NBSIR 87-3642

An Initial Investigation of the

Properties and Performance of

Magnesium Oxychloride-Based

Foam Thermal Insulation

Walter J. Rossiter, Jr. Paul W. Brown

U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

Center for Building Technology

Building Materials Division

Gaithersburg, MD 20899

December 1987

Prepared for: QC epartment of Energy

100 °f Conservation and Renewable Energy

tgton, DC 20585

87-3642

1987

C.2

NBSIR 87-3642

AN INITIAL INVESTIGATION OF THE

PROPERTIES AND PERFORMANCE OF

MAGNESIUM OXYCHLORIDE-BASED

FOAM THERMAL INSULATION

Research Information Center

National bureau of Standards

Gaithersburg, Maryland 20899

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Walter J. Rossiter, Jr. Paul W. Brown

U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

Center for Building Technology

Building Materials Division

Gaithersburg, MD 20899

December 1987

Prepared for: U.S. Department of Energy

Office of Conservation and Renewable Energy

Washington, DC 20585

U.S. DEPARTMENT OF COMMERCE, C. William Verity, Secretary

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director

TABLE OF CONTENTS

page

ABSTRACT iv

LIST OF TABLES v

LIST OF FIGURES v

1 . INTRODUCTION . 1

1 . 1 Background 1

1.2 Manufacture of Magnesium Oxychloride

Cement-Based Foam 3

2. EXPERIMENTAL . 5

2.1 Laboratory-Preparation of Foam Samples 5

2.2 Foam Samples from the Field 6

2.3 Measurement of Linear Shrinkage and Density. . . 6

2 . 4 Moisture Content 8

2.5 Measurement of Thermal Conductivity 8

2.6 X-Ray Diffraction Analysis 9

2.7 SEM Specimen Preparation and Analysis 10

2.8 Thermogravimetric Analysis 10

3. RESULTS AND DISCUSSION OF THE LABORATORY MEASUREMENTS. 12

3.1 Density and Moisture Content 12

3.2 Shrinkage 14

3.3 Thermal Conductivity 16

3.4 X-Ray Diffraction 19

3.5 Scanning Electron Microscopy 20

3.6 Thermogravimetric Analysis 22

4. RESULTS AND DISCUSSION OF FIELD OBSERVATIONS 27

5. SUMMARY AND RECOMMENDATIONS 29

5.1 Summary 29

5 . 2 Recommendations 32

6 . ACKNOWLEDGMENTS 33

7. REFERENCES 34

iii
ABSTRACT

This study is an initial investigation of the properties and

performance of magnesium oxychloride-based foam thermal insulation.

Tests and observations were performed on samples prepared in the

laboratory and also removed from one cavity of a wall of a woodframe house. The tests to characterize the foam included

measurements of density, moisture content, shrinkage, and thermal

conductivity, and analysis using X-ray diffraction, scanning

electron microscopy, and thermogravimetry techniques.

It was found that the foam had a thermal conductivity comparable

to that of other insulations used to retrofit walls of houses.

Shrinkage could not be quantified, but was seen to be generally

small. The moisture content of the foam removed from the house

was about 2 percent. The results of the analytical measurements

indicated that the laboratory-prepared samples and some of those

removed from the house were not identical. It was suggested that

further analysis be conducted to continue characterization of the

foam.

Key Words: characterization; density; foam; insulation;

magnesium oxychloride cement; moisture content; SEM;

shrinkage; thermal analysis; thermal conductivity;

X-ray diffraction

IV
1 . INTRODUCTION

1 . 1 Background

For the past decade, the Building Materials Division of the

National Bureau of Standards (NBS) has provided technical

assistance to the U.S. Department of Energy (DOE) in assessing

the properties and performance of insulation materials. This

technical assistance has included studies on new or non-conventional

insulation materials used for, among other applications, retrofitting

uninsulated cavities in walls of buildings. These studies have

generally involved a preliminary phase that included publication

of a review paper summarizing available technical data on the

insulation, and recommending research to fill in gaps in the

information data base. A notable example was a recent report on

the properties and performance of urea- formaldehyde foam insulations

[1]. A benefit in conducting such studies is the identification

of research needed to enhance the performance of the nation's

building inventory.

About 5 years ago, a new low-density (about 2.0 lbm/ft^ or

32 kg/m^) inorganic foam insulation became available in the

U.S. [2]. The production of the insulation is based on magnesium

oxychloride cement technology, but the chemical composition of

the product has not been described in the archival literature.

The manufacturer has indicated that the product is referred to in

general terms as an oxychloride cement foam insulation, but is

more properly described as a calcium magnesium oxychloride

1
silicate composition [2]. The insulation has been marketed for

use in a variety of building constructions including new and

existing wood-frame, steel-stud and masonry cavity walls, curtain

walls, and for filling hollow-cores in masonry block walls.

The insulation is foamed-in-place from aqueous solutions at the

building site in a manner similar to some plastic foams. The

unset foam insulation may be pumped under pressure into closed

cavities where access is obstructed and which may be difficult to

fill with loose-fill insulation. After application, the foam

hardens in place to a self-supporting material.

A review report on available data concerning the properties and

performance of the oxychloride cement-based foam insulation was

recently prepared [2]. The review indicated that data regarding

the characterization of the foam as thermal insulation were not

complete and that research was needed to provide data lacking on

the performance properties of the foam. Properties for which the

available data were limited included composition and structure,

durability, effect on other building materials, shrinkage, and

water absorption.

This paper presents the results of an initial investigation to

obtain data on the properties and performance of the oxychloride

cement-based foam insulation. Foam samples, prepared in the

laboratory and removed from a wood-frame house, were included in

2
the study. Measurements of density, moisture content, thermal

conductivity, and shrinkage, were combined with X-ray diffraction

(XRD) , scanning electron microscopy (SEM), and thermogravimetric

(TG) analyses.

The analytical techniques (i.e., XRD, SEM, and TG) provide data

concerning the chemical composition and cellular structure of the

foam. Their use enables comparison of foam products from

different installations to determine similarities and differences

in composition, and whether compositional or microstructural

changes are occurring in time.

1 . 2 Manufacture of Magnesium Oxychloride Cement-Based Foam

The manufacture of the low-density foam insulation has been

previously described [2] and only a summary is presented here.

Three major ingredients are involved: an aqueous cementitious

slurry (based on magnesium oxychloride technology), a surfactant

(or foaming agent) solution for cell generation, and compressed

air. The equipment for generation of the foam on site includes a

compressed air pump, and a mixing (or foaming) gun. The foaming

agent is first pumped into the gun, where the compressed air

mixes with it in an expansion chamber, and expands it into foam

bubbles. Just before the bubbles exit from the nozzle of the

gun, they are mixed with the cementitious slurry, which has been

pumped through a separate line into the gun. The foam is then

pumped from the gun. Expansion of the foam is complete at this

3
point and no expansion occurs after installation. Initial

hardening of the foam proceeds to an extent sufficient for it to

be self-supporting as it exits the gun. Complete hardening

reportedly occurs a few weeks after application. When it exits

from the nozzle of the foaming gun, the unset low-density foam

reportedly contains about 50 to 60 percent water by mass [2].

4
2 . EXPERIMENTAL

The following sequence constituted the experimental framework of

the study. Details of each procedure are given in the subsections

which follow. Laboratory foam samples were prepared in wooden

boxes and, periodically, the boxes were opened to observe

shrinkage. Foam specimens were removed from the opened boxes and

the selected properties were determined. In addition, a section

of a exterior wall of a house was opened to observe the foam in

service and to obtain a specimen for laboratory testing.

2 . 1 Laboratory-Preparation of Foam Samples

A commercially available foam was prepared by manufacturer

representatives according to their prescribed application

techniques. The formulation of the foam was proprietary. Boxes,

with interior dimensions of 610 x 610 x 90 mm (24 x 24 x 3.5

in.) and constructed from exterior-grade plywood and nominal 2x4

wooden studs, were filled with foam in the presence of NBS

research personnel. After filling, the boxes were maintained

with a long dimension in a vertical position at 23 + 3 °C

(73+5 °F) and 45+5 percent relative humidity. Periodically,

the boxes were opened for shrinkage observations and removal of

test specimens. These specimens are subsequently referred to as

laboratory specimens.

5
2 . 2 Foam Samples from the Field

Foam specimens were obtained from a wood-frame house located in a

rural northwest suburb of Washington, D.C. The wall construction

consisted of nominal 2x4 wooden stud framing with a lath and

plaster interior facing, and a rough-sawn wooden plank sheathing

and painted wooden siding as the exterior facing. No membrane

type vapor retarder was found in the wall cavity. The foam had

been installed in the walls of the house about one year before

the sampling. Specimens removed from the house are subsequently

referred to as field specimens.

In October 1986, an exterior wall section, about 0.2 m

2 (2 ft 2

) in area, was opened across one cavity (space between adjacent

studs) to observe the in situ foam insulation and to remove

samples. Some of the samples were sealed in glass jars for

subsequent determination of density and moisture content. After

removal of the foam, the empty cavity space was filled with

fibrous glass insulation and the wall was closed using the

original sheathing and siding.

2 . 3 Measurement of Linear Shrinkage and Density

Linear shrinkage of the foam samples in the wooden boxes was

measured using a rule or calipers graduated in millimetres in

accordance to a procedure that had been previously developed for

cellular plastic insulation [3]. The boxes were opened for each

measurement and then closed until the next determination.

6
Shrinkage measurements were made 28, 96, and 195 days after

foaming.

For purposes of this report, "wet density" is the density at

installation when the foam contains the water present during

formation and application. Wet density was calculated from the

mass of wet foam applied in tared 1-gallon metallic paint cans

and the volume of the cans. Weighing was performed using an

analytical balance with a sensitivity of 0.01 g.

To determine the amount of water present during application, the

filled cans without lids were allowed to remain at ambient

laboratory conditions and periodically reweighed. No provisions

were made to avoid exposure to atmospheric carbon dioxide.

Weighing was continued until a constant mass (+ 1 percent

difference between consecutive weighings over at least 24 hours)

was reached.

"Dry density" indicates the density of the foam insulation after

it releases moisture present during application and it reaches

equilibrium under normal laboratory environmental conditions.

The foam in this condition is, thus, not totally "dry" in that no

absorbed moisture is present.

The dry density of foam was determined using samples removed from

the wooden boxes. The procedure was according to that described

7
in ASTM Test Method for Apparent Density of Rigid Cellular

Plastics (D 1622). It was considered that the procedure in this

standard was appropriate for the cementitious foam in the study,

since some of its physical characteristics and density were

comparable to that of many cellular plastics.

2 . 4 Moisture Content

Percent moisture content (MC) of the foam specimens was determined

by measuring mass changes occurring during heating for 16 hours

at 98 + 2 °C (208 + 4 °F) in a laboratory oven without mechanical

convection:

MC % = [ (Mw - Md )/Md ] x 100

where Mw = mass of wet foam before heating, and

Md = mass of dry foam after heating.

Mass of the specimens was determined using an analytical balance

having a sensitivity of 0.01 g.

2 . 5 Measurement of Thermal Conductivity

Thermal conductivity measurements were carried out according to

ASTM Test Method for Steady-State Heat Flux Measurements and

Thermal Transmission Properties by Means of the Guarded-Hot-Plate

Apparatus (C 177). The metering area of the hot plate used was

circular with a diameter of 400 mm (16 in.). The insulation

specimen, having dimensions of 584 x 584 x 69 mm (23 x 23 x 2.7

in. ) was placed in a wooden frame with a thin non-metallic bottom

screen to hold the specimen during testing. The specimen was cut

to the frame size with a wire to avoid damage. The thickness of

8
the specimen was slightly greater than the wooden frame so that

the top surface of the specimen was in contact with the cold

plate of the guarded hot plate. The bottom screen surface of the

wooden frame was placed directly on the hot plate. Mean temperatures

for the thermal conductivity measurements were 12, 24, and 38 °C

(44, 75, and 100 °F), with a temperature differential across the

specimen of 28 °C (50 °F) in all cases. The hot plate apparatus

was operated in a one-sided mode, as described in ASTM Standard

Practice for Using the Guarded-Hot-Plate Apparatus in the OneSided Mode to Measure Steady-State Heat Flux and Thermal Transmission

Properties (C 1044).

2 .X-Ray Diffraction Analysis

X-ray diffraction (XRD) provides a means for identifying the

crystalline phases in a sample [4]. X-rays are diffracted by

planes of atoms in a crystal. Diffracted intensity at specific

angles (29) is indicative of the presence of specific compounds

in the sample.

Specimens were prepared for X-ray diffraction analysis by

grinding samples of the foam insulation in an agate mortar and

pestle. The resultant powders were back loaded into specimen

holders. Back loading is a standard technique for preparing a

powder sample for XRD analysis to minimize preferred orientation.

Specimens were step scanned from 4° - 65° 29 at a scan rate of

0 . 02°/second.

9
2 . 7 SEM Specimen Preparation and Analysis

Scanning electron microscopy (SEM) analyses were conducted to

characterize the cellular structure of the foam specimens. The

SEM technique provides good depth of field at high magnification

[5]. In the present study, the foam specimens for SEM analysis

were cut cylindrical in shape from larger samples using a cork

borer. They had lengths of about 10 to 15 mm (0.4 to 0.6

in.) and diameters of 10 to 12 mm (0.4 to 0.5 in.). Two SEM

specimen mounting stubs with 12 mm (0.5 in.) diameters were

bonded to the ends of the cut specimens with an epoxy adhesive.

When the adhesive had cured, the mounting stubs were pulled in

opposite directions, breaking the single cut specimen into two

mounted specimens with fractured surfaces.

The mounted specimens were sputter coated with a nominal 20 nm

(8 x 10“7 in.) gold conductive film to prevent surface electron

charging during SEM analysis. The fractured surfaces were

examined in the SEM using an acceleration voltage of 30 kV and

photographed at magnifications generally ranging from x20 to

x2000.

2 .Thermogravimetric Analysis

The thermogravimetry (TG) technique determines the weight change

of a sample as a function of temperature [6]. Samples are

normally heated at a selected rate, and the resultant thermograms

(plots of mass vs temperature) provide data concerning the

10
thermal stability of the samples, for example, temperatures of

thermal decompositions.

Foam specimens for thermogravimetric analysis were cut from large

samples using a laboratory scalpel. The specimens (about 2.6 to

3.8 mg) were heated from 40 to 490 °C (104 to 914 °F) in nitrogen

gas at a rate of 1 °C/min (1.8 °F/min) . The nitrogen flow rate

was 40 ml/min. The analyzer instrument was evacuated and then

filled with nitrogen prior to each run.

11
3. RESULTS AND DISCUSSION OF THE LABORATORY MEASUREMENTS

3 . 1 Density and Moisture Content

3.1.1 Wet Density. The magnesium oxychloride based-foam

insulation is applied wet. The moisture present during foam

application must subsequently be dried from the wall to avoid

damage to it. In the present study, it was of interest to

determine the wet density of the foam and the amount of moisture

released on drying, since these values can be related to field

practice and the amount of moisture that a freshly-installed wet

foam may release in the wall of a building.

Wet density was determined using metal cans to preclude moisture

absorption by the container after filling with wet foam. The

average wet density of the foam (three determinations) was 89

kg/m^ (5.6 lbm/ft^) with a coefficient of variation of 1 percent

(Table 1). Thirty-eight (38) days were required for the foam in

the metal cans to reach constant mass. During this period of

time, the foam samples in the cans each lost about 135 g (0.30

lbm) of water or 40 percent of their initial wet mass. The dry

density of the samples in the cans was not determined.

3.1.2 Dry Density. Dry density determinations were made on

specimens cut and removed from the wooden boxes 28 days after

foaming. The specimens removed from the boxes were found to

contain moisture, indicating that the foams applied in the wooden

boxes had not dried in 28 days. The specimen application boxes

12
were considered to be tight, resulting in slow drying. The foam

specimens, removed from the boxes, were placed on an open shelf

in the laboratory to dry. Nine days were required for the

moisture to be lost from the specimens and equilibrium mass to be

reached under normal laboratory conditions. During that time,

about 25 percent of the initial mass was lost, which provided

evidence that some of the initial moisture in the laboratory

samples was lost in the wooden boxes.

The average dry density of the foam (4 determinations) was

44 kg/m^ (2.8 lbm/ft^) with a coefficient of variation of 4.4

percent (Table 1). When the specimens, on which dry density was

determined, were heated for 16 hours at 98 + 2 °C (208 + 4 °F)

,

they lost, on the average, an additional 1.7 percent of their

mass. Heating for another 16 hour period produced no significant

additional change in mass. The mass lost on heating was taken to

be moisture.

Density specimens were again removed from the wooden boxes 96

days after foaming. In this case, the average value of dry

density (4 replicates) was 46 kg/m^ (2.9 lbm/ft^) with a coefficient

of variation of 3.5 percent (Table 1). In contrast to the

specimens removed from the wooden boxes after 28 days, the 96-day

specimens were essentially at equilibrium moisture content.

Thus, it was considered that the foams in the wooden

13
boxes had completed drying within the 68-day period following the

initial 28 days.

The dry density of three specimens removed from the house was

also determined. The average value was 48 kg/m3 (3.0 lbm/ft3

) with a coefficient of variation of 3.3 percent (Table 1). This

density was considered comparable to the value for the laboratory

specimens. The average mass loss on heating for the field

specimens, taken to be moisture content, was 2.2 percent.

3 . 2 Shrinkage

Shrinkage of a foam insulation may cause air gaps that result in

unwanted heat flow paths, and thus lower the thermal efficiency

of the insulated wall [7,8]. When the present study was planned,

it was intended to measure the percent shrinkage of samples

prepared in the wooden boxes. However, the shrinkage measurements

on the laboratory samples could not be quantified, but were found

to be generally small (see the paragraphs that follow)

Quantification of shrinkage was precluded because, where cracks

attributed to shrinkage were present, they were narrow in width

and randomly located across the bulk of the foam. Under such

conditions, it was not possible to determine the accumulated gap

space (necessary for a shrinkage calculation) created by the

shrinkage cracks.

14
All wooden boxes were opened by removing a plywood face 28 days

after filling. Three boxes for shrinkage were again opened after

96 and 195 days elapsed. The initial (28 day) observations

showed that the boxes were essentially full. A few small gaps,

penetrating through the foam from the front face of the box to

the back face, were found in two foam samples. In all cases, the

foam had adhered to the inner surfaces of the box. A narrow

crack was visible near the box sides and near the perimeter of

the foam samples. For each box, the width of the crack was

immeasurably small using a rule or calipers graduated in millimetres.

One box also had a narrow crack in the center of the foam. The

presence of the cracks was attributed to minor shrinkage of the

foam over the 28-day period. It was considered that the adhesion

of the foam to the inner surface of the boxes was greater than

the cohesive strength of the foam, resulting in the narrow

shrinkage cracks near the perimeter of the foam samples, and not

between the foam and the sides of the box.

After 96 and 195 days, when three boxes were again opened, the

cracks were more readily apparent than during the first opening.

In addition to the cracks near the perimeter of the foam, a

number of cracks were also found randomly throughout the bulk of

the foam. The width of the cracks were variable, with many being

about 1 to 2 mm (0.04 to 0.08 in.) wide. The narrowest were

considered immeasurably small, whereas the largest were found to

be about 5 to 7 mm (0.2 to 0.3 in.) wide. It is noted that a

15
single gap of 7 mm (0.3 in.) over a distance of 610 mm (24

in.) would represent slightly greater than 1 percent shrinkage.

In outlining the scope of the study, it was not intended to

measure foam shrinkage occurring in the metallic cans used for

wet density determinations. However, after 6 months exposure in

the laboratory, the foam samples in the cans were observed to

have shrunk more than (4.5 to 6 percent) those in the wooden

boxes. Although the significance of this observation, particularly

as related to the use of foams in wood-frame construction, is not

defined, this finding is reported since it raises concerns that

the factors affecting foam shrinkage are not completely understood.

In particular, one concern is whether foam shrinkage may vary

depending upon the application environment and, perhaps, on the

rate at which the freshly installed foam dries.

3 . 3 Thermal Conductivity

In planning the study, it was determined to perform thermal

conductivity measurements on two specimens removed from the

wooden boxes 28 days after foaming. These specimens would be

allowed to remain at ambient laboratory conditions for one week

before measurement. In this way, some residual moisture would

remain in the foam, as would be considered typical of the foam in

service where it would not be expected to be absolutely dry. The

plan proposed to determine the thermal conductivity first on the

"wet" specimens at a 24 °C (75 °F) mean temperature. Then, the

16
specimens would be dried in an oven and, subsequently, additional

thermal conductivity measurements would be made over a range of

mean temperatures. In practice, however, it was found that

specimens large enough for thermal conductivity measurements were

difficult to handle due to the inherent friability of the

insulation. This precluded carrying out the proposed measurement

procedure. The first specimen was damaged during drying in an

oven after the initial thermal conductivity measurement at 24 °C

(75 °F)

Thus, upon removal of the second specimen from the

application box, it was placed in the hot plate apparatus after

remaining at ambient laboratory conditions for a week. Thermal

conductivity measurements were made at three mean temperatures

without oven drying of the specimen.

The results of the thermal conductivity measurements are given in

Table 2. The values are comparable to those measured for other

retrofit insulations such as mineral fiber or cellulose [9]. The

foam specimens used for thermal conductivity measurement contained

2 or 3 narrow (< 1 mm) random cracks which formed while they

remained at ambient temperature upon removal from the wooden

boxes. The thermal conductivity values for the specimens with

narrow cracks are reported, since cracks were observed in the

foam sample examined in the house during the field phase of the

study. The laboratory specimens for thermal conductivity were,

thus, considered typical of that examined in the field. Also, as

given in Table 2, the density of the laboratory specimens was

17
comparable to that of the foam removed from the house. The

extent to which the cracks in the laboratory specimens contributed

to unwanted heat flow during the thermal measurements was not

determined, and requires further investigation.

As indicated in Table 2, thermal conductivity values for specimen

2 were measured for three mean temperatures. It is evident that

these values increased as the mean temperature of the test

increased. This relationship was linear with a correlation

coefficient of 0.997. After completion of the thermal conductivity

tests, a section of the specimen was dried in a laboratory

oven. It lost 1.8 percent of its mass during heating, which was

comparable to the mass loss found when other specimens in the

present study were subjected to the conditions of drying.

The thermal conductivity value of 0.0430 W/m *°C (0.298 Btu*in./h»

ft^.°F), determined in the present study at 24 °C (75 °F) for a

foam density of 47 kg/m^ (2.9 lbm/ft 3 ), may be compared with a

previously reported value. The literature reported value was

0.0371 W/m-°C (0.257 Btu * in. /h • f t^ . °F ) for a density of 33 kg/m^

(2.1 lbm/ft 3

) [2]. The literature reference did not specify the

mean temperature of the test. The foam in the present study was

found to have a thermal conductivity about 15 percent greater

than that previously reported. The difference may possibly be

attributed to the higher density of the foam in the present

study, with perhaps some contribution due to the cracks in the

18
specimens. This, of course, assumes that the mean temperature of

the literature test was about ambient laboratory temperature.

3 . 4 X-Ray Diffraction

X-ray diffraction (XRD) analyses were carried out on two laboratory

specimens and two field specimens. One of the field specimens

was taken from the vicinity of the outer side of the wall cavity,

and the other was the vicinity of the inner side of the cavity.

Analysis of the X-ray diffraction patterns obtained from the two

laboratory specimens indicated that the two were identical. The

field specimen obtained from the outer side wall cavity gave a

diffraction pattern which was also found to be virtually identical

to those of the laboratory specimens. These three specimens were

characterized by strong diffraction peaks at 2.37 (I/Io

*100)i,

3.19 (I/I0

* 60), and 1.57 °A (I/I0

* 50). Cole and Demediuk [10]

have published X-ray diffraction data for magnesium oxychloride

cements including the 3-form, 3Mg(OH) 2

* MgC^* 8H2O, and 5-form,

5Mg(OH) 2

* MgCl2

* 8 H2O. A comparison of the positions and relative

intensities of the above peaks from the present study with the

Cole and Demediuk data [10] indicated that the foams contained

some magnesium oxychloride material, but the percentage was not

ascertained. The comparison also did not provide determination

as to whether the oxychloride present was the 3 form or the 5

1 I/I0

is the ratio of the given peak intensity to that of

the most intense peak.

19
form, or if a mixture were present, the relative percentages of both.

Analysis of the field specimen from the vicinity of the inner

side of the wall cavity also showed the presence of the above

peaks. However, their intensities were significantly diminished

in this case. Rather, in this instance the following strong

peaks were observed: 2.99 (I/I o*100), 3.19 (I/I 0*86), 11.5 (I/Ip*

86 ), and 3.02 °A (I/I 0*79). The presence of strong 11.5 and 3.01

A peaks is suggestive of the presence of the chlorocarbonate

phase, Mg(OH) 2

* MgCl2

* 2MgC03 * 6 H2O, which forms as a result of the

carbonation of the magnesium oxychloride cement. The reaction of

carbon dioxide in air with magnesium oxychloride cements to form

a carbonation product has been described [10,11]. Sorrell and

Armstrong [11] have reported that the carbonation reaction can be

beneficial and have a stabilizing effect on the magnesium

oxychloride cements. It is noted that an investigation of

possible carbonation of the foam insulation was beyond the scope

of the present study, and should be the subject of further study.

3 . 5 Scanning Electron Microscopy

SEM analysis was conducted on two laboratory specimens. The

results indicated that the microstructures of the two were

generally the same. Fig. 1 shows a SEM photomicrograph taken of

a laboratory specimen at x20 magnification. It is evident that

the structure of the foam consists of cells that have a large

variability in size. Each of the cells was seen to have a number

20
of thin windows and ribs connecting the windows. Some of the

windows were open in that no membrane was present, whereas others

had membranes in place.

Fig. 2 is a SEM photomicrograph at x200 magnification. Cell

windows both with and without membranes are apparent. This

figure also shows that the surface of the cells between the

windows has a rough or pockmarked texture. In general, this

surface roughness was typical of the cellular structure of the

laboratory specimens. One exception was a limited area of one

specimen in which a cell wall was found to have the appearance of

needles

SEM analyses were also performed on two field specimens for

comparison with the photomicrographs of the laboratory specimens.

As with X-ray diffraction, one field specimen was taken from the

vicinity of the outer side of the wall cavity, and the other was

taken near the inner side of the wall cavity. At low magnification

(e.g., x20-xl00), the microstructure of the field specimens

appeared to be the same as that of the laboratory specimens.

However, higher magnification observations (e.g., x500) of the

surfaces of the cells indicated a marked difference between the

two field specimens. The microstructure of the specimen from the

outer side of the cavity was comparable to that of the laboratory

specimens. In contrast, in the case of the field specimen taken

from the inner side of the cavity, needles were observed on the

21
surface of many of the cells (Fig. 3).

The difference of surface characteristics of the microstructure

of the two field specimens, observed by SEM analysis, was

consistent with the results of the X-ray diffraction analysis.

As discussed. X-ray analysis also showed the laboratory specimens

to be essentially identical to the field specimen from the outer

side of the cavity; whereas the field specimen from the inner

side was different, possibly having formed some chlorocarbonate

The formation of a chlorocarbonate may produce a change in the

microstructure that was observed in the SEM analysis.

It is of interest to determine whether the needles observed in

the limited section of cell wall of one laboratory specimen was

due to incipient formation of the chlorocarbonate or other

reaction product. Further investigation is required to examine

this question.

3 . 6 Thermogravimetric Analysis

Thermogravimetric (TG) analyses were performed on foam specimens

prepared in the laboratory and obtained from the field. As was

the case of the SEM analyses, the field foam specimens were taken

from locations near the outer and inner sides of the wall

cavity. The results are presented in Fig. 4, and summarized in

Table 3. As evident from the Table 3, the mass loss results are

given for three temperature ranges: a low range between 40 to

22
175 °C (104 to 347 °F) , a medium range between 175 to 300 °C (347

to 572 °F), and a high range from 300 to 450 °C (572 to 914 °F).

The ranges were selected so that comparisons could be made (see

below) with data for magnesium oxychloride cements presented by

Cole and Demediuk [10].

A notable feature in Fig. 4 is that the mass loss curves for the

laboratory specimens and field specimens are not the same. In

particular, the laboratory-prepared specimens underwent about 30

percent total mass loss over the heating range; whereas the field

specimens lost about 40 percent of their mass. The increased

mass loss for the field specimens is accounted for by greater

mass losses in all three temperature ranges as compared to the

laboratory specimens (Table 3). These mass loss results cannot,

at this time, be related to the chemical composition of the foam,

since its formulation is proprietary.

The TG evidence regarding relative mass loss for the three

temperature ranges suggests that the composition of the laboratory

specimens and both field specimens may be different. This

finding contrasts sharply with the results of the X-ray diffraction

and SEM analyses which indicated the field specimen

23
from the outer side of the cavity was essentially the same as the

two laboratory specimens.

It is also evident from Fig. 4 that the mass loss curves for the

replicate laboratory specimens are comparable. The shapes of the

curves have marked similarity and the total mass loss over the

heating range is closely the same (29 vs. 32 percent). This

result supports those of the X-ray diffraction and SEM analyses

which indicated that the replicate laboratory specimens were

generally the same.

In agreement with the results of the X-ray diffraction and SEM

analyses, the TG evidence also suggests that two field specimens

may be different from each other. In particular, the curves in

the low temperature range have different slopes. The total

weight loss during heating for the outerside and innerside field

specimens was 39 and 44 percent, respectively.

The results of the thermogravimetric analyses in the present

study can be compared to those reported by Cole and Demediuk [10]

for the 3-form and 5-form magnesium oxychloride cements. Their

data (included Table 3) may be categorized into two major

temperature regimes over which mass loss occurred: a low range

from about 100 °C (212 °F) to about 175 °C (347 °F), and a high

range of about 300 to 460 °C (572 to 860 °F)

24
In the low range, the magnesium oxychloride cements underwent

dehydration to the same anhydrous phase [10]. The 3-form and 5-

form lost about 34 and 27 percent of their mass, respectively

when heated to about 175 °C (347 °F). These percents were

essentially equal to the theoretical percentage of water of

hydration present in each form. At higher temperatures, thermal

degradation of the anhydrous phase occurred. The additional loss

of mass by heating from about 300 to 460 °C (572 to 860 °F) was

about 26 percent for both the 3-form and the 5-form.

A comparison of the TG results of the present study (Table 3)

with those of Cole and Demediuk [10] suggests that the foam

insulation is neither a pure 3-form or 5-form magnesium oxychloride

cement, or a combination of the two. In particular, the percent

loss in mass of the insulation specimens in the present study was

considerably less, particularly over the low temperature range,

than reported by Cole and Demediuk for the magnesium oxychlorides.

Over the low temperature range, the mass loss in the present

study was 16 percent or less (Table 3), whereas that from Cole

and Demediuk was about 30 percent. The TG finding that the foam

insulation is neither a pure 3 -form or 5-form magnesium oxychloride

cement is not considered surprising, since the insulation is

prepared with fillers [2]. Fillers would be expected to alter

the mass loss curves of the foam in relation to the pure magnesium

oxychloride cements. Moreover, the manufacturer has indicated

that the foam may be more aptly described as a calcium magnesium

25
oxychloride silicate composition [2]. Further research is needed

to continue characterization of the foam insulation, and to

resolve the apparent inconsistencies between the present X-ray

diffraction and TG results.

26
4. RESULTS AND DISCUSSION OF FIELD OBSERVATIONS

The wall was opened from the exterior to provide access to the

foam insulation. The oak plank sheathing had been installed

diagonally to the studs, which did not allow opening more than

one cavity without removing many pieces of siding board.

Consequently, the observations of the in situ foam from the house

were limited. It cannot be overemphasized that the observations

reported here apply only to the house in question, because of

their limited extent. The scope of this initial study of the

properties and performance of these foams did not include a

comprehensive field survey of a number of installations.

Upon removing the sheathing from the house, it was apparent that

the installed foam had not completely filled the cavity space.

The foam was in the center of the cavity, with unfilled cavity

areas along both the left and right studs. The opening of an

incompletely filled cavity filled was unfortunate, for it

precluded taking measurements on shrinkage of the foam insulation.

Shrinkage is normally estimated by determining the width of gaps

created between the studs and the completely installed insulation.

The foam was found to be intact in the cavity. There was no

evidence of crumbling, although the foam was friable to handle. Both

horizontal and vertical cracks of varying widths were observed in

the foam. Most cracks were estimated to be no greater than 1 to

2 mm (0.04 to 0.08 in.) in width. In some cases, the cracks were

27
considered immeasurably narrow, and in one case, the largest

crack was found to be about 5 mm (0.2 in.) in width. Some of the

cracks completely traversed the thickness of the insulation.

Consequently, only relatively small pieces of the foam could be

removed from the cavity. A sample large enough for a thermal

conductivity measurement could not be obtained.

Four of the pieces of foam were weighed immediately in the field

upon removal from the wall. They were again weighed periodically

in the laboratory over a two week period during which they

remained unsealed and exposed to normal room conditions. The

samples showed no significant change in mass between the initial

and final weighing, indicating that these foam samples removed

from the wall contained no excessive accumulated moisture.

Upon removal of the foam from the cavity, a metal-sheathed

electrical cable was found in the cavity mounted along the right

stud. The foam had been in contact with the metal. No evidence

of corrosion was visually observed. Finally, no indications of

moisture problems (e.g., wet sheathing, water staining, and the

like) in the cavity were seen. Measurements of moisture contents

of the wooden members of the wall were not made.

28
5. SUMMARY AND RECOMMENDATIONS

5 . 1 Summary

This study was an initial investigation of the properties and

performance of magnesium oxychloride-based foam thermal insulation.

Tests and observations were performed on samples prepared in the

laboratory and also removed from one cavity of a wall of a woodframe house. The tests to characterize the foam included

measurements of density, moisture content, shrinkage, and thermal

conductivity, and analysis using X-ray diffraction, scanning

electron microscopy, and thermogravimetric techniques. It is

again emphasized that, because of the limited extent of the field

observations and laboratory testing, the information reported

applies only to the samples in the study. Based on the field

observations and on the results of the laboratory tests, the

following conclusions were made:

1. Thermal conductivity and dry density . The thermal conductivity

of the foam was typical of that for other retrofit insulations

ranging from 0.041 to 0.045 W/m»°C (0.28 to 0.31 Btu *in. /h -f t^.

°F). Over the temperature range tested, the thermal conductivity

increased linearly with an increase in the mean temperature of

the specimen. The thermal conductivity was found to be 15

percent higher than that previously reported. This finding may

have been due, in part, to testing specimens having dry densities

that were 50 percent higher than those previously reported for

the foam insulations, with some contribution due to minor cracks

in the specimens. The density of the foam removed from the house

29
was comparable to that of the samples prepared in the laboratory

for the present study.

2. Moisture Content . The foam insulation samples, prepared

wet in wooden boxes in the laboratory, lost their initial

moisture over 96 days while remaining under ambient laboratory

conditions. The moisture content of the resultant foam was about

2 percent. This value was comparable to that of the 1 year-old

foam removed from the wood-frame house, indicating that, in this

case, the insulation installed wet in the wall had lost the water

present during application.

3. Shrinkage . Shrinkage of the foam insulation was observed

for the laboratory samples prepared in wooden boxes, as indicated

by cracking of the foam. The shrinkage was generally small, as

evidenced by the widths of the shrinkage cracks. However, the

extent of shrinkage could not be quantified. Because the

shrinkage cracks were narrow and randomly located across the bulk

of the foam, it was not possible to determine the accumulated gap

space necessary for a shrinkage calculation. In the case of the

field sample, incomplete filling of the cavity precluded obtaining

shrinkage measurements.

4. Field Observations (Other Than Shrinkage) . The observations

from the field indicated that, for the cavity opened for inspection,

the installation of the foam was incomplete. The installed foam

was intact in the cavity without evidence of crumbling. Nevertheless

the foam was friable to handle. The field observations also

indicated no visible evidence of moisture problems in the cavity

30
examined.

5. Analytical Techniques . X-ray diffraction, scanning

electron microscopy, and thermogravimetric analysis offer useful

techniques for characterizing the magnesium oxychloride-based

foam insulations. The X-ray diffraction analysis provided

evidence that magnesium oxychloride cement was present in the

insulation, but did not indicate whether it was the 3 -form, 5-

form, or a combination of both. X-ray diffraction indicated that

the laboratory sample and the field sample from the outer side of

the cavity appeared to be identical. The technique also suggested

that the field sample from the inner side of the cavity may have

contained some chlorocarbonate, which may have formed through the

reaction of the magnesium oxychloride with the carbon dioxide in

air. The SEM analysis was consistent with the X-ray diffraction

analysis in that the laboratory samples, in general, had

microstructures similar to those of the field sample removed from

the outer side of the cavity. Conversely, the microstructure of

the field sample removed from the inner side of the cavity was

different, indicating that some change may have occurred. The

results of the thermogravimetric analysis were not completely

consistent with the those of the other two analytical techniques.

The thermograms for the two laboratory samples were comparable

with each other. However, the thermograms for the laboratory

samples were considered different from those of both field

samples. In addition, the thermogravimetric analysis results

were not consistent with thermograms published for pure magnesium

31
oxychloride cements. This latter finding was not surprising,

since it has been reported that the foam is prepared based on

magnesium oxychloride technology, but contains fillers and other

ingredients which may affect its composition.

5 . 2 Recommendations

As indicated, this initial study was limited in scope. Moreover,

the data obtained on foam characterization using the various

analytical techniques were, in some cases, inconsistent from one

method to the next, pointing out the need for additional

characterization. Thus, because of the limited scope of the

study and inconsistencies in some of the analytical data,

recommendations are made that the X-ray diffraction, SEM, and

thermogravimetric analyses be extended to provide further

characterization of the foam. Investigations should include

studies to quantify the composition of the cement-based insulation,

and to evaluate the potential of the cement to undergo carbonation

and the effect of carbonation on insulation performance.

32
6 . ACKNOWLEDGMENTS

This study was sponsored by the U.S. Department of Energy, Office

of Conservation and Renewable Energy. The authors gratefully

acknowledge the support of William Gerken, DOE, and David

McElroy, ORNL , for their encouragement and assistance during the

study. Thanks are also extended to their NBS colleagues who

assisted in the laboratory testing and report preparation: Jack

Lee and Ned Embree for sample preparation, and density and

moisture measurements; Thomas Somers and Thomas Faison for

thermal conductivity measurements; Paul Stutzman for X-ray

diffraction and SEM analyses; Willard Roberts for thermogravimetric

analysis; and Douglas Burch and Stephen Treado for valuable

review of a draft of the report.

Thanks and appreciation are also expressed to Douglas and Carmen

Palmer (Palmer Industries, Frederick, MD) who provided laboratory

samples, and made arrangements for obtaining field samples from

the house. Mr. Palmer also performed the necessary carpentry to

remove the foam from the house and restore its wall.

33
7. REFERENCES

1. Rossiter, Walter J., Jr. and Mathey, Robert G., "UreaFormaldehyde Foam Insulations: A Review of Their Properties

and Performance," National Bureau of Standards (U.S.),

Technical Note 1210 (March 1985), 70 pages.

2. Rossiter, Walter J., Jr. and Mathey, Robert G. , "Magnesium

Oxychloride Cement-Based Foam Insulation: A Review of

Available Information and Identification of Research Needs,"

National Bureau of Standards (U.S.), NBSIR 86-3326 (June

1986 )

40 pages

3. Rossiter, W.J., Jr., Ballard, D.B., and Sleater, G.A.,

"Elevated Temperature Effects on Urea-Formaldehyde Foam

Insulations Observed by Scanning Electron Microscopy," in

Thermal Insulation, Materials, and Systems for Energy

Conservation in the '80s , ASTM STP 789, F.A. Govan, D.M. Greason,

and J.D. McAllister, Eds. (1983), pp. 665-687.

4. Klug, H.P. and Alexander L.E., X-Ray Diffraction Procedures , 2nd. edition, Wiley, New York (1974).

5. Goldstein, J.I., et al.. Scanning Electron Microscopy and

X-Ray Microanalysis , Plenum Press, New York (1981).

6. Turi, E.A., Ed., Thermal Characterization of Polymeric

Materials , Academic Press, New York (1981).

7. Tye, R.P. and Desjarlais, A.O., "Performance Characteristics

of Foamed-in Place Urea-Formaldehyde Insulation," Oak Ridge

National Laboratory (U.S.), ORNL-Sub-78/86993/1 (June 1981),

36 pages.

8. McFadden, Peter W. , Azar, Kaveh, and Zebrowski, Thaddeus J.,

"The Thermal Resistance of In Situ Urea-Formaldehyde Foam

Insulation," J. Thermal Insulation, Vol. 6 (October 1982),

pp. 63-74.

9. Weidt, John, Saxler, Robert J., and Rossiter, Walter J.,

Jr., "Field Investigation of the Performance of Residential

Retrofit Insulation," National Bureau of Standards (U.S.),

Technical Note 1131 (September 1980), 67 pages.

10. Cole, W.F. and Demediuk, T. , "X-Ray, Thermal, and Dehydration

Studies on Magnesium Oxychlorides," Australian Journal of

Chemistry, Vol. 8, No. 2 (1955), pp. 231-251.

11. Sorrell, Charles A. and Armstrong, Charles R. , "Reactions

and Equilibria in Magnesium Oxychloride Cements," J. American

Ceramic Society, Vol. 59, No. 1-2 (1976), pp. 51-54.

34
Table 1. Results of Density Measurements

Specimen Determinations Density COVa

No. kg/mJ lbm/f

J o,*o Lab, wet 3 89 5.6

1

• O

Lab, dry 4 44 oo (N • 4.4

(28 days)

Lab, dry 4 46 2.9 3.5

(96 days)

House, dry 3 48 3.0 3.3

a. coefficient of variation

35
Table 2. Results of the Thermal Conductivity Measurements.

Specimen Density3 Mean Temp. Thermal Conductivity

No.

kg/m2

( lbm/f

2

) °c

( °F)

W/m °C

( Btu in./h ft 2 °F

1 47 24 0.0430

(2.9) (75) (0.298)

2 46 12 0.0408

(2.9) (44) (0.283)

2 46 24 0.0425

(2.9) (75) (0.294)

2 46 38 0.0450

(2.9) (100) (0.312)

a. Density was determined after the thermal conductivity

was measured.

36
Table 3. Results of Thermogravimetric Analyses.

Specimen Temperature Range

No. Low Medium High

40 - 175 °C

(104 - 347 °F)

175 - 300 °C

(347 - 572 °F

300 - 450 °C

(572 - 842 °F)

Mass Loss, % Mass Loss, % Mass Loss, %

Lab. 1 11 2 16

Lab. 2 11 2 19

Field

Outera

15 3 21

Field

Inner*3 16 4 24

3-form

MgOClc

34 negligible 26

5-form

MgOClc

27 negligible 26

a. Specimen was taken from the vicinity of the outer side of the cavity.

b. Specimen was taken from the vicinity of the inner side of the cavity.

c. Data are taken from Cole and Demediuk [10].

37
Fig. 1. SEM photomicrograph of a laboratory foam specimen at x20 magnification.

38
Fig. 2. SEM photomicrograph of a laboratory foam specimen at

x200 magnification.

39
Fig. 3. SEM photomicrograph of a field foam specimen at x2000

magnification. The specimen was removed from the inner

side of the wall cavity.

40
TEMPERATURE,

°F

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(1.8°F/rnin) 
NBS-114A (rev. 2 -ec) U.S. DEPT. OF COMM. 1. BIBLIOGRAPHIC DATA

SHEET (See instructions)

PUBLICATION OR

REPORT NO.

2. Performing Organ. Report NoJ 3. NBSIR 87 3642

Publication Date

4. TITLE AND SUBTITLE

An Initial Investigation of the Properties and Performance of Magnesium

Oxychloride-Based Foam Thermal Insulation

5. AUTHOR(S)

Walter J. Rossiter, Jr.; and Paul Brcwn

6. PERFORMING ORGANIZATION (If joint or other than NBS, see instructions) 7 . Contract/Grant No. NATIONAL BUREAU OF STANDARDS

U.S. DEPARTMENT OF COMMERCE

GAITHERSBURG, MD 20899

8. Type of Report & Period Covered

9. SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street. City. State. ZIP)

U.S. Department of Energy

Office of Conservation and Renewable Energy

Washington. DC 20585

10. SUPPLEMENTARY NOTES

| | Document describes a computer program; SF-185, FIPS Software Summary, is attached.

11. ABSTRACT (A 200-word or less factual summary of most significant information. If document includes a significant

bi bliography or literature survey, mention it here)

This study is an initial investigation of the properties and performance of magnesium

oxychloride-based foam thermal insulation. Tests and observations were performed on

samples prepared in the laboratory and also removed from one cavity of a wall of a

wood-frame house. The tests to characterize the foam included measurements of density,

moisture content, shrinkage, and thermal conductivity, and analysis using X-ray

diffraction, scanning electron microscopy, and thermogravimetry techniques.

It was found that the foam had a thermal conductivity comparable to that of other

insulations used to retrofit walls of houses. Shrinkage could not be quantified, but

was seen to be generally small. The moisture content of the foam removed frcm the

house was about 2 percent. The results of the analytical measurements indicated that

the laboratory-prepared samples and seme of those removed frcm the house were not

identical. It was suggested that further analysis be conducted to continue characterization of the foam.

12. KEY WORDS (Six to twelve entries; alphabetical order; capitalize only proper names; and separate key words by semicolon s) characterization; density; foam; insulation; magnesium oxychloride cement; moisture

content; SEM; shrinkage; thermal analysis; thermal conductivity; X-ray diffraction

13. AVAILABILITY

Unlimited

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Order From Superintendent of Documents, U.S. Government Printing Office, Washington, D.C.

20402.

PH Order From National Technical Information Service (NTIS), Springfield, VA. 22161

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PRINTED PAGES

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