Chi-sun Poon - Academia.edu (original) (raw)
Papers by Chi-sun Poon
Resources, Conservation and Recycling, 2007
In 2004, over 20 million tonnes of construction and demolition (C&D) ... more In 2004, over 20 million tonnes of construction and demolition (C&D) wastes were generated in Hong Kong. Since the local landfills will be saturated in about 8 years, it is important to find a viable way to reuse these waste materials as to alleviate the demand on public fill ...
Cement and Concrete Composites, 2014
ABSTRACT In this paper, the effects of high temperature exposure of recycled aggregate concretes ... more ABSTRACT In this paper, the effects of high temperature exposure of recycled aggregate concretes in terms of residual strengths, capillary water absorption capacity and pore size distribution are discussed. Two mineral admixtures, fly ash (FA) and ground granulated blast furnace (GGBS) were used in the experiment to partially replace ordinary Portland cement for concrete production. The water to cementitious materials ratio was maintained at 0.50 for all the concrete mixes. The replacement levels of natural aggregates by recycled aggregates were at 0%, 50% and 100%. The concretes were exposed separately to 300°C, 500°C and 800°C, and the compressive and splitting tensile strength, capillary water coefficient, porosity and pore size distribution were determined before and after the exposure to the high temperatures. The results show that the concretes made with recycled aggregates suffered less deteriorations in mechanical and durability properties than the concrete made with natural aggregates after the high temperature exposures.
Waste management (New York, N.Y.), 2006
The use of coarse recycled concrete aggregates (CRCA) in conjunction with fine recycled concrete ... more The use of coarse recycled concrete aggregates (CRCA) in conjunction with fine recycled concrete aggregates (FRCA) as sub-base materials has been widely studied. Although research results indicate that it is feasible to employ both CRCA and FRCA as granular sub-base, the influence of the unhydrated cement in the adhered mortar of the RCA on the properties of the sub-base materials has not been thoroughly studied. Generally, it is known that the strength of the sub-base materials prepared with RCA increases over time. However, this mechanism, known as the self-cementing properties, is not well understood and is believed to be governed by the properties of the fine portion of the RCA (<5mm). This paper presents an investigation on the cause of the self-cementing properties by measuring X-ray diffraction patterns, pH values, compressive strength and permeability of various size fractions of the FRCA obtained from a commercially operated construction and demolition waste recycling pl...
Cement and Concrete Composites, 2014
The use of 100% recycled glass as aggregates in architectural mortar is regarded as an environmen... more The use of 100% recycled glass as aggregates in architectural mortar is regarded as an environmentally friendly, cost-effective and attractive feature for construction applications due to the natural characteristics of glass (e.g. aesthetic pleasing, impermeability, chemical resistance properties). However, the need to use large quantities of white cement for architectural products may increase the overall cost of production. Therefore, the possibility of using a near-white coloured ground granulated blast furnace slag (GGBS) to replace white cement for architectural mortar production is an attractive option. This paper reports a study which is an extension of our previous work aiming to investigate the feasibility of using large volumes of GGBS (ranging from 15% to 75% white cement replacements) to produce self-compacting-based architectural mortars. To improve the appearance (whiteness) of the mortar, a small quantity of titanium dioxide (TiO2) was added to the selected mixes for comparison purposes. Fresh and hardened properties of the mortar including mini-slump flow, density, water absorption, flexural strength, equivalent compressive strength, drying shrinkage, alkali silica reaction (ASR) and acid attack resistance were investigated. The overall performance showed that it is feasible to use GGBS for the production of architectural mortar and 60% replacement of white cement by GGBS was determined to be optimal. The replacement significantly increased the flexural strength, and reduced the drying shrinkage and risk of ASR expansion, as well as improved the ability to resist acid attack of the mortar produced.
Materials & Design, 2011
Ling TC, Properties of architectural mortar prepared with recycled glass with different particle ... more Ling TC, Properties of architectural mortar prepared with recycled glass with different particle sizes. Materials and Design; 32 (5): 2675-2684.
Waste Management, 2009
Low grade recycled aggregates obtained from a construction waste sorting facility were tested to ... more Low grade recycled aggregates obtained from a construction waste sorting facility were tested to assess the feasibility of using these in the production of concrete blocks. The characteristics of the sorted construction waste are significantly different from that of crushed concrete rubbles that are mostly derived from demolition waste streams. This is due to the presence of higher percentages of non-concrete components (e.g. &amp;amp;amp;amp;amp;amp;amp;amp;gt;10% soil, brick, tiles etc.) in the sorted construction waste. In the study reported in this paper, three series of concrete block mixtures were prepared by using the low grade recycled aggregates to replace (i) natural coarse granite (10mm), and (ii) 0, 25, 50, 75 and 100% replacement levels of crushed stone fine (crushed natural granite &amp;amp;amp;amp;amp;amp;amp;amp;lt;5mm) in the concrete blocks. Test results on properties such as density, compressive strength, transverse strength and drying shrinkage as well as strength reduction after exposure to 800 degrees C are presented below. The results show that the soil content in the recycled fine aggregate was an important factor in affecting the properties of the blocks produced and the mechanical strength deceased with increasing low grade recycled fine aggregate content. But the higher soil content in the recycled aggregates reduced the reduction of compressive strength of the blocks after exposure to high temperature due probably to the formation of a new crystalline phase. The results show that the low grade recycled aggregates obtained from the construction waste sorting facility has potential to be used as aggregates for making non-structural pre-cast concrete blocks.
Resources, Conservation and Recycling, 1998
In urban mainland China, safe disposal of municipal solid waste (MSW) averaged at&amp;lt;... more In urban mainland China, safe disposal of municipal solid waste (MSW) averaged at&amp;lt; 2%. While China is struggling to meet the lower order needs in waste management, namely, providing adequate waste collection service, ensuring enough up to standard waste ...
Resources, Conservation and Recycling, 1999
... The first part was a survey on the attitude and opinion of Guangzhou citizens on ... Eight of... more ... The first part was a survey on the attitude and opinion of Guangzhou citizens on ... Eight of the items in the scale were worded such that agreement reflected acceptance of ... through the help of the Guangzhou Education Bureau and the Guangzhou Environmental Science Society. ...
Resources, Conservation and Recycling, 1998
... Post-consumer items recovered are restricted to used aluminium cans, brown and white goods, o... more ... Post-consumer items recovered are restricted to used aluminium cans, brown and white goods, old newsprint and metal cooking ware. In Hong Kong, food scrap, glass, ferrous alloys and PET bottles have very few or no outlets at all. ...
Materials and Structures, 2006
A finite element method using a proposed mesoscopic thermoelastic damage model (MTED) is verified... more A finite element method using a proposed mesoscopic thermoelastic damage model (MTED) is verified for simulating the cracking process of a concrete section reinforced with fibre-reinforced polymer (FRP) bars. The cracking was due to the significant difference in thermal expansion properties between the concrete and the FRP materials at elevated temperatures. The numerical study reveals that although a conventional elastic
Journal of Construction Engineering and Management, 2006
ABSTRACT
Indoor Air, 1999
Sixteen flights had been investigated for indoor air quality (IAQ) on Cathay Pacific aircraft fro... more Sixteen flights had been investigated for indoor air quality (IAQ) on Cathay Pacific aircraft from June 1996 to August 1997. In general, the air quality on Cathay Pacific aircraft was within relevant air quality standards because the average age of aircraft was less than 2 years. Carbon dioxide (CO 2 ) levels on all flights measured were below the Federal Aviation Administration (FAA) standard (30,000 ppm). The CO 2 level was substantially higher during boarding and de-boarding than cruise due to low fresh air supply. Humidity on the aircraft was low, especially for long-haul flights. Minimum humidity during cruise was below the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) minimum humidity standard (20%). The average temperature was within a comfortable temperature range of 23∫2aeC. The vertical temperature profile on aircraft was uniform and below the International Standard Organization (ISO) standard. Carbon monoxide levels were below the FAA standard (50 ppm). Trace amount of ozone detected ranged from undetectable to 90 ppb, which was below the FAA standard. Particulate level was low for most non-smoking flights, but peaks were observed during boarding and de-boarding. The average particulate level in smoking flights (138 mg/m 3 ) was higher than non-smoking flights (7.6 mg/m 3 ). The impact on IAQ by switching from low-mode to high-mode ventilation showed a reduction in CO 2 levels, temperature, and relative humidity.
Journal of hazardous materials, Jan 15, 2012
Recycled glass derived from cathode ray tubes (CRT) glass with a specific gravity of approximatel... more Recycled glass derived from cathode ray tubes (CRT) glass with a specific gravity of approximately 3.0 g/cm(3) can be potentially suitable to be used as fine aggregate for preparing cement mortars for X-ray radiation-shielding applications. In this work, the effects of using crushed glass derived from crushed CRT funnel glass (both acid washed and unwashed) and crushed ordinary beverage container glass at different replacement levels (0%, 25%, 50%, 75% and 100% by volume) of sand on the mechanical properties (strength and density) and radiation-shielding performance of the cement-sand mortars were studied. The results show that all the prepared mortars had compressive strength values greater than 30 MPa which are suitable for most building applications based on ASTM C 270. The density and shielding performance of the mortar prepared with ordinary crushed (lead-free) glass was similar to the control mortar. However, a significant enhancement of radiation-shielding was achieved when t...
Environmental Science & Technology, 2000
Leach tests alone cannot determine the actual performance and long-term environmental impacts of ... more Leach tests alone cannot determine the actual performance and long-term environmental impacts of solidified/stabilized waste because they do not provide information on the physical and chemical changes between waste and additives. This research study utilized ...
Environmental Management, 2000
This paper compares the public attitudes of three southern Chinese cities/towns, namely Guangzhou... more This paper compares the public attitudes of three southern Chinese cities/towns, namely Guangzhou, Dongguan, and Yuanzhou on waste recycling and avoidance, and the New Environmental Paradigm (NEP). The latter describes the concept of treating the resources and the ecosystems on Earth as things having their own rights rather than being subordinate and subservient to humans. These three places are chosen to represent areas in different stages of urbanization in the Guangdong province. As Hong Kong is also a southern Chinese city, where data of similar nature are available, comparison with Hong Kong is also made.
Engineering, Construction and Architectural Management, 2003
Hong Kong is running out of both reclamation sites and landfill space for the disposal of constru... more Hong Kong is running out of both reclamation sites and landfill space for the disposal of construction and demolition waste. This paper reports on the findings of a study, consisting of a questionnaire survey, interviews and work-site visits, to compare the use of low-waste building technologies in public housing and private residential projects in Hong Kong. The results show that
Construction Management and Economics, 2008
... designs (Chan and Lee, 1998; Mak, 1998; Wong and Yau, 1999; Lam, 2002; Chan ... was calculate... more ... designs (Chan and Lee, 1998; Mak, 1998; Wong and Yau, 1999; Lam, 2002; Chan ... was calculated by following the British Standards, the General Specifications used in Hong Kong, and ... Potential material and cost savings by using prefabrication in lieu of timber formwork were ...
Construction and Building Materials, 2013
• High temperature properties of concrete blocks made with clay brick aggregate (CBA) were examin... more • High temperature properties of concrete blocks made with clay brick aggregate (CBA) were examined. • At 300°C, the nature of CBA origin made the concrete blocks stronger/more stiff.
Construction and Building Materials, 2009
This paper presents the results of a study to compare the properties of concretes prepared with t... more This paper presents the results of a study to compare the properties of concretes prepared with the use river sand, crushed fine stone (CFS), furnace bottom ash (FBA), and fine recycled aggregate (FRA) as fine aggregates. Two methods were used to design the concrete mixes: (i) fixed water–cement ratio (W/C) and (ii) fixed slump ranges. The investigation included testing of
Construction and Building Materials, 2011
Effects of crushed glass cullet sizes, casting methods and pozzolanic materials on ASR of concret... more Effects of crushed glass cullet sizes, casting methods and pozzolanic materials on ASR of concrete blocks. Construction and Building Materials; 25 (5): 2611-2618.
Resources, Conservation and Recycling, 2007
In 2004, over 20 million tonnes of construction and demolition (C&amp;amp;amp;amp;amp;D) ... more In 2004, over 20 million tonnes of construction and demolition (C&amp;amp;amp;amp;amp;D) wastes were generated in Hong Kong. Since the local landfills will be saturated in about 8 years, it is important to find a viable way to reuse these waste materials as to alleviate the demand on public fill ...
Cement and Concrete Composites, 2014
ABSTRACT In this paper, the effects of high temperature exposure of recycled aggregate concretes ... more ABSTRACT In this paper, the effects of high temperature exposure of recycled aggregate concretes in terms of residual strengths, capillary water absorption capacity and pore size distribution are discussed. Two mineral admixtures, fly ash (FA) and ground granulated blast furnace (GGBS) were used in the experiment to partially replace ordinary Portland cement for concrete production. The water to cementitious materials ratio was maintained at 0.50 for all the concrete mixes. The replacement levels of natural aggregates by recycled aggregates were at 0%, 50% and 100%. The concretes were exposed separately to 300°C, 500°C and 800°C, and the compressive and splitting tensile strength, capillary water coefficient, porosity and pore size distribution were determined before and after the exposure to the high temperatures. The results show that the concretes made with recycled aggregates suffered less deteriorations in mechanical and durability properties than the concrete made with natural aggregates after the high temperature exposures.
Waste management (New York, N.Y.), 2006
The use of coarse recycled concrete aggregates (CRCA) in conjunction with fine recycled concrete ... more The use of coarse recycled concrete aggregates (CRCA) in conjunction with fine recycled concrete aggregates (FRCA) as sub-base materials has been widely studied. Although research results indicate that it is feasible to employ both CRCA and FRCA as granular sub-base, the influence of the unhydrated cement in the adhered mortar of the RCA on the properties of the sub-base materials has not been thoroughly studied. Generally, it is known that the strength of the sub-base materials prepared with RCA increases over time. However, this mechanism, known as the self-cementing properties, is not well understood and is believed to be governed by the properties of the fine portion of the RCA (<5mm). This paper presents an investigation on the cause of the self-cementing properties by measuring X-ray diffraction patterns, pH values, compressive strength and permeability of various size fractions of the FRCA obtained from a commercially operated construction and demolition waste recycling pl...
Cement and Concrete Composites, 2014
The use of 100% recycled glass as aggregates in architectural mortar is regarded as an environmen... more The use of 100% recycled glass as aggregates in architectural mortar is regarded as an environmentally friendly, cost-effective and attractive feature for construction applications due to the natural characteristics of glass (e.g. aesthetic pleasing, impermeability, chemical resistance properties). However, the need to use large quantities of white cement for architectural products may increase the overall cost of production. Therefore, the possibility of using a near-white coloured ground granulated blast furnace slag (GGBS) to replace white cement for architectural mortar production is an attractive option. This paper reports a study which is an extension of our previous work aiming to investigate the feasibility of using large volumes of GGBS (ranging from 15% to 75% white cement replacements) to produce self-compacting-based architectural mortars. To improve the appearance (whiteness) of the mortar, a small quantity of titanium dioxide (TiO2) was added to the selected mixes for comparison purposes. Fresh and hardened properties of the mortar including mini-slump flow, density, water absorption, flexural strength, equivalent compressive strength, drying shrinkage, alkali silica reaction (ASR) and acid attack resistance were investigated. The overall performance showed that it is feasible to use GGBS for the production of architectural mortar and 60% replacement of white cement by GGBS was determined to be optimal. The replacement significantly increased the flexural strength, and reduced the drying shrinkage and risk of ASR expansion, as well as improved the ability to resist acid attack of the mortar produced.
Materials & Design, 2011
Ling TC, Properties of architectural mortar prepared with recycled glass with different particle ... more Ling TC, Properties of architectural mortar prepared with recycled glass with different particle sizes. Materials and Design; 32 (5): 2675-2684.
Waste Management, 2009
Low grade recycled aggregates obtained from a construction waste sorting facility were tested to ... more Low grade recycled aggregates obtained from a construction waste sorting facility were tested to assess the feasibility of using these in the production of concrete blocks. The characteristics of the sorted construction waste are significantly different from that of crushed concrete rubbles that are mostly derived from demolition waste streams. This is due to the presence of higher percentages of non-concrete components (e.g. &amp;amp;amp;amp;amp;amp;amp;amp;gt;10% soil, brick, tiles etc.) in the sorted construction waste. In the study reported in this paper, three series of concrete block mixtures were prepared by using the low grade recycled aggregates to replace (i) natural coarse granite (10mm), and (ii) 0, 25, 50, 75 and 100% replacement levels of crushed stone fine (crushed natural granite &amp;amp;amp;amp;amp;amp;amp;amp;lt;5mm) in the concrete blocks. Test results on properties such as density, compressive strength, transverse strength and drying shrinkage as well as strength reduction after exposure to 800 degrees C are presented below. The results show that the soil content in the recycled fine aggregate was an important factor in affecting the properties of the blocks produced and the mechanical strength deceased with increasing low grade recycled fine aggregate content. But the higher soil content in the recycled aggregates reduced the reduction of compressive strength of the blocks after exposure to high temperature due probably to the formation of a new crystalline phase. The results show that the low grade recycled aggregates obtained from the construction waste sorting facility has potential to be used as aggregates for making non-structural pre-cast concrete blocks.
Resources, Conservation and Recycling, 1998
In urban mainland China, safe disposal of municipal solid waste (MSW) averaged at&amp;lt;... more In urban mainland China, safe disposal of municipal solid waste (MSW) averaged at&amp;lt; 2%. While China is struggling to meet the lower order needs in waste management, namely, providing adequate waste collection service, ensuring enough up to standard waste ...
Resources, Conservation and Recycling, 1999
... The first part was a survey on the attitude and opinion of Guangzhou citizens on ... Eight of... more ... The first part was a survey on the attitude and opinion of Guangzhou citizens on ... Eight of the items in the scale were worded such that agreement reflected acceptance of ... through the help of the Guangzhou Education Bureau and the Guangzhou Environmental Science Society. ...
Resources, Conservation and Recycling, 1998
... Post-consumer items recovered are restricted to used aluminium cans, brown and white goods, o... more ... Post-consumer items recovered are restricted to used aluminium cans, brown and white goods, old newsprint and metal cooking ware. In Hong Kong, food scrap, glass, ferrous alloys and PET bottles have very few or no outlets at all. ...
Materials and Structures, 2006
A finite element method using a proposed mesoscopic thermoelastic damage model (MTED) is verified... more A finite element method using a proposed mesoscopic thermoelastic damage model (MTED) is verified for simulating the cracking process of a concrete section reinforced with fibre-reinforced polymer (FRP) bars. The cracking was due to the significant difference in thermal expansion properties between the concrete and the FRP materials at elevated temperatures. The numerical study reveals that although a conventional elastic
Journal of Construction Engineering and Management, 2006
ABSTRACT
Indoor Air, 1999
Sixteen flights had been investigated for indoor air quality (IAQ) on Cathay Pacific aircraft fro... more Sixteen flights had been investigated for indoor air quality (IAQ) on Cathay Pacific aircraft from June 1996 to August 1997. In general, the air quality on Cathay Pacific aircraft was within relevant air quality standards because the average age of aircraft was less than 2 years. Carbon dioxide (CO 2 ) levels on all flights measured were below the Federal Aviation Administration (FAA) standard (30,000 ppm). The CO 2 level was substantially higher during boarding and de-boarding than cruise due to low fresh air supply. Humidity on the aircraft was low, especially for long-haul flights. Minimum humidity during cruise was below the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) minimum humidity standard (20%). The average temperature was within a comfortable temperature range of 23∫2aeC. The vertical temperature profile on aircraft was uniform and below the International Standard Organization (ISO) standard. Carbon monoxide levels were below the FAA standard (50 ppm). Trace amount of ozone detected ranged from undetectable to 90 ppb, which was below the FAA standard. Particulate level was low for most non-smoking flights, but peaks were observed during boarding and de-boarding. The average particulate level in smoking flights (138 mg/m 3 ) was higher than non-smoking flights (7.6 mg/m 3 ). The impact on IAQ by switching from low-mode to high-mode ventilation showed a reduction in CO 2 levels, temperature, and relative humidity.
Journal of hazardous materials, Jan 15, 2012
Recycled glass derived from cathode ray tubes (CRT) glass with a specific gravity of approximatel... more Recycled glass derived from cathode ray tubes (CRT) glass with a specific gravity of approximately 3.0 g/cm(3) can be potentially suitable to be used as fine aggregate for preparing cement mortars for X-ray radiation-shielding applications. In this work, the effects of using crushed glass derived from crushed CRT funnel glass (both acid washed and unwashed) and crushed ordinary beverage container glass at different replacement levels (0%, 25%, 50%, 75% and 100% by volume) of sand on the mechanical properties (strength and density) and radiation-shielding performance of the cement-sand mortars were studied. The results show that all the prepared mortars had compressive strength values greater than 30 MPa which are suitable for most building applications based on ASTM C 270. The density and shielding performance of the mortar prepared with ordinary crushed (lead-free) glass was similar to the control mortar. However, a significant enhancement of radiation-shielding was achieved when t...
Environmental Science & Technology, 2000
Leach tests alone cannot determine the actual performance and long-term environmental impacts of ... more Leach tests alone cannot determine the actual performance and long-term environmental impacts of solidified/stabilized waste because they do not provide information on the physical and chemical changes between waste and additives. This research study utilized ...
Environmental Management, 2000
This paper compares the public attitudes of three southern Chinese cities/towns, namely Guangzhou... more This paper compares the public attitudes of three southern Chinese cities/towns, namely Guangzhou, Dongguan, and Yuanzhou on waste recycling and avoidance, and the New Environmental Paradigm (NEP). The latter describes the concept of treating the resources and the ecosystems on Earth as things having their own rights rather than being subordinate and subservient to humans. These three places are chosen to represent areas in different stages of urbanization in the Guangdong province. As Hong Kong is also a southern Chinese city, where data of similar nature are available, comparison with Hong Kong is also made.
Engineering, Construction and Architectural Management, 2003
Hong Kong is running out of both reclamation sites and landfill space for the disposal of constru... more Hong Kong is running out of both reclamation sites and landfill space for the disposal of construction and demolition waste. This paper reports on the findings of a study, consisting of a questionnaire survey, interviews and work-site visits, to compare the use of low-waste building technologies in public housing and private residential projects in Hong Kong. The results show that
Construction Management and Economics, 2008
... designs (Chan and Lee, 1998; Mak, 1998; Wong and Yau, 1999; Lam, 2002; Chan ... was calculate... more ... designs (Chan and Lee, 1998; Mak, 1998; Wong and Yau, 1999; Lam, 2002; Chan ... was calculated by following the British Standards, the General Specifications used in Hong Kong, and ... Potential material and cost savings by using prefabrication in lieu of timber formwork were ...
Construction and Building Materials, 2013
• High temperature properties of concrete blocks made with clay brick aggregate (CBA) were examin... more • High temperature properties of concrete blocks made with clay brick aggregate (CBA) were examined. • At 300°C, the nature of CBA origin made the concrete blocks stronger/more stiff.
Construction and Building Materials, 2009
This paper presents the results of a study to compare the properties of concretes prepared with t... more This paper presents the results of a study to compare the properties of concretes prepared with the use river sand, crushed fine stone (CFS), furnace bottom ash (FBA), and fine recycled aggregate (FRA) as fine aggregates. Two methods were used to design the concrete mixes: (i) fixed water–cement ratio (W/C) and (ii) fixed slump ranges. The investigation included testing of
Construction and Building Materials, 2011
Effects of crushed glass cullet sizes, casting methods and pozzolanic materials on ASR of concret... more Effects of crushed glass cullet sizes, casting methods and pozzolanic materials on ASR of concrete blocks. Construction and Building Materials; 25 (5): 2611-2618.