236 American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) ISSN (Print) 2313-4410, ISSN (Online) 2313-4402 © Global Society of Scientific Research and Researchers http://asrjetsjournal.org/ Physical Properties, Strength and Durability of Selected Rocks from the Central Nepal Lesser Himalaya, Malekhu River Area for Building Stones Sunita Bhattaraia*, Naresh Kazi Tamrakarb a,bCentral Department of Geology, Tribhuvan University, Kirtipur, Kathmandu, Nepal aEmail: Sunitabhtry.828@gmail.com bEmail: nktam777@yahoo.com Abstract Strength and durability are crucial factors for the selection of rocks for building stones. This paper focuses on the study and evaluation of rocks of the Lesser Himalaya based on their physical properties, strength and durability. Nine different sites were selected for sampling appropriate rock types for building stones. Physical properties such as water absorption value, dry density, bulk specific gravity, saturation coefficient, porosity were determined. For mechanical strength, point load test and for chemical properties acid immersion test, salt crystallization test, methylene blue adsorption test and ethylene glycol soak test were carried out. Rocks of quartzite, granite, marble and dolomite showed higher strength values whereas rocks of quartzite, amphibolite and augen gneiss showed lower strength value. However, in terms of durability almost all rocks showed promising results except for carbonate rocks, i.e., marble and dolomite. Therefore, marble and dolomite are suitable for only interior uses such as wall cladding and interior flooring. Granite, metasandstone and quartzite with spaced foliation are suitable for dimension stones for both exterior and interior uses. Augen gneiss, amphibolite and quartzite with low strength and high durability are suitable for interior use only. From the evaluation, most of rocks showed suitable results regarding durability test. Keywords: Physical properties; Strength; Durability; Building stone; Lesser Himalaya. ------------------------------------------------------------------------ * Corresponding author. http://asrjetsjournal.org/ American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2017) Volume 35, No 1, pp 236-250 237 1. Introduction Physical properties, strength and durability are indispensable properties that help to evaluate the rocks for various applications. These properties are mandatory in characterizing natural building stones. Determination of these properties is of prime importance when deciding suitability of rocks for use under various environment and stress conditions [1:506]. Generally, durability and strength of rocks help to categorize various rock types and find their suitable end uses especially for building stones. Strength is the ability of a material to resist deformation induced by external forces, whereas durability of building stones is the measure of ability of stones to endure and maintain their distinctive characteristics of strength and resistance under its working conditions to cyclic variations of temperature, moisture content, and chemical environment [2]. Physical properties of rocks are the fundamental properties, which influences strength and durability [3:14, 4:257-258, 5:30, 6:44-45]. The amount of water absorbed by a stone can be indicated by porosity and saturation coefficient [6:45]. Pore size may also influence the durability as those with fine pores tend to be less durable compared to those with coarse pores [6:44]. Durability of building stones depends chiefly on effective porosity, water absorption, saturation coefficient, and strength, which indirectly influence resistance of rock materials to crystallization pressure [7:113]. Salt crystallization being the powerful weathering agent limits the durability of porous building stones [8:313]. High strength stones are more durable but may decrease with weathering pattern [3:16]. Strength and durability of each rock types can differ due to variation in their composition, physical properties, strength and resistance to weathering [1:506-513, 3:14-16, 7:113-127]. Figure 1: Location map of the study area The Malekhu River area is a hilly region of the Lesser Himalaya (Figure 1). It is one of the promising areas, where NW-SE trending rock units composing metamorphic, igneous and meta-sedimentary rocks, distribute pervasively across the Malekhu River. Present study intends to characterize the rock materials based on some physical properties, strength and durability, which are often considered fundamental for evaluating rocks for various building stones. 2. Methodology Reconnaissance survey was undertaken using 1:25,000 scale maps to assess geological parameters and rock American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2017) Volume 35, No 1, pp 236-250 238 mass conditions of the probable rock types including weathering grade, orientation of joint sets, joint spacing, joint size and shape. Nine different sites were selected to explore the rock mass and study their geology, rock mass characteristics and discontinuity. Rock mass characterization included Rock Mass Rating system (RMR) following [9:51-58]. Joint sets signifying the actual block shape, size and volume were determined following [10, 11]. About 10 kg of samples were collected from each of the nine study sites for laboratory analyses of petrography, physical properties, strength and durability. Rock samples taken from field was found to be slightly weathered after digging few centimeter. Study of rock thin-sections comprised of studying composition and texture of rocks under a polarizing microscope. Physical tests were made for prepared test samples. Water absorption value (WAV) and bulk specific gravity (G) were determined using core samples based on [12]. The samples were immersed in water for 48 hours, surface dried, weighed and calculated the percent of absorption. For G, samples were suspended in the distilled water and then weighed. Finally, WAV, G and dry density were determined and computed as: WAV = {W1-W0/W0} × 100 % (1) Where, W0 is weight of oven-dried sample (gm), and W1 is weight of wet sample after soaking (gm). G = {W0/ (W2-W4)} (2) Dry density = W0/V (3) Where, W0 is weight of oven-dried sample, W2 is weight of the saturated surface dried specimen in air (gm), W4 is weight of the soaked specimen in water (gm), and V = volume of a core sample. Porosity and saturation coefficient were determined for the core samples based on [6:83]. For porosity, core samples were dried (1030C) and then cooled in a vacuum desiccator at about 200C. Then, the samples were saturated with water to restore atmospheric pressure. The saturated samples were weighted in water (W4 gm) and in air (W5 gm), respectively. Then the samples were dried for 16 hours and then weighed (W6 gm). Finally, the specimens were immersed in water for 23 hours and again weighed (W7 gm). Porosity and saturation coefficient were computed using the following relations: Porosity (n) = {(W5-W6)}/ {W5-W4)} × 100 % (4) Saturation coefficient (SC) = {(W7 –W6)}/ {W5-W6)} (5) Point-load strength index test was carried out for lump samples in accordance with [13]. The test was carried out in less number of samples then it is required. During this test, the irregular lump samples were inserted in the testing machine and then load was steadily increased within the 10–20 s, where the failure load was recorded as P (Kilo newton) and the distance between cones were recorded as D’ in mm. The point-load strength index, Is was obtained as: Is = P/De 2 (6) American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2017) Volume 35, No 1, pp 236-250 239 Where, De2 for lump tests = 4(W×D') /π (mm2) (7), and W and D’ are respectively, the average width (mm) of the sample and distance (mm) between the cones at failure of the sample. The size corrected point-load strength index, (Is(50)) was obtained as: (Is(50)) = F×Is (8) Where, size correction factor F = √ (De/50) (9). From size corrected point-load strength index value, unconfined compressive strength value was determined using the empirical relations: For metasandstone [14]; UCS = 21.27 Is(50) (10) For granite [15]; UCS = 10.91 Is(50) + 49.03 (11) For other rocks [16], with porosity > 1 %; UCS = 24.83 Is(50) – 39.64 (12) and with porosity < 1 %; UCS = 10.22 Is(50) + 24.31 (13) Acid immersion test (AIT) was carried out following [6:85]. In this, cubic samples of size 4×4×1.5 cm3 were prepared and immersed in 200 ml solution of sulphuric acid solution. They were left for 10 days and then any changes taken place on the surface of the samples was noted. Crystallization test (CT) was carried out following [6:84], in which cubic samples of 4×4×4 cm3 were prepared and their dry weights were noted as (W1). The samples were then covered with sodium sulphate solution for 4 hours. Then the cubes were oven dried for about 18 hours and were weighed (W2) again after cooling for about half an hour. The procedure was repeated for 15 cycles. The mean percentage weight loss under crystallization test was obtained as: Mean % weight loss = Total % wt. loss/No. of cycles (12) Methylene blue adsorption test was conducted following [17]. A test sample of 1 gm of size 75 μm was dispersed in 30 ml water then titrated by adding 0.5 ml methylene blue solution. After each addition, the suspension was agitated for one minute and a drop removed with a glass rod was spotted onto a filter paper. This procedure was repeated until a pale hallo was seen to have formed when the filter paper was held up to daylight. The methylene blue adsorption value (MBAV) was calculated as: MBAV = {(0.1×V)/M} × 100 % (13) Where, V is the total volume of the methylene blue solution (in ml) added to suspension to reach end-point, and M is the test portion in grams. Ethylene glycol soak test was made following [18:287-302] to measure weatherability of stones. Here, 3× 3 ×3 cm3 cubic samples were soaked in ethylene glycol solution for 30 days and were noted day to day for any change in degree of disintegration at a time when the worse condition occurs. The ethylene glycol soak test index (EGSTI) values were determined by adding degree of disintegration with American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2017) Volume 35, No 1, pp 236-250 240 time, where index value ranges from 2 to 10, respectively. 3. Geological settings The Malekhu River flows from the South to the North across the geological units, and is a sixth order river. The author in [19:9-22] categorized the Lesser Himalaya of central Nepal into the Nawakot complex and the Kathmandu Complex which are separated by the Mahabharat Thrust (MT). Table 1: Stratigraphic columns of Lesser Himalayan Rock units (After Stöcklin, 1980) Unit Formation Main Lithology Apparent Thickness (m) Age K at hm an du C om pl ex Ph ul ch au ki G ro up Godavari Limestone Limestone, dolomite 300 Devonian Chitlang Formation Slate 1,000 Silurian Chandagiri Limestone Limestone 2,000 Cambro– Ordovician Sopyang Formation Calc-phyllite, slate 200 Cambrian Tistung Formation Metasandstone, phyllite 3,000 Late Precambrian B hi m ph ed i G ro up Markhu Formation Marble, schist 1,000 Late Precambrian Kulikhani Formation Quartzite, schist 2,000 Precambrian Chisapani Quartzite White quartzite 400 Precambrian Kalitar Formation Schist, quartzite 2,000 Precambrian Bhainsedobhan Marble Marble 800 Precambrian Raduwa Formation Garnetiferrous schist 1,000 Precambrian ——————————————— Mahabharat Thrust (MT) ———————————— ————— N aw ak ot C om pl ex U pp er N aw ak ot G ro up Robang Formation Phyllite, quartzite 200 – 1,000 Paleozoic Malekhu Limestone Limestone, Dolomite 800 Paleozoic Benighat Slate Slate, argillaceous dolomite 500 – 3,000 Paleozoic Lo w er N aw ak ot G ro up Dhading Dolomite Stromatolitic dolomite 500 – 1,000 Late Precambrian Nourpul Formation Phyllite, quartzite, dolomite 800 Late Precambrian Dandagaon Phyllite Phyllite 1,000 Late Precambrian Fagfog Quartzite White quartzite 400 Late Precambrian Kuncha Formation Phyllite, quartzite, Conglomerate, gritstone 5,000 Late Precambrian —————————————— Main Boundary Thrust (MBT) ——————————— ————— Siwalik Group Conglomerate, sandstone, mudstone, Several Kilometers Neogene American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2017) Volume 35, No 1, pp 236-250 241 The MT lies at the northern part of the study area and trends NW-SE across the Malekhu River area. The study area comprises the upper two formations of the Upper Nawakot Group, i.e. the Malekhu Limestone and the Robang Formation, and the Bhimphedi Group comprising of six formations, and the lower part of the Phulchauki Group (the Tistung Formation) of the Kathmandu Complex (Figure 2; Table 1). These units extend NW-SE and distributes throughout the Malekhu River watershed. The granitic intrusion exists at the core of the huge syncline, of which the present study area covers the part of the northern limb of the syncline. Limestone with grey phyllite, sericite quartzite, quartzite, amphibolite and schist are the major rock types in the Upper Nawakot Group. Garnetiferous schist, dark grey quartzite, crystalline marble, white quartzite, augen gneiss, schist, metasandstone, granite are the major rock types of the Bhimphedi Group and lower part of the Phulchauki Group. Figure 2: A geological map of the Malekhu River Area showing sample sites American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2017) Volume 35, No 1, pp 236-250 242 4. Results Nine rock samples were separated into six categories based on their textural and structural characteristics. These are: • Finely crystalline argillaceous dolomite (ML-Dolomite2) and laminated fine- to medium-grained metasandstone (TF-Metasandstone) • Foliated, medium to coarsely crystalline, white to light grey quartzite (RF-Quartzite1, RF-Quartzite2 ,CQ-Quartzite3) • Foliated, medium crystalline and green amphibolite (RF-Amphibolite) • Coarsely crystalline and dark grey Augen gneiss (KF-Augen gneiss) • Massive, coarsely crystalline white marble (BM-Marble), and • Massive, coarsely crystalline granite (TF-Granite). 4.1. Rock mass characteristics and discontinuity RF-Quartzite2 and TF-Metasandstone fall in fair category of rock mass class (Table 2). KF-Augen gneiss falls in very good category. Remaining rock samples are of good rock types. The block sizes of the rock samples (Vb) range from 0.1 to 12.7 m3. The block shape factor (β) varies from 21.7 to 124 (Table 2). Therefore, the block forms are compact, long, flat and both. The Block Quality Designation (BQD) value ranges from very poor to good. Table 2: Field descriptions of nine rock samples, rock mass characteristics, joint density, joint shape and volume. Sample Formation Location RMR category *1JD 1/m *2Vb m³ BSF *3β Block type *4BQD % ML-Dolomite Malekhu limestone 27°48'19"N 84°49'58"E 68 Good rock 18 5.67 22 Long and flat Very poor RF- Quartzite1 Robang Formation 27°48'11"N 84°50'04"E 67 Good rock 30 0.56 37 Flat Very poor RF- Amphibolite Robang Formation 27°48'04"N 84°50'07"E 74 Good rock 11 4.11 27 Compact Good RF- Quartzite2 Robang Formation 27°47'56"N 84°50'12"E 56 Fair rock 37 0.8 28 Compact Very poor BM-Marble Bhaisedobhan Marble 27²47'50"N 84°49'59"E 74 Good rock 14 1.26 75 Flat Poor CQ- Quartzite3 Chisapani Quartzite 27°46'51"N 84°49'50"E 72 Good rock 16 0.1 124 Long Very poor KF-Augen gneiss Kulikhani Formation 27°46'43"N 84°49'50"E 81 Very good rock 4.3 12.68 29 Compact Good TF-Meta sandstone Tistung Formation Tistung Formation 27°44'53"N 84°48'50"E 60 Fair rock 7.7 2.25 39 Flat Poor TF-Granite 27°44'47"N 84°49'08"E 74 Good rock 11 0.23 32 Compact Fair American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2017) Volume 35, No 1, pp 236-250 243 Rock mass determined from total rating: VGR = Very Good Rock, GR = Good Rock, FR = Fair Rock [9], *1JD = Joint density (per frequency 1/m), (BV) Block volume (*2Vb) = S1×S2×S3/(Sinγ1×Sinγ2×Sinγ3) (S1, S2 & S3 are the maximum, intermediate and minimum joint spacing in meters, γ1, γ2 & γ3 are intersection angles between these major joint sets obtained through stereographic projection), (BSF) Block shape factor (*3β) = (α2+α2×α3+α3)³/(α2×α3)² (α2 = S2/S1 and α3 = S3/S1) , *4BQD% = {(∑LSC>1m)/Ltsc}×100% ∑LSC>1m, summation of scan line length of joint sets more than 1 m and Ltsc is the total length of scan line (Very good = 90-100%, Good = 75-90%, Fair = 50-75%, Poor < 25 % [11:29]. 4.2. Microscopic level description Fine-grained siliceous dolomite has higher proportion of calcite and dolomite. Metasandstone has higher proportion of recrystallized quartz and randomly oriented mica minerals (Figure 3, Table 3). Light grey, fine- to medium-grained quartzite samples (RF-Quartzite1, RF-Quartzite2 and CQ-Quartzite3) have similar modal composition of quartz grains (Figure 4, 5 and 6). However, RF-Quartzite1 sample has coarser grain size and has higher percentage of sericite minerals compared to that in two other quartzite samples (Table 3). Foliation in RF-Quartzite1 is continuous while that in other two samples is spaced. Mineral grains of calcite and quartz grains are homogenous in dolomite and quartzite, respectively. Beside these samples, other samples have heterogeneous mineral grains. Massive and randomly oriented minerals occur in the samples of RF- Amphibolite, BM-Marble (Figure 7) and TF-Granite. Table 3: Field description of nine different rock types and their microscopic description Sample Formation Mineralogical Rock type Description Composition ML-Dolomite Malekhu limestone Light grey, medium grained, laminated Calcite & dolomite, quartz, feldspar, biotite, muscovite Dolomite RF-Quartzite1 Robang Formation White, coarsely crystalline Quartz, sericite, feldspar, biotite, muscovite Sericite Quartzite RF- Amphibolite Green, medium-coarse grained, foliated Amphibolite, quartz, feldspar, biotite, muscovite Amphibolite RF-Quartzite2 Light grey, coarse grained, lamina and foliated Quartz, feldspar, biotite, muscovite, sericite Quartzite BM-Marble Bhaisedobhan Marble White, medium-coarse, crystalline, slightly weathered Quartz, feldspar, biotite, muscovite, calcite & dolomite Marble CQ-Quartzite3 Chisapani Quartzite Light grey, coarse grained, foliated, porphyroblastic Quartz, feldspar, biotite, muscovite, chlorite Quartzite KF-Augen gneiss Kulikhani Formation Light grey, coarse grained, foliation present, porphyroblastic, gneissosity Quartz, feldspar, biotite, muscovite, sericite Augen gneiss TF- Metasandstone Tistung Formation Tistung Formation Light grey, coarse grained, porphyroblastic, foliated, lamina present Quartz, feldspar, muscovite, sericite, chlorite Meta- sandstone TF-Granite Light grey, coarsely crystalline, randomly oriented minerals. Quartz, feldspar, muscovite, biotite, muscovite, sercite Granite American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2017) Volume 35, No 1, pp 236-250 244 KF-Augen gneiss is coarse-grained and having augen shaped feldspars and large quartz grains with distinct gneissosity developed by micas (Figure 8). Samples of dolomite, quartzite, and augen gneiss exhibit higher packing density compared to other rock samples. Figure 8: Coarsely crystalline mineral grains of augen gneiss (KF-Augen gneiss) Figure 7: Coarsely crystalline calcite grains showing in marble (BM-Marble) Figure 6: Recrystallized quartz grains and preferred orientation of muscovite showing in quartzite (CQ- Quartzite3) Figure 5: Slightly foliated quartzite (RF-Quartzite2) Figure 4: Preferred orientation of muscovite, sericite and chlorite grains in sericite quartzite (RF- Quartzite1) Figure 3: Detrital quartz grains and slightly oriented mica grains showing in metasandstone (TF- Metasandstone) American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2017) Volume 35, No 1, pp 236-250 245 4.3. Physical properties Water absorption and bulk specific gravity vary from 0.35 to 2.24 % and from 2200 to 3200 kg/m³, respectively. The lowest water absorber among the rock sample is of augen gneiss and granite while the highest one is the sample of amphibolite. Dry density of different rock types ranges from 2.5 to 2.75 kg/m3. The water absorption and dry density of the rocks quartzite, marble, dolomite and granite satisfy with ASTM standard for the building stone. Porosity is low (<2%) in quartzite samples of the Robang Formation (RF- Quartzite1 and RF-Quartzite2) and the Chisapani Quartzite (CQ-Quartzite3). The samples augen gneiss (KF- AG) and marble (BM-Marble) have the porosity exceeding 2 %. The saturation coefficient ranges from 0.1 to 0.9 % (Table 4). The sample ML-Dolomite, CQ-Quartzite3 and TF-Granite have more than or equal to 0.8 % saturation coefficient indicating that these samples have potential towards frost damage and low durability [6:45]. 4.4. Strength Point-load strength index value ranges from 1.31 Mpa (KF-AG) to 8.11 Mpa (ML-Dolomite) (Table 4). Among six categories, the first (dolomite and metasandstone) and the third rock types (RF-Quartzite2 and CQ- Quartzite3) have higher point load strength indices, which range from 6.06 to 8.11 Mpa, compared to the other categories of rocks. The point-load strength index is moderate in samples of sericite quartzite (RF-Quartzite1 ii-type), amphibolite (iii-type) and granite (vi-type) ranging from 2.37 to 3.78 Mpa. Metasandstone (TF-Metasandstone) shows the highest UCS (128.9 Mpa) whereas augen gneiss (KF-Augen gneiss) gives the lowest UCS value (37.67 Mpa) (Table 4). Dolomite (ML-Dolomite) and quartzite’s (RF-Quartzite2& CQ-Quartzite3) have moderate UCS. However, sericite quartzite (RF-Quartzite1) of the Robang Formation possesses lower UCS value in comparison to other quartzite samples. 4.5. Durability In acid immersion test, samples BM-Marble and ML-Dolomite show severe and mild sign of decay, respectively (Table 4). In addition, rest of other samples show low sign of decay. From the crystallization test, the mean weight loss of all rock specimens varies from 0 to 1% indicating grade A category or most durable rocks [24] (Table 4). The MBAV varies from 0.44 to 0.89 % and most of the samples have less than 1% indicating that the clay material or swelling material is relatively negligible in them. Therefore, swelling potentiality of samples is very low [17]. Ethylene glycol soak test shows that soak test index is 2.0 in all samples indicating that they are chemically durable and well resistant against weathering [25:68-71]. American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2017) Volume 35, No 1, pp 236-250 246 Table 4: Evaluation of rock masses based on durability and strength of selected rock types Sample Rock types Physical properties Strength Durability *1WA V, % G, kg/ m³ *2Dry Densi ty, kg/m³ n , % S C Is(50), Mpa *3UC S, Mpa AIT *4C T, % MBA V, % *5 E G ST I ML- Dolomite Dolomit e 0.88 2.5 2.75 1 . 5 1 8.11 107 aMS D 0.51 (A) 0.5 2. 0 RF- Quartzite1 Sericite Quartzit e 0.97 2.6 2.49 1 . 5 0 2.37 49 LSD 0.01 (A) 0.44 2. 0 RF- Amphibolit e Amphib o-lite 2.24 3.2 2.76 1 . 6 0 3.78 63 LSD 0.1 (A) 0.87 2. 0 RF- Quartzite2 Quartzit e 1.11 2.4 2.42 0 . 5 0 6.07 111 LSD 0.1 (A) 0.78 2. 0 BM-Marble Marble 0.88 2.3 2.79 2 . 6 0 1.54 40 SSD 0.15 (A) 0.61 2. 0 CQ- Quartzite3 Quartzit e 1.55 2.5 2.9 0 . 2 1 6.16 113 LSD 0.01 (A) 0.67 2. 0 KF-Augen gneiss Augen gneiss 1.3 2.5 2.6 2 . 3 0 1.31 38 MS D 0.03 (A) 0.87 2. 0 TF-Meta sandstone Metasan d-stone 0.35 2.2 2.5 0 . 4 1 6.06 129 MS D 0.77 (A) 0.87 2. 0 TF-Granite Granite 0.38 2.5 2.56 0 . 8 1 4.88 102 MS D 0.13 (A) 0.89 2. 0 *1WAV (0.2 to 8 % [20-23], *2Dry density (ASTM , ranging from 1.76 to 2.8 kg/m3 [20-23]; *3UCS (12 to 138 Mpa [20-23]),*4CT = Crystallization test [grading: A ( <1 %), B ( 1-5 %), C ( 5-15 %), D ( 15-35 %), E ( 35- 100 %), F ( > 100 %) % wt. loss after [24], *5EGSTI (ranges from 2; rock material is more or less unaffected to 11; rock material totally broken down [25:69-70]); aMSD = mild sign of decay, LSD = low sign of decay, SSD = severe sign of decay. 5. Discussions Among six different categories, each rock type shows variation in strength value that ranges from medium to high strength [26]. Dolomite and quartzite samples show normal UCS value that ranges from 107.19 MPa in dolomite and 111.08 to 113.31 MPa in quartzite because of low WAV and higher density. Quartzite (RF- Quartzite2, CQ-Quartzite3), metasandstone and granite having higher resistance to load or higher strength value can be used for flooring, cladding and roofing of slabs etc [1:506]. Augen gneiss sample (KF-Augen gneiss) American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2017) Volume 35, No 1, pp 236-250 247 shows very low UCS value than that of average value ranging from 49 MPa to 196 MPa [27:6]. It is so because the micaceous minerals in rock are slightly weathered which gives space to secondary pore to develop while performing test. During the test, pores start to develop as micro-cracks and then slippage occurs along the micro-cracks [28]. In addition, it has coarse-grained texture having low amount of quartz (around 25 %) and higher WAV [3:14-16, 29:122]. Being similar composition quartzite sample RF-Quartzite1 has lower WAV and higher density but it has low UCS value. It is so because the quartzite sample has continuous foliation structure defined by a phyllo-silicate mineral, i.e. sericite. The higher content of sericite minerals and loosely interlocked quartz grain demonstrate the lower compressive strength value [29, 30]. Dolomite and marble samples have similar WAV and density value while being slightly weathered carbonate rock, BM-Marble exhibits lower strength value than that of ML-Dolomite. The normal strength value of dolomite is above 52 Mpa [21] and marble ranges from 116 to 162 Mpa [20]. TF-Amphibolite exhibits medium-grained, crystalline and interlocked fabric, higher WAV and higher porosity. Therefore, it has lower durability and moderate strength compared to other samples. Quartzite (RF-Quartzite1), amphibolite, and augen gneiss have low resistance to compressive load and are therefore suitable for interior cladding [6:42]. The point-load index value of foliated rock types are low because the foliated rock develops initial cracks while hammering and such cracks continue to develop further breakage that weakens the rocks. In terms of durability, except carbonate rocks all the samples show positive and good results. Metasandstone and dolomite exhibit higher % weight loss during crystallization test, which directly indicates that these rocks are less durable in comparison to other rock types and are susceptible to weathering [8:313]. Limestone, marble and calcareous rocks are susceptible to acid rain and not appropriate for external applications [3:22]. Except carbonate rocks, other rocks having higher durability can be used for exterior cladding of buildings particularly in polluted urban environments [6:42]. Therefore, durability is an essential parameter while considering for interior use rather than the strength. 6. Conclusions Among six different varieties of rocks which have been studied for suitability of building stones, the suitable rock types considering strength and durability are those of ML-Dolomite (Malekhu Limestone), RF-Quartzite2 (Robang Formation), CQ-Quartzite3 (Chisapani Quartzite), and TF-Metasandstone and TF-Granite from the Tistung Formation. Majority of the rock samples, except amphibolite (RF-Amphibolite), and marble (BM- Marble), exhibit moderate range of strength value, whereas quartzite (RF-Quartzite) and augen gneiss (KF- Augen gneiss) have the least strength values though they have higher durability. Durability tests of almost all the samples except carbonate rocks show suitable results. Rock samples of quartzite, metasandstone and granite with higher strength and durability are suitable for exterior and interior purposes such as flooring, cladding, roofing as slabs etc. In addition, the samples KF-Augen gneiss, RF-Amphibolite and RF-Quartzite1 with low strength and high durability are suitable for interior flooring, facing and cladding uses, and exterior facing and cladding applications. Dolomite and marble are suitable only for interior purposes such as interior flooring and wall cladding because of low durability and moderate strength values. Acknowledgments Authors are thankful to Chinese academy of science for providing financial support. Authors thank Central American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2017) Volume 35, No 1, pp 236-250 248 Department of Geology, Tribhuvan University, Nepal Electricity Authority, Soyambhu and Phulchok Engineering Campus, phulchok for providing facilities of equipment and laboratory facilities. References [1] Yilmaz, N.G., Goktan, R.M. and Yaşar, K. “Relations between some quantitative petrographic characteristics and mechanical strength properties of granitic building stone.” International Journal of Rock Mechanics and Mining Sciences, vol. 48, pp. 506-513, 2011. [2] Anon., 1983, The selection of natural building stone. Digest. 260. Building Research Establishment, Her Majesty’s Stationary Office. London. [3] Geoff quick. “Selective guide to the specification of dimension stone”, CSIRO building, construction and engineering, highett, Australia, issue 1, pp. 14–22. (www.discoveringstone.com) [4] Ozcelik, Y. and Ozguven, A. “Water absorption, drying features of different natural building stones.” Construction and building materials, vol. 63, pp. 257–258, 2014. [5] Yavuz, A.B. and Topal, T. “Thermal and salt crystallization effects on marble deterioration: examples from western Anatolia, turkey.” Engineering geology, vol. 90, pp. 30, 2007. [6] Harrison, D.J. and Bloodworth, A.J. Industrial Minerals Laboratory Manual: Construction Materials. Nottingham, United Kingdom: British geological survey, 1994, pp. 42–85. [7] Benavente, D., Garcia del cura, M.A., Fort, R. and Ordonez, S. “Durability estimation of porous building stones from pore structure and strength.” Engineering geology, vol. 74, pp. 113–127, 2004. [8] Benavente, D., Garcia del cura, M.A., Bernabeu, A. and Ordonez S. “Quantification of salt weathering in porous stones using an experimental continuous partial immersion method”. Engineering geology, vol. 59, pp. 313, 2004. [9] Bieniawski, Z.T. Engineering rock mass classifications. New York: John Wiley & Sons, 1989, pp. 51– 58. [10] Palmström, A. “Measurements of and correlations between Block size and Rock Quality Designation (RQD).” Tunnels and underground space technology, vol. 20, pp. 352–377, 2005. [11] Elci, H. and Tuck, N. “Rock mass block quality designation for marble production.” International Journal of Rock Mechanics and Mining sciences, vol. 69, pp. 26–30, 2014. [12] ASTM international. “Standard Test Method for Absorption and Bulk Specific Gravity of Dimension Stone.” ASTM C97/C97M-15, West Conshohocken, PA, US, 2015. Available: (www.astm.org). http://www.discoveringstone.com/ http://www.astm.org/ American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2017) Volume 35, No 1, pp 236-250 249 [13] ASTM International. “Standard Test Method for Determination of Point Load Strength Index of rock”. ASTM D5731–02, West Conshohocken, PA, US, 2002. Available: (www.astm.org). [14] Diyuan, L. and Wong, L.N.Y. “Point load test on metasedimentary rocks and correlation to UCS and BTS.” Rock mechanics and rock engineering, vol. 46, pp. 913–915, 2013. [15] Mishra, D.A. and Basu, A. “Estimation of uniaxial compressive strength of rock materials by index tests using regression analysis and fuzzy inference system.” Engineering Geology, vol. 160, pp. 54–68, 2013. [16] Kahraman, S., Gunaydin, O. and Fener, M. “The effect of porosity on the relation between uniaxial compressive strength and point load index.” International journal of rock mechanic & Mining sciences, vol. 42 (4), pp. 584–589, 2005. [17] Ohio, DOT. “Determination of Methylene Blue Adsorption Value of Mineral Aggregate Fillers and Fines.” supplement 1052, Sep. 22 1995. [18] Haskins, D.K. and Bell, F.G. “Drakensberg basalts: their alteration, breakdown, and durability.” Quarterly Journal of Engineering Geology, vol. 28, pp. 287–302, 1995. [19] Stöcklin, J. “Geology of Nepal and its regional Frame.” Journal of the Geological Society of London, vol. 137, pp.9–22, 1980. [20] ASTM International. “Standard Specification of Marble Dimension Stone.” ASTM C503/503M-10, West Conshohocken, PA, 2010. Available: (www.astm.org). [21] ASTM International. “Standard Specification of Limestone Dimension Stone.” ASTM C568/568M-10, West Conshohocken, PA, US, 2010. Available: (www.astm.org). [22] ASTM International. “Standard Specification of Granite Dimension Stone.” ASTM C615/615M-10, West Conshohocken, PA, US, 2011. Available: (www.astm.org). [23] ASTM International. “Standard Specification of Quartzite Dimension Stone.” ASTM C616/616M-10, West Conshohocken, PA, US, 2010. Available: (www.astm.org). [24] Honeyborne, D.W. The building Limestone of France. London: Building Research Establishment Report, 1982, 116p. [25] Bell, F.G. and Jermy, C.A. “The geotechnical character of some South African dolerites, especially their strength and durability.” Quarterly Journal of Engineering Geology and Hydrogeology, vol. 33, pp. 68-71, 2000. [26] Bieniawski, Z.T. Engineering classification of jointed rock masses. South Africa: South African http://www.astm.org/ http://www.astm.org/ http://www.astm.org/ http://www.astm.org/ http://www.astm.org/ American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2017) Volume 35, No 1, pp 236-250 250 institution of civil engineers, 1973, vol. 15 (12) pp. 335–344. [27] Bureau of Indian standards. “Indian Standard Method of identification of Natural Building stones.” India IS: 1123-1975, 2003. [28] Romana, M. and Vasarhely, B. “A discussion on the decrease of unconfined compressive strength between saturated and dry rock samples.” in 11th International congress on rock mechanic (ISRM), 2007, 4p. [29] Abd E.L-Hamid, M.A., Draz, W.M., Ismael, A.F., Gouda, M.A. and Sleem, S.M. “Effect of petrographical characteristics on the engineering properties of some Egyptian ornamental stones.” International journal of scientific and engineering research, vol. 6 (7), pp. 116-123, July-2015. [30] Behrestaghi, M.H.N, Rao S. K., and Ramamurthy, T. “Engineering geological and geotechnical responses of schistose rocks from dam project areas in India.” Engineering geology, vol. 44 (1-4), pp. 183–201, Oct. 1996. 7. Recommendations Care should be taken to minimize the formation of micro-cracking in samples while preparing samples for the tests. For strength test, core samples are better than the lump samples. In field, discontinuity analysis might help to determine tentative block shape that ultimately help to know exact size and shape of blocks. The physical, chemical and mechanical test can be used to assess preliminary investigation of rock types for building stone. Based on durability and strength, the most suitable rock type among the sample is quartzite.