FACTORS CONTROLLING DURABILITYOF SOME EGYPTIAN NON-STYLOLITIC MARBLEIZED LIMESTONE TO SALT WEATHERING H.El Shayab1, G. M. Kamh1, N.G.Abdel Ghafour2, and M.L.Abdel Latif 2

Faculty of Science, Menofyia University, Egypt1, Housing and Building National Research Center, Egypt2,Keywords: Marbleized limestone; Durability; Salt crystallization; Non-Styolitic limestone.ABSTRACTNowadays, marbleized limestone becomes one of the most important sources of the mineral wealth in Egypt as they have beautiful colors (white, grey, rose, yellow and creamy.etc) make it very suitable for decoration purposes. Non-styolitic marbleized limestone which not contains styolitic surfaces. The current study aims to study different factors controlling durability of non-styolitic marbleized limestone against salt crystallization weathering. The achievement aim of the research was required nine representative samples were collected from the studied areas. Three samples from each of the studied areas. The studied samples was characterized by various instrumental methods before salt weathering, to determine its mineralogical composition, chemical composition and pore physical properties respectively. The obtained results revealed that both of Duwi and Delga studied samples nearly have the same average M% 1.63and 1.51 respectively and consequently A.I. stage of deformation. On the other hand, average M% of Wata studied samples is 0.29 i.e. lower than two other studied areas. Wata studied samples are more durable against salt crystallization test than Duwi and Delga. The difference in salt crystallization durability may be resulted from one of the following factors: Microscopic textural effect as both of micrite and skeletal percent are in directly proportional to durability of stones to salt weathering. Dolomite mineral present as a secondary are in indirectly proportional to durability of stones to salt weathering. Increase in MgO% also associated with decrease the durability of studied samples against salt crystallization test. Finally, all factors affecting positively against salt crystallization test presents in Wadi Wata studied samples rather than others two areas.1. INTRODUCTIONThroughout the history, the term marble commercially to describe all of the ornamental stones regardless their geological origin. This leads to an overlap between marbleized limestone and the well known true marble. A marbleized limestone (compact limestone) is a hardened limestone subjected to advanced stages of diagensis or recrystallization without metamorphism and represents one of the sedimentary origins. Consequently, it becomes widely used allover Egypt. Some of Egyptian marbleized limestone called styolitic marbleized limestone which contains irregular serrated surfaces called styolites. Others not contain such these surfaces called non-styoltic marbleized limestone. The last type (non-styoltic marbleized limestone) the subject of the current research.

In the last decades, much concern has been focused on the study characterization of the two marbleized limestone types in Egypt e.g. Gomma and Rashwan;(1975); Darweesh and Nour El- Din (2000); Attia (2007) and Abdel latif (2011).

As salt crystallization is the most damaging weathering agent affecting building materials and one of the primary agents in the loss of our architectural heritage. Therefore, Egyptian and worldwide researchers were interested in studying the deterioration of different types of building stones particular limestone by salt crystallization For instance, Arnold and Zehnder (1991) Goudie and Viles (1997); Kovacs (2009); Alves et al., (2009) and Kamh and Ogushi (2012).

In Egypt limited previous work related to study durability of marbleized limestone against salt crystallization so, in the present study we will concern with it in detail including: textural effect, mineralogical effect, and chemical composition effect. Figure1. Simplified location map of the studied samples. Sample area

1. Gabal Duwi

2. Wadi Wata

3. Delga

2. Materials and Methods

2.1. Sampling

Nine representative samples were collected from the studied areas (Fig.1).Three samples from each of the studied areas. The studied samples of Gabal Duwi symbolized Th1 to Th3 from Wadi Wata symbolized T1 to T3 and finally, Delga representative samples symbolized W1 to W3. All of the collected samples have been selected from currently used quarries away from jointing and schistosity places. It is noticed that samples of both Gabal Duwi and Delga are characterized by their creamy to off-white color and also their high percent mega fossils contents which can be detected by naked eye. On the other hand, Wadi Wata studied samples marked by its yellow to kaki color with trace or absent mega fossils content. 2.2. Methodology

2.2.1. Mineralogical techniques

Detailed mineralogical composition has been investigated using transmitting polarizing microscope (Olympus BX50, Japan), X-ray diffraction (XRD) X-ray model XPert ProPhillips MPD PW 3050/60 X-ray diffractometer. Scanning electron microscope model (Inspect SFEI Company, Holland) with accelerating voltage of 200 v to 30 kv with magnification up to 300,000 X. It used in the recent research to detect the effect of salt crystallization test on the studied samples.

2.2.2. Chemical composition

Chemical analysis of major oxides was determined for the nine studied samples using X-ray Fluorescence (XRF) (Phillips PW 1400 Spectrometer, Holland).

2.2.3. Pore size distributionPore size distribution (PSD) was measured for three random samples using Mercury Intrusion Porosimetry (MIP) working at low and high mercury pressure to ensure reaching the nano-pores of the tested sample. The results of MIP also reflected important factors of stone durability called Salt Susceptibility Index (SSI) that is defined as stones susceptibility before artificial weathering (salt crystallization) depended on MIP.

2.3.4. Salt crystallization test

For each stone type, cubic specimens were subjected to the salt crystallization test described in EN 12370:1999 (using sodium sulphate).After salt crystallization test, the mass loss of each specimen and Alternative Index, A.I (cycle at which the first damage occurs) were detected. 3. Result and discussion3.1. Mineralogical compositionThe mineralogical composition of the studied samples conducted for petrographical description of the studied 15 thin sections revealed that G.Duwi marbleized limestone consist of a few dolomite rhombs embedded in a matrix of fine-grained limestone (microsparsize) with relicts of micrite (Fig.2a). The studied samples can be classified texturally as Wackstone (Dunhum, 1962) with Composition of Fossiliferous Biomicrite to Biosparmicrite (Folk, 1959). Petrographically, Wadi Wata studied samples consist of microgranular mosaic of small crystal (ooids) formed by recrystalization with average size (2-10 m). Most ooids in the studied thin sections are of a simple and single type (micritic and concentric) (Fig.2b). The studied samples can be classified as ooids packstone to grainstone (Dunhum, 1962) or classified as poorly washed oosparite (Folk, 1959).The petrographical studies of Delga marbleized limestone faices show that the major constituents are bioclasts (skeletal grains). More than 85% of these skeletal grains are Nummlites with sparitic size (> 10 m). Moreover, some lithoclasts (fragmented rock particles) are embedded into this micritic matrix (Fig.2C).Itcan be classified pertographically as Packstone (Dunhum ,1962) or ranged from poorlywashed Biosparite to Unsorted Bio Spar rite (Folk, 1959).XRD analyses conducted for the three selected samples (Fig.3).It showed that calcite mineral represents the main constituents for all of the studied samples. Moreover, dolomite was detected in G.Duwi studied sample with higher semi quantitative percentage%. Quartz recorded in minor amounts w ith other constituents such as mud. Dependence on the mineralogical composition of the studied faices it can be classified as following: G.Duwi can be classified as dolomitic limestone while, both of Wata and Delga samples classified as high-calcium limestone (Pettijohn, 1975).

Figure 2. Thin section Photmicrographs of the examined samples.

a. G.Duwi b.Wadi Wata c.Delga Figure3. X-ray diffractograph presents the mineralogical composition of the examined samples..3.2Chemical Analysis

The complete composition of the studied samples including Oxides, chloride, sulphates A.I.R, and LOI has been listed in table (1). The results revealed that CaO is the main oxide in all studied samples ranged from 52.47 in G.Duwi to 56.7 in Wata by wt%. MgO represents second occurred oxides with an average 3.7 wt% in Duwi samples. According to chemical classification the studied samples of G.Duwi are dolomitic limestone While, Wata and Delga are high calcium limestone according to percent of MgO% wt (Pettijohn, 1975). Table (1): Complete chemical analysis of the studied samples.

Sample name

SiO2

%Al2O3

%Fe2O3

%CaO

%MgO

%Na2O

% K2O

%P2O5

%SO3

% Cl

%LOI

%A.I.R

%Total

%

Th1 0.400.10.0452.973.10.06Z 0.030.020.060.0140.41.899.98

Th20.300 0.280.0552.83.80.06Z 0.030.010.040.0140.21.899.39

Th30.300.20.0252.474.40.05Z 0.020.030.050.0239.81.799.01

Avg0.330.190.0352.743.760.05Z 0.020.010.050.0140.131.7699.46

T10.640 030.3854.690.400.04Z 0.010.030.060.0143.50.3899.79

T20.670.020.3854.570.430.04Z 0.010.030.070.0142.630.4199.27

T30.610.020.3854.940.410.03Z 0.010.030.050.0143.010.3699.86

Avg0.640.020.3854.730.410.03Z 0.010.030.060.0143.040.3899.64

W10.260.070.1156.710.010.02Z 0.010.030.040.0141.850.499.52

W20.34 0.060.1256.840.050.03Z 0.020.030.020.0241.390.699.52

W30.150.050.1256.580.010.02Z 0.010.040.030.0142.660.299.88

Avg0.250 0.060.1156.710.020.02Z 0.010.030.030.0141.960.499.64

3.3. Pore size distribution (MIP)

MIP was conducted for three of the studied samples Figure (3). The obtained results table (2) show micro pores size and SSI of the studied samples and revealed that: all of the studied samples have uniform pore size ranging from 0.01:0.60 microns less than 5 Microns. SSI of the studied samples are also show similarity as all of it are very salt resistant. From the previous results it is detectable that all of the studied samples nearly have the same behave against salt weathering. Figure 4. Graphical relation between Incremental pore volume (mL/g) and pore radius (micron) For examined samples.

Table (2): Pore size and SSI of the studied samples.AreaMicro pore

size

SSIIdentification

G.Duwi 0.01 to 0.60

microns3.46Very salt resistant

Wadi Wata3.46

Delga2.77

3.4. Salt crystallization test

Salt crystallization test were conduct for nine studied samples (Three from each of the studied areas. The obtained results table (3) reflected the Change in weight of the studied samples over 15 cycles from W0 to W15 consequently; loss in weight (gm), M% and average M% for each area were calculated Figure (5). Dependence on the obtained results A.I. was also noticed and recorded. Durability class and values were represented graphically on Barry diagram Figure (6). The obtained results reflected that both of Duwi and Delga studied samples nearly have the same average M% 1.63and 1.51 respectively and consequently A.I. stage of deformation. On the other hand, average M% of Wata studied samples is 0.29 i.e. lower than two other studied areas. So, its A.I. stage later than others as it has been started loss its weight on 122nd stage. It can be concluded from these results that Wata studied samples are more durable than Duwi and Delga against salt crystallization test. The obtained results revealed that Duwi and Delga belong to class B durability. While, Wata studied samples belonged to class A of durability (Miglio et al, 2000). Mineralogically, the salt weathering product which helps us on following this process is thenardite phase of calcium sulphate CaSO4 which can be noticed clearly by SEM Figure (7).

Table (3): The weight loss and alternative index of all studied samples over 15cycles.SampleIntial weight (gm) W0W3W6W9W12W15loss in weight (gm)M%Avg M%. A.I

T1148.95148.84148.9149.18148.89148.95-0.001-0.130.29122nd

T2149.92149.92150.01150.11149.62149.85-0.071-0.47

T3148.50148.61148.88149.98148.46148.08-0.42-0.28

Th1145.65146.22146.77145.32143.88142-3.65-2.51.639Th

Th2142.09142.44143.66140.55140.55140.32-1.77-1.2

Th3140.60141.22141.55139.45139.33138.89-1.71-1.21

W1147.94147.99148.3146.8146.33145.80-2.14-1.41.519 Th

W2143.20143.55144.07142.08141.55140.54-2.66-1.85

W3144.89144.9145.22144.12143.88143.01-1.88-1.29

Figure 5. The weight loss by salt crystallization M% of different studied non-styolitic marbleized limestone.

Wata Delga Duwi Figure 6. Barry diagram of the average weight loss % for studied samples after 15 cycles ofsalt weathering

.

Figure 7. SEM photomicrograph showing formation of thenardite crystals associated with micro-cracks in sample components.3.4. Factors controlling salt crystallization weathering

Regardless similarities between studied samples for some characterization affected on salt crystallization weathering such as pore size distribution, SSI and main chemical and mineralogical composition. The difference between it against salt crystallization may be resulted from one of the following factors:

3.4.1. Microscopic textural effect

It includes the effect of homogeneity in grain shape and size on the salt crystallization weathering. As we mentioned in petrogrphical describtion Wata studied samples consist of oolitic grains which characterized by homogenous size and shape lead to increase the durability of it against salt weathering (Alves et al., 2009).As shown in Figure (8) the increase in a portion of micrite in Duwi and Delga studied samples moreover, the higher portion of skeletal grains leads to decrease its durability against salt weathering (Alves et al., 2009). It can be concluded that homogeneity of grins is directly proportional to durability of stones to salt weathering. On the other hand, both of micrite and skeletal percent are in directly proportional to durability of stones to salt weathering. Figure 8. The average content % of petrographical components of examined samples.3.4.2. Mineralogical effect

It includes the effect of the secondary minerals average content%. As mentioned in the mineralogical composition by XRD Duwi and Delga studied samples appear higher average semi quantative of dolomite Figure (9). It gives it a type of heterogeneity in mineralogical composition as a result of dolomitization by which calcite converts to dolomite associated with formation of more micro pores. It leads to more degradation, weight loss and earlier A.I. stage. So, it can be concluded that dolomite mineral present as a secondary are in indirectly proportional to durability of stones to salt weathering. 3.4.3. Chemical composition effectIt involves the effect of secondary major oxides (MgO) %. As it shows increase with increase in dolomite minerals so, Duwi studied samples shows relative increase in MgO% consequently to its relative increase in dolomite than others. It means that increase in MgO% also associated with decrease the durability of studied samples against salt crystallization test.

Figure 9. The average mineralogical composition % of examined samples.4. Conclusion 1. The three areas studied samples shows similarities in general mineralogical, chemical and physical pore sizes.

2. The difference in their durability against salt weathering may be resulted from the effect of one or more of the following factors: microscopic textural effect, mineralogical composition and chemical composition.3. Textural homogeneity of grins is directly proportional to durability of stones to salt weathering.

4. Both of micrite and skeletal percent are in directly proportional to durability of stones to salt weathering

5. Dolomite mineral present as a secondary are in indirectly proportional to durability of stones to salt weathering. Also, MgO% also associated with decrease the durability of studied samples against salt crystallization test.

6. Wadi Wata studied samples have the factors lead to increase its durability against salt weathering than two other studied areas.7. It is recommended to use Wadi Wata studied samples in areas subject to salt weathering than others.

5. References:

Abd El latif, M.L. (2011) Mineralogical and Geochemical studies of some Egyptian ornamental stones and their utilization in building material industry. Msc .Thesis, Fac. Sci., Helwan Univ., Egypt, 1-191.Attia ,M.A.R. (2007). Characterization of Eocene Limestones from Khashm ELRaqaba area, El- Galala El-Qibliya ,Egypt and their suitability as ornamental stones. Msc .Thesis, Fac.Sci., Beni Suef Univ,Egypt,1- 188.

Alves, C., Figueiredo , C., Braga, M., Maurcio, A. and Burros, L.,A.(2009). Aesthitic failure of limestone under salt crystallization test. 3rd Int. Conf. Integrity, Reliability and Failure, Porto/Portugal. Paper Ref: S2007_P0317.

Arnold A., Zehnder K. (1991). Monitoring Wall Paintings Affected by Soluble Salts. The Conservation of wall paintings, Getty Conservation Institute, 103-135.

Barry, A., R. (1991). The durability of porous stone, stone industries, (26) (10), 22-25.

Darweesh, H.M. and Nour El- Din, M.(2000) Characterization of some Egyptian Granites and Marbles as dimensional stones. Bull. NRC, Egypt 25, 4, 323-339.Dunham, R. J. (1962). The classification of carbonate rocks according to depositional texture.(Ed.E.M.Ham), Mem. Am. Ass.Petrol. Geol., 108-121.Folk, R.I. (1959). Practical Petrographic classification of limestone, Bull. Amer. Assoc. Petrol. Geol., 43, .1-33.

Gomma,W.A. and Rashwan , H.M.(1975).Experimental determination of the physical and mechanical properties of some Egyptian ornamental stones . Rock Mech., 6, 247-253.

Goudie A., Viles, H. (1997). Salt Weathering Hazards, John Wiley & Sons, 241.

Kamh, G. M. E. and Oguchi, C. T.(2012) Alteration index, normalized weight and geomorphic changes of dimensional limestone on artificial weathering Int. Journal for Restoration of Buildings and Monuments, 18, 6, 381-396.

Kovcs, T. (2009). Durability of Crystalline Monumental Stones in Terms of Thier Petrophysical Chracteristics. PhD Thesis, Alma Mater Studiorum Univ. Bologna 1-240.

Miegelo, B.F., Rhichardson, D.M., Yates, T.S., and West,.D.(2000). Assessment of the durability of porous limestones: Specification and interpretation of test data in UK practice, Dimension stone cladding: Design, construction, Evaluation, and Repair. ASTM STP 1394, K. R. Hoigard , E.D., 58-70. Pettijohn,F.J. (1975). Sedimentary rocks 3rd Edition., New work: Harper and Row,628. () - - - . : - . : . Num

Lit

Mi:Micrite Ms:Microsparite Sp:Sparite D:Dolomite

Num: Nummlites lit:Lithoclasts Ool:Oolits Pi:Pisolites

C

b aA

Pio

Ool

aaA

Th311

W111

M%1

Th

Ca

T3

Th111

Th211

Cr

W311

W211

Ca

T2

T1

2

1

3

D

Ms

Ca

Ca

Ca

Ca

Ca

Ca

Ca

D

Qz

Duwi

Wata

Delga

Cps

2

Mic

Ca:Calcite D:Dolomite Qz:Quartz

1