Papers by Author: Zhu Ge Yan

Abstract: This paper will provide a review of the current research on the material characterisation and mechanical behaviour of polymer enhanced silica aerogels. Aerogels have been in existence for many years; however, the engineering applications of aerogels have been limited due to their poor mechanical behaviour. Recently a new type of polymer enhanced silica aerogel, a nanostructured form of silica has been developed. The new material is having a low density, very low thermal conductivity, excellent acoustic insulation and high mechanical which makes it ideal for energy efficient building material. This paper will discuss the start-of-the-art development of this material and issues to apply the material in energy efficient buildings.

Abstract: This paper presents the outcomes from a laboratory based research study undertaken to evaluate the fundamental properties of permeable concrete, including compressive strength, global and local strain, elastic modulus (stiffness), porosity and permeability. Six permeable concrete mixtures were made with constant water - cement ratio of 0.34, using different aggregate sizes and sand percentages. The compressive strength range was 15-35 MPa, while the permeability varied between 1.5 to 5.5mm/s and the porosity varied between 25 to 35 %. Two testing methods were used to measure the strain and modulus of elasticity (MOE) of the permeable concrete namely, platen-to-platen method and strain gauge method. Considerable difference was found between the MOEs obtained by the two methods. The MOE determined using the platen-to-platen method consistently were lower in value, which has been attributed to the softness of the capping components, the interface between the specimens and the platen and overall machine compliance. The pore characteristics and their distribution were seen to have an influence on the material responses such as material stiffness and strain. A comparison drawn between the axial strain obtained by the strain gauge measurement and that deduced from the platen-to-platen measurement was undertaken to evaluate the strain homogeneity along with possible detection of the localization phenomena.

Abstract: One of the most important characteristics of porous concrete is the ability to capture and transport water. The permeability of porous concrete is therefore needs to be evaluated. This paper will investigate various methods for testing the permeability of porous concrete and compares the different results from falling head and constant head tests. The hydraulic theories were then applied into the analysis to determine the permeability of the porous concrete samples.

Abstract: The study reported here involves the evaluation of the ultimate bending stress (bending strength) of hybrid sandwich panels using a simple comparative statistical analysis. Four sets of beam were tested with each set consisting of modified beams (MB) and unmodified beam (UB) samples. A total of 42 beam samples were tested using 3 point bending followed by statistical inference analysis using a t-test. The results show that the introduction of an intermediate layer has a significant effect on increasing the bending strength of the new hybrid sandwich panel composite.

Abstract: The authors conducted research aimed at developing a new type of permeable concrete material with enhanced structural strength. This paper presents and discusses the results of their investigation on the unaxial compressive stress-strain relationship of porous concrete made with two different mix designs with constant water to cement ratio. The concrete mixes were designed with a target compressive strength between 15-25 MPa and target porosity between 10-15% to study the effect of pore sizes on the stress-strain curve. The average pore space was increased by increasing the relative amount of large aggregate. The reduction in the relative amount of fine aggregate increased the average pore space and resulted in a reduction in mix stiffness and a marginal increase in ultimate strength.

Abstract: With the increasing popularity of pervious concrete as a pavement material, researchers and concrete manufacturers have paid more attention to research needs. Pervious concrete is currently used in low traffic volume areas such as parking lots, footpaths and driveways. This is because it generally has lower strength than conventional concrete. This paper aims at developing a computational model to simulate the behaviour of pervious concrete under compression. Since compressive strength is one of the most important properties for concrete, a virtual model will provide a better understanding of its mechanical performance, which in turn will improve both the mix design and the material strength in the future. The discrete element method was applied and the results of calculations based on particle flow analysis are compared to the experimental data.