Keywords

1 Introduction

Rapid developments in capital of Malaysia, Kuala Lumpur, are encroaching the whole area of the city. Many of the engineering structures are built upon rock mass such as high rise buildings, railways and highways for transportation systems and tunnelling for raw water supply. Since, many substructures are constructed on rock masses; it is very essential to have a proper knowledge for technical communities who involve in the projects on the engineering properties of the material found in the structures in Kuala Lumpur.

Geologically, there are two main types of rocks that are mostly found in Kuala Lumpur which are granite and limestone. In Kuala Lumpur, about one third of the area is on limestone formation. The geologic setting of Kuala Lumpur and Ipoh (city in the state of Perak) is strikingly similar where the granite intruded the sedimentary formation of limestone [1]. The limestone is dominantly found at the centre of Kuala Lumpur city meanwhile, granite mostly bounded at the eastern area of Kuala Lumpur towards the Main Range of Peninsular Malaysia. The design and construction in limestone area have various problems to geotechnical engineers due to karstic features of limestone such as steeply inclined bedrock, cavities, slump zones and sink holes. The construction problem is mostly due to piling works.

Granite is the rock that is considered as having a massive structure, and is often assumed as stable and suitable for any construction projects. In Malaysia, incident of rock slides may have happened several times in the past but they were not too obvious as the Bukit Lanjan rock slide which blocked the nearby highway and caused the closure for 6 months [2]. The problem faced by granitic rock is when it is exposed to weathering that causes rock material to decay and deteriorate. Slopes and terrains are the most risky area for granite formation. Examples of such failure include the highland Tower tragedy in 1993, rockslide at Bukit Lanjan in 2003 and landslide at Bukit Antarabangsa in 2008. All these cases involve construction on granite on hill slopes.

This research was carried out to provide information on engineering properties and characteristics of Kuala Lumpur granite and limestone. This research study was conducted based on the ongoing highway project connecting Sungai Besi to Ulu Kelang in Kuala Lumpur city. The main objective of this research work is to determine the physical and geological properties of limestone and granite through a series of testing conducted on the rock samples. The findings from this laboratory testing will be used to determine the physical and mechanical properties of limestone and granite; and to characterise the geology of limestone and granite by petrography study. The engineering characterisation of rocks from Kuala Lumpur significantly provides information to the geotechnical practitioners, rock mechanics society and engineering geology communities on this natural material from a place in tropical region.

2 Materials and Methods

The rock samples for this study were provided by a site investigation contractor who is responsible to report the result of engineering properties from Kuala Lumpur area to the consultant of the project (Fig. 1). All laboratory tests were conducted in Universiti Teknologi MARA Rock Mechanics Laboratory. A total of 64 numbers of rock samples from 32 boreholes were collected during site investigation works using borehole drilling method. The tests were referred to the Standard of Rock Characterisation Testing from International Society of Rock Mechanics manual (ISRM) [3]. In this research, there were five laboratory tests that were conducted to measure the engineering parameters of granite and limestone rock materials. The tests were divided into two groups which are the determination of physical and mechanical properties of rock. Physical properties identification was done by petrography description while determination on mechanical properties was conducted by several tests including uniaxial compression strength (UCS), point load test (PLT), Brazilian test and slake durability test.

Fig. 1
figure 1

Samples from borehole locations

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3 Result and Analysis

Upon completing the laboratory tests, results were recorded and classified based on the types of tests.

3.1 Uniaxial Compressive Strength (UCS)

The uniaxial compression test is the main test in the laboratory for the rock samples. This is a destructive test that was performed on cylindrical rock specimen by compressing or loading them to get the maximum load to fail. Upon failure, the rock specimen usually fractures by axial, brittle splitting or fails in shear, depending on the specimens affected by the platens of testing machine and the surface quality of the particle, Tables 1 and 2 indicate the results for granite and limestone of UCS.

Table 1 Result of UCS for granite
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Table 2 The result of UCS for limestone
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3.2 Point Load Strength

Point load test is another simple index test for rock material. It gives the standard point load index, Is(50) that was calculated from the point load at failure and the size of the specimen, with size correction to an equivalent core diameter of 50 mm. The result is tabulated in Tables 3 and 4 for granite and limestone, respectively.

Table 3 Results of point load for granite
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Table 4 Results of point load for limestone
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3.3 Tensile Strength

Brazilian test is interpreted as indirect method to determine the tensile strength of the rock. The test is to measure the weakest point of rock specimen due to tensile load. Result of tests is Tabulated in Tables 5 and 6. The tensile strength of the rock is calculated from failure load (P), specimen diameter (D) and specimen thickness (t) by the following formula:

Table 5 Result for Brazilian test of granite
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Table 6 Result for Brazilian test of limestone
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$${\text{Tensile strength}} = \frac{0.636P\,(100)}{Dt}$$
(1)

where

P :

Load of failure (N)

D :

Diameter of specimen (mm)

t :

Thickness of specimen (mm)

3.4 Slake Durability

The slaking process involves two groups of different rocks which are granite and limestone. The purpose is to measure the differences in durability between granite and limestone from the same place of taking. Table 7 shows the slake durability index of granite and limestone throughout the slake process.

Table 7 Slake durability of granite and limestone
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3.5 Petrographic Analysis

3.5.1 Granite

The mineral in thin section are seen by Plan Achro FP 10X/0.25. In granite, feldspars and quartz are major constituent minerals. Feldspars can be divided into two types which are alkali feldspars and plagioclase feldspars that consist of 25 % of mineral constituent, respectively. Alkali feldspars are more common than plagioclase, because they are more resistant to chemical weathering. Simple twinning as seen in Fig. 2 is very common in monoclinic alkali feldspar and this serves to distinguish them from plagioclases since the latter usually shows lamellar twinning as well as simple twinning.

Fig. 2
figure 2

Microscopic image of granite and limestone

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Quartz is also the most abundant grain in granite with 40 % mineral constitution. The matrix between the quartz and feldspar grains contains dark minerals such as biotite, olivine or hornblende commonly present in granite constitute 10 % of the thin section specimen of granite.

3.5.2 Limestone

Calcite cement is usually fairly coarse grained and constitutes 100 % in the limestone rock as it is originated from calcium carbonate mineral based such as shell brachiopod. Occasionally they are so coarse resulting in a poikilitic texture. Figure 2 shows sandstone in which the detrital grains are subangular to surrounded quartz. The cement is calcite of such a grain size that there are only a few crystals in the field of view shown.

4 Discussions

Based on the result of the engineering properties for granite and limestone of this study, there are two types of characteristics which are physical and mechanical characteristic. For mechanical characteristic, four types of tests have been conducted which are UCS, point load test, Brazilian test and slake durability test. The value that obtained from UCS is 15.96–103.85 MPa for granite and 4.17–87.88 MPa for limestone. Then for the point load test, the value for the granite is 3.0–8.5 MPa and for the limestone is 0.5–8.5 MPa. For the third test which is Brazilian test, the result was 2.4–9.4 MPa for granite while 2.6–10.6 MPa for limestone. The result for slake durability test is indicating in percentage which is different from other test. The result is 98.0–99.0 % for granite and 96.4–97.9 % for limestone. The physical characteristic test was conducted by petrography study. The mineral content found in granite are feldspar, quartz and a little of dark minerals. The percentage of each mineral is different due to the origin of granite during crystallisation and cooling process. Calcite was only mineral found in limestone sample in the study. The summary of the engineering characterisation of granite and limestone from Kuala Lumpur is shown in Table 8.

Table 8 Summary of engineering characterisation of granite and limestone of Kuala Lumpur
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The results were compared with the established value of each strength categories to remark the quality of the rock [4, 5].

5 Conclusions

It can be concluded that this study has provided significant information of the engineering characterisation for granite and limestone from Kuala Lumpur. The strength quality of UCS for granite and limestone varies from very low to high strength, meanwhile for point load index, the quality is from medium to high strength and very low to high strength for granite and limestone, respectively. The wide range of strength quality is may be caused by weathering and dissolution of both the types of rock. However, most of the samples have high durability index.