Civil Engineering

Investigation on the feasibility of using completely decomposed tuff as a river sand substitute for concrete production

In light of the unsustainable provision of river sand in Hong Kong and the limitations of existing river sand substitutes, Hong Kong urgently needs to discover new river sand substitutes to meet the growing demand for concrete. Hence, this project aims to investigate the feasibility of using “CDT sand” in completely decomposed tuff (CDT) as river sand substitute for concrete production.

3D Print Ultra-High Performance Concrete (UHPC)

With the introduction of 3D printing technology, a new era of the construction industry can finally be formed! Traditionally, buildings are constructed by using wooden formwork as a mold to hold the concrete. However, engineers started researching ways to implement 3D printing technology into the construction industry, which would help reduce the waste of wood and shorten the construction time. So far, little research on 3D-printable Ultra-high Performance Concrete (UHPC) is done, and our project is to help with the research. We are designing some concrete mixes that are 3D-printable. We check their fresh state properties like workability and printability, as well as their hardened state properties such as compressive strength. We have successfully printed some models, and we are looking forward to promoting 3D-printable UHPC for the construction industry to use.

Influence of Disinfectants on Microbial Water Treatment Processes

During the COVID-19 pandemic, the use of disinfectants has surged in order to contain the spread of the virus. Many disinfectants will be sent to wastewater treatment plants after use for treatment before discharging back to the environment. Nevertheless, studies have shown that large amounts of disinfectants can inhibit biological reactions during the wastewater treatment process. The activated sludge process, which counts on microorganisms to break down complex organic matters in wastewater, is particularly susceptible to disinfectants. Hence, this study aims to investigate the inhibitory effects of two common active ingredients of disinfectants, namely QACs and sodium hypochlorite, on the activated sludge process. It is hoped that the study will be able to recommend an active ingredient of disinfectant that has the required efficacy and the least impact on the wastewater treatment system.

New Geo-material for Reclamation: Utilizing local marine deposit and fly ash for backfilling

Hong Kong is facing an increasing demand of reclamation land use. However, we are facing an unstable supply and increasing price of the tradition backfilling material – sand. Therefore, we need to investigate an alternative. Ash-strengthed marine deposit can be a solution. Marine deposit can gain strength after mixing with cement, coal ash and water. This material can also reuse contaminated marine deposit. Therefore, the feasibility of using ash-strengthened marine soil is going to be investigated.

Electrospun reusable nanofibrous membrane filters for environmental applications

Water and air pollution have become major challenges for humans in the 21 century. With limited accessible resources, a sustainable solution is needed for pollution control. Electrospun nanofibrous membranes are made of tiny fibers in nano scales with high pororsity. The special features make the membranes highly efficient and durable in pollutant adsorption. Moreover, by simple washing with easily accessible agents, the membranes can be almost fully regenerated to achieve reusability. There is high commercialization and sustainability value behind this project.

Impact of Different Factors on Hyporheic Exchange in a Meandering Pool-riffle Stream

The hyporheic zone (HZ) is the region of saturated sediment surrounding a stream which connects surface water and groundwater flow. The overlying water with dissolved matters infiltrates into the HZ, stays there for some time and interacts with groundwater, and exfiltrates out of the HZ, resulting in hyporheic exchanges (HE).

Most of the rivers are designed with narrow bottom section and large upper section of concrete streambed which results in bad river eco-system. In recent decades, more and more stream restoration projects involve the recovery of HE, however, effective guidance in restoring HE is still missing. Therefore, this study aims to examine the effectiveness of different key factors (e.g., stream discharge, slope, sinuosity and groundwater flow) in restoring HZ in a meandering channel with floodplain using flume experiments and numerical simulations.

The Solaris Hybrida

The Solar H stands for Solaris Hybrida, which is the latin of Solar Hybrid. It is a revolutionary lighting experience that combines conventional solar tube that diverts light into buildings, solar powered led, solar-tracking panels and the unique modular add-ons.

Enhanced Landslide Mobility Analysis Using Unmanned Aerial Vehicles

Unmanned Aerial Vehicle is a remote sensing technique utilizing photogrammetry for inspection, surveillance and modelling issues. The application of UAV as a surveying tool allows geotechnical engineer to capture topographic data for landslide suspected site is relatively new. It is advantageous to adopt UAV technique to inaccessible natural terrains and unstable slopes which have repetitive failures. Those useful data would be extracted for further landslide analysis, and is particularly applicable for debris flow runout analysis which is sensitive to the topographic profile. Computed result shows UAV resolution accuracy with less than 20mm. This project evaluates the resolution of UAVs and compares their applicability for post-landslide mobility assessment by 2-Dimensional Debris Mobility Model (2D-DMM).

Self‐healing, microencapsulation and granular materials

Foundation quality is of paramount importance to all civil engineering works. Since it governs the safety of the structures and buildings stood above it. However, settlement in foundation is found very common, in which it comes as a natural deterioration process. Maintenance work for foundation can be challenging and costly. Having said that, inspired by the adopting of self-healing capsules in concrete improvement, this study aims to mimic and incorporate similar self-healing technology in strengthening of soil.

Performance of Sustainable Cement for Marine Construction

Chloride attack of concrete in particular for marine structures is a serious global issue where it can lead to severe deterioration of the concrete, drastic reduction in strength of structures and safety concerns. The world is urging for a remedy to this situation. A green alternative to Ordinary Portland Cement (OPC), Alkaline-activated Slag (AAS), is found to be having 70%-150% higher chloride binding capacity than that of OPC, making it a potential antidote to this issue. This project aimed to analyse the chloride resistance of AAS in the marine environment, to provide better predict the service life of marine structures and to find ways to enhance the durability of concrete in aggressive conditions. With AAS, let us ‘cement’ a sustainable future.