School of Civil and Environmental Engineering (CEE)

​​​​​​​​​Name of NTU Supervisor

Research Title

A/P Robert Tiong​A Study on BIM-based models for construction performance and productivity evaluation of PPVC construction technologies/ methods
CLKTIONG@ntu.edu.sg Prefabricated, Prefinished, Volumetric Construction (PPVC) technique represents a very attractive solution under DfMA approach and is considered as new game-changing construction technology that being adopted in Singapore construction industry which provides significant advancement for building constructions. For PPVC, modules complete with internal finishes, fixtures and fittings are manufactured in factories, and are then transported to construction site for installation in a Lego-like manner. The objective of this research is to study on BIM-based performance and productivity evaluation of PPVC construction technologies/ methods. Furthermore, this study strives to study on NTU PPVC projects, carry out Post-construction analysis and provide lessons learnt report in order to share learning points gained from NTU PPVC projects. This study will contribute to improve the construction productivity by evaluating the use of Building Information Modelling for Prefabricated Pre-finished Volumetric Construction.
A/P Robert Tiong
A study on BIM-based models for underground construction productivity
​​CLKTIONG@ntu.edu.sg BIM application in construction has recently gained attention from industry practitioners. Therefore, there is a need for further research in this field of how it enhances construction productivity for underground construction and tunnelling works. As a result, this study is aimed to investigate how BIM can benefit the construction industry in terms of productivity of underground construction projects. Student will visit and interview construction firms who have installed BIM and find out the relationship between BIM implementation and productivity improvement for underground construction works. A brief study on Cost and benefit analysis will be carried out. Student should have interest in BIM and exposure to construction works especially in underground construction.
Prof Harianto Rahardjo​​Influence of in-situ void ratio on the infiltration characteristics of residual soils​
​​​​CHRAHARDJO@ntu.edu.sg
​Global climate change especially the precipitation and drought periods has given rise to cases of natural hazard like slope instability. The rainfall-induced slope instability which results in severe socio-economic losses is largely influenced by the soil properties like soil water characteristics curve, the coefficient of permeability, effective cohesion, and effective friction. The infiltration characteristics in a slope vary at different soil depth indicating the need to consider the effect of void ratio. This project aims to study the influence of in-situ void ratio on the infiltration characteristics of residual soil through a series of laboratory tests. The resulting database of the depth-dependent hydraulic characteristics from the laboratory tests shall be used in conjunction with the % sand, % clay and % fine to develop a reliable statistical model. The reliable prediction of parameters governing infiltration using the model shall be undertaken to conduct finite element based seepage modelling.

 

For further information, please click on the link here:

https://eps.ntu.edu.sg/client/en_US/usmsul/

​​​Prof Harianto Rahardjo​​Analytical Analyses on Tree Stability
​​​CHRAHARDJO@ntu.edu.sg
​Trees are essential parts of the environment as they provide numerous advantages to human life. Planting trees in urban areas can reduce heat island effect and air pollution. However, tree failures can be a problem in Singapore during windstorms and could endanger public safety as well. Therefore, it is advantageous to explore tree stability from an engineering perspective. The root-soil plate of tree can be regarded as the structural foundation from the traditional engineering perspective. Beams could be used to represent the common shallowly rooted system in Singapore. This project aims to analytically solve the response of the beam or root-soil plate under gravity and moment loads created by the canopy and wind pressure. Winkler foundation will be applied to estimate the deflection from the elastic supporting soil and the response of the beam foundation. The analytical results will be used to compare with the numerical results and the monitored field data.

 

For further information, please click on the link here:

https://eps.ntu.edu.sg/client/en_US/usmsul/

​​Prof Harianto Rahardjo​​Effect of Confining Pressure on Soil-water Characteristic curves of Dual Porosity Soil
​​CHRAHARDJO@ntu.edu.sg
​The knowledge of unsaturated soil is indispensable for geotechnical problems such as rainfall-induced slope failure, collapsible soil and liquefaction. Some of those problems occurred within colluvial and residual soils that can be observed in tropical country including Singapore. The engineering behavior of unsaturated soil is significantly controlled by soil-water characteristic curve (SWCC) of the soil. The SWCC shows the relationship between volumetric water content and matric suction of the soil. Many residual and colluvial soils are classified as dual porosity soils which are associated with bimodal SWCC. Past studies indicated that the uniqueness of the SWCC are influenced by different parameters, such as confining pressure, compaction state, initial void ratio, initial water content and initial stress state. Up to now, no studies have been carried out to investigate the effect of confining pressure on SWCC.  The objective of this project is to study the effect of the confining pressure on the SWCC of dual porosity soil. The scope of the project involves measurements of drying and wetting soil-water characteristic curve (SWCC) using advanced triaxial apparatus and development of mathematical model to describe the effect of confining pressure on SWCC.


 

For further information, please click on the link here:

https://eps.ntu.edu.sg/client/en_US/usmsul/

Asst/P Qian Shunzhi Speedy self-healing cementitious materials via genetic modification of bacteria

SZQian@ntu.edu.sg

 

​Cementitious materials are commonly used in civil infrastructures. Despite of many advantages, cracking related problems persist, such as leakage, loss of stiffness, and even structural failures, which are more severe for underground structures. With many caverns and tunnels, Singapore is particularly vulnerable to this problem. This kind of problem will be addressed in this proposal via genetically modified bacteria based self-healing concrete (SHC).

Unlike manual repair, when concrete is cracked, the embedded bacteria will be activated automatically due to exposure to natural environments, therefore releasing calcium carbonate via metabolic conversion of nutrients to heal concrete without external intervention. Compared to expensive, labor intensive and sometimes dangerous manual repair, bacteria-based self-healing concrete has great advantages due to low cost and no labor requirement. In previous study, researchers applied Bacillus to improve healing efficiency with certain success. However, their wild type bacteria still suffers from too long healing time, vulnerable to high pH environment in cement and no recovery of mechanical strength. Our novel approach is to apply transposon mutagenesis method to the Bacillus bacteria so that a fast growing and better resistance to high pH strain can be obtained, therefore allowing for more robust and speedy self-healing in novel bendable concrete. The student will be guided by an experienced research staff in addition to supervision of Prof Qian Shunzhi.

Asst/P Qian Shunzhi Multi-scale mechano-electrical design for bendable concrete based self-sensing composite material
SZQian@ntu.edu.sg​Improper design, construction and/or deterioration of concrete structures, e.g. large cracking, may lead to loss of structural stiffness, strength, or even collapse in some extreme cases, such as the tragic 1986 Hotel New World Collapse in Singapore and 2004 Charles de Gaulle Airport Collapse in France, killed 33 and 4 people, respectively. The challenge to maintain the safety of concrete structures will become even greater as Singapore strives to build much higher and deeper to cater for its increasing population, which involves much more complicated designs, constructions, loadings and environments (e.g. underwater/undersea infrastructure/city).

To address this long-lasting concern, a more prudent method is to use self-sensing concrete to automatically monitor structural health condition to greatly improve its safety and help save human lives. Proposed is the development of fundamental understanding on the multiple-level mechanical/electrical coupled behaviour of self-sensing phenomena in bendable concrete material. This is accomplished through systematic redesign of bendable concrete incorporating conductive raw materials via refined micro-level mechanics design tools, multiple-level modelling of the self-sensing behaviour by linking the micro-level of fibre, matrix and their interactions, meso-level of single crack behaviour with macro-level concrete behaviour, followed by experimental studies on the mechanical loadings, physical properties, and environmental exposure conditions that is optimal for self-sensing to occur.  

It is expected that this research will produce a set of guidelines for achieving reliable bendable concrete based self-sensing and create a set of materials design tools to meet these strict requirements, ultimately resulting in concrete which improve the overall health and safety of countless concrete structures. Specifically, the proposed work will focus on the following objectives:

  1. Design bendable concrete based on micro-level mechanics model;
  2. Develop multiple-level model for self-sensing behaviour of above material;
  3. Investigate mechanical/physical/environmental effects on the self-sensing concrete.
Prof Harianto Rahardjo​​Soil-water Characteristic Curve and Permeability Function of Residual Soil
CHRAHARDJO@ntu.edu.sg
​Residual soil slope is mostly encountered in an unsaturated condition. The engineering behaviour of unsaturated soil is significantly controlled by soil-water characteristic curve of the soil. The soil-water characteristic curve shows the relationship between volumetric water content and matric suction of the soil. Varying climatic conditions such as periodical dry and wet periods in a tropical country like Singapore result in soils near ground surface to be subjected to cycles of drying and wetting. Under the same stress state, a soil exhibits different hydraulic characteristics and different water contents when it follows a drying process (evaporation) as opposed to following a wetting process (infiltration). These differences are referred to as hysteresis of soil. Different soil properties produce different degrees of hysteresis during drying and wetting processes. Some soils exhibit a distinct hysteresis while other soils exhibit insignificant hysteresis. The objective of this project is to understand the effects of soil properties on the degree of hysteresis of soil through laboratory tests on hydraulic and basic properties of soil. The scope of the project involves measurements of index properties and drying and wetting soil-water characteristic curve using small-scale centrifuge, Tempe cell, and pressure plate.

 

For further information, please click on the link here:

https://eps.ntu.edu.sg/client/en_US/usmsul/

​​Dr. Cise UnluerEnhancing the microstructure and strength gain of sustainable cement binders​

UCise@ntu.edu.sg

 

​Portland cement (PC), the most widely used construction material, is responsible for 5-7% of anthropogenic CO2 emissions. Alternative magnesium oxide (MgO) based binders present technical and sustainability advantages over PC due to their lower manufacturing temperatures; ability to sequester significant quantities of CO2; and complete recyclability. This study will focus on developing fully recyclable MgO concrete mixes with enhanced microstructure and performance by increasing hydration and carbonation degrees. Enhancement of carbon sequestration will be performed through an investigation of the performance and microstructure of a range of compositions, with the goal of maximizing hydration and carbonation. Hydration and carbonation mechanisms will be evaluated by isothermal calorimetry and microstructural analyses including scanning electron microscopy (SEM), X-ray diffraction (XRD) and thermogravimetry/differential thermal analysis (TG/DTA). Performance mechanisms will be studied by measuring the porosity and unconfined compressive strength (UCS) of the prepared mixes. Final results will highlight the main parameters controlling the hydration and carbonation processes and suggest optimized formulations with enhanced sustainability and performance.

Duration of project: Minimum of 6 months

Assoc Prof Lim Teik Thye
Graphene-based adsorbents and carbocatalysts for synergistic adsorption-oxidation of antibiotics and pesticides in wastewater

 cttlim@ntu.edu.sg

 

 

​Non-metal, carbon–based catalysts such as activated carbon (AC), graphene oxide (GO), reduced graphene oxide (rGO), carbon nanotubes (CNTs) and graphitic carbon nitride are alternative catalytic materials for application in water decontamination. They provide a potential solution to the metal leaching problem associated with the metal-based catalysts. Besides, they also demonstrate good adsorption capacity for organic pollutants due to their large surface areas and large density of active surface sites. This research will focus on development of functionalized graphene for water decontamination. It comprises two parts: (1) synthesis of various rGO and GO and functionalize them to create adsorption and catalytic active sites, and (2) conducting experiments to evaluate the performance of the functionalized rGO and GO to illustrate the synergistic adsorption and catalytic oxidation processes for pollutant removal. The oxidants to be applied include persulfate, peroxymonosulfate, hydrogen peroxide or ozone. The students will be trained to use TEM, FESEM, XPS, XRD, AFM, etc for material characterizations. If time allows, the student can also incorporate density functional theory (DFT) into the research program. The students with adequate academic training in the fields of material science, chemistry or chemical engineering, and proven research enthusiasm, are preferred for this internship research. 

Duration: 6 months, or equivalent to a typical duration for a master degree's research project   

Assoc Prof Leong Eng Choon Water characteristic curves of geosynthetic clay liners
 CECLEONG@NTU.EDU.SG

The use of geosynthetic clay liners (GCL) started in the United States in 1988 for solid waste containment as a backup to a geomembrane. There are many GCLs in the market but essentially a typical GCL consists of a bentonite layer sandwiched between two geotextiles. The geotextile below the layer of bentonite is the carrier textile and the geotextile above the layer of geotextile is the cover textile.

The engineering function of a GCL is to act as a barrier in a containment system to leachate or other liquids and sometimes gases. As such, they are used as replacements for either compacted clay liners or geomembranes, or they are together with compacted clay liners and geomembranes. The effectiveness of the GCL relies on the saturation of the bentonite clay layer during service. Normally the GCL is laid dry and the is wetted by the underlying soil.

Hence the water characteristic curve of the GCL is an important design input parameter to the containment system. The scope of the project involves laboratory determination of the water characteristic curve of the GCL using several types of apparatuses. Comparison with water characteristic curves of other GCLs will also be made.

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Prof Harianto Rahardjo​​
Sensitivity Analyses on Factors Influencing Tree Stability through Numerical Modelling  
CHRAHARDJO@ntu.edu.sg

Trees are essential parts of the environment as they provide numerous advantages to human life. Planting trees in urban areas can reduce heat island effect and air pollution. However, tree failures can be a problem in Singapore during windstorms and could endanger public safety as well. Therefore, it is advantageous to explore tree stability from an engineering perspective by considering tree stem as above-ground structure and root-soil plate as foundation.

There are several factors associated with climatic conditions such as wind and rainfall intensity together with leaf area density, soil strength parameters and wood strength parameters that influence tree stability. Therefore, it is necessary to evaluate the importance of each factor in the overall stability of tree, as well as the sensitivity of tree stability with respect to the changes in these factors.

In this study, numerical modelling will be used to evaluate the importance of these factors on tree stability in order to minimize the use of destructive and expensive field methods. In the end, parametric studies will be carried out to assess the spectrum of influence of these controlling factors for tree stability.


For further information, please click on the link here

https://eps.ntu.edu.sg/client/en_US/usmsul/​
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Asst Prof Wu Wei
Excavation-induced failure of intact granite under in-situ stress conditions
wu.wei@ntu.edu.sg
​Climate change could cause intense storms and prolonged droughts. To mitigate flooding and manage water supply, a solution for a land-scarce city is to build an underground drainage and reservoir system, which is composed of tunnels and caverns for water transport and storage. In the construction of underground facilities, the mechanical response of rocks is a critical factor for identifying potential geological hazards.

 

For example, rocks at a great depth may have mechanical response different from those at a shallow depth. The likelihood of rock burst occurring increases as the excavation depth increases. The objective of this study is to investigate unloading-induced failure modes of intact granite subjected to in-situ stresses. For intact granite at different depths, the unloading process may induce different failure modes, from a quiet slip failure to an explosive failure. A better understanding of excavation-induced failure of intact granite could help us optimize excavation strategies and reduce potential geological risks.

Assist. Prof. Grzegorz Lisak
Materials for environmental protection and monitoring
g.lisak@ntu.edu.sg​
​Protection and monitoring of natural waters for toxic components is essential for human well-being. Since the content of pollutants occurring in natural ecosystems should be kept as low as possible, there is an ongoing search for analytical methods with ever lower detection limits for detection of pollutants as well as constant search for new technologies for removal of toxins from the environment.

 

Thus, the project will be devoted to exploration of novel materials for environmental protection and monitoring in order to develop more efficient and more sensitive environmental sensors and pollutant removal platforms. Those materials, among many, will involve, e.g. different papers and textiles, conducting and non-conducting polymers and nano particles. Primarily use of the material will be towards water based analysis and removal of pollutants, however, gas sensors and air pollutant removal platforms will be also considered. The development of the new materials will be possible owing to the utilization of state-of-art instrumentation at NTU and support from national and international collaborators.

Assoc Prof Robert Tiong Catastrophe risk modeling and management
CLKTIONG@ntu.edu.sg

The objective of the project is to develop state-of-the-art concepts and practices in managing catastrophes such as  earthquakes,  floods, with a focus on the development of innovative methodologies in  risk modelling and management such as  flood risk mapping, damage evaluation and mitigation management. The project also aims to investigate the effects of climate change on flood magnitude and frequency, and evaluate the possibilities of reducing economic, financial and social losses by adopting scientific decision-support tools. The research outputs are also expected to help better understand the role of uncertainty in evaluating flood risks as well as the sources of risk and their quantification, and improve flood forecasting and warning, long-term mitigation planning, and emergency management response in south-east Asia.

The objectives of this project may also include identifying  the financial engineering methodologies and analytics that are suitable for modelling alternate risk transfer mechanisms such as catastrophe bonds and other financial and insurance instruments. It also aims to develop the framework on catastrophe insurance as well as the application of catastrophe micro-insurance for selected developing areas. It will investigate how sustainable and long term risk reduction solutions and innovative products in finance and insurance could be developed to assist in transferring and spreading the risks for the benefit of Asian countries.

Assoc Prof Leong Eng Choon ​Suction on the surface of residual soil slopes.
CECLEONG@NTU.EDU.SG​Most residual soil slopes have deep groundwater table. The soil between the surface and the groundwater table is in various states of unsaturation which depends on a number of factors. Such factors include soil type, soil profile, geometry of the slope, slope direction, climatic conditions and depth of the groundwater table. The degree of saturation of the soil is indicated by the negative pore-water pressure or matric suction when referenced to pore-air pressure. The suction profile plays an important role in governing the amount of water flowing into the soil or leaving the soil as vapour, and the stability of the slope. This project involves field work to measure the suction on the surface of a number of residual soil  slopes to better understand the factors affecting the suction profile.


 

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