Maan Hassan | University of Technology/Iraq (original) (raw)

Papers by Maan Hassan

Engineering and Technology Journal

Titanuim dioxide represents a novel photocatalyst material that can be used in different ways for... more Titanuim dioxide represents a novel photocatalyst material that can be used in different ways for air pollutants remediation. Air pollutants that are spreaded in the surrounding air could be transferred to more complex materials, especially in the presence of sunlight. To study the possibility for the reduction of these pollutants a laboratory tests have been conducted on the coated specimen substrate by using nitric oxide as pollutant gas, and there efficiency in gas removal was monitored with time. Two different particle sizes of TiO 2 have been used; micro with particle size range between 150-200 nm and nano PC105 with particle size 20+ 5 nm, both are 100% anatse. Two coatings methods were applied on cementitious substrate material dip and spray to study the photochemical reaction with TiO 2 , aqueous solution prepared by dispersing 3g/L of TiO 2 with deionized water and ethanol. Results show that using nano and micro size TiO 2 aqueous solutions were effective in the removal of nitric oxide with variations in the time consumed for the removal. Using nano aqueous solution in both dip and spray methods gives the same removal efficiency reached to 98.85% ,while using micro aqueous solution the removal reached to 98.08% when dip method was used and 87.69% when spray method was used.

Engineering and Technology Journal

IOP Conference Series: Materials Science and Engineering, 2020

Present study aims to observe the consequence of varying the intensity of the accelerating impres... more Present study aims to observe the consequence of varying the intensity of the accelerating impressed electrical current and situations of wetting-drying as hybrid accelerated corrosion regime on synthetically corroded concrete specimens, especially the loss of steel mass. Small-scaled reinforced concrete columns were fabricated and synthetically corroded by altered accelerating corrosion situations by applying an impressed current with intensity ranging between (50 and 500 μA/cm2). Moreover, the impressed current joined with two dissimilar durations of wetting-drying cycles for assessment. The steel mass losses during and at the end of the accelerated corrosion process were calculated, also, cracking configuration and damage shape were observed for accelerating corrosion. The outcomes designated that the hybrid method (impressed current joined with cycles of saline solution wetting and drying series) can be employed adequately to simulate the regular corrosion process in the reinfor...

IOP Conference Series: Materials Science and Engineering, 2019

In Iraq pavements materials are exposed to various distresses due to the adverse environmental co... more In Iraq pavements materials are exposed to various distresses due to the adverse environmental conditions and heavy traffic. The improvement of performance of flexible pavements is necessary for decreasing these distresses. The objective of this research is to improve the mixing efficiency of nano-silica particles with asphalt binder. Two mixer type (mechanical and high shear), rotational speeds (2000, 4000 and 6000 rpm), and mixing period (30 and 60 minutes) were assessed. Three nano-silica per cent 2%, 4%, and 6% by weight of asphalt were added and the asphalt binder mixtures were prepared by heating at mixing temperature 140 °C. Furthermore, comparisons were made to assess the modified asphalt binder characteristics such as penetration value, softening point, temperature sensitivity (penetration index), ductility and rotational viscosity. Results showed that the use of nano silica as an additive was useful in improving the asphalt binder characteristics. Generally, has been found...

Engineering and Technology Journal

 Three types of chemical admixtures and curing regimes were used with ultra-highperformance conc... more  Three types of chemical admixtures and curing regimes were used with ultra-highperformance concrete (UHPC).  150 MPa compressive strength is secured after 72 hours using Hyperplast PC-202 and curing at 90ºC.  UHPC mixtures require high admixture dosages, resulting in prolonged setting time. The types of post-setting curing and high range water reducing (HRWR) admixture used in Ultra-High-Performance Concrete (UHPC) mixtures play significant roles in determining their rheological and mechanical properties. This study compares the performance of three types of HRWR admixtures commercially available when added to UHPC mixtures under three different curing regimes. Mixtures made with the different superplasticizers were evaluated for their flow, 45mins flow retention, and setting time as fresh mix properties. Compressive strength was also tested for each mixture after 3, 7, and 28 days of curing at the investigated various curing regimes. Sika Viscocrete 180GS produced the highest mixture flow and flow retention levels with a 241 mm flow and 93.7% flow retention. Sika Viscocrete 168-1 produced the best results of setting time with 3 hours as compared to 12 hours with Sika Viscocrete 180GS. Using Hyperplast PC-202, the required 150 MPa compressive strength was secured as early as 3 days of curing with a 48hrs-90ºC curing regime. Using the same HRWR admixture, compressive strength values slightly lower than 150 MPa were reached after 7-28 days when the 72hrs-60ºC regime was adopted. The last curing regime was recommended for producing architectural UHPC units to minimize the delayed formation of ettringite.

This paper aims to investigate the influence of replacement of cement with nano and micro silica ... more This paper aims to investigate the influence of replacement of cement with nano and micro silica admixtures on some durability properties of concrete such as water absorption, chloride content and pH tests. Three replacement ratios (5%,10%,15%) of micro silica and four replacement proportions (0.5%,1.5%,3%,5%) for nano silica were used in this study. Two exposure conditions were considered for chloride content test: wetting-drying and full immersing exposure in 6% of chloride ions solution, NaCl type. Results showed that mixes of %5 micro silica and 5% nano silica had lower content of chloride (about 0.19% and 0.18%) for wetting-drying and full immersing exposure respectively. For water absorption test, all mixes incorporated micro and nano silica, except for %5 micro silica mix, showed lower absorption than control mixes. For pH test, results indicated that the adding of nano and micro silica didn’t affect adversely the alkalinity of concrete. Key wards: Nano silica; micro silica; ...

SSRN Electronic Journal, 2021

The fire resistance of cement-based composite mortars is highly dependent on their mechanical, ch... more The fire resistance of cement-based composite mortars is highly dependent on their mechanical, chemical, and thermal characteristics. This study presents the results of an experimental investigation on the mechanical properties and microstructure of nano-calcined montmorillonite clay (NCMC) cement mortars at high temperatures. The NCMC was prepared via thermal activation of nano-clay, and the produced mortars with progressive NCMC replacements were subjected to temperatures of up to 900 °C. The fire-resistance properties of the produced mortars and their role were analysed through thermo gravimetric analysis, X-ray diffraction, and scanning electron microscopy. Both the residual compressive and flexural strengths of mortars containing NCMC improved after the addition of NCMC. However, the residual compressive strength was enhanced more than the flexural strength, owing to the higher sensitivity of the former to microcracks emerging at elevated temperatures. Microstructural results r...

Journal of Physics: Conference Series, 2021

Waste material recycling in mortar production not only provides a promising resource for producin... more Waste material recycling in mortar production not only provides a promising resource for producing high-quality mortar, but it also aids in properly addressing the waste disposal issue. This study investigates the potential of utilizing blast furnace slag wastes as a supplementary cementitious material in blended cement-based mortars. The experimental program includes investigation of compressive strength of cement-based mortar composites contained different types and percentages of slag wastes. The mortar specimens were prepared and cured following related international standards. After curing, the compressive strengths of the tested specimens were assessed and compared with control specimens. The influence of the chemical composition of the investigated slag types on the resulted strength of the blended cement mortar was also discussed. Results of this study revealed that the chemical compositions of the raw slag wastes have significant effects on the pozzolanic activity of the pr...

Engineering and Technology Journal, 2015

Concrete elastic modulus is a basic property required for the appropriate predicting of its basic... more Concrete elastic modulus is a basic property required for the appropriate predicting of its basic behavior and for its correct implementation in a variety of constructional and engineering applications. This study presents an experimental and analytical evaluation of elastic modulus of high performance concretes (HPC) produced by steel fiber and silica fume. The aim of this study is to develop the elastic modulus property of HPC and to show the applicability of ACI models to predict the elastic modulus of HPC from compressive strength. Four volume fractions of steel fiber with an aspect ratio (fiber length/ fiber diameter) of 60 were used (0, 0.5, 1.0, and 2.0 %). Incorporations of silica fume into the concrete were 0% and 15% by weight as a cement replacement. Water/cement ratio was ranged (0.28-0.4) with different amount of superplasticizer, and the reference slump was 170 mm. Both compressive and elastic modulus tests were made on hardened concretes reinforced with steel fibers a...

Engineering and Technology Journal, 2008

Background: In classical phenylketonuria (PKU) phenylalanine (Phe) accumulates due to functional ... more Background: In classical phenylketonuria (PKU) phenylalanine (Phe) accumulates due to functional impairment of the enzyme phenylalanine hydroxylase caused by pathogenic variants in the PAH gene. PKU treatment prevents severe cognitive impairment. Blood Phe concentration is the main biochemical monitoring parameter. Between appointments and venous blood sampling, Austrian PKU patients send dried blood spots (DBS) for Phe measurements to their centre. Coronavirus disease-19 (COVID-19), caused by the SARS CoV-2 virus, was classified as a pandemic by the World Health Organization in March 2020. In Austria, two nationwide lockdowns were installed during the first and second pandemic wave with variable regional and national restrictions in between. This retrospective questionnaire study compared the frequency of Phe measurements and Phe concentrations during lockdown with the respective period of the previous year in children and adolescents with PKU and explored potential influencing factors. Results: 77 patients (30 female, 47 male; mean age 12.4 [8-19] years in 2020) from five centres were included. The decline of venous samples taken on appointments in 2020 did not reach significance but the number of patients with none or only one DBS tripled from 4 (5.2%) in 2019 to 12 (15.6%) in 2020. Significantly more patients had a decline than a rise in the number of DBS sent in between 2019 and 2020 (p < 0.001; Chi 2 = 14.79). Especially patients ≥ 16 years sent significantly less DBS in 2020 (T = 156, p = 0.02, r = 0.49). In patients who adhered to DBS measurements, Phe concentrations remained stable. Male or female sex and dietary only versus dietary plus sapropterin treatment did not influence frequency of measurements and median Phe. Conclusion: During the COVID pandemic, the number of PKU patients who stopped sending DBS to their metabolic centre increased significantly, especially among those older than 16 years. Those who kept up sending DBS maintained stable Phe concentrations. Our follow-up system, which is based on DBS sent in by patients to trigger communication with the metabolic team served adherent patients well. It failed, however, to actively retrieve patients who stopped or reduced Phe measurements.

In this study, the mechanical properties of five different cement based repairing materials were ... more In this study, the mechanical properties of five different cement based repairing materials were evaluated. These materials were classified into two groups: laboratory made materials with or without admixtures (3 types), and other two types of commercial proprietary pre-packaged with additives. Mechanical properties, such as compressive strength, modulus of rupture and drying shrinkage were studied. Results show that these mechanical properties were varying significantly from each other. The drying shrinkage of the commercial proprietary repair materials was less than that of the conventional mortar. This will lead to a reduced cracking risk in the former repair materials compared to the latter. Through the regression analysis on the experimental data collected, power relation with coefficient of determination of 0.766 is obtained between compressive and modulus of rupture.

IOP Conference Series: Earth and Environmental Science, 2021

In any industrial or municipal population areas, the excess sewage sludge produced by wastewater ... more In any industrial or municipal population areas, the excess sewage sludge produced by wastewater treatment plant WWTP creates significant problems due to its growing quantity and possibly containing toxic materials or heavy metals. The concrete industry is one of the fields where wastewater sludge, as well as other wastes, could be utilized inefficient way. The inclusion of wastewater sludge in materials incorporated with cement reduces some of the costly and high energy stages of usage, and the obtained product is often safe and stable. Several studies promoted that the reuse of sludge in concrete can be an ideal solution to get rid of its negative effects, especially the hazardous ones, as it is an effective alternative to reuse the sludge for land applications. The main aim of this study is to present the recent methods of utilizing wastewater dried, dehydrated, and/or raw sludge in concrete industries. The present review revealed the difficulty of choosing the most general techn...

Advances in Cement Research, 2018

The aim of this work was to improve the long-term performance of fabricated eco-cement composites... more The aim of this work was to improve the long-term performance of fabricated eco-cement composites and demonstrate the value-added use of carbon dioxide (CO2) in manufacturing sustainable products with better dimensional stability and moisture resistivity. Experiments were on pressed and non-pressed composites, fabricated with and without carbon dioxide curing. Dimensional stability comparisons were made between composites of date palm fibre and cement subjected to different moisture conditions, including air-dried, oven-dried and saturated conditions. Their flexural performances were then evaluated and compared with control specimens. The results revealed that the application of pressing and carbon dioxide curing as accelerating processing techniques have significant influences on the resultant products. The oven-dried composites exhibited poor flexural toughness behaviour compared with the air-dried or saturated specimens. Fibre growth in the transverse direction due to moisture co...

Engineering and Technology Journal, 2020

Corrosion of reinforcement has been identified as the deterioration mechanism of reinforced concr... more Corrosion of reinforcement has been identified as the deterioration mechanism of reinforced concrete structures, which seriously affects the safety and integrity of structures. The corrosion of the embedded reinforcing steel in concrete is a major problem facing civil engineers today, which initiates 80% of the reinforced concrete structures deterioration. This paper reveals the outcomes of an experimental investigation on the mechanical performance (residual strength) of circular steel reinforced columns which have been damaged by corrosion of the steel rebar. Small scale circular reinforced concrete columns with a diameter of 100 mm and 300 mm in height were adopted. Different rates of steel reinforcement mass loss (corrosion damage) ranged between 10%, 20% to 30 % were created in the columns by using a galvanostatic accelerated corrosion method combined with wetting-drying cycles. The uniaxial compression test was implemented for damaged columns up to failure. Based on the exper...

Construction and Building Materials, 2020

Journal of Engineering and Technological Sciences, 2020

Tailoring reflectance and conductance was achieved through layer by layer assembly of a silver ac... more Tailoring reflectance and conductance was achieved through layer by layer assembly of a silver acetate based multilayer coating. The coating was applied over glass and cement substrates by sol-gel spin coating and by brush painting, respectively. The structural, optical and electrical characteristics and the composition of the coating were studied. The diffraction peaks for all films revealed that the face-centered cubic lattice of the silver crystal structure and the films with more layers had a higher degree of crystallinity. The optical characteristics showed that having more layers leads to decreasing transmittance and increasing reflectance. The I-V characteristics of all samples showed typical ohmic contacts in a voltage range of -1 to 1 V. The conductance increased drastically as the coating developed into multiple layers. The eight-layer coated glass and cement based substrates had very low surface resistance, at 4 Ω and 2 Ω at 1 V, respectively. The study also revealed ...

IOP Conference Series: Materials Science and Engineering, 2020

Nitric oxide generated from various sources like car combustion is one of the most surrounding po... more Nitric oxide generated from various sources like car combustion is one of the most surrounding pollutants. Titanium dioxide considered an environmentally friendly active photocatalytics that can be used with building materials safely and effectively to react with nitric oxides in the presence of UV radiation from sunlight. To study the possibility for the reduction of air pollutants two strategies were adopted. First one included mixing of micro particles of TiO2 with cement paste in two percentages: 3% and 6%. In the second one mortar substrates were coated with micro TiO2 (mT) aqueous solution by either dipping or spraying coating method. A laboratory test procedure was adopted to assess the performance of the prepared photoactive specimens. The specimens were subjected to NO gas and there efficiency in gas removal was monitored with time. Results showed that coating strategy was more effective than mixing strategy in term of gaseous pollutants removal. The comparison between the ...

Engineering and Technology Journal

Titanuim dioxide represents a novel photocatalyst material that can be used in different ways for... more Titanuim dioxide represents a novel photocatalyst material that can be used in different ways for air pollutants remediation. Air pollutants that are spreaded in the surrounding air could be transferred to more complex materials, especially in the presence of sunlight. To study the possibility for the reduction of these pollutants a laboratory tests have been conducted on the coated specimen substrate by using nitric oxide as pollutant gas, and there efficiency in gas removal was monitored with time. Two different particle sizes of TiO 2 have been used; micro with particle size range between 150-200 nm and nano PC105 with particle size 20+ 5 nm, both are 100% anatse. Two coatings methods were applied on cementitious substrate material dip and spray to study the photochemical reaction with TiO 2 , aqueous solution prepared by dispersing 3g/L of TiO 2 with deionized water and ethanol. Results show that using nano and micro size TiO 2 aqueous solutions were effective in the removal of nitric oxide with variations in the time consumed for the removal. Using nano aqueous solution in both dip and spray methods gives the same removal efficiency reached to 98.85% ,while using micro aqueous solution the removal reached to 98.08% when dip method was used and 87.69% when spray method was used.

Engineering and Technology Journal

IOP Conference Series: Materials Science and Engineering, 2020

Present study aims to observe the consequence of varying the intensity of the accelerating impres... more Present study aims to observe the consequence of varying the intensity of the accelerating impressed electrical current and situations of wetting-drying as hybrid accelerated corrosion regime on synthetically corroded concrete specimens, especially the loss of steel mass. Small-scaled reinforced concrete columns were fabricated and synthetically corroded by altered accelerating corrosion situations by applying an impressed current with intensity ranging between (50 and 500 μA/cm2). Moreover, the impressed current joined with two dissimilar durations of wetting-drying cycles for assessment. The steel mass losses during and at the end of the accelerated corrosion process were calculated, also, cracking configuration and damage shape were observed for accelerating corrosion. The outcomes designated that the hybrid method (impressed current joined with cycles of saline solution wetting and drying series) can be employed adequately to simulate the regular corrosion process in the reinfor...

IOP Conference Series: Materials Science and Engineering, 2019

In Iraq pavements materials are exposed to various distresses due to the adverse environmental co... more In Iraq pavements materials are exposed to various distresses due to the adverse environmental conditions and heavy traffic. The improvement of performance of flexible pavements is necessary for decreasing these distresses. The objective of this research is to improve the mixing efficiency of nano-silica particles with asphalt binder. Two mixer type (mechanical and high shear), rotational speeds (2000, 4000 and 6000 rpm), and mixing period (30 and 60 minutes) were assessed. Three nano-silica per cent 2%, 4%, and 6% by weight of asphalt were added and the asphalt binder mixtures were prepared by heating at mixing temperature 140 °C. Furthermore, comparisons were made to assess the modified asphalt binder characteristics such as penetration value, softening point, temperature sensitivity (penetration index), ductility and rotational viscosity. Results showed that the use of nano silica as an additive was useful in improving the asphalt binder characteristics. Generally, has been found...

Engineering and Technology Journal

 Three types of chemical admixtures and curing regimes were used with ultra-highperformance conc... more  Three types of chemical admixtures and curing regimes were used with ultra-highperformance concrete (UHPC).  150 MPa compressive strength is secured after 72 hours using Hyperplast PC-202 and curing at 90ºC.  UHPC mixtures require high admixture dosages, resulting in prolonged setting time. The types of post-setting curing and high range water reducing (HRWR) admixture used in Ultra-High-Performance Concrete (UHPC) mixtures play significant roles in determining their rheological and mechanical properties. This study compares the performance of three types of HRWR admixtures commercially available when added to UHPC mixtures under three different curing regimes. Mixtures made with the different superplasticizers were evaluated for their flow, 45mins flow retention, and setting time as fresh mix properties. Compressive strength was also tested for each mixture after 3, 7, and 28 days of curing at the investigated various curing regimes. Sika Viscocrete 180GS produced the highest mixture flow and flow retention levels with a 241 mm flow and 93.7% flow retention. Sika Viscocrete 168-1 produced the best results of setting time with 3 hours as compared to 12 hours with Sika Viscocrete 180GS. Using Hyperplast PC-202, the required 150 MPa compressive strength was secured as early as 3 days of curing with a 48hrs-90ºC curing regime. Using the same HRWR admixture, compressive strength values slightly lower than 150 MPa were reached after 7-28 days when the 72hrs-60ºC regime was adopted. The last curing regime was recommended for producing architectural UHPC units to minimize the delayed formation of ettringite.

This paper aims to investigate the influence of replacement of cement with nano and micro silica ... more This paper aims to investigate the influence of replacement of cement with nano and micro silica admixtures on some durability properties of concrete such as water absorption, chloride content and pH tests. Three replacement ratios (5%,10%,15%) of micro silica and four replacement proportions (0.5%,1.5%,3%,5%) for nano silica were used in this study. Two exposure conditions were considered for chloride content test: wetting-drying and full immersing exposure in 6% of chloride ions solution, NaCl type. Results showed that mixes of %5 micro silica and 5% nano silica had lower content of chloride (about 0.19% and 0.18%) for wetting-drying and full immersing exposure respectively. For water absorption test, all mixes incorporated micro and nano silica, except for %5 micro silica mix, showed lower absorption than control mixes. For pH test, results indicated that the adding of nano and micro silica didn’t affect adversely the alkalinity of concrete. Key wards: Nano silica; micro silica; ...

SSRN Electronic Journal, 2021

The fire resistance of cement-based composite mortars is highly dependent on their mechanical, ch... more The fire resistance of cement-based composite mortars is highly dependent on their mechanical, chemical, and thermal characteristics. This study presents the results of an experimental investigation on the mechanical properties and microstructure of nano-calcined montmorillonite clay (NCMC) cement mortars at high temperatures. The NCMC was prepared via thermal activation of nano-clay, and the produced mortars with progressive NCMC replacements were subjected to temperatures of up to 900 °C. The fire-resistance properties of the produced mortars and their role were analysed through thermo gravimetric analysis, X-ray diffraction, and scanning electron microscopy. Both the residual compressive and flexural strengths of mortars containing NCMC improved after the addition of NCMC. However, the residual compressive strength was enhanced more than the flexural strength, owing to the higher sensitivity of the former to microcracks emerging at elevated temperatures. Microstructural results r...

Journal of Physics: Conference Series, 2021

Waste material recycling in mortar production not only provides a promising resource for producin... more Waste material recycling in mortar production not only provides a promising resource for producing high-quality mortar, but it also aids in properly addressing the waste disposal issue. This study investigates the potential of utilizing blast furnace slag wastes as a supplementary cementitious material in blended cement-based mortars. The experimental program includes investigation of compressive strength of cement-based mortar composites contained different types and percentages of slag wastes. The mortar specimens were prepared and cured following related international standards. After curing, the compressive strengths of the tested specimens were assessed and compared with control specimens. The influence of the chemical composition of the investigated slag types on the resulted strength of the blended cement mortar was also discussed. Results of this study revealed that the chemical compositions of the raw slag wastes have significant effects on the pozzolanic activity of the pr...

Engineering and Technology Journal, 2015

Concrete elastic modulus is a basic property required for the appropriate predicting of its basic... more Concrete elastic modulus is a basic property required for the appropriate predicting of its basic behavior and for its correct implementation in a variety of constructional and engineering applications. This study presents an experimental and analytical evaluation of elastic modulus of high performance concretes (HPC) produced by steel fiber and silica fume. The aim of this study is to develop the elastic modulus property of HPC and to show the applicability of ACI models to predict the elastic modulus of HPC from compressive strength. Four volume fractions of steel fiber with an aspect ratio (fiber length/ fiber diameter) of 60 were used (0, 0.5, 1.0, and 2.0 %). Incorporations of silica fume into the concrete were 0% and 15% by weight as a cement replacement. Water/cement ratio was ranged (0.28-0.4) with different amount of superplasticizer, and the reference slump was 170 mm. Both compressive and elastic modulus tests were made on hardened concretes reinforced with steel fibers a...

Engineering and Technology Journal, 2008

Background: In classical phenylketonuria (PKU) phenylalanine (Phe) accumulates due to functional ... more Background: In classical phenylketonuria (PKU) phenylalanine (Phe) accumulates due to functional impairment of the enzyme phenylalanine hydroxylase caused by pathogenic variants in the PAH gene. PKU treatment prevents severe cognitive impairment. Blood Phe concentration is the main biochemical monitoring parameter. Between appointments and venous blood sampling, Austrian PKU patients send dried blood spots (DBS) for Phe measurements to their centre. Coronavirus disease-19 (COVID-19), caused by the SARS CoV-2 virus, was classified as a pandemic by the World Health Organization in March 2020. In Austria, two nationwide lockdowns were installed during the first and second pandemic wave with variable regional and national restrictions in between. This retrospective questionnaire study compared the frequency of Phe measurements and Phe concentrations during lockdown with the respective period of the previous year in children and adolescents with PKU and explored potential influencing factors. Results: 77 patients (30 female, 47 male; mean age 12.4 [8-19] years in 2020) from five centres were included. The decline of venous samples taken on appointments in 2020 did not reach significance but the number of patients with none or only one DBS tripled from 4 (5.2%) in 2019 to 12 (15.6%) in 2020. Significantly more patients had a decline than a rise in the number of DBS sent in between 2019 and 2020 (p < 0.001; Chi 2 = 14.79). Especially patients ≥ 16 years sent significantly less DBS in 2020 (T = 156, p = 0.02, r = 0.49). In patients who adhered to DBS measurements, Phe concentrations remained stable. Male or female sex and dietary only versus dietary plus sapropterin treatment did not influence frequency of measurements and median Phe. Conclusion: During the COVID pandemic, the number of PKU patients who stopped sending DBS to their metabolic centre increased significantly, especially among those older than 16 years. Those who kept up sending DBS maintained stable Phe concentrations. Our follow-up system, which is based on DBS sent in by patients to trigger communication with the metabolic team served adherent patients well. It failed, however, to actively retrieve patients who stopped or reduced Phe measurements.

In this study, the mechanical properties of five different cement based repairing materials were ... more In this study, the mechanical properties of five different cement based repairing materials were evaluated. These materials were classified into two groups: laboratory made materials with or without admixtures (3 types), and other two types of commercial proprietary pre-packaged with additives. Mechanical properties, such as compressive strength, modulus of rupture and drying shrinkage were studied. Results show that these mechanical properties were varying significantly from each other. The drying shrinkage of the commercial proprietary repair materials was less than that of the conventional mortar. This will lead to a reduced cracking risk in the former repair materials compared to the latter. Through the regression analysis on the experimental data collected, power relation with coefficient of determination of 0.766 is obtained between compressive and modulus of rupture.

IOP Conference Series: Earth and Environmental Science, 2021

In any industrial or municipal population areas, the excess sewage sludge produced by wastewater ... more In any industrial or municipal population areas, the excess sewage sludge produced by wastewater treatment plant WWTP creates significant problems due to its growing quantity and possibly containing toxic materials or heavy metals. The concrete industry is one of the fields where wastewater sludge, as well as other wastes, could be utilized inefficient way. The inclusion of wastewater sludge in materials incorporated with cement reduces some of the costly and high energy stages of usage, and the obtained product is often safe and stable. Several studies promoted that the reuse of sludge in concrete can be an ideal solution to get rid of its negative effects, especially the hazardous ones, as it is an effective alternative to reuse the sludge for land applications. The main aim of this study is to present the recent methods of utilizing wastewater dried, dehydrated, and/or raw sludge in concrete industries. The present review revealed the difficulty of choosing the most general techn...

Advances in Cement Research, 2018

The aim of this work was to improve the long-term performance of fabricated eco-cement composites... more The aim of this work was to improve the long-term performance of fabricated eco-cement composites and demonstrate the value-added use of carbon dioxide (CO2) in manufacturing sustainable products with better dimensional stability and moisture resistivity. Experiments were on pressed and non-pressed composites, fabricated with and without carbon dioxide curing. Dimensional stability comparisons were made between composites of date palm fibre and cement subjected to different moisture conditions, including air-dried, oven-dried and saturated conditions. Their flexural performances were then evaluated and compared with control specimens. The results revealed that the application of pressing and carbon dioxide curing as accelerating processing techniques have significant influences on the resultant products. The oven-dried composites exhibited poor flexural toughness behaviour compared with the air-dried or saturated specimens. Fibre growth in the transverse direction due to moisture co...

Engineering and Technology Journal, 2020

Corrosion of reinforcement has been identified as the deterioration mechanism of reinforced concr... more Corrosion of reinforcement has been identified as the deterioration mechanism of reinforced concrete structures, which seriously affects the safety and integrity of structures. The corrosion of the embedded reinforcing steel in concrete is a major problem facing civil engineers today, which initiates 80% of the reinforced concrete structures deterioration. This paper reveals the outcomes of an experimental investigation on the mechanical performance (residual strength) of circular steel reinforced columns which have been damaged by corrosion of the steel rebar. Small scale circular reinforced concrete columns with a diameter of 100 mm and 300 mm in height were adopted. Different rates of steel reinforcement mass loss (corrosion damage) ranged between 10%, 20% to 30 % were created in the columns by using a galvanostatic accelerated corrosion method combined with wetting-drying cycles. The uniaxial compression test was implemented for damaged columns up to failure. Based on the exper...

Construction and Building Materials, 2020

Journal of Engineering and Technological Sciences, 2020

Tailoring reflectance and conductance was achieved through layer by layer assembly of a silver ac... more Tailoring reflectance and conductance was achieved through layer by layer assembly of a silver acetate based multilayer coating. The coating was applied over glass and cement substrates by sol-gel spin coating and by brush painting, respectively. The structural, optical and electrical characteristics and the composition of the coating were studied. The diffraction peaks for all films revealed that the face-centered cubic lattice of the silver crystal structure and the films with more layers had a higher degree of crystallinity. The optical characteristics showed that having more layers leads to decreasing transmittance and increasing reflectance. The I-V characteristics of all samples showed typical ohmic contacts in a voltage range of -1 to 1 V. The conductance increased drastically as the coating developed into multiple layers. The eight-layer coated glass and cement based substrates had very low surface resistance, at 4 Ω and 2 Ω at 1 V, respectively. The study also revealed ...

IOP Conference Series: Materials Science and Engineering, 2020

Nitric oxide generated from various sources like car combustion is one of the most surrounding po... more Nitric oxide generated from various sources like car combustion is one of the most surrounding pollutants. Titanium dioxide considered an environmentally friendly active photocatalytics that can be used with building materials safely and effectively to react with nitric oxides in the presence of UV radiation from sunlight. To study the possibility for the reduction of air pollutants two strategies were adopted. First one included mixing of micro particles of TiO2 with cement paste in two percentages: 3% and 6%. In the second one mortar substrates were coated with micro TiO2 (mT) aqueous solution by either dipping or spraying coating method. A laboratory test procedure was adopted to assess the performance of the prepared photoactive specimens. The specimens were subjected to NO gas and there efficiency in gas removal was monitored with time. Results showed that coating strategy was more effective than mixing strategy in term of gaseous pollutants removal. The comparison between the ...