Applied Mechanics and Materials Vols. 754-755

Abstract: This paper presents the first results of complex study concerning the protection of reinforcing steel used in concrete structures from civil and industrial buildings. The obtained coatings have multiple purpose, increasing the corrosion resistance but also the adherence with the concrete, improving the overall performance of concrete and its durability.

Abstract: This work presents the experimental tests carried out to evaluate the behaviour of different types of shear connectors proposed for cold formed steel (CFS) section integrated with ferrocement slab as potential used for composite beam. Ten push-out test specimens of cold-formed steel lipped channel sections connected with ferrocement slab were tested. Three types of shear connectors were studied comprised of bolts, self-drilling-screw and bar angle. The connection behavior is analysed in terms of its load-slip relationship and the failure mode. The parametric studies were performed to investigate the effect on the shear connector’s capacity by varying the number of layers of wire mesh used in ferrocement slab and types of shear connector used. A theoretical analysis (Eurocode 4) was carried out to verify the experiment results. The results show that the experimental and theoretical proved to have good agreement with each other.

Abstract: This paper presents an observation on fly ash quality in East Jawa, Indonesia. The ash samples were collected from 16 fly ashes produced by some Indonesian power plants. The samples are majority categorized as class F fly ashes with good pozzolanic characteristics according to the standard. The samples were examined for their physical, chemical and mechanical properties with compression test. The test was conducted by making some mortars and paste containing fly ash as cement replacement in accordance with three methods. The compressive strength results were compared with the control specimens made from ordinary Portland cement to obtain a strength activity index (SAI). The results showed that physical properties of fly ash influenced the mechanical properties of mortars more than those showed by chemical characterization.

Abstract: Concern towards reducing waste disposed by Malaysian palm oil industry, palm oil fuel ash (POFA) and oil palm shell (OPS) that poses negative impact to the environment has initiated research on producing oil palm shell lightweight aggregate concrete (OPS LWAC) containing palm oil fuel ash. The present investigation looks into the effect of palm oil fuel ash content as partial cement replacement to compressive strength and acid resistance of oil palm shell lightweight aggregate concrete. Two types of mix, plain OPS LWAC and another one containing POFA as partial cement replacement have been used in this research. Cubes of 100 x 100 x 100 (mm) were water cured for 28 days before subjected to compressive strength test and acid resistance test. The findings indicate that suitable integration of POFA content would ensure occurrence of optimum pozzolanic reaction leading to densification of concrete internal structure which increases the compressive strength and better durability to acid attack. Integration of 20% POFA successfully assist concrete to achieve the highest compressive strength and exhibit superior resistance against acid attack compared to other mixes.

Abstract: This paper presents the performance of an emerging prefabricated composite system made from profiled steel sheeting and dry board. Six full-scale wall specimens were prepared and tested under axial load. The results of the experimental investigation showed that the performance of the composite walls is governed by the strength of profiled steel sheeting while the dry board performed as a wall sheathed. A partial interaction between the profiled steel sheeting and dry board was achieved by using self-drilling screws. The maximum axial load capacity is 1329kN for the double sheathed wall. The failure behavior of single and double sheathed composite wall exhibited similar pattern such as global buckling and cracking. The developed composite wall system was found the great potential in prefabricated and modular construction in Malaysia.

Abstract: Reinforced concrete structures work in the marine environment are easily erroded by the environment, the most dangerous intrusion by chloride ions. Chloride ions from the environment penetrate into concrete layer and cause reinforcement corrosion. The high chloride binding capacity in concrete helps reducing the reinforcement corrosion. The chloride binding capacity in concrete is largely dependent on the cement type. This paper investigated the chloride binding capacity of various binary and ternary binders. Chloride contents in mortars prepared with various binary and tinery binders were determined by chemical titration methods combining with microstructure analysis SEM. The experimental results showed that the chloride binding capacity of tinery binders which contains Ordinary Portland cement (OPC), blast furnace slag mixed with silica fume is highest.

Abstract: Electrochemical chloride extraction – ECE is an effective method to rehabilitate reinforced concrete structure, which has been corroded. This study investigated concentration of chloride remained in concrete and half-cell potential of the steel reinforcement after ECE using interrupting period of electricity current. Efficiency of ECE using Ca (OH)₂ was surveyed with two current density of 0.5 and 1A/m². In this study, ECE treatment was proceeded intermittently in approximately 8 weeks. Results pointed out that chloride concentration decreased to 30 – 60% significantly, especially at in the vicinity of reinforcing steel. Simultaneously, half-cell potential of the steel reinforcement after 4 weeks halted treatment stabilizes in low-corrosion rate.

Abstract: Compressive strength of concrete is the major mechanical properties of concrete that need to be focused on. Poor compressive strength will lead to low susceptibility of concrete structure towards designated actions. Many researches have been conducted to enhance the compressive strength of concrete by incorporating new materials in the concrete mixture. The dependencies towards natural resources can be reduced. Therefore, this paper presents the results of an experimental study concerning the incorporation of artificial lightweight bubbles aggregate (LBA) into cementations mixture in order to produce comparable compressive strength but at a lower densities. Three concrete mixtures containing various percentages of LBA, (10% - 50% of LBA) and one mixture used normal aggregate (NA) were prepared and characterized. The compressive strength of LBA in concrete was identified to be ranged between 39 MPa and 54 MPa. Meanwhile, the densities vary between 2000 kg/m³ to 2300 kg/m³.

Abstract: Profiled Steel sheeting Dry Board (PSSDB) system is a lightweight composite structural system consisting of profiled steel sheeting, mechanically connected to a dry board using self-drilling and self-tapping screw. The objective of this study is to investigate the effect of geopolymer concrete infill in PSSDB system with half board (PSSHDB), focus on its deflection serviceability limit at mid-span region. Geopolymer concrete was chosen to be as infill in the PSSDB floor system due to its high compressive strength as compared to normal concrete and its potential as an alternative concrete since it does not utilize Ordinary Portland Cement (OPC). This study used a modified PSSHDB panel using a half-sized dry board. In achieving this objective, forecasting the behavior of the system in laboratory experiments will be taken into account as the research approach. Experimental results found that with the use of geopolymer concrete infill, the mid-span deflection on the PSSHDB floor system can be reduced to 41% as compared to the use of normal concrete infill. This indicates an increase in the stiffness of this system due to the effect of infill geopolymer concrete.

Abstract: Ordinary Portland Cement (OPC) concrete is one of the most widely used construction materials globally, though its production in construction has negative environmental impact. About 0.9 ton of CO₂ is emitted for every one (1) ton of cement produced. In order to reduce the amount of CO₂ emission from cement industry, the utilization of supplementary cementitious materials such as pulverized fuel ash (PFA), blast-furnace slag and natural pozzolans is common and effective. Geopolymer is an inorganic binder material and can be produced by a geopolymeric reaction of alkali activating solution with silica and alumina rich source materials such as PFA and blast-furnace slag. In this study, the durability of concrete such as the resistance to sulfuric acid and sulfate solutions due to the effect of blended as of PFA and palm oil fuel ash (POFA), along with alkaline activators were investigated. Consequently, the optimum mix design of the blended ash geopolymer (BAG) concrete and OPC concrete specimens were prepared with water to cement ratio of 0.5 by mass as control. The micro structural analysis by X-ray diffraction (XRD) was done. BAG concrete showed better performance in 2% sulfuric acid and 5% sulfate solutions. From micro structural analysis, it was evident that BAG binder gel (N-A-SH) produced more durable material compared with C-S-H binder gel of OPC. The BAG concrete is strongly recommended to be used as an alternative to OPC concrete in addition to its environmental friendliness. Abundant PFA and POFA can be efficiently utilized to produce a high performance concrete.