Kamarudin Ahmad

University of Technology Malaysia | UTM · School of Civil Engineering

Enzymatic induced calcite precipitation (EICP) is a novel, innovative, sustainable and environmentally friendly technique for soil improvement. EICP utilizes extracted free urease enzyme to induce calcite precipitation. Being enzymatic reaction, EICP process is susceptible to variation in pH, temperature, concentrations of reactants and urease enzy...

The performance of marine clay (MC) treated with embedded polyurethane (PU) piles under vertical load is assessed through three-dimensional finite element (FE) simulations. The results of the FE analyses were validated using small scale physical model tests. The influence of pile length ratio and area ratio of the embedded PU piles in MC were also...

The deep soil mixing method (DSM) is known as a reliable and cost-efficient method of ground improvement which has been studied in great detail for peat stabilisation. The method has gained popularity for peat soil because of its improvement and broad applicability. The study aims to review the published literature focusing on small-scale and 1 g p...

The use of deep cement mixing (DCM) columns is an effective and affordable technique for ground stabilization. However, designing this method can be complex due to uncertainties in the geotechnical properties of the soil and DCM columns, area improvement ratio, column arrangement, and required cement content. This study aimed to address this issue...

A drainage system that is used to flow excess rainfall infiltration is an excellent alternative to enhance lateral diversion capacity at the interface of Grade VI and Grade V soil slope layers thus delaying breakthrough occurrences. This study aims to explore the performance of porous transport layer on slope behavior via numerical simulation by Ge...

Disaster such as earthquake has an impact to water resources particularly groundwater. The migration of pollutant in groundwater is crucial particularly due to earthquake impact. In addition, the soil moisture content also might influence the pollutant migration. Therefore, this paper presents the investigation of light non-aqueous phase liquid (LN...

The use of deep cement mixing (DCM) columns for soil stabilization is an economical and reliable ground improvement technique that has been studied extensively. The aim of this article is to review the ultimate bearing capacity (UBC) of soft soils improved by DCM columns in a series of 1 g physical modelling tests. Reliable databases of 35 stabiliz...

The accurate determination of the subgrade reaction modulus (Ks) of soil is an important factor for geotechnical engineers. This study estimated the Ks of soft soil improved with floating deep cement mixing (DCM) columns. A novel prediction model was developed that emphasizes the accuracy of identifying the most significant parameters of Ks. Severa...

To select a site for sanitary landfilling, it is paramount that geotechnical analysis is conducted to acquire relevant data for the purpose of studying soil properties. One of the basic requirements for the landfill site selection process is geotechnical criteria. This ensures that the chosen sites are founded on an impermeable soil deposit having...

It is not uncommon for mining activity to generate wastes associated with negative engineering impacts include susceptibility to runoff due to the absence of vegetation, erosion, and sinkhole. Due to their high degree of permeability, movement of heavy metal contaminants in waste soils and aquifers occurs actively along with the hydrogeological par...

Enzymatic induced calcium carbonate precipitation (EICP) is a biomediated soil improvement technique that utilizes free enzyme to produce a biocement material. This research investigated by performing test tube test the effect of varying urea-CaCl2 concentrations from 0.25 to 1.25 M on the mass and efficiency of calcium carbonate precipitation form...

Enzyme-induced calcite precipitation (EICP) is a biocementation technique that has the potential to improve the engineering properties of sand. The effectiveness of the EICP treatment was evaluated based on the unconfined compressive strength (UCS) tests at various concentrations of cementation reagent (CCR) and curing periods. The treated sand was...

Enzyme induced calcite precipitation (EICP) or biocementation has rapidly evolved in the last decade as an environmentally friendly ground improvement technique. In EICP, plant-derived urease enzyme is used to trigger the hydrolysis of urea in the presence of calcium ions to produce calcium carbonate (CaCO 3 ) precipitate within the soil matrix. De...

Exploring the biological process to enhance the engineering properties of soil have received enormous recognition in recent years. Enzymatic induced calcium carbonate precipitation (EICP) is one of the bio-inspired methods of utilizing free urease to precipitates calcite from urea and calcium ions for bettering the geotechnical properties of poor s...

Residual granite soil from Malaysia shows some problematic features such as: high void ratio, low natural dry density, and loose of apparent cohesion of the soil immediately after rain due to wetting. This study is aimed to evaluate the influence of suction and density on unsaturated behavior of the residual granite soil e.g., the yield stress (σc)...

Marine clay (MC) is recognised as an unfavourable soil in the construction field, given it continues to present problems of bearing capacity, consolidation, and settlements. In this paper, polyurethane was used to improve the properties of MC using a different mix ratio of polyol and isocyanate. The marine clay was characterised examining the parti...

The strength of residual soil treated via biocementation means by employing enzymatic induced calcium carbonate precipitation (EICP) was assessed based on the standard recommended for compacted clay liner. EICP treated samples were prepared at four different concentrations of cementation solution (urea-CaCl 2 ) (0.25, 0.50, 0.75 and 1.00 M) and at...

Recently, biocementation has become a trend of soil improvement. Nevertheless, few studies were conducted in its application to improve engineering properties of fine-grained soil. In this study, digital image technique (DIT) was employed to determine the effect of biocementation via enzymatic induced calcium carbonate precipitation (EICP) techniqu...

Enzyme-induced calcium carbonate precipitation (EICP) is a bio-inspired technique that uses urease to activate the urea-hydrolysis reaction to produce CaCO3 precipitation. This study was conducted to assess the effect of cementation solution concentrations on the plasticity and swell behavior of residual clay soil. The findings showed that the plas...

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 (C...

. 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 beari...

This paper presents the laboratory study on the dynamic characteristics of marine clay subject to cyclic load over a long period of time. Remoulded marine clay samples were used to conduct the experiments using a dynamic triaxial machine. Confining pressure and loading frequency were varied while pore pressure development, resilient strains and pla...

Abstract The strength of sandy soil can be improved via enzyme-induced calcium carbonate (CaCO3) precipitation (EICP). This method is a sustainable and environmentally friendly soil improvement technique that forms calcium carbonate between and around the soil particles. The formation of CaCO3 is achieved through the hydrolysis of urea that is cata...

Groundwater resources benefits to human activity for developing country. Groundwater contamination is crucial, particularly due to the amount of leakage and spillage of hydrocarbon liquids such as light non-aqueous phase liquids (LNAPLs), resulting in contaminated the groundwater and unsafe for domestic and agriculture activities. Penetration of hy...

The rainfall-induced residual soil slope stability issues constitute a major threat to both lives and property particularly in tropical country which characterized as intense and long duration rainfall. Capillary barrier system (CBS) is a well-known alternative in controlling the pore-water pressure built up and percolation. There were various stud...

Groundwater contamination is crucial, particularly due to hydrocarbon liquid leakages. Additionally, the vibration impact affects the migration of hydrocarbon through the subsurface soil to the groundwater surface which is causes by the dynamic stress that is imposed on the soils. Therefore, this paper presents the investigation and discussions on...

Reutilization of solid waste such as Tire Derived Aggregate (TDA) and mixing it with soft soil for backfill material not only reduces the required volume of backfill soil (i.e., sand-mining procedures; reinforcement), but also preserves the environment from pollution by recycling. TDA is a widely used material that has a good track record for impro...

Groundwater contaminations due to hydrocarbon or organic solvent spills in saturated or unsaturated zones affect the water resources. The quantity of hydrocarbon spills in the groundwater might influence the hydrocarbon migration. In addition, the soil moisture content in influencing the rate of migration is also unknown. Therefore, this paper pres...

Abandoned mines contaminated with heavy metal wastes pose health risk and environmental hazard. Common methods in managing these wastes include pond storage, dry sacking, underground and ocean disposal and phytho-stabilisation but these does not address the associated risks regarding migration of contaminated liquid or when the soil structure is co...

Soil stabilisation is one type of ground improvement technique regarded as effective in minimising foundation problems associated with marine clay (MC). In this paper, in-depth micro-level analysis was conducted on MC stabilised with 8% Polyurethane (PU). The effectiveness of PU as a stabiliser was evaluated using unconfined compressive strength (U...

This study aims to simulate the stabilization process of fibrous peat samples using end-bearing Cement Deep Mixing (CDM) columns by three area improvement ratios of 13.1% (TS-2), 19.6% (TS-3) and 26.2% (TS-3). It also focuses on the determination of approximate stress distribution between CDM columns and untreated fibrous peat soil. First, fibrous...

Like soils of other regions in the world, some tropical soils are also associated with problems of low strength. To improve engineering characteristics of soils, several methods have been employed worldwide which are categorized as mechanical, chemical, thermal and electrical. The aim of this research is to compare the compaction characteristics of...

Vibrations from vehicle traffic, machinery and operations from construction activities such as blasting are examples of some natural and man-made vibration phenomenon’s that can cause dynamic stress when imposed onto soils. In order to ensure sustainability of the geo-environment, the impacts caused by these vibrations as well as the changes in moi...

In evaluating a suitable type of stabiliser, investigating geochemical characteristics is important for improving the properties of soil. This paper assessed the geochemistry of marine clay samples collected from Batu Pahat, Johor, Malaysia. The parameters investigated were pH, loss on ignition (LOI) and the quantities of sulphate, chloride, nitrat...

To protect groundwater from leachate contamination in sanitary landfill involve the use of hydraulic barriers i.e. liners and covers. Nonetheless, can these barriers continue to impede the migration of leachate over a long period? A full-scale experiment would be prohibitively costly and time consuming. The only feasible recourse therefore is to co...

Preventing groundwater contamination from the most common method of solid waste disposal technique i.e. landfilling is by proving hydraulic barriers. Accordingly, water movement in unsaturated soil is important in the analysis of leachate migration in soil material used as hydraulic barrier in waste containment systems. A full-scale experiment woul...

A laboratory experiment was carried out to determine the concentration of cementation reagent that will produce the maximal amount of calcium carbonate induced by Bacillus Megaterium. The optimum condition for calcium carbonate precipitation was evaluated for its application in improving the geotechnical properties of soil. The process was studied...

The recent need to develop infrastructure, driven by global population growth is forcing societies to construct on any soil type available within their vicinity including weak soils. However, due to the poor physical and engineering properties of weak soils, they are not suitable for construction purposes. Given many ground improvement techniques t...

In engineering practice, natural and man-made vibration phenomenon can cause dynamic stress to be imposed on soils such as blasting, construction operations and machinery, and vehicle traffic vibrations. This issue need to be addressed to ensure the geo-environment is sustainably secure. Laboratory experiments were conducted to characterize the beh...

As leachate has been a source of groundwater contamination worldwide, this paper examines the phenomenon of leachate migration on different gradations of compacted laterite soil used as sanitary landfill liners. Three different soil gradations (30%, 40% and 50% with respect to fines content) used in this study were compacted in circular acrylic col...

Engineering practices, natural and man-made vibrations phenomena such as blasting, construction machinery and operations, and vehicle traffic vibrations can cause stresses to soils. In addition, changes in moisture content may affect the speed of liquid penetrating the soils. Therefore, the impacts due to vibrations and changes in moisture contents...

This study applied two feed-forward type computational methods to estimate the Unconfined Compression Strength (UCS) of stabilized peat soil with natural filler and cement. For this purpose, experimental data was obtained via testing of 271 samples at different natural filler and cement mixture dosages. The input parameters for the developed UCS (o...

Laterite soil, as one of the major groups of tropical residual soils, was investigated in application for engineered sanitary landfill liner. The laterite soil was used as a stand-alone material without any additives and subjected to different gradation to check its geotechnical potentiality as a sustainable material for liner. Specimens were prepa...

Screw Driving Sounding (SDS) test has been developed in Japan as the improved version of the Swedish Weight Sounding (SWS) test. The development of SDS is to reduce the drawbacks of the SWS with the integration of rod friction estimation. Deep boring with Standard Penetration Tests (SPT) together with soil sampling for laboratory tests have been th...

Contaminants flow through compacted soil liners and coversare usually considered under saturated conditions during design stage. Whereas, the compacted soil barriers in reality are neither completely saturated nor completely dry, rather they are in an unsaturated state. Thus, unsaturated flow principles need to be properly simulated to determine th...

Malaysia is known as a developing country with increasing number of population, thus increasing in demand for electricity. In 2010, 40% of electricity in Malaysia is generated by coal power plants. Thus, there will be an abundance of coal ash that can be reused in order to minimize the waste. Previous researchers have opted the use of these coal as...

This paper reviews the effects of gradation on hydraulic conductivity and volumetric shrinkage properties of compacted laterite soil liner. The distribution of different grain sizes affects the engineering properties of soil such as compressibility, swelling and shrinkage, shear strength, and hydraulic conductivity. It is observed that there are di...

Laterite soil was investigated to find out the effects of fines content and to identify the micro-structural and molecular characteristics to evaluate its potentiality as a compacted soil landfill liner material. Tests were carried out on natural soil and reconstituted soil by dry weight of soil samples to determine the physical and engineering pro...

The use of hydraulic barriers in sanitary landfills has become an impeccable means of protecting the groundwater system from leachate. A question to be asked is, can these barriers continue to impede the migration of leachate over a long period? This paper investigates the phenomenon of leachate migration in compacted laterite soil used as liner in...

Many chemicals stabilisation techniques are being employed all over the world to improve the engineering and physical properties of the problematic soils and reduce the potential damages caused by them. Out of those chemical stabilisation technics, application of Polyurethane to improve the strength of marine clay was investigated in the laboratory...

This paper presents the recent review on the effects of gradation on hydraulic conductivity and shear strength properties of compacted laterite soil liner. The distribution of different grain sizes affects the engineering properties of soil such as compressibility, shear strength, and hydraulic conductivity. It is observed that there are variations...

In view of the large movement required to mobilise the base resistance of bored piles and difficulty in base cleaning, the end bearing resistance often ignored in current design practice that will result in excessive rock socket length. Many attempts have been made to correlate the end bearing resistance with the uniaxial compressive strength of in...

Fibrous peats feature high compressibility and correspondingly very low strength. In this study, an investigation into the compressibility of untreated and stabilized fibrous peat with different binders—namely cement, lime, gypsum, and fly ash—is presented. The technique adopted for sample preparation was aimed at simulating the in-situ condition o...

The failure mechanism of backfill material for retaining wall was studied by performing a numerical analysis using the finite element method. Kaolin is used as backfill material and retaining wall is constructed by Polymer Concrete. The laboratory data of an instrumented cantilever retaining wall are reexamined to confirm an experimental working hy...

The aim of this paper was to determine the ultimate vertical bearing capacity of rectangular rigid footings resting on homogeneous peat stabilized by a group of cement deep mixing (CDM) columns. For this purpose, a series of physical modeling tests involving end-bearing and floating CDM columns were performed. Three length/ depth ratios of 0.25, 0....

This research aims to investigate the effect of temperature changes on the compression index and collapse potential of the residual granitic soil that is widely encountered in Malaysia. An experimental study was conducted on the compacted soil using a modified temperaturecontrolled oedometer. Temperatures of 27, 40, and 60 ºC were applied on two se...

Lack of consideration in the soil behaviors related to drying and wetting phenomenon namely volume change and collapsibility may cause damages to foundations, buildings, and other structures. This research reports an experimental work carried out to examine the collapsibility behavior of residual laterite soils under cyclic drying and wetting proce...

The use of Tire-Derived Aggregates (TDA) as highly permeable light weight material has been highlighted in different aspects of geotechnical engineering such as retaining walls, embankments and roads. In addition, in terms of human health and environmental matters, TDA usage is gaining attention. This paper gives an insight into the effect of TDA o...

Conventional deep soil mixing techniques are often used to improve soft soil properties in terms of their settlement, bearing capacity and shear strength characteristics. This technique has a wide range of applications such as improvement of embankment stability, slope stability, braced excavation and sea walls which can be performed in different s...

Lack of consideration in unsaturated soils behaviors namely volume change and collapse have caused lots of damages to foundations, buildings, and other structures. Such behaviors are related to drying and wetting phenomena. This paper presents results from triaxial tests on unsaturated clayey soil of Yasouj subjected to drying and wetting cycles us...

Double-porosity is an important characteristic in soil that is found to influence the migration of fluids within the soil. Of late, a number of laboratory experiment studies have been carried out on the flow of water through soil media with double-porosity characteristics as well as on the mechanical aspects of the double-porosity structure of t...

SUMMARYA numerical model describing the flow of multiphase, immiscible fluids in a deformable, double-porosity featured soil has been developed. The model is focused on the modelling of the secondary porosity features in soil, which is more relevant to groundwater contamination problems. The non-linear saturation and relative permeabilities were ex...

Physical model experiments were conducted to observe the migration of light non-aqueous phase liquids (LNAPL) in a double-porosity soil medium. The double-porosity characteristics of the soil were simulated through aggregation of kaolin which resulted in well-defined intra-aggregate and inter-aggregate pores. Digital images were collected to monito...

The results of shear box and consolidation tests on electrokinetically-treated tropical residual soil are presented. Injections of selected chemicals (calcium chloride, aluminium chloride and phosphoric acid) into the soil samples at the anodes or cathodes were carried out in cylindrical electrokinetic cells via applications of 30 V DC electrical p...