Ibrahim Yakub

Sustainable nanopozzolan modified cement: characterizations and morphology of calcium silicate hydrate during hydration

There are environmental and sustainable benefits of partially replacing cement with industrial by-products or synthetic materials in cement based products. Since microstructural behaviours of cement based products are the crucial parameters that govern their sustainability and durability, this study investigates the microstructural comparison between two different types of cement replacements as nanopozzolan modified cement (NPMC) in cement based product by focusing on the evidence of pozzolanic reactivity in corroboration with physical and mechanical properties. Characterization and morphology techniques using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), energy-dispersive X-ray spectroscopy (EDS), and scanning electron microscopy (SEM) were carried out to assess the pozzolanic reactivity of cement paste modified with the combination of nano- and micro silica as NPMC in comparison to unmodified cement paste (UCP) of 0.5 water to cement ratio (w/c). Results were then substantiated with compressive strength (CS) results as mechanical property. Results of this study showed clear evidence of pozzolanicity for all samples with varying reactivity with NPMC being the most reactive.

Physicochemical characterization of modified multicomponent binder mortar in relation to calcium hydroxide leaching

This paper presents and discusses the results of the study on the effects of modified multicomponent binder mortar (MMCB) on calcium hydroxide (CH) leaching to form calcium carbonate (CaCO3) on the surface of cement based products, investigated in laboratory environment at daily room temperature (T) and relative humidity (RH) in the range of 18–28°C and 65–90%, respectively. Pozzolans used as cement replacement were Fly Ash Class F (FA) and Silica Fume (SF). Polymers used as a cement additive were styrene butadiene rubber (SBR) (Synthomer Grade 29Y46) and styrene acrylic ester (SAE) (Revacryl Grade 477). The influence of these materials on mortar has been discussed by researchers separately but their combinative influence on CH leachate has not been researched yet. CH leachate intensities in terms of percentages of (CaCO3) resulted from Puddle Test (PT) and Standard Chemical Method (SCM) were compared systematically between MMCB samples with unmodified control mortar (UCM) of 0.4w/c in order to get a better understanding of how the combination of pozzolan and polymer influence CH leaching. The findings were discussed and substantiated physically and mechanically with the initial surface absorption test (ISAT) and compressive strength test results and micro structurally with the characterization and morphology of calcium hydroxide (CH) and calcium silicate hydrate (C-S-H) from EDS and SEM images. The results showed that MMCB had less formation of CaCO3 (calcite) compared to UCM with validation from the physicochemical and mechanical analysis that

Physicochemical characterization of polymer composite cement systems

The early hydration behaviour of two different polymer composites cement systems (PCCS) that hypothetically affects efflorescence has been investigated through physicochemical characterization namely Puddle Test (PT), Standard Chemical Method (SCM), Compressive Strength Test (CS), X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). PCCS mortar samples were prepared with water-to-cement ratio (w/c) of 0.50. Commercially available polymer additives namely Styrene Butadiene Rubber (SBR) and Styrene Acrylic Ester (SAE) with different percentages of addition of 5%, 7% and 10% to cement were used. All samples were dried cured and tested at day 28. Efflorescence was accelerated by using PT. Its intensity, in terms of the amount of Calcium Carbonate (CaCO3) precipitated on samples’ surfaces, was quantified by using SEM. Results of the PCCS were then compared to the conventional cement system. Based on this study, PCCS can potentially reduce efflorescence where validation from CS, XRD analysis and SEM images showed that the evidence of the pore blocking effects of PCCS in early hydration hence can indirectly improve concrete durability and sustainability.

Physical and Mechanical Properties of Industrial Waste Modified Mortar

This paper presents and discusses the results of the study on physical and mechanical properties of Industrial Waste Modified Mortar (IWMM) in comparison to Unmodified Mortar (UM). Industrial wastes used as ternary cement replacement were Micro Silica (MS) and Finely Ground Waste Vase (FGWV). Porosity and compressive strength of cement based products are the crucial properties that reflect the durability. Results of this study showed incorporation of 15%MS and 20%FGWV as ternary binders reduced 32.8% porosity and increased 4.3% compressive strength of mortar.

Influence of Mortar Incorporating Silica Based Waste Material on the Formation of C-S-H and Mechanical Strength Properties

Recent studies have been carried out to utilize waste glass in construction as partial cement replacement. This paper investigates the formation of Calcium Silicate Hydrate (C-S-H) and strength characteristics of mortar in which cement is partially replaced with glass powder by replacement level of 10%, 20% and 30%. Mortar cubes containing varying particle sizes in the ranges of 150-75μm, 63-38 μm and lower than 38 μm and in a water to cement ratio of 0.45 and 0.40 have been prepared. Replacement by 10% cement with glass powder reveals high compressive strength and produces more C-S-H at 28 days than other levels of replacement.

Adsorption Isotherm of Chromium (VI) into Zncl2 Impregnated Activated Carbon Derived by Jatropha Curcas Seed Hull

Hexavalent chromium is carcinogenic and should be removed from industrial wastewater before discharged into water resources. Adsorption by using activated carbon from biomass is an economic and conventional way on removing the heavy metal ions from wastewater. In this research, activated carbon is synthesized from Jatropha curcas L. seed hull through chemical activation with ZnCl2 and carbonized at 800 °C (JAC/ZnCl2). The activated carbon has been characterized using FTIR, SEM-EDX, BET and CHNS-O analyzer. Adsorption isotherms have been analysed using Langmuir and Freundlich models to determine its removal mechanism. The maximum adsorption capacity of Cr (VI) metal ions onto JAC/ZnCl2 activated carbon is 25.189 mg/g and following Langmuir isotherm model which is monolayer adsorption.

Effects of Solvent/Solid Ratio and Temperature on the Kinetics of Vitamin C Extraction from Musa Acuminata

This work studied on the kinetics of Vitamin C extraction from banana peel at different solvent/solid concentration and temperature. Musa Acuminata was ground into smaller sizes before contacted with methanol as a solvent in an ultrasonic bath. To study the effect of solvent/solid ratio, 4.5, 5.0 and 10.0 ml/g ratio were used for the extraction at fixed temperature. Then, the temperature was varied with the heating element available in the ultrasonic bath at 30, 45 and 60 °C, to study the effect of temperature on the extraction kinetics. It was found that high solvent/solid ratio (10 ml/g) provides more solute-solvent contact and prevents the extracted Vitamin C from coming into contact with the air. Besides, higher temperature (60 °C) contributes sufficient kinetic energy for Vitamin C distribution in the solvent which is important to prevent degradation with air. The best fitted kinetic model for Vitamin C extraction from Musa Acuminata is Ana et al. (2007) with equilibrium concentration of 0.05 g/L and 0.40 g/L.hr extraction rate.

MICROSTRUCTURAL STUDY ON THE EFFECTIVENESS OF COMMERCIAL POLYMER EMULSION AS CEMENT ADDITIVES TO MITIGATE EFFLORESCENCE

The occurrence of calcium carbonate (CaCO 3 ) effl orescence phenomenon is not new and is generally found in the form of unsightly white deposits on the surface of cement products. It appears just after completion of building construction and causes aesthetically unpleasant sight. This paper presents and discusses the results of microstructural study on the effectiveness of commercial polymer emulsion as cement additives to mitigate effl orescence on cement-based products that are dry-cured in the concrete laboratory at daily room temperature (T) and relative humidity in the range of 18°C‐28°C and 65%‐90%, respectively. Polymers used as cement additives were styrene acrylic ester (SAE) and styrene butadiene rubber (SBR) emulsion. Due to their pore-blocking characteristics and interaction with cement to improve mortar quality, they are added into cement to form mortar used for repair purposes. In order to investigate on how they can microstructurally infl uence effl orescence formation, effl orescence intensities (EI) in terms of percentages of CaCO 3 resulting from the combination of puddle test and standard chemical method were compared systematically between all samples on 28, 60 and 90 days and the fi ndings were discussed and corroborated physicochemically using initial surface absorption test, X-ray diffraction (XRD), thermogravimetric analysis (TGA) and morphology using scanning electron microscopy (SEM). Results indicated that 10% and 5% SAE addition signifi cantly reduced primary effl orescence and secondary effl orescence, respectively, in comparison to SBR and Control. The infl uence were on chemical reactivity, interaction between polymer and cement and on the movement of the polymer particles within the hydrating mortar as hydration progressed to form pore-blocking effects in the microstructures of cement-based materials and were refl ected in the XRD patterns, TGA/DTG analysis, SEM images and the decreased initial surface water absorption.

Defects Generation in Ge/GeO2 Structure

Thermal oxidation of Ge was performed in dry oxygen ambience at atmospheric pressure at temperature ranging between 375 and 575°C. From SE analysis, the slope of Ge oxide growth and extinction coefficient (k) increases while refractive index (n) does not change with oxidation temperature. The reduction of activation energy for Ge thermal oxidation was explained by the retardation of diffusion oxidant through GeO2 film during Ge oxidation. The generation of an oxygen-defect region in the Ge oxide layer at 490°C oxidation was confirmed by XPS analysis and an O2 anneal at 375°C was effective to reduce this oxygen deficiency.

Advances in Intelligent and Soft Computing: Potential Application of Service Science in Engineering

This paper discusses the potential of emerging service science with engineering applications. First the definition and classification of service for engineering discipline are detailed and elaborated. Based on that, this paper focuses on the potential application of service science in the Construction Industry namely Building Information Modeling (BIM). Elaborate discussion on the service value of BIM leads to suggestion for further research in specific areas namely the interaction between experts from the world’s major BIM player in order to improve the implementation of BIM.