Lightweight aggregate is the generic name of a group of aggregates having a relative density lower than normal aggregates (natural sand, gravel, and crushed stone), sometimes is referred to as low density aggregate. Depending on the source and the method of production, lightweight aggregates exhibit considerable differences in particle shape, texture and properties. Lightweight expanded clay aggregate (LECA) is among the common lightweight materials that have been applied successfully in civil engineering works. Many studies have been conducted to investigate the performances of LECA used in structural and geotechnical applications. They are favourable materials used in projects where weight is an issue because the materials can help reduce dead loads and lateral forces by more than half in installations over structures and those with soft soils. LECA is an eco-friendly nature-based waste product that combines the same benefits as brick tiles. LECA is indestructible, non-combustible, and impervious to attack by dry-rot, wet-rot and insects. This paper focused on the properties of LECA aggregates supplied by LEXCA Sdn. Bhd. through laboratory tests in accordance to the standard specifications. The properties of several LECA produced from different country and production plants are also reviewed for comparative purpose. In addition, the material properties evaluated from previously conducted research also was discussed. It was found that, even though LECA was produced from the same raw materials, it has certain range of property values. The properties of LECA shows their suitability and potential for replacing natural aggregates in many civil engineering works. It is hoped that, the properties presented in this paper could help others who conduct study especially numerical analysis using LECA as geotechnical materials.

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Over the last decades, numerical modelling has gained practical importance in geotechnical engineering as a valuable tool for predicting geotechnical problems. An accurate prediction of ground deformation is achieved if models that account for the pre-failure behaviour of soil are used. In this paper, laboratory results of the consolidated drain (CD) triaxial compression tests and one-dimensional consolidation tests of marine clay were used to determine the hardening soil model (HSM) parameter for use in Plaxis 3D analyses. The parameters investigated for the HSM were stiffness, strength and advanced parameters. The stiffness parameters were secant stiffness in CD triaxial compression test ($$E_{50}^{\text{ref}}$$ E 50 ref ), tangent stiffness for primary oedometer loading test $$(E_{\text{oed}}^{\text{ref}} )$$ ( E oed ref ) , unloading/reloading stiffness $$(E_{\text{ur}}^{\text{ref}}$$ ( E ur ref ) and power for the stress-level dependency of stiffness (m). The strength parameters were effective cohesion ($$c_{\text{ref}}^{\text{'}}$$ c ref ' ), effective angle of internal friction ($$\phi^{\text{'}}$$ ϕ ' ) and angle of dilatancy ($$\psi^{\text{'}}$$ ψ ' ). The advanced parameters were Poisson’s ratio for unloading–reloading (ν) and K0-value for normal consolidation $$\left( {K_{\circ}^{\text{nc}} } \right)$$ K ∘ nc . Furthermore, Plaxis 3D was used to simulate the laboratory results to verify the effectiveness of this study. The results revealed that the stiffness parameters $$E_{50}^{\text{ref}} , E_{\text{oed}}^{\text{ref}} , E_{\text{ur}}^{\text{ref}}$$ E 50 ref , E oed ref , E ur ref and m are equal to 3.4 MPa, 3.6 MPa, 12 MPa and 0.7, respectively, and that the strength parameters $$c_{\text{ref}}^{\text{'}}$$ c ref ' , $$\phi^{\text{'}}$$ ϕ ' , $$\psi^{\text{'}}$$ ψ ' and $$K_{\circ}^{\text{nc}}$$ K ∘ nc are equal to 33 kPa, 17.51°, 1.6° and 0.7, respectively. A final comparison of the laboratory results with the numerical results revealed that they were in accordance, which proved the efficacy of the study.

Problematic soil such as marine clay causes structures or pavement to crack and collapse as marine clay possesses low bearing capacity. Therefore, ground improvement is usually conducted to improve the bearing capacity. Since the use of cement for strengthening weak soil is not environmental-friendly, the aim of this study is to improve the bearing capacity of marine clay using polyurethane (PU) columns. The properties of the marine clay collected from Batu Pahat determined were particle size distribution, Atterberg’s limits, specific gravity, and compressibility were determined. A series of small-scale physical modelling was conducted with a tank’s size of 500 mm x 500 mm x 200 mm. The 1:1 ratio of poly and isocyanate was injected into the cored hole for the column formation with the area improvement ratio was set as 12.6%. The loading process was conducted 1 day after column installation. Double tangent method from the stress-displacement curve was employed to determine the ultimate bearing capacity of the marine clay. The ultimate bearing capacity of the untreated marine clay was 50 kPa. In addition, the results showed that the ultimate bearing capacity of the marine clay increased with the length of the PU columns. A maximum improvement ratio of 220% was achieved for the end bearing PU columns. Comparing the improvement ratio with the published data showed that PU columns had a better performance than soil cement or deep mixing cement columns due to its lightweight and high strength. Therefore, the replacement of cement with PU is workable and sustainable in ground improvement method.

Uniaxial compressive strength (UCS) is one of the most widely used strength parameters in geotechnical design. The value is obtained through direct testing method, carried out through careful procedures of testing in a laboratory setting. As such, it is relatively more expensive, more tedious and requires longer time to complete. Considering that UCS is highly important, Engineers often utilize indirect methods, namely the Point Load Test, to obtain the Point Load Index Strength (Is(50)). From this test, the results are correlated in order to predict the UCS value. One of the general correlations is provided by ISRM where UCS=20-25 Is(50). However, it is highly contested as it is not universal for all types of rocks. The main focus of this research is to find the correlation of UCS and Is(50) in the Penang Island area. This research would also attempt to classify the granites according to strength. This study showed that the Penang Island Granites are “weak to very strong” granites with UCS values between 24.76 to 156.82MPa. The granites from the North Pluton are classified as “medium strong to very strong” with UCS values between 37.11 to 156.82MPa. The granites from the South Pluton are classified as “weak to very strong” with UCS values between 24.76 to 141.59 MPa. The recommended correlation between UCS and Is(50) are (1) Overall: 8.385 Is(50) + 30.016 (2) North Pluton: 7.93 Is(50)+ 35.606 (3) South Pluton: 9.03Is(50)+20.138.