Evaluation of Cretaceous-Tertiary Limestone for Building and Dimension Stones in Erbil, Kurdistan Region of Iraq

Abstract


Introduction
Limestone is one of the oldest natural materials used in building construction, due to the high demand for construction in the 21 st century, commercial limestone is one of the most crucial low-cost natural materials used, with inertness characteristics that is environmentally safe, clean, and desirable appearance, high strength and durability, light color shades which reflects most of the sun UV-ray when exposed to as a dimension stone (non-absorptive), and large deposits in Kurdistan region with easy quarrying and working (Al-Shimari and Abdullah, 2019).Dimension stone is used for exterior building decoration (cladding) and monumental purposes.Limestone used in dimension stone should be thick and well-bedded, a massive block with desirable thickness, free from stylolite, with nearly regular dimensions, resistance to physical and chemical weathering, since lately the rain in most of the Kurdistan region are acidic rains due to the harmful gases that released by private electric generators and bad crude oil qualities from traffics, dimension stones should be free from impurities that deteriorate its appearance, take up polishing, and economically it should be easily quarried and processed (Quick, 2000).Suitability of the limestone used in building stone is high compressive strength, low thermal conductivity, good density, low porosity and water absorpsion (Saleh, 2012) Al-Diney (1998) evaluated the limestone and dolomite rock in Ain-Arnab from Anbar Governate as a building stone and dimension stone according to its density, particle shape, absorption, and dynamic properties, and showed that some of them are suitable for such purpose.Dhaher (2009) studied the physical and geotechnical properties of Pila Spi, Fatha, and Injana Formation in the Shaqlawa area.Saleh (2012) studied the suitability of limestone from Nineveh Governorate in NW Iraq and confirmed its suitability for building stone.Omar and Ismail (2015) studied the suitability of the Pila Spi Formation (Middle-Late Eocene) in the Koya area of NE Iraq by applying physical and mechanical tests, and found their suitability for building stone.Merza and Rashid (2019) evaluated the Pila Spi Formation in the Qara Dagh area, Iraqi Kurdistan region for dimension stones, by applying physical, chemical, and mechanical tests to find their suitability for such purposes.Al-Shimari and Abdullah (2019) studied the suitability of Sinjar limestone rocks from South Western limb of the Kosrat anticline as a building material and found that they have suitable compressive strength and act as a thermal insulator for up to 80°C.Othman et al., (2021) predicted the TBM performance of the Pila Spi formation in the Qara Dagh anticline, NE Iraq, they found that the rocks are hard enough to be used in construction.Khalid (2021) evaluated rocks of the Pila Spi Formation of the Duhok anticline for building stones in the Kurdistan region of Iraq, showing that some samples are suitable for interior and exterior wall cladding and exterior fencing and decoration.
This study aims to evaluate a suitable limestone rock in Erbil city in terms of their ability to provide suitable conditions for living within severe weather conditions during summer and winter seasons by comparing their physical, mechanical and chemical properties within appropriate building and dimension stone standards, on the contrary, to gain economic status by increasing internal profit and workforce, since Iraq imports most of its construction materials from outside.

Geological Setting
Samples of limestone rock were selected from Qamchuqa Formation in the core of Binabawi anticline, which consists of light brownish grey dolomitic limestone and represents 50-75m thickness, Aqra-Bekhme Formation in the Northern limb of Shakrok anticline consists of light grey dolomitic limestone of 90-120m thick, Shiranish Formation in the Eastern plunge of Pirat anticline consists of 120-150m marly limestone, Southern limb of Safin anticline consists of 90-120m light grey marly limestone (Fig. 1), southern limb of Harir anticline consists of 100-140m milky grey marly limestone, and in the plunge of Shakrok anticline consists of 90-120 milky grey marly limestone, Pila Spi Formation in the Northern limb of Pirmam anticline consists of 55-90m milky grey marly limestone, Khurmala Formation in the southern limb of Binabawi anticline consists 5-15m limestone and dolomite, Fatha Formation in the Northern limb of Kory syncline consists of 30-50m clayey limestone, Anah Formation in the southern Qarachugh anticline consists of 10-25m chalky limestone, and Euphrates Formation in the Northern Qarachugh anticline consists of 20-35m dolomitic limestone (Fig. 2), (Table 1).Tectonically these Formations located in the core and limb of anticlines within the High Folded Zone which represents point locations of 1, 2, 3, 4, 5, 6, 7, 8, and 9, and low folded zone which represents point locations of 10 and 11 (Fig. 2), the studied areas were affected by numerous tectonic activities, especially folding and faulting (Buday andJassim, 1987 andJassim andGoff, 2006).The limestone rocks mostly were well bedded, slightly dolomitic, and slightly fossiliferous.

Materials and Methods
The field studies represented plotting the longitude and latitude of the sample stations by using Garmin GPS and measuring bed thickness, recording joint, fracture, color of the specimens (chert and pyrite nodules if present) and surface texture (Table.1), in the following table the number of the point locations from geological map also recorded.In this study several petrographical study for the identification of mineral, fabric, texture, grain size, and diagenesis, for better evaluation of the limestone rock suitability and resistant properties (Egesi and Tse, 2011).Physical study of true and apparent specific gravity, dry density, true and apparent porosity, water absorption, moisture content, saturation coefficient, thermal conductivity, color, and efflorescence were carried out for better conclusion of the rock nature.Mechanical properties of the rock are determined by applying compressive strength test.Chemical properties of the rock applied for determining the ratio of oxides by X-ray fluorescence and durability test applied for better understanding limestone rocks resistance to Na2SO4, MgSO4, and HCl.

Polishing
Polishing of 15X10X5cm dimension samples is one of the dominant procedures in determining the suitability of limestone rocks for decoration and cladding, for this purpose, massive rocks are cuttied by a diamond saw, then grinding with F400 carborundum F600 carborundum, and finally F1000 carborundum grains for better smooth surface according to ASTM C-568-03 (006).

Petrographic Study
Petrographic study of limestone rocks carried out under the transmitted light microscope for assessing their grain size, grain types (skeletal and non-skeletal), groundmass of (mini-micrite with crystal sizes <1µ, micrite of <3.5µ, and micro-sparite between 5-10µ), mineralogy, texture, matrix, weathering, and diagenetic evidence of cementation or dissolution (Egesi and Tse, 2011).This study plays an important role in explaining the strength behavior of the rock, since cement type and grain size have a great effect on the building stone, coarse spar-cemented limestones are more durable than fine micritic limestones (Sedman and Barlow, 1989).Aesthetic appeal of color and texture also plays a promote role in dimension stones.The slides were tested by using red alizarin solution for differentiation between calcite and dolomite (Friedman, 1965).For this purpose thin sections were prepared for all samples represented as BQ, SA, PtS, SS, HS, ShS, Pmp, BK, KF,QSA, and QNE in Department of Earth Sciences and Petroleum, College of Sciences, Salahaddin University.

Bulk and apparent specific gravity
It is specified as one of the index properties of the rock, the specific gravity of the rock is affected by the volume, mass, and density, afterward, a low-volume rock with high mass tends to have high density and high specific gravity.Apparent specific gravity values are greater than bulk specific gravity, since, they include only solid grains.The samples were dried for 24 hours at 105°C, then allow to cool down at room temperature for 30 mins, the dry weight (Wd) of the sample was recorded by using sensitive balance to nearest 0.1 gm (Wd), the rock sample is then placed inside a desiccator and distilled water added to allow soak for 48 hours, then taken out from the water and the surface dried with a wet cloth, its saturated surface dry weight recorded (Wsat).The rock sample was placed inside a basket in a water bath hung with a sensitive balance to record submerged weight (Wsub).this test applied in the Department of Earth Sciences and Petroleum/ College of Sciences/ Salahaddin University.
Bulk specific gravity is the ratio of the unit weight solid grains and pores in between them which are occupied by gas, water, or air, to the same weight of water (Ftouhi, 1989), and measured according to ASTM C-97-09 (004) as given in the equation below: Where: Wd: dry weight (gm), Bulk.S.G: Bulk Specific Gravity (gm/cm 3 ), and Wsub: submerged weight (gm).
While apparent specific gravity represents ratio of the unit weight solid grains and pores in between them which are sealed (non-permeable to water) to the same weight of water, apparent specific gravity is measured according to ASTM C-97-09 (004).

Dry density
It is mass of the dry sample per unit volume of the sample, the dry density values changes within narrow limits compared to the wet density values, since they are related to the mineral composition and porosity, rocks with low porosity and high solid components tend to have high dry density, the dry density of the rocks increases with increasing depth.The dry density and porosity are among the important factors that affect the mechanical properties of the rock ASTM C-97-09 (010), The dry density measured according to ASTM C-127-01 (004).

Porosity
The porosity is the ratio of the pore spaces to the total volume of the rock.The porosity of the limestone aggregates depends on apparent and true specific gravity, density, water absorption, packing, binding material, grading, and affected by the shape and size of the grains and their orientation, since rocks of high porosity tend to have lower density with high water absorption and vice versa (Khalid, 2006, Hussein, 2010and 2012).The porosity of the stones is important to be determined in order to obtain their susceptibility for weathering conditions, thermal conductivity, and compressive strength (Ali et al., 1991).The porosity of the rock represents primary and secondary, the primary porosity formed during the formation of the rock, but the secondary porosity formed due to recrystallization, dolomitization, and weathering.

Partial porosity
The ratio of the size of the pores to the total volume of the rock is measured without air deflation inside the pores (Honeyborne, 1982).The samples dried at 105C until three successful readings approached to record the dry weight of the sample (Wd), then submerged in 4 ml water for 24 hours, then totally submerged in water for 48 hours, the surface is gently wiped with a wet cotton cloth to record saturated weight (Wsat), then weighted while hanged in the basket inside water for the submerged weight (Wsub).

Total porosity
Its ratio of the size of the pores to the total volume of the rock, measured with air deflation inside the pores (Honeyborne, 1982), the test procedure is similar to partial porosity measurement, but after drying the sample will be placed in a desiccator for air deflation inside the pores, then the water inserted with high-pressure into the desiccator for fulfilling the pores with water instead of air for 48 hours.Always total porosity values are higher than partial porosity.

Water absorption
Water absorption is the ratio of the weight of pores water (Pw) which is absorbed within complete 48 hours to the total dry weight of the rock volume (Wd) ASTM C-127-01 (004), it depends on its porosity, which affects its physical properties of shrinkage, strength, durability, resistance, and soundness (Zhang, 2005), rocks with low water absorption values tend to have high stability to frost and thawing processes.

Moisture content
Its one of the basic properties of the rock that influences the durability and elasticity of the rock through freezing and thawing processes (Zhang, 2005), moisture content depends on the porosity, density, and permeability of the rock and is measured by the weight of the water in the rock volume (Ww) to the dry weight of the rock volume (Wd) according to ASTM C-127-01 (004).

Saturation coefficient
It is the ratio between partial porosity and total porosity (Mc Millan et al., 1999).This property is used to qualify the rock used for building in terms of freezing, since, the rock which has a saturation coefficient <0.8 qualified as frost resistance rock, reflects that water can't occupy more than % 80 of its pores, while rocks with saturation coefficient between 0.8-0.85 are medium resistant and saturation coefficient >0.85 cannot be qualified as frost resistance rock in most of the cases ASTM C-127-01 (004)

Thermal conductivity
The quality of limestone rocks in terms of thermal property to conduct heat is thermal conductivity, it depends on several factors; porosity, mineral composition, texture, anisotropy, density, and pore-filling fluids.The external factors are climatic changes such as changes in temperature, sunlight, rain, wind, and others.The thermal conductivity of limestone rocks plays an important role when studying their suitability for building, since, it will perform to the human desire for a suitable environment inside their building, limestone rocks are chemically inert when exposed to heat.rocks with low coefficient thermal conductivity are desirable, since, they will reduce energy consumption by air conditioners or heaters inside the building during summer and winter seasons, also reduces environmental pollution by harmful gases released by electric generators, since, less energy required for conditioning inside buildings, and resists stresses resulting from high contrast in temperature that leads to continual expansion and contraction of the building stone that causes loss of the mechanical properties of the rock.
Limestone samples were cuttied by a Diamond Core Drill Saw to enhance cylindrical shapes of 3cm thickness and 1.25cm radius (Fig. 3a), to completely take place inside the plastic mold (Fig. 3b).The instrument used for measuring thermal conductivity composed of a caliber of two cylinders, the first contains a heater that applies heat to one of the surfaces, and the second contains a sensor that records the temperature (Fig. 3c).When the temperature rises the free electrons in the outer orbits of atom moves due to the kinetic energy of the electronic clouds increases which allows heat transfer to the nearby clouds where there is a high energy.This transfer of heat takes place in heat conductor materials like metals, however, the same mechanism can take place within rock crystal structures, in which each atom has a specific location in relation to surrounding atoms.Atoms vibration within the crystal structure allows other neighboring atoms to vibrate inside crystal structure (Van Vlack, 1973).According to the Forir law, the amount of heat transferred through a unit area is proportional to the heat gradient in the direction of heat flow.K value represents the amount of heat transferred per unit time through a unit area of a building with unit thickness when the difference between the two surfaces is a one-degree unit W/mc ASTM C-168-00 (004).

Color
One of the most important physical properties of limestone rocks used in dimensional stone is color, since dimension stone used for exterior walls decoration, for this purpose its vital to have a clean and desirable appearance, the color of the limestone rock affected primarily by pyrite, iron oxide and chert nodules, which should be free from deleterious minerals that may deteriorate its surface by forming stain rust during chemical weathering (Tucker, 1991), limestone rocks with yellowish shades represent iron oxide impurities, grey shades represent organic material content, pink colors represent ferric iron oxides and clay content (Surdashy, 2022).Rock chips of fresh surface washed and dried in the oven, then compared with the Munsell rock color chart, (Pereia et al., 2015 ) which primarily depends on three attributes of color HVC (Hue, Value, and Chroma), where H represents the color of the rock, V represents the value of the color (light and dark), and C represents how weak or strong this color.

Efflorescence
Limestone rocks used as dimension stones should not contain high amounts of soluble salts, especially of sulfates, since during drying and wetting conditions through seasonal changes, these soluble salts precipitate on the surface of dimension stone as a whitish discoloration powder called efflorescence, which deteriorates its outer look and its non-desirable, for this purpose an efflorescence test carried out by immersing 2000 gm of crushed limestone of 5cm in a distilled water that are half immersed in the water for about 1 month when the water evaporated must be refilled until half of the crushed stone, then the crushed stones dried for 5-6 hours at 105C until three constant weight recorded successfully, allow to cool down in room temperature, then if the crushed stone has a high amount of soluble salts in the form of sulfates it will appear as efflorescence on the surface according to ASTM C-127-01 (004).

Compressive strength test
it is resistance to the vertical compression applied to it at the failure point, therefore it is ability of the rock to back load-bearing components of a building (Taylor and Harold, 1991;Quick, 2002).It represents the relationship between the maximum internal strength and durability of the rock and uniaxial external strength applied directly on the core samples used for determining rocks strength and hardness.There are several factors that the compressive strength depends on according to rocks bulk density, water absorption, apparent porosity, texture, cementing material, and mineralogical composition, This test is used to measure the ability of the limestone as a building material (Taylor and Harold, 1991;Quick, 2002).The uniaxial compressive strength is calculated according to Iraqi Standard No.2715, 1987 andASTM C-170 (004).Economically compressive strength is applied for determining the limestone rocks susceptibility, and type of quarrying during extraction, since harder rocks need heavy blast than softer rocks that can be quarried easily, also for determining the amount of breakage during handling, transport, mixing, and compaction resulting from building loads.
Core samples drilled out from larger limestone blocks of nearly 30x25x20cm by diamond core drill with 3500W capacity, water used continuously as a lubricant during drilling on the limestone blocks by diamond core drill with core sample diameter's more than (4.7 cm) and height to diameter ratio of (> 1.5/1) according to ASTM C-170-90 (004) (Fig. 4a), cutting and polishing the top and base edges of the core cylinders to stand right and regular and to uniformly divide the load that applied on it under the compressive strength test machine, also a sheet of wood pad is placed between the platen and the specimen at each end to minimize friction within the load bearing plate (Fig. 4b).Core samples are dried in an oven for at least 48 hours at 60 C, therefore weight (gm) for each core sample measured after 47, 48, and 49 hrs, then drying is continued until there are 3 successive hourly readings at the same weight, since humid core samples gives uncorrected readings when load is applied.for measuring compressive strength load applied at a uniform rate not exceeding (1500KN) on the core samples with an average load rate of (0.75 N/mm2/sec) or (690 KPa/sec) which was selected in the devices control panel until failure and the load at the failure point is recorded according to ASTM, C-170-90 (004), and the failure condition required (5-10min) according to (ISRM, 1979) standards for measuring the compressive strength of cylindrical core samples of rocks.The compressive strength of the cylindrical cores increases with increasing bulk density and decreasing apparent porosity and water absorption.Digital Industrial Compression Testing Machine with 2000 KN capacity used for measuring the strength of the limestone cores in the laboratories of College of Civil Engineering/ Salahaddin University.
The area of the core samples plays a great role in measuring compressive strength, therefore the diameter and height are measured for each core sample before appling the load.since the core samples represent cylindrical shapes, therefore the area of the cylinders was measured to calculate the compressive strength of the cores according to standard requirements of ASTM C-2938-95 (004).The uniaxial compressive strength is calculated according to the Iraqi Standard No.2715, 1987 and ASTM C-170-90 (999) as follows: Where: A: area of cylindrical cores facing the load plate (cm²), π: Pi of cylinder, r: radius of the cylindrical core samples (cm), and h: height of the cylindrical core samples (cm), S: compressive strength (kg/ cm²), W: pressure value at failure (kg), and A: area of cylindrical cores facing the load plate (cm²)

Chemistry
The chemical properties of the selected samples were carried out by X-Ray Fluorescence in Kansaran Binaloud Laboratory in Iran city.Samples were prepared by pulverizing the limestone rocks to <0.075mm (U.S. sieve size).The durability of building stone strongly depends on the impurities inside the limestone aggregate being used, therefore it should contain >4% fine clay, silt and dust particles, chlorides, debris, shells, sulfates, organic matter, chalk, marcasite, pyrite, mica, and metallic particles, and >16% sand.According to BS 882 defines the Fine clay, silt and dust as any material passing 0.075 mm sieve, they have ability to coat the aggregate surface, and weakens the matrix and aggregate bond, and increases demand for water during working and mixing, which in fact decreases the hardness and strength of the building stone.Chlorides in the form of sodium salts increases the corrosion in the building constructions, the BS 5328-8.9recommends 0.01 to 0.05% chloride.Shells and organic matter cause staining on the surface of concrete, ASTM C-33-8 (011) recommends 0.5% of shell and organic matter in building and dimension stones.Chalk particles inside limestone decrease the mechanical quality of the building stone by increasing softness and porosity, especially under freeze and thawing conditions causing popping due to expansion.Alkali, sulfate and mica should be <0.01% in the limestone aggregates used for building stone, since, they tend to reduce the hardness by decreasing the density of the limestone contained.Iron, pyrite, salt, and coal are not accepted in the building stone as they deteriorate the outer surface when used as a dimension stone.

Durability
The durability test method was used for determining the limestone's resistance to freezing and thawing, alkali reactivity, and susceptibility to frost action.A soundness test is used to qualify the aggregate in terms of degradation and disintegration due to the crystallization of salts in the pores during wetting and drying cycles.The durability of the dimension stone depends on the density, porosity, water absorption, and saturation coefficient, since, high-density rocks tend to have low porosity and low saturation coefficient, otherwise, during tough weathering conditions of winter, the rock will absorb water from rain and moist and causes freeze and thaw criteria which in part physically deteriorate its aspects, for this reason, durability measured by using Na2SO4 or MgSO4.The other method used for measuring the durability of dimension stones for better evaluation of the resistance of the rock to acid rain by etching a smooth and flat surface of limestone with diluted HCl of 0.10% this acid removes the carbonate material inside the limestone but leaves the impurities behind, and will show the probable texture of the limestone surface after it has weathered for a limited time (Harrison and Bloodworth, 1994).The soundness test of building stone according to BS 812-8.4 when Na2SO4 used the 400 gm of fine aggregates distribution limit that passed 9.50mm (3/8) screen and retained 0.25mm (No. 50) sieve and 6000 gm of coarse aggregate distribution limit that passed 12.5mm (1/2) sieve and retained 4.75mm (No. 4) sieve is soaked in a saturated solution of Na2SO4 at 21°C for 16-18 hours, the samples are then allowed to drain for 15 mins and dried at 105°C until obtaining a constant weight, this test procedure repeated in five cycles, within each cycle the freezing and thawing activity forms by growing crystals of Na2SO4 within the pores and susceptible for breakage of the rock into smaller particles.After completing the five-cycle test procedure the aggregates are washed with distilled water to remove Na2SO4, and then dried and sieved with the same sieve sizes used before for calculating the % loss.The durability test reactivity measured according to ASTM C-586-8 (004).

Polishing
All of the samples withstand and takes up polishing with a smooth, non-porous, and dense aspects (Fig. 5a, b, c,d,e,f,g,h, and i), except for KF showed high amount of porosity on its outer surface (Fig. 5j) and QSA breaks up during polishing (Fig. 5k) due to high porosity.

Efflouerescence
The studied samples do not show efflorescence on their outer surface (Fig. 7), except for QSA and KF showed low efflorescence, which represents the presence of low salt that evaporated onto their exterior surface due to their high water absorption by porosities in them.

Apparent and true specific gravity, density, porosity, and water absorption
The bulk specific gravity (B.S.G) and apparent specific gravity (A.S.G) of the limestone rocks show that rocks with higher density BQ, SA, PmP, BK, and QNE tend to have higher specific gravity too, while rocks with lower density KF and QSA tend to have a lower specific gravity (Fig. 8a and d).Suitability of the limestone rocks for dimension stone in terms of water absorption (W.A), density, and compressive strength (Table 2) according to the ASTM C-568-03 (004) and Iraqi Standard No.13-87 (989) shows that KF and QSA are class I of high water absorption, low density, and low compressive strength values, which are accepted as dimension stone (Table 3).PtS, SS, HS, and ShS are of Class II with medium water absorption, density, and compressive strength values, which are recommended as dimension stones.BQ, SA, PmP, BK, and QNE are of Class III with low water absorption and high density and compressive strength values which are highly recommended as dimension stones.
The moisture content (M.C) of the BQ, SA, PmP, BK, and QNE is low, since their water absorption is also low due to low partial porosity (P.Porosity) and true porosity(T.Porosity) (Fig. 8a), while SA, PtS, SS, and HS have medium moisture content due to medium water absorption hence have medium porosity (Table 2).KF and QSA have high moisture content due to high water absorption and high porosity according to ASTM C-127-01 (000).
The saturation coefficient (S.C) of BQ, SA, PmP, BK, and QNE is low due to low porosity and permeability which are classified as frost-resistant rocks, while PtS, SS, HS, and ShS have medium saturation coefficient values due to medium porosity and permeability which classified as medium frost resistant rocks, and KF and QSA have high saturation coefficient values due to high porosity and permeability (Table 2) which classified as non-frost resistant rocks according to ASTM C-127-01 (004).
Suitability of limestone rocks for building stone in terms of dry density and porosity according to ASTM C-97-09 (010) and Levorson, 1970 Classification shows that KF and QSA are of low density and high porosity, which are accepted as building stone (Table 4).PtS, SS, HS, and ShS are of medium density and porosity, which are highly recommended as building stone, and BQ, SA, PmP, BK, and QNE are of high to very high density and low to no porosity in them, which is recommended as building stone

Thermal conductivity
Thermal conductivity of the studied samples according to ASTM C-1057-03 (recommends stone to be used as building and dimension stone should have a thermal conductivity of nearly 0.92 W/mc and a density of 2.3 gm/cm3 (Table 5), the samples of PtS, SS, HS, and ShS are within the standard range, since, they have medium density, porosity, and thermal conductivity values (Table 6).However, BQ, SA, PmP, BK, and QNE have higher thermal conductivity due to their high density and low porosity (Fig. 8c and d), which are not economical when used as building stone.KF and QSA have low thermal conductivity due to their low density and high porosity, which are not desirable as building stones however, in some cases can be used as an insulator.

Color
The color of the limestone rocks shows white color for QSA due to high CaCO3 content without impurities, while the yellowish-grey color of BQ, ShS,BK, and QNE represents dolomite, iron oxide and organic matter impurities (Table 7), the light grey color of SA, PmP, PtS, SS, HS, and KF may be due to the presence of organic materials  Hawkins, 1986;and Franklin & Dusseault, 1989) due to their high density and low porosity (Table 8), while SA, PtS, SS, HS, and ShS are moderately weak according to (ISRM, 1981 andFranklin &Dusseault, 1989), but SA will be strong according to (Hawkins, 1986), (Fig. 8a & b).KF and QSA are weak according to ISRM, 1981, and moderately weak according to (Franklin & Dusseault, 1989) but only KF is moderately strong according to (Hawkins, 1986) (Table 9) due to their low density and high porosity in them.
Table 8.Classification of uniaxial compressive strength for suitability of the rock in building (MPa) according to (ISRM, 1981), (Hawkins, 1986), and (Franklin & Dusseault, 1989)    The chemical analysis showed that CaO in BQ, SA, PmP, BK, and QNE ranges between 29-30 and MgO ranges between 20-21 (Table 10), QSA classified as very high purity limestone, ShS as high purity limestone, PtS as medium purity limestone, HS as medium purity slightly dolomitic limestone, KF as low purity slightly dolomitic limestone, SS as low purity slightly dolomitic limestone, BQ, SA, BK, and QNE as impure highly dolomitic limestone, and PmP as impure highly calcitic dolomite (Table 11) according to Harrison, 1993 andTeodorovich, 1950  SiO2 is low in SS, QSA, PtS, and ShS 0.11 to 0.70, while in PmP and KF is 4.59 and 5.06 due to clay content, as Al2O3, Na2O, and K2O also represent clay mineral content (Erlström, 2009;and Jennerheim, 2016), therefore KF with higher SiO2 content also contains higher Al2O3, Na2O, and K2O than other samples, Fe2O3 is high in BQ and low in SS.P2O5 is low within all samples due to low apetite content (Parekh et al., 1977;Cullers, 2002).LOI (loss on ignition) represents the volatilized or burned contents at higher temperatures.recommend Na2SO4 to be less than 12% loss, for MgSO4 15% loss, and for HCl to be less than 10% when used for building and dimension stone.BQ, SA, PmP, BK, QNE, PtS, SS, HS, and Shs meets the requirements (Table 12), and have high durability for freezing, thawing, and acid rains, while KF and QSA are beyond the standard requirements that have low durability for acid rains and non-frost resistance.

Conclusions
The samples of BQ, SA, PmP, BK and QNE are not recommended as building and dimension stones, since they are not economic due to their high thermal conductivity, although they have high compressive strength values, frost resistance, and durability properties, and no efflorescence.
Samples of PtS, SS, HS, and ShS are highly recommended as dimension stone and building stone, due to their moderately strong compressive strength values, frost resistance, and durability properties, they also take up polishing easily, they are nearly well-bedded and regular, no efflorescence, lighter shades of colors which reflects back most of the UV rays, and have standard thermal conductivity values, which makes them economic as a building stone Samples of KF and QSA are not accepted as dimension stones, due to their low frost resistance values and non-durable properties, cannot take up polishing, and low efflorescence, while they are accepted as buildings with low load-bearing due to its weak to moderately weak compressive strength values, and low thermal conductivity, which in some cases they can be used as an insulator in buildings.

Fig. 2 .
Fig.2.Geological map showing the locations of the selected sections for building and dimension stone(Sissakian, 2000) : thermal conductivity, A: heat exposed area of the sample A=r 2 *π =4.9cm 2 , ΔT: difference in temperature between surface exposed to heat and surface receiving heat, ΔX: sample thickness = 3cm, and W= Watt

Fig. 3 .
Fig. 3. (a) Cylindrical samples for thermal conductivity test (b) Cylindrical sample inside the mold (c) Thermal conductivity instrument measurement

Fig. 4
Fig. 4 (a)Cylindrical core (b) Compressive strength test of cylindrical core samples by using Digital Industrial Compression Testing Machine

Fig. 7 .
Fig. 7. Studied samples show low to non-efflorescence on their exterior surface

Table 1 .
Location, thickness and coordination of the selected limestone rocks

Table 2 .
Physical properties value of limestone rock as a building stone.

Table 3 .
Physical and mechanical standard properties of limestone rocks used as dimension stone according to the ASTM C-568-03 (004) and Iraqi Standard, No.13-87

Table 5 .
Standard thermal conductivity values for different building and dimension stone materials according to ASTM C-1057-03

Table 6 .
Thermal conductivity of the studied samples according to ASTM C-1057-0

Table 7 .
Color name of the limestone rocks suitability for dimension stone according toMunsell chart,  2009

Table 9 .
Compressive strength test results of cylindrical limestone cores of Shiransh Formation in Pirat anticline

Table 11 .
Limestone purity classification according to CaCO3 ratio according toHarrison and Teodorovich.

Table 12 .
Weight loss% of limestone aggregates by durability test