Remedial work for an iconic building in Sydney, Australia is currently being carried out. Two faç... more Remedial work for an iconic building in Sydney, Australia is currently being carried out. Two façade mortars, capable of matching the current exposed quartz aggregate finish and achieving a 40 years design life, are required. In order to ensure the quality of the imported quartz aggregates for this project, test have been carried out for particle size distribution, density, wet/dry strength variation, sodium sulphate soundness and Los Angeles Abrasion value. The two mortar mixes employed for repair work (Form & Pour and Hand Applied mixes) were comprehensively assessed for mix workability, compressive strength in warm and cold conditions, drying shrinkage, bond strength and coefficient of thermal expansion. The mortar durability assessment included chloride resistance as per NT443 and NT492 specifications, electrical resistivity as per AASHTO TP95 requirements, together with accelerated carbonation and accelerated weathering for colour variation assessment. The chloride resistance a...
Laboratory investigations were carried out to assess the potential of the crushed recycled glass ... more Laboratory investigations were carried out to assess the potential of the crushed recycled glass as natural sand replacement using ratios of 30%, 45% and 60%. Replacement of cementitious materials in concrete was also considered using cement replacement ratios of 7.5%, 15% and 25% of powder glass. The effects of glass sand replacement and cementitious materials replacement with powder glass on fresh and hardened concrete properties were assessed. It was concluded that with the incorporation of 45% of crushed glass as a natural sand replacement, the compressive and flexural strengths have marginally increased, while the indirect tensile strength marginally decreased. The concrete with glass as the natural sand replacement had lower shrinkage and significant lower chloride diffusion coefficient. Concretes with powder glass as cementitious materials replacement showed lower compressive strength and marginally higher drying shrinkage than the control mix, but meeting the concrete mix de...
Over the last decade there has been an increasing need for low carbon footprint building material... more Over the last decade there has been an increasing need for low carbon footprint building materials. Concrete is a high contributor to CO2 emissions due to the carbon intensive nature of Portland Cement production, so the use of SCMs has increased accordingly. These conventional “green” concretes replace high CO2 intensive traditional Portland Cement with SCM (usually fly ash and/or ground granulated blast furnace slag GGBFS). Unfortunately there are performance trade-offs as these concretes typically exhibit lower early strength gain and higher drying shrinkage than the standard concretes. This paper outlines the development of low carbon footprint concretes with less SL and more SCMs. The associated concretes have compressive strength gain similar to conventional concretes, but much lower drying shrinkage and improved durability properties. This high SCM binder was trademarked Zep and the concrete products made from it are marketed as Envisia .
Sustainable Construction Materials and Technologies (SCMT)
Efforts have been made to use the waste glass in concrete industry, either as the partial sand re... more Efforts have been made to use the waste glass in concrete industry, either as the partial sand replacement, or as partial cementitious materials replacement. Two previous papers, regarding the intensive laboratory and field trials data, were presented in Ancona in 2010 and in Kyoto in 2013. Since glass itself is unstable in the alkaline environment of concrete, as a result, it is of great interest to assess the concrete durability properties and its performance after five years of trafficking. The durability properties have been tested in terms of alkaline silica reaction, if any, and interface zone with aggregate, water absorption, water sorptivity, water permeability, void contents, and chloride migration test. The performance assessment includes the compressive strength, the density and the wear resistance. This paper presents the feasibility and limitations when glass sand or glass powder is partially used in concrete mixes. EXPERIMENTAL METHODOLOGY Three types of concretes were used to build a 100 meters long pavement at Boral's Dunmore Quarry, South of Sydney, Australia, including control concrete, concrete with glass sand and concrete with glass powder. The control concrete consists of compliant materials by local pavement specifications. For the glass sand concrete, the total sand in the control mix was replaced with 45% glass sand, while for the glass powder concrete, the total cementitious content in the control mix was replaced by 15% glass powder [Dumitru et al. 2010, 2013].
The key structural element in most industrial enterprises is the concrete floor slab. The aim of ... more The key structural element in most industrial enterprises is the concrete floor slab. The aim of floor design is to select the most economical thickness while considering sufficient reinforcement to control the amount and size of cracks to a level consistent with the intended use of the floor. However, one of the most common causes of cracking in industrial floors is that the tensile stresses exceed the tensile strength of the concrete due to the shrinkage contraction. Therefore, there is a need for slabs that are reinforced with mesh to be saw cut in order to release the stresses due to the shrinkage. However, the distance between the sawn joints is related to the shrinkage of the concrete. Recently, considerable interest has been generated in the use of steel fibre reinforced concrete in order to control the tensile cracking of the composite material and reduce the number of joints especially in internal industrial floors. Boral has developed a low carbon, low shrinkage and high f...
Laboratory investigations, using recycled glass as natural sand replacement and powdered glass as... more Laboratory investigations, using recycled glass as natural sand replacement and powdered glass as cementitious materials replacement, have resulted in concrete mixes properties well within current specification requirement. The major benefits of concrete mixes using crushed glass as natural sand replacement were lower drying shrinkage and significant lower chloride diffusion coefficients. The results of this investigation were presented at the second International Conference on Sustainable Construction Materials and Technologies, in Ancona, Italy, in 2010. This paper, documents the results of a field concrete pavement trial, using crushed recycled glass as natural sand replacement, and powdered glass as cementitious material replacement. It was concluded that, partial natural sand replacement with crushed recycled glass and, partial replacement of cementitious materials with powdered glass, can meet the current concrete pavement specification requirements, with the exception of abra...
High drying shrinkage of concrete has the potential to impact adversely on the durability, aesthe... more High drying shrinkage of concrete has the potential to impact adversely on the durability, aesthetics and serviceability of concrete structures. Methods to reduce drying shrinkage of concrete have traditionally been to use special cements (e.g. SL Cement), water reducing admixtures and more recently, shrinkage reducing admixtures (SRA’s). This paper assesses the shrinkage reduction potential of two common shrinkage reducing agents and compares it with a new, low shrinkage concrete (trademarked as ENVISIA TM ). A 32 MPa ENVISIA TM concrete was compared against a typical 32MPa concrete with addition of each agent at the dosage of up to 7 litres per cubic meter. It was noted that addition of shrinkage reducing agent had lower water demand, longer setting time, more or less bleed water (depending on the admixture type), and slightly lower 1-day compressive strength but higher later compressive strength. The free drying shrinkage can be reduced up to 30-37% when 7L per cubic meter dosage...
Laboratory investigations were carried out to assess the potential of the crushed recycled glass ... more Laboratory investigations were carried out to assess the potential of the crushed recycled glass as natural sand replacement using ratios of 30%, 45% and 60%. Replacement of cementitious materials in concrete was also considered using cement replacement ratios of 7.5%, 15% and 25% of powder glass. The effects of glass sand replacement and cementitious materials replacement with powder glass on fresh and hardened concrete properties were assessed. It was concluded that with the incorporation of 45% of crushed glass as a natural sand replacement, the compressive and flexural strengths have marginally increased, while the indirect tensile strength marginally decreased. The concrete with glass as the natural sand replacement had lower shrinkage and significant lower chloride diffusion coefficient. Concretes with powder glass as cementitious materials replacement showed lower compressive strength and marginally higher drying shrinkage than the control mix, but meeting the concrete mix de...
Synopsis: The concrete industry relies heavily on the measured concrete compressive strength to m... more Synopsis: The concrete industry relies heavily on the measured concrete compressive strength to make momentous decisions. The real situation is that no matter how carefully a cylinder is finished, its end surface probably exhibits some irregularities. As required by AS 1012.9, the finished end of a concrete cylinder must be capped or ground before it is crushed for compressive strength. Sulphur and rubber capping are widely accepted methods. However, care must be taken for sulphur capping method especially for high strength concrete, where capping thickness of 1-2 mm and adequate strength of capping compounds are required. Rubber capping method is not permitted in AS 1012.9 for testing concrete strength over 80MPa. Alternatively, concrete cylinders can be ground using a grinding machine. Data presented in this paper compares the effects of four types of cylinder preparation methods on compressive strength, including sulphur capping, rubber capping, single end grinding and double end...
SF (silica fume) has been widely used in high performance concrete manufacturing due to its pozzo... more SF (silica fume) has been widely used in high performance concrete manufacturing due to its pozzolanic reactivity and the filler effect of ultra-fine particles. Recently ultra-fine grades of fly ash and metakaolin have been assessed and compared with SF concretes. This paper evaluates four commercially available products in manufacturing high performance concrete, including two SF (control I and II), one ultra-fine fly ash and one ultra-fine metakaolin. The study firstly assessed the properties of each raw material, including the loss of ignition, particle size distribution, relative water demand, relative strength, available alkali, and pozzolanic index. Concrete trial mixes were further carried out to assess the concrete properties, including workability by slump, compressive strength development up to 91 days, drying shrinkage up to 91 days, durability in terms of sorptivity and rapid chloride migration coefficient tests NT 492. The study has concluded that at a given workability (slump of 200 mm), the concrete with ultra fine fly ash required about 15-25 kg/m 3 less water, and achieved about 5-20 MPa higher compressive strength in 91 days, depending on the type of the SF used as the control. The sorptivity and chloride migration coefficient data show that concrete with ultra fine fly ash can achieve similar durability properties with SF used as control. The concrete with ultra-fine metakaolin requires similar water to control I and about 9 kg/m 3 more water than control II. The ultra-fine metakaolin concrete develops higher strength than control I, with similar compressive strength when compared to control II mix. This concrete mix has the lowest drying shrinkage than both controls and ultra-fine fly ash concretes. In terms of durability properties (sorptivity and chloride diffusion tests), concrete with ultra-fine metakaolin showed the best performance, especially at early age (i.e. 28 days). Therefore, it is possible to manufacture high performance concrete with ultra-fine fly ash or ultra-fine metakaolin to replace SF.
Journal of Civil Engineering and Architecture, 2015
Due to the shortages of natural sands along the east coast of Australia in particular and the nee... more Due to the shortages of natural sands along the east coast of Australia in particular and the need to fully utilise fines produced in quarry operations, progress has been made in utilising blends of manufactured sands and natural sands in concrete pavements. This paper documents some of the constraints in utilising larger proportions of manufactured sands in concrete pavements. These constraints are mainly caused by the current level of knowledge regarding the impact of manufactured sands on skid and abrasion resistance of concrete pavements. This paper presents a brief review of literature on this subject in the USA, France and UK. It also briefly documents work recently carried out in Australia by CCAA (Cement Concrete and Aggregates Australia), referring to the skid and abrasion resistance of concrete pavements using manufactured sands. The paper concludes that there is no relationship between the free silica content and the skid resistance. With regard to the abrasion resistance, it is rather the curing conditions and the compressive strength that are more important in achieving good results.
Boral has developed a lower carbon concrete, called Envisia®, using a ground slag product. With a... more Boral has developed a lower carbon concrete, called Envisia®, using a ground slag product. With a typical blend of 60% ZEP and 40% SL cement, and has similar plastic properties to conventional concrete. Unlike traditional high SCM concrete, there is no compromise on early strength and it exhibits much lower free drying shrinkage. These properties have been presented previously at the CIA 2013 conference. Since then, comprehensive research has been carried out to assess the durability properties of Envisia®, in particular chloride resistance, water permeability and alkali silica reactivity (ASR). A 60MPa Envisia® concrete developed for marine applications was compared with an equivalent grade of conventional concretes (SL/FA and SL/GGBFS). In comparison with traditional marine concrete (SL/GGBFS), Envisia® shows much lower chloride diffusion coefficient by both NT492 and NT443 tests, lower water sorptivity by ASTM C1585 method and lower water permeability by DIN 1048 test. Envisia® i...
Remedial work for an iconic building in Sydney, Australia is currently being carried out. Two faç... more Remedial work for an iconic building in Sydney, Australia is currently being carried out. Two façade mortars, capable of matching the current exposed quartz aggregate finish and achieving a 40 years design life, are required. In order to ensure the quality of the imported quartz aggregates for this project, test have been carried out for particle size distribution, density, wet/dry strength variation, sodium sulphate soundness and Los Angeles Abrasion value. The two mortar mixes employed for repair work (Form & Pour and Hand Applied mixes) were comprehensively assessed for mix workability, compressive strength in warm and cold conditions, drying shrinkage, bond strength and coefficient of thermal expansion. The mortar durability assessment included chloride resistance as per NT443 and NT492 specifications, electrical resistivity as per AASHTO TP95 requirements, together with accelerated carbonation and accelerated weathering for colour variation assessment. The chloride resistance a...
Laboratory investigations were carried out to assess the potential of the crushed recycled glass ... more Laboratory investigations were carried out to assess the potential of the crushed recycled glass as natural sand replacement using ratios of 30%, 45% and 60%. Replacement of cementitious materials in concrete was also considered using cement replacement ratios of 7.5%, 15% and 25% of powder glass. The effects of glass sand replacement and cementitious materials replacement with powder glass on fresh and hardened concrete properties were assessed. It was concluded that with the incorporation of 45% of crushed glass as a natural sand replacement, the compressive and flexural strengths have marginally increased, while the indirect tensile strength marginally decreased. The concrete with glass as the natural sand replacement had lower shrinkage and significant lower chloride diffusion coefficient. Concretes with powder glass as cementitious materials replacement showed lower compressive strength and marginally higher drying shrinkage than the control mix, but meeting the concrete mix de...
Over the last decade there has been an increasing need for low carbon footprint building material... more Over the last decade there has been an increasing need for low carbon footprint building materials. Concrete is a high contributor to CO2 emissions due to the carbon intensive nature of Portland Cement production, so the use of SCMs has increased accordingly. These conventional “green” concretes replace high CO2 intensive traditional Portland Cement with SCM (usually fly ash and/or ground granulated blast furnace slag GGBFS). Unfortunately there are performance trade-offs as these concretes typically exhibit lower early strength gain and higher drying shrinkage than the standard concretes. This paper outlines the development of low carbon footprint concretes with less SL and more SCMs. The associated concretes have compressive strength gain similar to conventional concretes, but much lower drying shrinkage and improved durability properties. This high SCM binder was trademarked Zep and the concrete products made from it are marketed as Envisia .
Sustainable Construction Materials and Technologies (SCMT)
Efforts have been made to use the waste glass in concrete industry, either as the partial sand re... more Efforts have been made to use the waste glass in concrete industry, either as the partial sand replacement, or as partial cementitious materials replacement. Two previous papers, regarding the intensive laboratory and field trials data, were presented in Ancona in 2010 and in Kyoto in 2013. Since glass itself is unstable in the alkaline environment of concrete, as a result, it is of great interest to assess the concrete durability properties and its performance after five years of trafficking. The durability properties have been tested in terms of alkaline silica reaction, if any, and interface zone with aggregate, water absorption, water sorptivity, water permeability, void contents, and chloride migration test. The performance assessment includes the compressive strength, the density and the wear resistance. This paper presents the feasibility and limitations when glass sand or glass powder is partially used in concrete mixes. EXPERIMENTAL METHODOLOGY Three types of concretes were used to build a 100 meters long pavement at Boral's Dunmore Quarry, South of Sydney, Australia, including control concrete, concrete with glass sand and concrete with glass powder. The control concrete consists of compliant materials by local pavement specifications. For the glass sand concrete, the total sand in the control mix was replaced with 45% glass sand, while for the glass powder concrete, the total cementitious content in the control mix was replaced by 15% glass powder [Dumitru et al. 2010, 2013].
The key structural element in most industrial enterprises is the concrete floor slab. The aim of ... more The key structural element in most industrial enterprises is the concrete floor slab. The aim of floor design is to select the most economical thickness while considering sufficient reinforcement to control the amount and size of cracks to a level consistent with the intended use of the floor. However, one of the most common causes of cracking in industrial floors is that the tensile stresses exceed the tensile strength of the concrete due to the shrinkage contraction. Therefore, there is a need for slabs that are reinforced with mesh to be saw cut in order to release the stresses due to the shrinkage. However, the distance between the sawn joints is related to the shrinkage of the concrete. Recently, considerable interest has been generated in the use of steel fibre reinforced concrete in order to control the tensile cracking of the composite material and reduce the number of joints especially in internal industrial floors. Boral has developed a low carbon, low shrinkage and high f...
Laboratory investigations, using recycled glass as natural sand replacement and powdered glass as... more Laboratory investigations, using recycled glass as natural sand replacement and powdered glass as cementitious materials replacement, have resulted in concrete mixes properties well within current specification requirement. The major benefits of concrete mixes using crushed glass as natural sand replacement were lower drying shrinkage and significant lower chloride diffusion coefficients. The results of this investigation were presented at the second International Conference on Sustainable Construction Materials and Technologies, in Ancona, Italy, in 2010. This paper, documents the results of a field concrete pavement trial, using crushed recycled glass as natural sand replacement, and powdered glass as cementitious material replacement. It was concluded that, partial natural sand replacement with crushed recycled glass and, partial replacement of cementitious materials with powdered glass, can meet the current concrete pavement specification requirements, with the exception of abra...
High drying shrinkage of concrete has the potential to impact adversely on the durability, aesthe... more High drying shrinkage of concrete has the potential to impact adversely on the durability, aesthetics and serviceability of concrete structures. Methods to reduce drying shrinkage of concrete have traditionally been to use special cements (e.g. SL Cement), water reducing admixtures and more recently, shrinkage reducing admixtures (SRA’s). This paper assesses the shrinkage reduction potential of two common shrinkage reducing agents and compares it with a new, low shrinkage concrete (trademarked as ENVISIA TM ). A 32 MPa ENVISIA TM concrete was compared against a typical 32MPa concrete with addition of each agent at the dosage of up to 7 litres per cubic meter. It was noted that addition of shrinkage reducing agent had lower water demand, longer setting time, more or less bleed water (depending on the admixture type), and slightly lower 1-day compressive strength but higher later compressive strength. The free drying shrinkage can be reduced up to 30-37% when 7L per cubic meter dosage...
Laboratory investigations were carried out to assess the potential of the crushed recycled glass ... more Laboratory investigations were carried out to assess the potential of the crushed recycled glass as natural sand replacement using ratios of 30%, 45% and 60%. Replacement of cementitious materials in concrete was also considered using cement replacement ratios of 7.5%, 15% and 25% of powder glass. The effects of glass sand replacement and cementitious materials replacement with powder glass on fresh and hardened concrete properties were assessed. It was concluded that with the incorporation of 45% of crushed glass as a natural sand replacement, the compressive and flexural strengths have marginally increased, while the indirect tensile strength marginally decreased. The concrete with glass as the natural sand replacement had lower shrinkage and significant lower chloride diffusion coefficient. Concretes with powder glass as cementitious materials replacement showed lower compressive strength and marginally higher drying shrinkage than the control mix, but meeting the concrete mix de...
Synopsis: The concrete industry relies heavily on the measured concrete compressive strength to m... more Synopsis: The concrete industry relies heavily on the measured concrete compressive strength to make momentous decisions. The real situation is that no matter how carefully a cylinder is finished, its end surface probably exhibits some irregularities. As required by AS 1012.9, the finished end of a concrete cylinder must be capped or ground before it is crushed for compressive strength. Sulphur and rubber capping are widely accepted methods. However, care must be taken for sulphur capping method especially for high strength concrete, where capping thickness of 1-2 mm and adequate strength of capping compounds are required. Rubber capping method is not permitted in AS 1012.9 for testing concrete strength over 80MPa. Alternatively, concrete cylinders can be ground using a grinding machine. Data presented in this paper compares the effects of four types of cylinder preparation methods on compressive strength, including sulphur capping, rubber capping, single end grinding and double end...
SF (silica fume) has been widely used in high performance concrete manufacturing due to its pozzo... more SF (silica fume) has been widely used in high performance concrete manufacturing due to its pozzolanic reactivity and the filler effect of ultra-fine particles. Recently ultra-fine grades of fly ash and metakaolin have been assessed and compared with SF concretes. This paper evaluates four commercially available products in manufacturing high performance concrete, including two SF (control I and II), one ultra-fine fly ash and one ultra-fine metakaolin. The study firstly assessed the properties of each raw material, including the loss of ignition, particle size distribution, relative water demand, relative strength, available alkali, and pozzolanic index. Concrete trial mixes were further carried out to assess the concrete properties, including workability by slump, compressive strength development up to 91 days, drying shrinkage up to 91 days, durability in terms of sorptivity and rapid chloride migration coefficient tests NT 492. The study has concluded that at a given workability (slump of 200 mm), the concrete with ultra fine fly ash required about 15-25 kg/m 3 less water, and achieved about 5-20 MPa higher compressive strength in 91 days, depending on the type of the SF used as the control. The sorptivity and chloride migration coefficient data show that concrete with ultra fine fly ash can achieve similar durability properties with SF used as control. The concrete with ultra-fine metakaolin requires similar water to control I and about 9 kg/m 3 more water than control II. The ultra-fine metakaolin concrete develops higher strength than control I, with similar compressive strength when compared to control II mix. This concrete mix has the lowest drying shrinkage than both controls and ultra-fine fly ash concretes. In terms of durability properties (sorptivity and chloride diffusion tests), concrete with ultra-fine metakaolin showed the best performance, especially at early age (i.e. 28 days). Therefore, it is possible to manufacture high performance concrete with ultra-fine fly ash or ultra-fine metakaolin to replace SF.
Journal of Civil Engineering and Architecture, 2015
Due to the shortages of natural sands along the east coast of Australia in particular and the nee... more Due to the shortages of natural sands along the east coast of Australia in particular and the need to fully utilise fines produced in quarry operations, progress has been made in utilising blends of manufactured sands and natural sands in concrete pavements. This paper documents some of the constraints in utilising larger proportions of manufactured sands in concrete pavements. These constraints are mainly caused by the current level of knowledge regarding the impact of manufactured sands on skid and abrasion resistance of concrete pavements. This paper presents a brief review of literature on this subject in the USA, France and UK. It also briefly documents work recently carried out in Australia by CCAA (Cement Concrete and Aggregates Australia), referring to the skid and abrasion resistance of concrete pavements using manufactured sands. The paper concludes that there is no relationship between the free silica content and the skid resistance. With regard to the abrasion resistance, it is rather the curing conditions and the compressive strength that are more important in achieving good results.
Boral has developed a lower carbon concrete, called Envisia®, using a ground slag product. With a... more Boral has developed a lower carbon concrete, called Envisia®, using a ground slag product. With a typical blend of 60% ZEP and 40% SL cement, and has similar plastic properties to conventional concrete. Unlike traditional high SCM concrete, there is no compromise on early strength and it exhibits much lower free drying shrinkage. These properties have been presented previously at the CIA 2013 conference. Since then, comprehensive research has been carried out to assess the durability properties of Envisia®, in particular chloride resistance, water permeability and alkali silica reactivity (ASR). A 60MPa Envisia® concrete developed for marine applications was compared with an equivalent grade of conventional concretes (SL/FA and SL/GGBFS). In comparison with traditional marine concrete (SL/GGBFS), Envisia® shows much lower chloride diffusion coefficient by both NT492 and NT443 tests, lower water sorptivity by ASTM C1585 method and lower water permeability by DIN 1048 test. Envisia® i...
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