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The present study investigates the behavior of axial loaded circular concrete filled hollow steel section (CFHSS) columns. A nonlinear finite element model using ABAQUS program was developed to investigate the fire behavior of the inspected columns from previous fire tests. The study variables include column dimensions, steel section wall thickness, concrete strength, concrete types (plain or reinforced), and fire protection thickness. The comparison indicated that the results obtained from the model were within acceptable limit of accuracy of 15%. A sensitivity study was carried out to investigate the influence of the output of the numerical model including the Poisson’s ratio of concrete, thermal conductance at the steel-concrete interface, frictional contact at steel-concrete interface, and imperfection buckling of columns. Based on the sensitivity analysis, several modelling suggestions were given in this paper which will be beneficial for further study.

Cold-formed steel (CFS) is known as slender or class 4 section due to high ratio of web-to-thickness ratio. The compressive strength of this type of section is usually very low as it tends to fail due to distortion and warping before reaching the actual compressive strength. The aim of this study is to determine the ultimate capacity of build-up lipped CFS assembled with ferrocement jacket where web-stiffener is provided as the proposed composite column (CFFCC) is under axial compression load. Nine specimens of composite columns were prepared and tested. The main parameters varied in the CFFCC columns are column height, cold-formed steel thickness and influence of ferrocement jacket and web-stiffener. There are three different heights of the CFFCC composite column namely 2000mm, 3000mm and 4000mm used in this study. All CFFCC columns were tested under axial load where a thick steel plate is used to evenly distribute the applied load. The results show the effect of providing both the ferrocement jacket to increase the confinement effect and the web stiffener to provide sufficient lateral support to the column web. A significant increase in both the strength and the ductility of the specimens under axial loading has been recorded. The strength capacity of CFFCC has been improved by about 178% greater than that of bare steel column. Also it is found that, axial load capacity of CFS-ferrocement jacket composite columns (CFFCC) were increased with the increase in thickness of CFS. The use of web-stiffener has improved the axial load capacity of the column but not that significant.

Cold-formed steel (CFS) is known to be a thin section. Thus it is considered a weak slender steel section which limits the compression capacity of the column. The aim of this study was to determine the ultimate capacity of built-up lipped CFS (assembled with ferrocement jacket) as composite column (CFFCC) under axial compression load. Nine specimens of composite columns were prepared and tested. The main parameters that varied in the CFFCC columns were column height, cold-formed steel thickness, and influence of ferrocement jacket. There were are three different heights of the CFFCC composite column namely 2000mm, 3000mm and 4000mm used in this study. All CFFCC columns were tested under axial load by a thick steel plate. The results indicated that ferrocement jacket provided sufficient lateral support to the column web and significantly increased both the strength and ductility of the specimens under axial loading. The strength capacity of CFFCC improved significantly, about 149% greater than that of bare steel column section. It was also found that the axial load capacity of CFS-ferrocement jacket composite columns (CFFCC) had increased significantly (in the range of 20% to 40%) as thickness of CFS increased.

This paper presented the compressive strength of geopolymer paste with different NaOH concentration and morphology analysis for sintered artificial aggregate. This artificial aggregate was produce based on mix design with highest compressive strength which is 12 M. The sample was cured at 70 ̊C for 24 hours and then it was exposed to different temperature at range 500 ̊C to 700 ̊C. Scanning Electron Microscopy (SEM) has been used to identify the formation of microstructure. The geopolymer artificial aggregate was an alternative ways to produce a greener environmental. In this study, the compressive strength for different Na2SiO3/NaOH ratio has been analyzed. The morphology for best mix design then were analyze for different curing temperature. The result shows fly ash based geopolymer paste with 12 M of NaOH concentration shows excellent result with 7.30 MPa at 2.5 ratio of Na2SiO3/NaOH and for geopolymer artificial aggregate, when temperature of heat treatment increased, the open porosity of porous geopolymer surface decreased.

Geopolymerization is an alternative for ceramic industry by using clay based material such as kaolin or calcined kaolin geopolymer. Geopolymer paste is initially produced by alkaline activation of calcined kaolin with NaOH and Na2SiO3 solution), dried at 80oC for 4 hours, pulverized and sieved to fixed particle size powder. The parameters involved in this processing route (alkali concentration, kaolin or calcined kaolin to activator ratio, alkali activator ratio and heating conditions) are investigated. Geopolymeric powder is added with water to produce slurry to be coated on the surface of clay ceramic. It undergoes heat treatment at high temperature to produce glaze on the surface. Flexural strength and hardness analysis are studied. Result evidences the processing show of incresing strength value between 8-10% after treatment with geopolymer glaze and also the Vickers hardness values of geopolymers improved.

The application of geopolymer as a coating was not widely explored by other researchers and therefore the study of kaolin based geopolymer coating applied on different types of clay substrate (unsintered and sintered) was carried out. The geopolymer coating paste were initially prepared by mixed the kaolin with alkaline activator (NaOH and Na2SiO3) until homogeneous mixture was obtained. After that, the geopolymer paste then applied on the surface of clay substrates and left to cure at 80oC for 24 hours and sintered at 800oC respectively for 2 hours. Flexural, compression test and SEM for morphology analysis are studied. Based on the results obtained, it shows that kaolin based geopolymer coating can contribute in improving the substrate strength, while curing and sintering temperature applied to the geopolymer coating on different substrate can influence the interaction between substrate and geopolymer paste to diffuse according to SEM image proved.

With increased activity in construction, deficiency of building materials and construction waste improvements have encouraged the development of new building materials. Conventional construction bricks are usually made from clay and sand, which are mixed and molded in various method and need to be dried and burned. Geopolymer bricks making process consume less energy and low cost in term of production compared to conventional bricks. The development of geopolymer brick is an important step towards produce bricks with better performance and environmental friendly material This research focusing on the processing process of the clay-based geopolymer brick from the mixing until the curing by using a geopolymer brick making machine.

The nonlinear stiffness matrix method was incorporated to investigate the structural performance of steel portal frames with semirigid connections. A portal frame with unstiffened extended end-plate connection was designed to demonstrate the adequacy of the proposed method. Besides, the seismic performance of steel portal frames with semirigid connections was investigated through time history analysis where kinematic hysteresis model was assigned to semirigid connections to account for energy dissipation and unloading stiffness. Based on the results of the study, it was found that generally semirigid connections influenced the force distribution which resulted in the decrease in base shear and lighter frame compared to the rigid one. The results also indicated that there was no direct relationship between maximum displacement at the top and connection stiffness in high-rise frames.