Journal of Sustainable Cement-Based Materials, 2021
Abstract The deposition of textile waste into landfill has reached an unsustainable level and rai... more Abstract The deposition of textile waste into landfill has reached an unsustainable level and raises serious environmental issues across the world. Transforming textile waste into fiber reinforcement in cementitious composites offers a sustainable resolution toward a circular textile economy. This article presents a comprehensive review of environmental concerns, recycling routes for textile waste, together with an in-depth review of the engineering properties of concrete incorporating recycled textiles. In general, the incorporation of these recycled fibers from textile waste enhances strain capacity, crack control, durability, and energy absorption of concrete via dual effects: bridging action (direct mechanism) and refinement of pore distribution (indirect effect). An improvement in compressive strength can be achieved by the utilization of a small dosage of recycled fibers or recycled fiber fabrics in concrete (strength < 40 MPa). Finally, the cost and environmental benefits for eco-efficient building application are also evaluated to draw the attention of researchers toward these potentially recyclable waste materials.
Corrosion of cast iron water pipes, particularly localized pitting corrosion, can propagate leaks... more Corrosion of cast iron water pipes, particularly localized pitting corrosion, can propagate leaks and bursts of pipelines which can lead to expensive repairs or replacement. One of the primary mechanisms which cause localized pitting corrosion within potable water networks is microbiologically influenced corrosion (MIC) due to the action of biofilms on the pipe surface. City West Water (CWW), one of the four water companies servicing Melbourne, conducts an ongoing condition assessment program of its potable water pipelines. One of the non destructive testing technologies CWW uses as part of this program on its critical water mains to assess extent of corrosion is magnetic flux leakage (MFL). The information from this program feeds back into CWW's asset management risk model and subsequently the water mains renewal program. In December 2014, a section of water main located at Bridge Rd in Richmond, Victoria was excavated as part of the condition assessment program. Soil samples a...
Major port infrastructure authorities need to make strategic decisions in advance of tipping poin... more Major port infrastructure authorities need to make strategic decisions in advance of tipping points being reached to avoid 'catastrophic failure of essential physical assets'. Whilst simulation techniques are commonly used to estimate future degradation and service of physical infrastructure according to their sensitivity to various environmental parameters (such as depth of high tide, temperature, wetting and drying cycles etc), there has been no consideration of the altered levels of vulnerability and exposure that will result from a changing climate. This knowledge deficiency also applies to life cycle modelling which provides an important evidence base for divisions affecting the protection and maintenance of different forms of seaport infrastructures. This project explores the effects of climate change on structural resilience of seaports. Main activities comprise of three components: (a) Mapping and characterising the vulnerability of different port infrastructure acco...
In marine environments and where de-icing salts are applied, the degradation of reinforced concre... more In marine environments and where de-icing salts are applied, the degradation of reinforced concrete structures due to chloride induced corrosion of the reinforcement is a major problem. The expansive nature of the corrosion process results in cracking of
The utilization of industrial and agricultural by-products for the production of alkali activated... more The utilization of industrial and agricultural by-products for the production of alkali activated concrete (AAC) has the potential to yield significant benefits towards sustainability goals. To be a viable material, the construction industry requires a construction material that achieves the requisite strength and the other property requirements as specified in codes and standards while demonstrating improved sustainability criteria. Fly ash and Rice Husk Ash (RHA) are abundantly available waste products, principally located in Asian countries. Currently, a significant proportion of these materials are disposed of in landfills, lagoons and rivers but offer potential to utilize in AAC. Hence, the identification of variables associated with fly ash and fly ah-RHA blended AAC by utilizing fly ash and RHA is vital. This study quantifies the environmental and economic factors by assessing the Greenhouse gas (GHG) emission, environmental impacts and benefits, and cost analysis of utilizing fly ash and RHA in AAC compared to Portland Cement (PC) concrete. Alkaline activator is a key component responsible for the highest GHG emission, cost and environmental impact amounts obtained for fly ash geopolymer and blended alkali-activated concrete compared with PC concrete. Alkali activators contribute to 74% of the total GHG emission, while heat curing contributed only 9% to the total GHG emission. The addition of 10% RHA to alkali-activated concrete showed a slight benefit for the analysis. Utilization of waste fly ash and RHA is responsible for providing significant benefits in terms of fresh and marine water ecotoxicity by avoiding waste disposal at the dumpsites, rivers, and storage lagoons.
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Abstract The deterioration of structures due to reinforcement corrosion is a major problem both i... more Abstract The deterioration of structures due to reinforcement corrosion is a major problem both in Australia and globally. The corrosion of the reinforcement can lead to rust staining, cracking spalling, and eventually structural failure if no remedial action is taken. In order to assess the condition of a structure a visual inspection is often the first step, with any defects noted. Further visual inspection or installation of monitoring equipment may then be made to identify any subsequent deterioration that occurs. These activities can often be time consuming and expensive, both in the undertaking and in the analysis of the data. This paper reports the use of laser scanning technology to monitor the condition and deterioration of reinforced concrete specimens and relate the level and rate of crack growth with a standard visual inspection.
The increase of carbon emissions due to the annual growth of portland cement (PC) production has ... more The increase of carbon emissions due to the annual growth of portland cement (PC) production has promoted research into the development of sustainable green concrete using a range of readily available industrial waste materials. The present study is focused on developing two high-volume fly ash (HVFA) concretes with cement replacement levels of 65% (HVFA-65) and 80% (HVFA-80). The required lime for both HVFA concrete mixtures was initially determined and the optimized mixture designs identified, based on the 28-day compressive strength, by varying the low-calcium Class F fly ash-hydrated lime composition. The optimized concrete mixtures achieved a compressive strength of 53 and 40 MPa (7.69 and 5.80 ksi) for HVFA-65 and HVFA-80 concretes, respectively. The early-stage strength development is dependent on the matrix produced in the specific HVFA concrete, which is itself dependent on the number of unreacted fly ash spheres. The increase of fly ash and hydrated lime dosage in HVFA concrete increases the rate of hydration of the C 3 A and C 4 AF phases, but decreases the hydration of the C 3 S phase, which resulted in lower early-age strength development than occurs in PC concrete. It was noted that the initial setting time of HVFA concretes increase with an increase of fly ash content. However, addition of hydrated lime accelerates the hydration and decreases the final setting time for HVFA concretes.
h i g h l i g h t s For confined specimens bond strength initially increases as corrosion proceed... more h i g h l i g h t s For confined specimens bond strength initially increases as corrosion proceeds. Unconfined specimens display no clear relationship. The variation between top and bottom cast bars reduced as cover increased. The effect of confinement reduced as cover increased. There was little scaling effect between the 12 and 16 mm bars.
International Journal of Concrete Structures and Materials, 2016
This paper presents the effect of silica fume and nano silica, used individually and in combinati... more This paper presents the effect of silica fume and nano silica, used individually and in combination with the set accelerator and/or hydrated lime, on the properties of class F high volume ultra fine fly ash (HV-UFFA) cement composites, replacing 80 % of cement (OPC). Compressive strength test along with thermogravimetric analysis, X-ray diffraction and scanning electron microscopy were undertaken to study the effect of various elements on the physico-chemical behaviour of the blended composites. The results show that silica fume when used in combination with the set accelerator and hydrated lime in HV-UFFA cement mortar, improves its 7 and 28 day strength by 273 and 413 %, respectively, compared to the binary blended cement fly ash mortar. On the contrary, when nano silica is used in combination with set accelerator and hydrated lime in HV-UFFA cement mortar, the disjoining pressure in conjunction with the self-desiccation effect induces high early age micro cracking, resulting in hindering the development of compressive strength. However, when nano silica is used without the additives, it improves the 7 and 28 day strengths of HV-UFFA cement mortar by 918 and 567 %, respectively and the compressive strengths are comparable to that of OPC.
This paper reports on an experimental program investigating the durability and mechanical propert... more This paper reports on an experimental program investigating the durability and mechanical properties of alkali activated slag concrete (AASC). The AASC was prepared using ground granulated blast furnace slag activated by high concentration alkali solution. The mechanical properties were determined by compressive strength and elastic modulus. The durability characteristics of AASC were measured using Ultrasonic Pulse Velocity (UPV) and permeable voids tests. The result showed that AASC developed a comparable strength to Portland Cement (PC) concrete over the short term. However, the material displayed an increase in voids, as well as a reduction of velocity over time. This could lead to the material displaying inferior performance over longer periods of time.
This paper reports results of an experimental programme to measure changes in bond characteristic... more This paper reports results of an experimental programme to measure changes in bond characteristics of plain round reinforcement as a result of corrosion. Principal parameters included in the investigation are the amount of corrosion, the presence of confining reinforcement in the form of links, cover thickness and the initial condition of the reinforcement. In the absence of confining links, bond strength of bars cast near the bottom of a pour is found to reduce with increasing corrosion. However, although top-cast bars were initially weaker, small amounts of corrosion were sufficient to raise bond strength to that of bottom-cast bars. With increasing corrosion, strength reduced in a similar manner to bottom-cast bars. Confining reinforcement had little influence on bond strength prior to the onset of corrosion, but plays an important role in maintaining strength once corrosion becomes established. Results from these tests suggest that surface crack width may provide a better parame...
The linear polarisation resistance (LPR) method can be used to measure the active rate of corrosi... more The linear polarisation resistance (LPR) method can be used to measure the active rate of corrosion of steel reinforcement in concrete structures. However a single measurement may be sensitive to the ambient environmental conditions and thus may not be representative of the mean annual rate of corrosion. The LPR measurement may be dependent upon the temperature at the time of sampling and on any wetting/drying effects resulting from rainfall and wind or sunshine. Recent studies have examined the behaviour of a series of reinforced concrete specimens subject to chloride contamination or carbonation induced corrosion in a controlled laboratory environment. LPR measurements taken at frequent intervals have been related to a wet/dry cycle imposed upon the specimens to promote corrosion activity. In addition, similar studies have been carried out, of an in situ reinforced concrete specimen exposed to the ambient weather conditions. The study is only partly completed, but interim results show the variability of LPR measurements and the in¯uences the environment may exert on single spot measurements.
This paper reports results of an experimental programme to measure changes in friction characteri... more This paper reports results of an experimental programme to measure changes in friction characteristics of the interface between reinforcement and concrete as a result of the formation of corrosion products on the surface of the steel. The aim of the study was to determine whether a weak corrosion layer contributes to reported reductions in residual bond capacity. Corrosion was carried out under accelerated conditions using three different conditioning regimes. Principal parameters included in the investigation are conditioning regime, the amount of corrosion, and the stiffness of the restraint to expansion of the corrosion products. Experimental results indicate that corrosion products do not impair friction characteristics of a bar/concrete interface when surface crack width does not exceed 1.0 mm.
The implementation of sustainable development in civil engineering society has led to the use of ... more The implementation of sustainable development in civil engineering society has led to the use of new materials with low environmental impact. Ordinary Portland cement (OPC) is the primary material in the production of traditional concrete. However, the manufacturing of OPC has led to environmental concerns over the production of CO2. The use of fly ash and slag, the most commonly used industrial by-products, as replacements for PC, has helped to reduce these CO2 emission. Recent research has also shown that it is possible to use fly ash or slag as a sole binder in concrete by activating them with alkali components through a polymerization process. However, the main issue of the use of fly ash as a replacement material for cement is the need of heat curing regime to achieve structural integrity. While, the standard curing regime used for OPC concrete can be applied to the alkaliactivated slag (AAS) due to the similar characteristic of the hydration product. This paper reports the detail of the experimental work that has been undertaken to investigate the strength of AAS/fly ash (AASF) mortar blends. The AASF specimens were prepared using a mix of ground granulated blast-furnace slag (GGBS) and low calcium class F fly ash activated by high alkaline solution. The mix compositions of slag to fly ash were 1:
The durability of concrete has a profound impact on the service life of structural elements. Indo... more The durability of concrete has a profound impact on the service life of structural elements. Indonesia has extensive peat soils, which provide a highly aggressive environment for concrete structures. Geopolymer concrete has demonstrated good durability when exposed to acid /sulphate conditions similar to those encountered in peat soils. This paper investigates the performance of geopolymer concretes produced using Indonesian type F fly ash under sulphate and acid chemical attack. Geopolymer concrete specimens have been exposed for 12-months in a range of solutions: 5% sodium sulphate, 5% magnesium sulphate, 1% and 3% sulphuric acid, and simulated peat solution. The mechanical and durability properties of specimens together with a control concrete have been monitored for compressive strength, change in mass, water absorption and volume of permeable voids, ultra pulse velocity, air and water permeability, pH profile, and microstructural analysis (XRD, SEM/EDS). The control immersed in...
The increase of carbon emission due to annual growth of Portland cement (PC) production has enfor... more The increase of carbon emission due to annual growth of Portland cement (PC) production has enforced research into the development of sustainable green concrete using a range of readily available industrial waste materials. The present study is focused on developing two high volume fly ash (HVFA) concretes with cement replacement levels 65% (HVFA‒65) and 80% (HVFA‒80). Initially, the required lime for both HVFA concrete mixes were determined, and then the optimized mix design identified, based on 28-day strength, by varying the fly ash‒lime combination. The optimized mixes achieved a compressive strength of 53MPa and 40MPa, for HVFA‒65 and HVFA‒80 concretes, respectively. Similar to PC concrete, both HVFA concretes showed high resistance to chloride penetration, water absorption and carbonation at 28 days. The early stage strength development is dependent upon the matrix produced in the specific HVFA concrete, which is itself dependent upon the number of unreacted fly ash spheres.
Journal of Sustainable Cement-Based Materials, 2021
Abstract The deposition of textile waste into landfill has reached an unsustainable level and rai... more Abstract The deposition of textile waste into landfill has reached an unsustainable level and raises serious environmental issues across the world. Transforming textile waste into fiber reinforcement in cementitious composites offers a sustainable resolution toward a circular textile economy. This article presents a comprehensive review of environmental concerns, recycling routes for textile waste, together with an in-depth review of the engineering properties of concrete incorporating recycled textiles. In general, the incorporation of these recycled fibers from textile waste enhances strain capacity, crack control, durability, and energy absorption of concrete via dual effects: bridging action (direct mechanism) and refinement of pore distribution (indirect effect). An improvement in compressive strength can be achieved by the utilization of a small dosage of recycled fibers or recycled fiber fabrics in concrete (strength < 40 MPa). Finally, the cost and environmental benefits for eco-efficient building application are also evaluated to draw the attention of researchers toward these potentially recyclable waste materials.
Corrosion of cast iron water pipes, particularly localized pitting corrosion, can propagate leaks... more Corrosion of cast iron water pipes, particularly localized pitting corrosion, can propagate leaks and bursts of pipelines which can lead to expensive repairs or replacement. One of the primary mechanisms which cause localized pitting corrosion within potable water networks is microbiologically influenced corrosion (MIC) due to the action of biofilms on the pipe surface. City West Water (CWW), one of the four water companies servicing Melbourne, conducts an ongoing condition assessment program of its potable water pipelines. One of the non destructive testing technologies CWW uses as part of this program on its critical water mains to assess extent of corrosion is magnetic flux leakage (MFL). The information from this program feeds back into CWW's asset management risk model and subsequently the water mains renewal program. In December 2014, a section of water main located at Bridge Rd in Richmond, Victoria was excavated as part of the condition assessment program. Soil samples a...
Major port infrastructure authorities need to make strategic decisions in advance of tipping poin... more Major port infrastructure authorities need to make strategic decisions in advance of tipping points being reached to avoid 'catastrophic failure of essential physical assets'. Whilst simulation techniques are commonly used to estimate future degradation and service of physical infrastructure according to their sensitivity to various environmental parameters (such as depth of high tide, temperature, wetting and drying cycles etc), there has been no consideration of the altered levels of vulnerability and exposure that will result from a changing climate. This knowledge deficiency also applies to life cycle modelling which provides an important evidence base for divisions affecting the protection and maintenance of different forms of seaport infrastructures. This project explores the effects of climate change on structural resilience of seaports. Main activities comprise of three components: (a) Mapping and characterising the vulnerability of different port infrastructure acco...
In marine environments and where de-icing salts are applied, the degradation of reinforced concre... more In marine environments and where de-icing salts are applied, the degradation of reinforced concrete structures due to chloride induced corrosion of the reinforcement is a major problem. The expansive nature of the corrosion process results in cracking of
The utilization of industrial and agricultural by-products for the production of alkali activated... more The utilization of industrial and agricultural by-products for the production of alkali activated concrete (AAC) has the potential to yield significant benefits towards sustainability goals. To be a viable material, the construction industry requires a construction material that achieves the requisite strength and the other property requirements as specified in codes and standards while demonstrating improved sustainability criteria. Fly ash and Rice Husk Ash (RHA) are abundantly available waste products, principally located in Asian countries. Currently, a significant proportion of these materials are disposed of in landfills, lagoons and rivers but offer potential to utilize in AAC. Hence, the identification of variables associated with fly ash and fly ah-RHA blended AAC by utilizing fly ash and RHA is vital. This study quantifies the environmental and economic factors by assessing the Greenhouse gas (GHG) emission, environmental impacts and benefits, and cost analysis of utilizing fly ash and RHA in AAC compared to Portland Cement (PC) concrete. Alkaline activator is a key component responsible for the highest GHG emission, cost and environmental impact amounts obtained for fly ash geopolymer and blended alkali-activated concrete compared with PC concrete. Alkali activators contribute to 74% of the total GHG emission, while heat curing contributed only 9% to the total GHG emission. The addition of 10% RHA to alkali-activated concrete showed a slight benefit for the analysis. Utilization of waste fly ash and RHA is responsible for providing significant benefits in terms of fresh and marine water ecotoxicity by avoiding waste disposal at the dumpsites, rivers, and storage lagoons.
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Abstract The deterioration of structures due to reinforcement corrosion is a major problem both i... more Abstract The deterioration of structures due to reinforcement corrosion is a major problem both in Australia and globally. The corrosion of the reinforcement can lead to rust staining, cracking spalling, and eventually structural failure if no remedial action is taken. In order to assess the condition of a structure a visual inspection is often the first step, with any defects noted. Further visual inspection or installation of monitoring equipment may then be made to identify any subsequent deterioration that occurs. These activities can often be time consuming and expensive, both in the undertaking and in the analysis of the data. This paper reports the use of laser scanning technology to monitor the condition and deterioration of reinforced concrete specimens and relate the level and rate of crack growth with a standard visual inspection.
The increase of carbon emissions due to the annual growth of portland cement (PC) production has ... more The increase of carbon emissions due to the annual growth of portland cement (PC) production has promoted research into the development of sustainable green concrete using a range of readily available industrial waste materials. The present study is focused on developing two high-volume fly ash (HVFA) concretes with cement replacement levels of 65% (HVFA-65) and 80% (HVFA-80). The required lime for both HVFA concrete mixtures was initially determined and the optimized mixture designs identified, based on the 28-day compressive strength, by varying the low-calcium Class F fly ash-hydrated lime composition. The optimized concrete mixtures achieved a compressive strength of 53 and 40 MPa (7.69 and 5.80 ksi) for HVFA-65 and HVFA-80 concretes, respectively. The early-stage strength development is dependent on the matrix produced in the specific HVFA concrete, which is itself dependent on the number of unreacted fly ash spheres. The increase of fly ash and hydrated lime dosage in HVFA concrete increases the rate of hydration of the C 3 A and C 4 AF phases, but decreases the hydration of the C 3 S phase, which resulted in lower early-age strength development than occurs in PC concrete. It was noted that the initial setting time of HVFA concretes increase with an increase of fly ash content. However, addition of hydrated lime accelerates the hydration and decreases the final setting time for HVFA concretes.
h i g h l i g h t s For confined specimens bond strength initially increases as corrosion proceed... more h i g h l i g h t s For confined specimens bond strength initially increases as corrosion proceeds. Unconfined specimens display no clear relationship. The variation between top and bottom cast bars reduced as cover increased. The effect of confinement reduced as cover increased. There was little scaling effect between the 12 and 16 mm bars.
International Journal of Concrete Structures and Materials, 2016
This paper presents the effect of silica fume and nano silica, used individually and in combinati... more This paper presents the effect of silica fume and nano silica, used individually and in combination with the set accelerator and/or hydrated lime, on the properties of class F high volume ultra fine fly ash (HV-UFFA) cement composites, replacing 80 % of cement (OPC). Compressive strength test along with thermogravimetric analysis, X-ray diffraction and scanning electron microscopy were undertaken to study the effect of various elements on the physico-chemical behaviour of the blended composites. The results show that silica fume when used in combination with the set accelerator and hydrated lime in HV-UFFA cement mortar, improves its 7 and 28 day strength by 273 and 413 %, respectively, compared to the binary blended cement fly ash mortar. On the contrary, when nano silica is used in combination with set accelerator and hydrated lime in HV-UFFA cement mortar, the disjoining pressure in conjunction with the self-desiccation effect induces high early age micro cracking, resulting in hindering the development of compressive strength. However, when nano silica is used without the additives, it improves the 7 and 28 day strengths of HV-UFFA cement mortar by 918 and 567 %, respectively and the compressive strengths are comparable to that of OPC.
This paper reports on an experimental program investigating the durability and mechanical propert... more This paper reports on an experimental program investigating the durability and mechanical properties of alkali activated slag concrete (AASC). The AASC was prepared using ground granulated blast furnace slag activated by high concentration alkali solution. The mechanical properties were determined by compressive strength and elastic modulus. The durability characteristics of AASC were measured using Ultrasonic Pulse Velocity (UPV) and permeable voids tests. The result showed that AASC developed a comparable strength to Portland Cement (PC) concrete over the short term. However, the material displayed an increase in voids, as well as a reduction of velocity over time. This could lead to the material displaying inferior performance over longer periods of time.
This paper reports results of an experimental programme to measure changes in bond characteristic... more This paper reports results of an experimental programme to measure changes in bond characteristics of plain round reinforcement as a result of corrosion. Principal parameters included in the investigation are the amount of corrosion, the presence of confining reinforcement in the form of links, cover thickness and the initial condition of the reinforcement. In the absence of confining links, bond strength of bars cast near the bottom of a pour is found to reduce with increasing corrosion. However, although top-cast bars were initially weaker, small amounts of corrosion were sufficient to raise bond strength to that of bottom-cast bars. With increasing corrosion, strength reduced in a similar manner to bottom-cast bars. Confining reinforcement had little influence on bond strength prior to the onset of corrosion, but plays an important role in maintaining strength once corrosion becomes established. Results from these tests suggest that surface crack width may provide a better parame...
The linear polarisation resistance (LPR) method can be used to measure the active rate of corrosi... more The linear polarisation resistance (LPR) method can be used to measure the active rate of corrosion of steel reinforcement in concrete structures. However a single measurement may be sensitive to the ambient environmental conditions and thus may not be representative of the mean annual rate of corrosion. The LPR measurement may be dependent upon the temperature at the time of sampling and on any wetting/drying effects resulting from rainfall and wind or sunshine. Recent studies have examined the behaviour of a series of reinforced concrete specimens subject to chloride contamination or carbonation induced corrosion in a controlled laboratory environment. LPR measurements taken at frequent intervals have been related to a wet/dry cycle imposed upon the specimens to promote corrosion activity. In addition, similar studies have been carried out, of an in situ reinforced concrete specimen exposed to the ambient weather conditions. The study is only partly completed, but interim results show the variability of LPR measurements and the in¯uences the environment may exert on single spot measurements.
This paper reports results of an experimental programme to measure changes in friction characteri... more This paper reports results of an experimental programme to measure changes in friction characteristics of the interface between reinforcement and concrete as a result of the formation of corrosion products on the surface of the steel. The aim of the study was to determine whether a weak corrosion layer contributes to reported reductions in residual bond capacity. Corrosion was carried out under accelerated conditions using three different conditioning regimes. Principal parameters included in the investigation are conditioning regime, the amount of corrosion, and the stiffness of the restraint to expansion of the corrosion products. Experimental results indicate that corrosion products do not impair friction characteristics of a bar/concrete interface when surface crack width does not exceed 1.0 mm.
The implementation of sustainable development in civil engineering society has led to the use of ... more The implementation of sustainable development in civil engineering society has led to the use of new materials with low environmental impact. Ordinary Portland cement (OPC) is the primary material in the production of traditional concrete. However, the manufacturing of OPC has led to environmental concerns over the production of CO2. The use of fly ash and slag, the most commonly used industrial by-products, as replacements for PC, has helped to reduce these CO2 emission. Recent research has also shown that it is possible to use fly ash or slag as a sole binder in concrete by activating them with alkali components through a polymerization process. However, the main issue of the use of fly ash as a replacement material for cement is the need of heat curing regime to achieve structural integrity. While, the standard curing regime used for OPC concrete can be applied to the alkaliactivated slag (AAS) due to the similar characteristic of the hydration product. This paper reports the detail of the experimental work that has been undertaken to investigate the strength of AAS/fly ash (AASF) mortar blends. The AASF specimens were prepared using a mix of ground granulated blast-furnace slag (GGBS) and low calcium class F fly ash activated by high alkaline solution. The mix compositions of slag to fly ash were 1:
The durability of concrete has a profound impact on the service life of structural elements. Indo... more The durability of concrete has a profound impact on the service life of structural elements. Indonesia has extensive peat soils, which provide a highly aggressive environment for concrete structures. Geopolymer concrete has demonstrated good durability when exposed to acid /sulphate conditions similar to those encountered in peat soils. This paper investigates the performance of geopolymer concretes produced using Indonesian type F fly ash under sulphate and acid chemical attack. Geopolymer concrete specimens have been exposed for 12-months in a range of solutions: 5% sodium sulphate, 5% magnesium sulphate, 1% and 3% sulphuric acid, and simulated peat solution. The mechanical and durability properties of specimens together with a control concrete have been monitored for compressive strength, change in mass, water absorption and volume of permeable voids, ultra pulse velocity, air and water permeability, pH profile, and microstructural analysis (XRD, SEM/EDS). The control immersed in...
The increase of carbon emission due to annual growth of Portland cement (PC) production has enfor... more The increase of carbon emission due to annual growth of Portland cement (PC) production has enforced research into the development of sustainable green concrete using a range of readily available industrial waste materials. The present study is focused on developing two high volume fly ash (HVFA) concretes with cement replacement levels 65% (HVFA‒65) and 80% (HVFA‒80). Initially, the required lime for both HVFA concrete mixes were determined, and then the optimized mix design identified, based on 28-day strength, by varying the fly ash‒lime combination. The optimized mixes achieved a compressive strength of 53MPa and 40MPa, for HVFA‒65 and HVFA‒80 concretes, respectively. Similar to PC concrete, both HVFA concretes showed high resistance to chloride penetration, water absorption and carbonation at 28 days. The early stage strength development is dependent upon the matrix produced in the specific HVFA concrete, which is itself dependent upon the number of unreacted fly ash spheres.
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