Muhammad Fauzi Mohd Zain

An expert system for mix design of high performance concrete

This paper describes a prototype expert system called HPCMIX that provides proportion of trial mix of High Performance Concrete (HPC) and recommendations on mix adjustment. The knowledge was acquired from various textual sources and human experts. The system was developed using hybrid knowledge representation technique. It is capable of selecting proportions of mixing water, cement, supplementary cementitious materials, aggregates and superplasticizer, considering the effects of air content as well as water contributed by superplasticizer and moisture conditions of aggregates. Similar to most expert systems, this system has explanation facilities, can be incrementally expanded, and has an easy to understand knowledge base. The system was tested using a sample project. The systems selection of mix proportions and recommendations regarding mix adjustment were compared favourably with those of experts. The system is user-friendly and can be used as an educational tool.

On the Utilization of Pozzolanic Wastes as an Alternative Resource of Cement

Recently, as a supplement of cement, the utilization of pozzolanic materials in cement and concrete manufacturing has increased significantly. This study investigates the scope to use pozzolanic wastes (slag, palm oil fuel ash and rice husk ash) as an alkali activated binder (AAB) that can be used as an alternative to cement. To activate these materials, sodium hydroxide solution was used at 1.0, 2.5 and 5.0 molar concentration added into the mortar, separately. The required solution was used to maintain the flow of mortar at 110% ± 5%. The consistency and setting time of the AAB-paste were determined. Mortar was tested for its flow, compressive strength, porosity, water absorption and thermal resistance (heating at 700 °C) and investigated by scanning electron microscopy. The experimental results reveal that AAB-mortar exhibits less flow than that of ordinary Portland cement (OPC). Surprisingly, AAB-mortars (with 2.5 molar solution) achieved a compressive strength of 34.3 MPa at 28 days, while OPC shows that of 43.9 MPa under the same conditions. Although water absorption and porosity of the AAB-mortar are slightly high, it shows excellent thermal resistance compared to OPC. Therefore, based on the test results, it can be concluded that in the presence of a chemical activator, the aforementioned pozzolans can be used as an alternative material for cement.

Dry boards as load bearing element in the profiled steel sheet dry board floor panel system—structural performance and applications

Abstract This paper describes the application of various types of dry boards that are normally used as non-load bearing building components, as a structural component in an innovative lightweight composite structural flooring panel system known as the Bondek II/Cemboard Composite Flooring Panel (BCCFP) system. The composite panel system consists of profiled steel sheeting attached to a top layer dry board by simple mechanical connectors. In the proposed system, dry board plays a dual role, firstly in providing a flat floor surface covering the corrugated profiled steel sheeting, and secondly, it helps in enhancing the stiffness and strength of the composite system. The role of dry boards in the BCCFP system and the performance of the system using various types and thickness of dry boards are investigated. In addition, the effect of varying the spacing of screws on the panel performance is also studied. From test results, it was found that the application of dry boards in the BCCFP system could increase the flexural stiffness of the composite panel by between 12.8% to as high as 26.3% compared to that of the steel sheeting alone for the various tested samples. The stiffness value of a typical practical configuration of the BCCFP system comprising of 1.0 mm thick Bondek II attached to 16 mm Cemboard with screw spacing of 100 mm was found to be 166 kNm 2 /m with a percentage interaction value of 21.3%. The introduction of a layer of dry board to the bare steel sheeting alone has been shown able to increase by 12.2% the moment capacity value from 8.2 kNm/m of the steel sheeting alone to 12.2 kNm/m of the typical BCCFP system mentioned above. It can be concluded that the dry boards, which are normally used in non-load bearing applications, are having great potential to be used as components in load bearing structural system. Some interesting applications of the system in real buildings are also highlighted in this paper.

Advances in Photocatalytic CO2 Reduction with Water: A Review

In recent years, the increasing level of CO2 in the atmosphere has not only contributed to global warming but has also triggered considerable interest in photocatalytic reduction of CO2. The reduction of CO2 with H2O using sunlight is an innovative way to solve the current growing environmental challenges. This paper reviews the basic principles of photocatalysis and photocatalytic CO2 reduction, discusses the measures of the photocatalytic efficiency and summarizes current advances in the exploration of this technology using different types of semiconductor photocatalysts, such as TiO2 and modified TiO2, layered-perovskite Ag/ALa4Ti4O15 (A = Ca, Ba, Sr), ferroelectric LiNbO3, and plasmonic photocatalysts. Visible light harvesting, novel plasmonic photocatalysts offer potential solutions for some of the main drawbacks in this reduction process. Effective plasmonic photocatalysts that have shown reduction activities towards CO2 with H2O are highlighted here. Although this technology is still at an embryonic stage, further studies with standard theoretical and comprehensive format are suggested to develop photocatalysts with high production rates and selectivity. Based on the collected results, the immense prospects and opportunities that exist in this technique are also reviewed here.

Artificial Photosynthesis using LiNbO3 as Photocatalyst for Sustainable and Environmental Friendly Construction and Reduction of Global Warming: A Review

Artificial photosynthesis using LiNbO3 as a photocatalyst has emerged as an important technology leading to the formation of eco-friendly end products. An interesting part of this technology is its ability to directly convert pollutants into the harmless substances in the contaminant source. This technology possesses enormous potential for the reduction of “global warming.” This article reviews recent developments and future potential applications of this emerging technology and provides information on the parameters that control its process. The effects of the photosynthetic reaction of LiNbO3 on cementations materials and indoor air conditioning are also reviewed in this article.

Development of a Zero-Cement Binder Using Slag, Fly Ash, and Rice Husk Ash with Chemical Activator

The increasing demand and consumption of cement have necessitated the use of slag, fly ash, rice husk ash (RHA), and so forth as a supplement of cement in concrete construction. The aim of the study is to develop a zero-cement binder (Z-Cem) using slag, fly ash, and RHA combined with chemical activator. NaOH, Ca(OH)2, and KOH were used in varying weights and molar concentrations. Z-Cem was tested for its consistency, setting time, flow, compressive strength, XRD, SEM, and FTIR. The consistency and setting time of the Z-Cem paste increase with increasing RHA content. The Z-Cem mortar requires more superplasticizer to maintain a constant flow of % compared with OPC. The compressive strength of the Z-Cem mortar is significantly influenced by the amounts, types, and molar concentration of the activators. The Z-Cem mortar achieves a compressive strength of 42–44 MPa at 28 days with 5% NaOH or at 2.5 molar concentrations. The FTIR results reveal that molecules in the Z-Cem mortar have a silica-hydrate (Si-H) bond with sodium or other inorganic metals (i.e., sodium/calcium-silica-hydrate-alumina gel). Therefore, Z-Cem could be developed using the aforementioned materials with the chemical activator.

Concrete road barriers subjected to impact loads: An overview

Concrete barriers prevent vehicles from entering the opposite lane and going off the road. An important factor in the design of concrete barriers is impact load, which a vehicle exerts upon collision with a concrete barrier. This study suggests that a height of 813 mm, a base width of 600 mm, and a top width of 240 mm are optimum dimensions for a concrete barrier. These dimensions ensure the stability of concrete barriers during vehicle collisions. An analytical and experimental model is used to analyze the concrete barrier design. The LS-DYNA software is utilized to create the analytical models because it can effectively simulate vehicle impact on concrete barriers. Field tests are conducted with a vehicle, whereas laboratory tests are conducted with machines that simulate collisions. Full-scale tests allow the actual simulation of vehicle collisions with concrete barriers. In the vehicle tests, a collision angle of 25°, collision speeds of 100 km per hour, and a vehicle weighing more than 2 t are considered in the reviewed studies. Laboratory tests are performed to test bridge concrete barriers in static condition.

Prediction of strength and slump of rice husk ash incorporated high-performance concrete

Abstract This paper describes the development of statistical models to predict strength and slump of rice husk ash (RHA) incorporated high-performance concrete (HPC). Sixty samples of RHA incorporated HPC mixes having compressive strength range of 42–92 MPa and slump range of 170–245 mm were prepared and tested in the laboratory. These experimental data of sixty RHA incorporated HPC mixes were used to develop two models. Six variables namely water-to-binder ratio, cement content, RHA content, fine aggregate content, coarse aggregate content and superplasticizer content were selected to develop the models and ultimately to predict strength and slump of RHA incorporated HPC. The models were developed by regression analysis. Additional five HPC mixes were prepared with the same ingredients and tested under the same testing conditions to verify the ability of the proposed models to predict the responses. The results of the prediction of the models showed good agreement with the experimental data. Thus the dev...

Effects of Medium Temperature and Industrial By-Products on the Key Hardened Properties of High Performance Concrete

The aim of the work reported in this article was to investigate the effects of medium temperature and industrial by-products on the key hardened properties of high performance concrete. Four concrete mixes were prepared based on a water-to-binder ratio of 0.35. Two industrial by-products, silica fume and Class F fly ash, were used separately and together with normal portland cement to produce three concrete mixes in addition to the control mix. The properties of both fresh and hardened concretes were examined in the laboratory. The freshly mixed concrete mixes were tested for slump, slump flow, and V-funnel flow. The hardened concretes were tested for compressive strength and dynamic modulus of elasticity after exposing to 20, 35 and 50 °C. In addition, the initial surface absorption and the rate of moisture movement into the concretes were determined at 20 °C. The performance of the concretes in the fresh state was excellent due to their superior deformability and good segregation resistance. In their hardened state, the highest levels of compressive strength and dynamic modulus of elasticity were produced by silica fume concrete. In addition, silica fume concrete showed the lowest level of initial surface absorption and the lowest rate of moisture movement into the interior of concrete. In comparison, the compressive strength, dynamic modulus of elasticity, initial surface absorption, and moisture movement rate of silica fume-fly ash concrete were close to those of silica fume concrete. Moreover, all concretes provided relatively low compressive strength and dynamic modulus of elasticity when they were exposed to 50 °C. However, the effect of increased temperature was less detrimental for silica fume and silica fume-fly ash concretes in comparison with the control concrete.

Underground soil and thermal conductivity materials based heat reduction for energy-efficient building in tropical environment

In this paper, an alternative way of releasing heat of building is investigated in order to reduce energy demand of building built in tropical environment. Underground soil is considered as a source for extracting heat from building through thermal conductivity pipes. Thermal conductivity pipes are considered to be fixed on the inner faces of the walls and their lower part to be inserted to the ground where temperature is lower than the indoor temperature. The entire analyses were done numerically using ANSYS 11. Heat flow between two systems was studied and the performance of the thermal conductivity pipes was examined. The room temperature in the presence of thermal conductivity pipes as well as mechanical cooling system and other passive energy-efficient techniques of building were also studied. The underground soil was demonstrated to act as a heat sink and absorb heat released from the rooms and the thermal conductivity pipes would play a role in transferring heat from the rooms to the underground soil. The system works efficiently when it is used with other mechanical or passive cooling systems. In this way, energy saving measure could be possible to reduce building temperatures by around 3℃.