Papers by Author: Zhu Ge Yan

Abstract: This paper presents a discussion of factors affecting the performance of fly ash based geopolymer, and some recent innovations on fly ash based geopolymer. The characteristics of fly ash based geopolymer are discussed in terms of the effects of raw material selection, alkaline activators, and curing procedures. Nowadays, researchers have used geopolymer as a cementitious material to develop innovative geopolymer materials, such as porous, fibre reinforced and foam fly ash based geopolymer concrete, which are greener than the traditional cementitious material. The high-calcium fly ashes could be used to produce porous fly ash based geopolymer composites with satisfactory mechanical properties. The addition of fibres increases greatly the ductility of geopolymer. Foam can be added to the geopolymeric mixture to produce lightweight concrete. However, the manufacturing of fly ash-based geopolymer foam concrete has not been explored too much.

Abstract: Porous concrete is one of the innovative and promising concrete products, which is featured with a relatively high water permeability rate. Compared with conventional concrete products, due to the lack of fine aggregates in the mix design of porous concrete, the void spaces between the coarse aggregates remains unfilled and causes a large amount of porosity in the hardened concrete mass. On the other hand, the strength of porous concrete is usually lower than that of the conventional concrete products due to the lack of fine aggregates. For the purpose of achieving a relatively high strength of porous concrete while maintaining a good permeability of pavements, the mix design of porous concrete is modeled as a Markov Chain Monte Carlo (MCMC) system and a Gibbs Sampling method based approach is developed to approximate the optimal mix design. The simulation results show that, by using the proposed approach, the system converges to the optimal solution quickly and the derived optimal mix design achieves the tradeoff between the compressive strength and the permeability rate.

Abstract: In this paper, transmission line systems are modeled as multi-span cable structures. A force method model is proposed for analysing the static response of the multi-span cables with small sags. The accepted cable model reduces to two groups of differential equations (the equilibrium equations in y, z directions) and an integral equation (the compatibility equation). Substituting the differential equation solutions into the compatibility condition, the governing equation is obtained in terms of the tension component in chord direction. This equation has been named the force method equation (FME). In this way the infinite-degree-of-freedom dynamic system is effectively simplified to a system with only one unknown. Finally, one example is presented to illustrate the application of the proposed force method.