52 1484 0.87 1.41 0.052 1069 0.55 1174.8 1436 0.93 0.88 1160

300 350 328 195.0 0.65 16.2 1620 1486 19.8 1.33 1486 0.89 1.58 0.068 1044 0.57 1175 - - - -

12

Table A2 Required thermal insulation thickness and compositions characteristics

Aggregate type w/c Ρdry (kg/m3)

λdry flux meter

(W/mºC) Uwall 2Uwall Umáx (I1)

mín(2Uwall; Umáx)

Tmín insul. XPS (cm)

tmín insul. Thermal mortar (cm)

reference

0.35 2328 2.37

0.47 0.94 1.75 0.94

2.4 4.6

0.45 2239 2.22 2.4 4.6

0.55 2217 2.16 2.4 4.6

Leca

0.35 1727 1.27 2.1 4.0

0.45 1688 1.14 2.0 3.8

0.55 1662 1.04 1.9 3.7

Stalite

0.35 1885 1.55 2.2 4.2

0.45 1845 1.30 2.1 4.0

0.55 1772 1.20 2.1 3.9

Lytag

0.35 1825 1.35 2.2 4.1

0.45 1759 1.25 2.1 4.0

0.55 1722 1.25 2.1 4.0

Argex

0.35 1486 1.02 1.9 3.7

0.45 1488 1.02 1.9 3.7

0.55 1418 0.88 1.8 3.4