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CHEMICAL ENGINEERING JOURNAL VOL.1, NO.1, JANUARY 2012 4

4

The Influence of Aggregate Type on the Physico-Mechanical

Properties of Magnesia Cement Pastes

Medhat S. El-Mahllawy, Hassan A. Hassan and Ayman M. Kandeel

Abstract

The work concerns physico-mechanical properties of

magnesia cement pastes-specially magnesium oxychloride

(MOC) cement pastes-mixed with different types of

aggregate. Fine and coarse carbonate quarry waste and

sand dunes resulted in the six mixes were studied. Three

mixes included the aggregates without water glass

treatment while the remaining mixes contained aggregatestreated with water glass. The influence of the aggregate

types on the water absorption, bulk density, compressive

strength and other properties of the magnesium oxychloride

(MOC) cement pastes at 3, 7, 28 days of curing were

determined. Also, water soaking at 90 days curing was

measured. The results revealed that the water/solid ratio,

aggregate type, aggregate size, and water glass additive

affected greatly on the properties of the MOC cement

pastes. Among the studied mixes, the mix containing treated

sand dune aggregate is found the most suitable forusing as

a starting point in a suitable practice.

Index Termscarbonate quarry waste, magnesium

oxychloride cement, physico-

mechanical properties, Sand dunes,

1.INTRODUCTION

Magnesia cements have been attracted attention for many

years due to their properties and potential applications. One

type of magnesia cement, magnesium oxychloride (MOC)

cement, also known as Sorel cement, is a type of non-

hydraulic cement formed by mixing powdered magnesiumoxide (MgO) with a concentrated solution of magnesium

chloride (MgCl2).

M. S. El-Mahllawy*, H. A. Hassan and A. M. Kandeel are with the Raw

Building Materials and Processing Technology Research Institute.

The Housing and Building National Research Center, Cairo, Egypt.87 El-Tahrir St., Dokki, Giza, Egypt. P.O. Box 1770, Cairo.

E-mail of the corresponding author*:[email protected].

Manuscript received January 6, 2012.

The MOC cement has many superior properties

compared to ordinary Portland cement. It has high fire

resistance, low thermal conductivity, good resistance to

abrasion and is unaffected by oil, grease and paints [1]. It is

also distinguished by a high strength/bonding, quick setting

time and does not require humid curing [2].

Magnesia (MgO) is mostly produced by calcination of

magnesite (MgCO3) at a temperature around 750C. The

quality or reactivity of the formed magnesium oxide

powder is largely affected by calcination temperature, firing

duration and particle size. The reactivity of MgO increases

with decreasing crystal sizes through decreasing the firing

temperature and increasing the surface area of crystals

[3 and 4]. The thermal history of the magnesite is the main

variable affecting surface area and reactivity of the

magnesia; these both increase as temperature increases up

to 900C and then decrease [5]. This in turn influences both

the reaction rate and the properties of the reacted product of

magnesium oxychloride cement.

Calcination of magnesia limits its reactivity. In the range

of 500-1000oC, magnesium carbonate is progressively

transformed into magnesia. Between 1000-1250o

C,a reorganization of the surface occurs. Above 1250oC,

particles melt and agglomerate. The theoretical surface area

as well as the reactivity of magnesia decreases [6].

The setting and hardening of the MOC cement takes

place in a through-solution reaction and is based on the

reaction between MgCl2 and MgO [7]. Four main reaction

phases in the ternary MOC system are found; 2MgO (OH)2.

MgCl2.4H2O (phase2), 3Mg(OH)2. MgCl2. 8H2O

(phase3), 5Mg(OH)2.MgCl2.8H2O (phase 5), 9Mg(OH)2.

MgCl2.5H2O (phase9), and Mg(OH)2, brucite. These

phases exist as reinforced components in the ternary system

at ambient temperature [8].

Magnesium oxychloride cement has many good

engineering and mechanical properties, but it has a poor

water resistance, causing significantly decreased strength

of hardened MOC paste in water thereby

limiting its engineering applications. Consequently, many

investigations on the water resistance of MOC cements

have been carried out over the years [9]. Additives that can

greatly improve the water resistance of MOC cement are

soluble silicates such as sodium silicate, phosphoric acid
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and soluble phosphates, including the phosphates of alkali

metals, the phosphates of alkali earth metals, iron,

aluminum, and the phosphates of ammonia. Small amount

of these compounds can improve the water resistance of

MOC cement pastes significantly.

The presence of magnesium carbonate as an impurity in

magnesia and grinding a powder allow a better reactivity,

because the dissociation of magnesium carbonate is quickerthan that of magnesia [6].

This work aims to study the effect of different treated and

non- treated aggregate types; carbonate quarry waste of two

sizes and sand dunes made with different water/solid (w/s)

ratios on the physico-mechanical properties of the hardened

magnesium oxychloride cement pastes.

II.Experimental Procedures

A. Materials

The materials used in the current research are magnesite(M), sand dunes (SD) and carbonate quarry waste (CQW)

as aggregates. Magnesite as a raw material is extracted from

the southern Eastern Desert of Egypt associated with

mafic and ultramafic serpentinzed rocks. Calcination of

commercial Egyptian magnesite at about 750oC for 2h

produced a white to light yellow color of magnesia (MgO)

powder that was used in this investigation. The sand was

collected from the Quataniya sand dunes at 6th October

south Cairo, Western Desert of Egypt. The carbonate quarry

waste was taken from Gebel Attaqa area, Cairo-Suez desert

road, Egypt. Here, considerable amounts of carbonate

quarry waste in the form of powder as by-product from the

stone crushers are produced. This fine quarry waste is beingcollected, accumulated in the site, and the utilization of the

waste is a big problem from aspects of safe disposal,

environmental pollution and health hazards. In this study,

two sizes were used, passed from 1 mm and 90micrometer

sieves.

Also, additives were used in the present study;

commercial grade of the available water glass (Na2SiO3)

aqueous solution and the powder salt of ammonium

dihydrogen phosphate (NH4H2PO4) for improving the water

resistance of the Sorel cement.

B. Sample Preparation

The mixtures were prepared with the aid of a laboratory

bench top mixer first by dissolving the MgCl2 and

NH4H2PO4 in sufficient quantity of water and secondly by

adding the dry materials (magnesium oxide powder and the

aggregate) incrementally to the mix and lastly by adding the

residual water demand to achieve good workability; in case

of water glass addition, it was added before pouring of the

residual water. The water- to- solid ratio was different for

all mixtures according to the type aggregates. It was

controlled by obtaining good workability during the

experiment. Following mixing, specimens were prepared by

placing the MOC cement paste in steel cube molds of a size

of 5x5x5 cm. The solidified specimens were demolded after

24h and then cured in the air at the ambient lab conditions

(202oC and relative humidity 65 5%) until testing at 3, 7

& 28 days. Care was taken to reduce the amount of airvoids as much as practically possible. The mixing

procedure was the same for all paste mixes each of which

was represented by 20 cube samples. Six mixtures of

different aggregates percentage (Tables 1 and 2) were

prepared for studying the physico-mechanical properties of

the air cured specimens at different ages. Mixtures A2, A4

and A6 (group A) were based on non-treated aggregates

while mixtures A3, A5 and A7 (group B) were based on

water glass treated aggregates.

C. Test Methods

The solid materials were tested as follows.

The chemical analysis was performed on the ground

pressed aggregates powder using Philips PW 1400 XRF as

well as following the test method described in the American

Society for Testing and Materials [10].

The particle size distribution was determined using the

dry sieve analysis method of the International Organization

for Standardization (ISO) for fine aggregates [11].

The mineralogical composition was characterized by

X-ray diffraction (XRD).The XRD analysis was carried out

on the powdered samples passed through the 25m sieve

using XRD apparatus of X'pert Pro type (Netherlands). The

analysis was run using Cu K radiation in the range 2from 5-50 with acceleration voltage condition of 40 kV

and 40 mA. The interpretation of the obtained phases was

achieved by the X'Port high score PDF-2 database software

on CD-Release 2006. The semi-quantitative estimation of

the obtained phases was calculated by the software based

on the half width method of the detected main peaks.

The physico-mechanical properties of the hardened

blended magnesium oxychloride cement paste mixtures

were studied after 3, 7 and 28 days of curing. The water of

consistency, bulk density, water absorption and

compressive strength were determined according to ASTM

standards [12-15]. Also, the durability of MOC cement

specimens air cured for two weeks was determine by water

soaking for 3 months at the lab ambient conditions.


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Table 1. Mix composition of mixtures with non- treated

aggregates (Group A)

Mixcode

Mix composition Quantity

% by wt.

W / S

ratio

Remarks onaggregate

A2

- MgO- Carbonatequarry waste- MgCl2- NH4H2PO4- Mixing water

33.80

33.80

16.90

0.24

15.26

0.18

CQS: Passed

from 1mm sieve

diameter(Coarse

aggregate).

A4

- MgO- Carbonate quarry

waste

- MgCl2- NH4H2PO4- Mixing water

35.62

35.62

17.81

0.25

10.70

0.12

CQS: Passed

from 90 m

sieve diameter

(Fine

aggregate).

A6

- MgO- Sand dunes- MgCl2- NH4H2PO4- Mixing water

36.94

36.94

18.47

0.26

7.39

0.08SD: Natural.

Table 2. Mix composition of mixtures with water glass treated

aggregates (Group B)

Mixcode

Mix composition Quantity

% by wt.

W / Sratio

Remarks onaggregate

A3

- MgO- Carbonatequarry waste


33.60

33.60

16.800.24

9.04

0.11

CQS: Passed

from 1 mm

sieve diameter

and treated with

water glass

A5

- MgO- Carbonate quarrywaste


34.4034.40

17.20

0.24

6.88

0.08

CQS: Passed

from 90 m

sieve diameter

and treated with

water glass

(100 ml).

A7

- MgO- Sand dunes- MgCl2- NH4H2PO4- Mixing water

35.00

35.0017.50

0.24

5.26

0.06

SD: Natural and

treated with

water glass

(100 ml).

III.Results and Discussion

A. Characterization of the Aggregate Raw Materials

The chemical composition of the used aggregates is listed

in Table 3. As expected, MgO is the main oxide in

magnesite, SiO2 is the main oxide in sand dune while SiO2,

CaO and MgO are the main oxides in the carbonate quarry

waste. The high value of loss on ignition (L.O.I) for

magnesite and carbonate quarry waste is due to the

releasing of a high content of CO2 during ignition. The

composition of the carbonate quarry waste refers to

including the aggregate on quartz, calcite and dolomite as

shown subsequently.

Table 3. Chemical analysis of the raw materials used (wt.%)

Oxide

content%

Magnesite(M) Sand dunes(SD)

Carbonate quarry

waste(CQW)

SiO2 1.20 93.88 20.20

Al2O3 0.07 3.76 1.94

Fe2O3 1.29 0.68 2.64

CaO 2.36 0.55 29.81

MgO 79.50 0.37 15.38

Na2O 0.01 0.21 0.25

K2O 0.01 0.09 0.20

SO3 0.43 0.02 0.39

TiO2 0.01 0.10 0.23

P2O5 0.01 0.01 0.06

L.O.I 15.01 0.23 28.81

The XRD patterns and their identified phases are shown

in Fig.1. In the XRD diffractograms, several typical

minerals are identified. The sand dune aggregate is

composed of quartz mineral SiO2 (100%). This is in

agreement with observations by other researchers. The

XRD of carbonate quarry waste is consistent with the

chemical analysis showing a composition of approximately

40% quartz, 35% dolomite CaMg(CO3)2 and 25% calcite

CaCO3. The magnesite aggregate is composed essentially of

pericales mineral, approximately 90% MgO and 10%

portlandite mineral Ca(OH)2. The mineralogical analysis of

each aggregate shows the same composition as that

revealed by the chemical analysis.

Fig. 1. X-ray diffraction patterns of the aggregates used
http://en.wikipedia.org/wiki/Calciumhttp://en.wikipedia.org/wiki/Carbonhttp://en.wikipedia.org/wiki/Carbonhttp://en.wikipedia.org/wiki/Calciumhttp://en.wikipedia.org/wiki/Oxygenhttp://en.wikipedia.org/wiki/Oxygenhttp://en.wikipedia.org/wiki/Oxygenhttp://en.wikipedia.org/wiki/Calciumhttp://en.wikipedia.org/wiki/Calciumhttp://en.wikipedia.org/wiki/Carbonhttp://en.wikipedia.org/wiki/Carbonhttp://en.wikipedia.org/wiki/Calciumhttp://en.wikipedia.org/wiki/Calcium


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The grain size distribution of the aggregates is illustrated

in Fig. 2. The size of studied aggregates is less than 1.8mm

and larger than 300 m, i.e. the aggregate maximum size is

1.18mm. As seen, the sand dune is the finest aggregate

followed by magnesite and carbonate quarry waste, in that

order. The graded materials belong to the fine aggregate

size [16]. Due to its fineness, sand dune, is expected to be

more reactive than the other studied aggregates.

Fig. 2. Grain size distribution based on dry sieves analysis of

theaggregate usedB. Physico-Mechanical Properties of the Hardened

MOC Cement Specimens

In order to study the effect of aggregate on the physico-

mechanical properties of hardened MOC specimens, testsDone were the water of consistency, bulk density, water

absorption, water soaking and compressive strength (dry

and wet).

C. Water Demand

In order to obtain the same workability, the water/solid

ratios (w/s) of the water glass non-treated mixes A2, A4

and A6 (group A) are 0.18, 0.12 and 0.08, respectively, cf.

Tables 1-2 and Figure 1. In other words, the mix which

contains coarse aggregate of dolomite requires the largest

water/ solid ratio followed by the mix which contains fine

aggregate of dolomite and the mix containing sand dunes in

that order. This is due to the larger water absorption of the

coarse dolomite aggregate than the fine dolomite aggregate

and sand dunes, so that the water/solid ratio increases with

aggregate size. Moreover, the siliceous sand aggregate

attains the lowest water absorption of the studied aggregates

[17]. The water / solid ratio of water glass treated mixes

A3, A5 and A7 (group B) are 0.11, 0.08 and 0.06,

respectively. The lowest values of group B compared to

group A are due to the aggregates of the former-as opposed

to the latter- group being treated with water glass as

reflected in the reduced the w/s ratio. The cement pastes of

the group B achieved the same arrangement of the group A

with the non treated aggregates.

D. Bulk Density

The bulk density of the cement specimens of all mixes

(groups A and B) as a function of the curing period (3, 7and 28 days) is plotted in Fig. 3. The bulk density depends

on the packing of the particles, which in turn depends on

shape, density, surface texture, and grading of the particles.

The figure shows that for the hardened MOC cement

pastes of group A mix A6 provides the highest bulk density

followed by A4 and A2, in that order. This may be due to

the higher specific gravity of sand dunes ( 1.40 -1.60

g/cm3) than the quarry waste (0.70 -1.20 g/cm3) [18]. Also,

the bulk density is seen to increase with increasing curing

period. Moreover, the bulk density of the cured cement

paste of mix A4 gives higher values of bulk density than

those of mix A2 at all curing times. This may be attributed

to the specific gravity of fine dolomite aggregate being

smaller than the coarse dolomite aggregate. This is

confirmed by the material having a higher density in the

solid state than the broken (crushed) state which in turns

has a higher density than the pulverized (dust) state (the

lowest). Group B followed the same trend as group A as

specimens of mix A7 have the highest bulk density

followed by A5 and A3, in that order. It is observed that the

bulk densities of equal matures mixes of groups A and B

containing the same aggregate are generally higher for the

latter group. This may be explained by the solubility of

silica in the alkaline media. Thus, MgO has high alkalinity,

reaching a maximum pH value of 10 [19] which provokesthe increase of amorphous silica solubility which in turn

fills the voids and bonds the matrix together, so that the

cement paste becomes harder than that without water glass.

This is supported by the finding of others [20].

It is known that the solubility of quartz in pure water at

25 C is about 6 parts per million whereas that of vitreous

silica is at least 10 times greater. The high solubility of

silica, especially the amorphous type, is obtained in alkaline

media (pH value higher than 9) and particularly the

solubility of amorphous silica at temperatures below 100oC

has been the subject of many investigations [21].

0

20

40

60

80

100

0.1 1 10

Sieve Size, mm

PercentPassing

MgO (LOCAL)

SAND DUNE

Carbonate Quarry Waste
http://www.amazon.com/s/ref=ntt_athr_dp_sr_1?_encoding=UTF8&sort=relevancerank&search-alias=books&field-author=M.%20G.%20Alexanderhttp://www.amazon.com/s/ref=ntt_athr_dp_sr_1?_encoding=UTF8&sort=relevancerank&search-alias=books&field-author=M.%20G.%20Alexander


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1.75

1.8

1.85

1.9

1.95

2

2.05

2.1

2.15

2.2

2.25

3 7 28

Curing time (Days)

Bulkde

nsity(gm/cm)

A2

A4

A6

A3

A5

A7

3

Fig. 3. Bulk density of hardened MOC cement specimens at 3, 7

and 28 daysair curing.E. Water Absorption

Water adsorption of the air cured specimens of the groupsA and B after immersion in tap water for 24h are plotted in

Fig. 4. It is observed that the hardened magnesium

oxychloride (MOC) cement past of mix A2 provides higher

values of water adsorption than mixes A4 and A6 at all

curing times. This indicates that the coarse dolomite

aggregate absorbs more water than the fine dolomite

aggregate and sand dunes. Mix A6 which contains sand

dunes affords lower values of water absorption at all curing

times. This is due to the physical properties of sand which

commonly have lower water absorption than carbonate

aggregate (quartz, calcite and dolomite). The MOC cement

specimens of group B show lower water absorption than

those of group A with the same aggregate but with andwithout water glass treatment, respectively This could be

attributed to various factors such as: (a) water glass acts as

a bonding agent (b) water glass is a sodium silicate solution

that in the presence of MgCl2 produces very fine sized

silicon chloride particles which can fill the pores acting as

a water repellant, causing the water absorption to decreases

(c) the amorphous silica may fill the voids between the

grains reducing water absorption (d) a chemical reaction

between the water glass and the aggregate permanently

binding the silicates to the aggregate surface making them

far more wearable and water repellent [22].

At any given curing time, mix A7 attained the lowest

water absorption of all mixes. The sodium silicate may act

as a glue producing a thin layer on sand grains to bond them

together [23]. However, aggregate treated with sodium

silicate solution significantly reduces porosity. In addition,

water absorption increases as the curing progresses. This is

likely ascribed to the escape of free water from the

specimens as indicated by the decrease in weight of the air

cured specimens with increasing curing time. This is shown

by the experimental tests. From this point of view, the

affinity of the cement specimens to absorb water is

increased as the curing time increases

0

1

2

3

4

5

6

7

8

3 7 28

Curing time (Days)

Waterabsorpti

on(%)

A2

A4

A6

A3

A5

A7

Fig. F Fig. 4. Water absorption of hardened cement specimens of the

different mixes at different air curing times after

immersion in tap water for 24 hours

F. Water Soaking

Table 4 shows the effect of soaking time on the splitting

of soaked MOC cement specimens. All specimens sustained

successfully the passive effect of water until 5 days of the

immersion in water. Continued immersion in water until

day 10 caused simple splitting on the specimen surfaces

except for mixes A3 and A7. Further water immersion until

day 15 resulted in clear cracks and sever splitting of all

specimens, mixes A3 and A7 excepted. To verify the

resistivity of specimens A3 and A7, they were immersed in

water for 90 days. It may due to that the expansion effect

according to formation of Mg(OH)2 from non reacted MgOwith water. The volume expansion due to the hydration of

MgO has been linked to cracking [24]. However, such

cracking only occurs provided the expansion of the material

is constrained [25]. If a sufficient amount of MgO is used,

the hydration occurs at a rate without causing cracking due

to delayed hydration; this can be achieved by calcination of

magnesite at low temperatures (< 750oC) forming products

that are resistive to the breakdown in water [24].

The study confirms that specimens made of mixes A3

and A7 submerged in water did not split. This may be due

to the type of aggregate used, the low water absorption and

the presence of water glass and ammonium dihydrogen

phosphate in appreciable amounts. Other mixes may needenough amounts of these additives. Note that the addition of

soluble phosphates to MOC improves the water resistance

by precipitation of totally insoluble phosphate complexes

[26] according to the following equations:

MgO + H2O= Mg (OH)2

3Mg (OH)2+2H3PO4= Mg 3((PO)4)2 + 6H2O
http://en.wikipedia.org/wiki/Porosityhttp://en.wikipedia.org/wiki/Porosity


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Table 4. Visual observation of water soaked hardened

specimens of the different mixes

Specimens of

the

mix code

Splitting versus soaking time, days

0 - 5 6 - 10 11 -

15

16 -

90

A2

No evidence

for splitting

for the all

specimens

Simplesplitting at the

specimens

surfaces.

Severe splitting

and clear cracks

A4

A6

A5

A3

No splitting

A7

G. Compressive Strength

The dry and wet compressive strength of the hardenedMOC specimens of groups A and B at different air curing

times up to 28 days are presented in Figs. 5 and 6,

respectively. It can be seen that the strength of the MOC

specimens of groups A and B increases with the increase of

the curing times. It is revealed that the specimens of mix A7

have the maximum strengths at all curing ages, while the

specimens of A2 have the minimum strengths. Also, the

water glass treated specimens (A7, A5 & A3) provide

higher values than the corresponding non treated specimens

(A6, A4 & A2) i.e. specimens of the SD (treated and non

treated aggregate) provide the highest values followed by

CQW (treated and non treated aggregates) and then M

(treated and non treated aggregates).The wet compressive strength of the cured MOC

specimens are lower than the dry compressive strength at

the same curing age and follow the same trends of the dry

specimens. Moreover, the lower w/s ratio, the higher the

strength of the hardened MOC specimens. It is evident that

the water to solid ratio plays an important role in the

compressive strength property. Thus, the low strength

values of mix A2 may be caused by the high content of free

water which forming a large quantity of pores in the matrix.

This is supported by the fact that the specimens of mix A2

attain the maximum water absorption at all curing times

(2.397.35%). Thus, many pores inside the body skeleton

are formed which soften the body.

It would appear that the prerequisites for achieving high

performance MOC are: (1) the production of phase 5

(5Mg(OH)2.MgCl2.8H2O),(2) reduction of the content of

non reacted MgCl2 content, and (3) obtaining a reasonable

workability with an appropriate setting time [3]. When

MgO is mixed with MgCl2 solution, MOC gel paste is

produced forming a network which strengthens the

specimens as the curing time increases [27].

It is likely that upon the addition of water to the dry

mix, the ammonium dihydrogen phosphate dissolves in the

water to form an acidic solution which reacts with MgO at

the surface of the magnesia particles. When sufficient

hydrates are formed, the cement paste sets and hardens,

thereby increasing the strength as observed by others [20].

50

100

150

200

250

300

350

400

450

500

3 7 28

Curing time (Days)

Compressivestrength(kg/cm)

Dry A2

Dry A4

Dry A6

Wet A2

Wet A4

Wet A6

2

Fig. 5 Fig.5. Dry and wet compressive strength of the hardened

pastes made from mixes A2, A4 and A6 cured in

air up to 28 days

50

100

150

200

250

300

350

400

450

500

550

3 7 28

Curing time (Days)

C

ompressivestrength(kg/cm)

Dry A3

Dry A5

Dry A7

Wet A3

Wet A5

Wet A7

2

Fig. 6. Fig. 6. Dry and wet compressive strength of the hardened

pastes made from mixes A3, A5 and A7 cured in

air up to 28 days.

IV. Conclusion

The influence of carbonate quarry waste and sand dune as

aggregates on the physico-mechanical properties of

hardened magnesium oxychloride (MOC) cement pasteswas studied. The following conclusions can be drawn from

the present study.

- The MOC mixes which contain water glass treated sand

dunes provide the highest bulk density, compressive

strength and water resistivity as well as the lowest water

absorption.

- The mix which contains fine dolomite aggregate (water

glass treated or non treated) attains improved physico-


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mechanical values over those of mixes containing coarse

dolomite aggregate even after treatment by water glass.

- Treatment of the aggregates by water glass improves the

physico-mechnical properties for all mixes.

- The w/s ratio is an important parameter for controlling the

properties of magnesia cement specimens containing

water glass treated as well as non treated aggregates. This

is in analogy with the increase in compressive strength ofPortland cement specimens with the decrease in free

water.

- The study suggested that mix A7 based on sand dune

aggregate is a suitable starting point for the application of

MOC, magnesium oxychloride cement.

References

[1] Bensted, J; Barnes, P.: Structure and performance of

cements. 2nd Ed. Spon Press, London, 2002.

[2] Maravelaki, K.; Moraitou, G.: Sorel's cement mortars

decay susceptibility and effect on Pentelic marble. Cerm.

Concr. Res. 29(12),1929-1935, 1999.[3] Li, Z.; Chau, C.: Influence of molar ratios on properties

of magnesium oxychloride cement. Cem. Concr. Res. 37

(6), 866-870, 2007.

[4] Kandeel, A.: Effect of grain size of Mgo powder on the

physico-mechanical properties of magnesium oxysulfate

cement paste. Egypt. J. Appl. Sci. 24(12B), 521-530,

2009.

[5] Birchal, V.; Rocha, S.; Ciminelli V.: The effect of

magnesite calcination conditions on magnesia hydration.

Miner. Eng. 3 (14-15), 1629-1633, 2000.

[6] Soud'ee, E.; P'era, J.: Inflence of magnesia surface on

the setting time of magnesia-phosphate cement. Cem.

Concr. Res. 32, 153-157, 2002.

[7] Urwongse, L.; Sorrell C.: The system Mgo-MgCl2-H2O

at 23oC. J. Amer. Cram. Soc. 63, 501-504, 1980.

[8] Beaudoin, J.; Ramachandran, V.: Strength development

in magnesium oxychloride and other cements. Cem.

Concr. Res. 5 (6), 617-30, 1975.

[9] Chuanmei, Z.; Dehua, D.: Research on the water

resistance of magnesium oxychloride cement and its

improvement. J. South China Univ. 23 (6), 673679,

1995.

[10] ASTM-Designation D7348: Standard Test Methods for

Loss on Ignition (LOI) of Solid Combustion Residues.

Annual Book of ASTM Standards, V.05.06, USA, 2008.[11] ISO 6274: Conrete-sieve analysis of aggregate. 1St

(ed.), pp.06-01, 1982.

[12] ASTM-Designation C187: Standard test method for

normal consistency of hydraulic cement. Annual Book of

ASTM International standards, V. 04.01, USA, 2004.

[13] ASTM-Designation C109 / C109M: Standard test

method for compressive strength of hydraulic cement

mortars (Using 2-in. or [50-mm] cube specimens. Annual

Book of ASTM Standards, V. 04.01, USA, (2008.

[14] ASTM-Designation C1585: Standard Test Method

for Measurement of Rate of Absorption of Water by

Hydraulic-Cement Concretes. Annual Book of ASTM

Standards, V.04.02, USA, 2004.

[15] ASTM-Designation C134: Standard test methods for

size, dimensional measurements, and bulk density of

refractory brick and insulating firebrick. Annual Book of

ASTM Standards, V.15.01, USA, 2010.[16] ASTM-Designation C125: Standard Terminology

Relating to Concrete and Concrete Aggregates. Annual

Book of ASTM Standards, V.04.02, USA, 2010.

[17] Smith, M.; Collis, L.; Fookes, P.; Lay, J.; Sims, L.:

Aggregates: sand, gravel and crushed rock aggregates for

construction purposes. The Geological Society, London.

3rd Ed., 2001.

[18] Alexander, M.; Mindess, S.: Aggregates in Concrete

(Modern Concrete Technology). 448 p. Spon Press,

London, 2005.

[19] Jianli, M.; Youcai, Z.; Jinmei, W.; Wang, L.: Effect of

magnesium oxychloride cement on

stabilization/solidification of sewage sludge. J. Const.Build. Mat. 24, 79-83, 2010.

[20] Ding, Z.; Li, Z.: Effect of aggregates and water contents

on the properties of magnesium phosphor-silicate cement.

Cem. Concr. Comp. 27, 11-18, 2005.

[21] Fournier, R.; Rowe, J.: The solubility of amorphous

silica in water at high temperatures and high pressures.

Amer. Miner. 62, 1052-1056, 1977.

[22] Ito, T.; Sobue, K.; Ohya, S.: Water glass bonding for

micro-total analysis system. Sensor and Actuators B:

Chemical, 81 (2-3), 187-195, 2002.

[23] Lucas, S.; Tognonvi, M.; Gelet, J., Soro, J.; Rossignol S.:

Interactions between silica sand and sodium silicate

solution during consolidation process. J. Non-Crystalline

Solids 357 (4), 1310- 1318, 2011.

[24] Harrison, J.: Reactive magnesia oxide cements. In:

W.I.P. Organisation (ed.), Australia, 2001.

[25] Vandeperre, L.; Liska, M.; Al-Tabbaa, A.:

Microstructures of reactive magnesia cement blends. Cem.

Concr. Comp. 30, 708-714, 2008.

[26] Kurdowski W, Sorrentino F. Special cements, in: P.

Barnes (Ed.), structure and performance of cement, Appl.

Sci. Pub., London , p. 539, Chapter 10, 1983.

[27] Dehua D. The mechanism for soluble phosphate to

improve the water resistance of magnesium oxychloride

cement. Cem Concr. Res. 33 (9): 1311: 1317, 2003.

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