The effects of fly ash on the compressive strength, pore size distribution and chloride-ion penetration of recycled aggregate concrete were investigated. Two series of concrete mb:tures were prepared. The concrete mi...The effects of fly ash on the compressive strength, pore size distribution and chloride-ion penetration of recycled aggregate concrete were investigated. Two series of concrete mb:tures were prepared. The concrete mixtures in series I had a water-to-binder ratio and a cement content of 0.55 and 410 kg/ m^3 , respectively. The concrete rnixtures in series II had a water-to-binder ratio and a cement content of 0.45 and 400 kg/ ml respectively. Recycled aggregate was ased as 20% , 50% , and 100% replacements of natural coarse aggregate in the concrete mixtures in both series. In cutdition, fly ash was used as 0% , 25% and 35% by weight replacements of cement. The results show that the compressive strengths of the concrete decreased as the recycled aggregate and the fly ash contents increased. The total porosity and average porosity diameter of the concrete increased us the recycled aggregate content increased. Furtherrruore , an increase in the recycled aggregate content decreased the resistance to chloride ion penetration. Nevertheless, the replacement of cement by 25% fly ush improved the resistance to chloride ion penetration and pore diameters and reduced the total porosity of the recycled aggregate concrete.展开更多
Low-grade fly ash (rejected fly ash,rFA),a significant portion of the pulverized fuel ash (PFA) produced from coal-fired power plants and rejected from the ash classifying process,remains unused due to its high carbon...Low-grade fly ash (rejected fly ash,rFA),a significant portion of the pulverized fuel ash (PFA) produced from coal-fired power plants and rejected from the ash classifying process,remains unused due to its high carbon content and large particle size (>45μm).But it is thought that the rejected ash may have potential uses in chemical stabilization/solidification (S/S) processes which need relatively lower strengths and a lower chemical reactivity.Flue Gas Desulphurisation (FGD) sludge is a by-product of air pollution control equipment in coal fired power plants whose chemical composition is mainly gypsum.As there is no effective usage of both of these two materials,it is of interest to research on the possible activation of rFA using FGD.This paper presents experimental results of a study on the properties of rFA activated by the FGD in rFA-cement pastes.Different percentages of FGD were added into the mix to study the effects of the FGD on the reaction of the rFA blended cement pastes.The results show that FGD takes effect as an activator only at late curing ages.Adding Ca(OH) 2 enhances the effect of FGD on activating the hydration of rFA.Also,10% FGD by weight of rFA is the optimal addition in the rFA-cement pastes.The results of the compressive strength measurements correlate well with the porosity results.展开更多
For lack of laboratory and field performance data on stabilization of reclaimed asphalt pavement (RAP) aggregate and stabilized soil (S) for road bases and subbases construction, the influences of RAP/S ratio, cem...For lack of laboratory and field performance data on stabilization of reclaimed asphalt pavement (RAP) aggregate and stabilized soil (S) for road bases and subbases construction, the influences of RAP/S ratio, cement and fly ash content, modifying agent (MA) on the compact, unconfined compressive strength, indirect tensile strength and water stability of the CIR mixtures were investigated. The experimental results showed that the maximum dry density and the optimum moisture content of the mixture changed significantly with the RAP/S ratio and cement-fly ash content. Unconfined compressive strength, indirect tensile strength and water stability were improved significantly by the addition of MA, and the water stability was improved by nearly 20% on average. Scanning electron microscopy(SEM) images indicated that MA accelerated the hydration of cement-fly ash system. Needle-like AFt and fibrous C-S-H gel were observed in the mixtures, which resulted in the cementation effect among the CIR mixture particles and a more compact microstructure. All these could be the cause of high strength of the CIR mixtures with MA.展开更多
Pervious concrete is recommended,which is of great benefit to the ecological environment and human living environment.In this paper,the influences of five water-cement ratios and four fly ash contents to replace the c...Pervious concrete is recommended,which is of great benefit to the ecological environment and human living environment.In this paper,the influences of five water-cement ratios and four fly ash contents to replace the cement by mass with a water-cement ratio of 0.30 on the properties of Recycled Aggregate Pervious Concrete(RAPC)were studied.Following this,based on the Grey relational-Technique for Order Preference by Similarity to an Ideal Solution(TOPSIS)optimization method,the strength,permeability,abrasion loss rate,and material costs of RAPC were adopted as evaluation indices to establish a mix proportion optimization model.The results show that the increase of water-cement ratio and fly ash replacement level of RAPC leads to decreased compres-sive strength while an increase in the permeability and abrasion loss rate.According to test results based on the optimal model 0.30 was identified as the best mix proportion.In addition,ecological-economic analysis of RAPC raw materials was carried out by comparing different natural aggregates.The results of EE(embodied energy)and ECO 2e(embodied CO_(2) emission)pointed out that the combination of recycled aggregate and fly ash leads to sig-nificant ecological and economic benefits.展开更多
In order to seek the effective method of increasing the coal combustion effi-ciency and to obtain the dcsign data for a certain kind of coal in fluidized bed combustors(FBCs),the experiments of coal combustion charact...In order to seek the effective method of increasing the coal combustion effi-ciency and to obtain the dcsign data for a certain kind of coal in fluidized bed combustors(FBCs),the experiments of coal combustion characteristics were conducted in a FBC facil-ity with the cross-section of 0.3m×0.3m and 6m in height.The variations of carbon con-tent of particles with recycle ratio,particle diameter,sample location and flow direction,the effects of bed temperature and fluidizing velocity on combustion efficiency and the va-riations of the temperature characteristic and combustion fraction in freeboard were inves-tigated.The experimental results indicate that using fly ash recycle not only can increasethe combustion efficiency,but also can improve the operation performances obviously.展开更多
The feasibility of utilization of flue gas desulfurization (FGD) gypsum and Class-C fly ash (CFA) to prepare CFA-based geopolymer were studied. The results showed that geopolymer made from 90% CFA and 10% FGD gyps...The feasibility of utilization of flue gas desulfurization (FGD) gypsum and Class-C fly ash (CFA) to prepare CFA-based geopolymer were studied. The results showed that geopolymer made from 90% CFA and 10% FGD gypsum (FGDG) which was thermally treated at 800 ℃ for 1 h obtained the better compressive strength of 37.0 MPa. The micro characteristics and structures of the geopolymer samples of CFA and CFA-FGDG were tested by XRD, FT-IR, and SEM-EDXA after these samples cured at 75 ℃ for 8 h followed by 23 ℃ for 28 d. Both the geopolymer samples of CFA and CFA-FGDG have significant asymmetric stretching of A1-O/Si-O bonds and Si-O-Si / Si-O-A1 bending band. In geopolymer sample of CFA-FGDG, a small quantity of lathy products probably being the ettringite wrapped over the spherical fly ash particle, and the concentration of sulfur is much more than that in geopolymer sample of CFA. It is indicated that FGD gypsum may react during alkali-activated and geopolymeric process.展开更多
A tool for calculating the economic and environmental impacts of the use of byproducts of industrial processes that can substitute for perishable resources was presented.This was exemplified by fly ash(the fine fracti...A tool for calculating the economic and environmental impacts of the use of byproducts of industrial processes that can substitute for perishable resources was presented.This was exemplified by fly ash(the fine fraction of ash originating from coal burned to generate electricity and collected by filtering exhaust gases leaving the furnace),added to soil as a component of sewage sludge stabilized with fly ash and lime(NVS).Application to soil of NVS has potential agricultural and environmental advantages and disadvantages.The costs and benefits of such application were calculated using both a database and expert opinions.The calculations assumed a representative assemblage of soils and crops,with weights assigned to each crop type and soil characteristic.The annual weighted benefits(additional income for the farmer)and costs per hectare reached 324$/ha and 131$/ha respectively.Major potential benefits include:Chemical fertilizer replacement,159$/ha;Improvement to the soil’s physical properties,75$/ha;Supply of vital trace elements,33$/ha.Major potential costs were:Regulatory limitations on marketing of crops pending proof of absence of risk of heavy metals or radionuclides accumulation in these crops,(17$/ha and 36$/ha respectively);Application and incorporation cost,50$/ha.The presented estimates of the costs and benefits refer to the array of soils and conditions typical to Israel.It is possible to maximize potential benefits by applying fly ash only to the most suitable agricultural soils while improper use of fly ash will increase the costs incurred from its use.展开更多
Municipal solid waste incineration(MSWI) fly ash is a by-product from municipal waste incineration.According to incomplete statistics, each year more than one million tons MSWI fly ash was produced in China. Owing to ...Municipal solid waste incineration(MSWI) fly ash is a by-product from municipal waste incineration.According to incomplete statistics, each year more than one million tons MSWI fly ash was produced in China. Owing to high heavy elements content, widely used disposal methods of landfill are not suitable for MSWI fly ash treatment. In this study, by using MSWI fly ash as raw materials, glassceramics was synthesized for the solidification of heavy metals and waste recycle. Process parameters, including composition, heat treatment temperature and time, were studied and optimized. Under optimizing conditions, the product has good properties of density of 3.42 g·cm^(-3) and Vickers hardness of 6.91 GPa. Moreover, the leaching concentration of heavy metal elements meets allowable values of toxicity characteristic leaching procedure(TCLP).This study offers an alternative for MSWI fly ash recycle.展开更多
Coal fly ash(CFA)is the main combustion residue of fine ground coal in the process of coal-fired thermal power generation,and crude glycerol(CG)is the byproduct of biodiesel production.The novel polyurethane/CFA(PU/CF...Coal fly ash(CFA)is the main combustion residue of fine ground coal in the process of coal-fired thermal power generation,and crude glycerol(CG)is the byproduct of biodiesel production.The novel polyurethane/CFA(PU/CFA)foam composites were prepared from CFA and CG.Two kinds of CFA,CFAI and CFAII were used as fillers for the property enhancement of PU/CFA composites,and the effects on foaming behavior and the reinforcement for the PU/CFA composites were investigated.It was found that the addition of CFA can prolong the rising time and tack-free time,and the maximum rising time and tack-free time increased to 40 s and 42 s.Meanwhile,the maximum compressive strength of PU/CFAI and PU/CFAII increased to 0.2186 MPa and 0.2284 MPa with the addition of CFA.The thermogravimetric analysis showed that the PU/CFA composites underwent three stages of thermal decomposition,and the amount of carbon residue increased from 23.11%to 67.91%with increasing CFA dosage.Moreover,the values of the limit oxygen index increased from 21.5%to 23.7%with the incorporation of CFA into the PU foam matrix,indicating that CFA improved the thermal stability and flame retardant performance of the composites.This study provided a new method for the recycling and high-value utilization of CG and CFA.展开更多
Recycled concrete is a material with the potential to create a sustainable construction industry.However,recycled concrete presents heterogeneous properties,thereby reducing its applications for some structural purpos...Recycled concrete is a material with the potential to create a sustainable construction industry.However,recycled concrete presents heterogeneous properties,thereby reducing its applications for some structural purposes and enhancing its application in pavements.This paper provides an insight into a solution in the deformation control for recycled concrete by adding supplementary cementitious materials fly ash and blast furnace slag.Results of this study indicated that the 50%fly ash replacement of Portland cement increased the rupture modulus of the recycled concrete.Conversely,a mixture with over 50%cement replacement by either fly ash or slag or a combination of both exhibited detrimental effect on the compressive strength,rupture modulus,and drying shrinkage.The combined analysis of environmental impacts and mechanical properties of recycled concrete demonstrated the possibility of optimizing the selection of recycled concrete because the best scenario in this study was obtained with the concrete mixture M8(50%of fly ash+100%recycled coarse aggregate).展开更多
This research studies the impact of different types of coarse aggregate on the behavior of geopolymer concrete based on both fly ash (FA) and ground granulated blast furnace slag (GGBFS) in different marine environmen...This research studies the impact of different types of coarse aggregate on the behavior of geopolymer concrete based on both fly ash (FA) and ground granulated blast furnace slag (GGBFS) in different marine environments. Aiming to solve the problems caused by the construction and demolition waste and the depletion of natural aggregates, in the present study coarse recycled aggregates is used to produce new green concrete with a fly ash-slag based geopolymer. By this examination, the research seeks to improve the quality and productivity of concrete used in construction and hydraulic projects. For this research, four mixtures containing different types of coarse aggregate in two different water environments were used. The utilized mixtures contained natural aggregate concrete (NAC) such as basalt and crushed marble. Also, recycled coarse aggregate concrete (RAC), which totally replaced natural aggregate, was presented in this paper such as crushed concrete and crushed ceramic. For this study, in the sieve analysis;specific and unit weights, was recorded. Furthermore, the mechanical properties were determined, using a compressive test that was conducted on the 7th, 28th, 56th and 90th days at different water environments;potable water (PW) and sea water (SW). Durability test was also performed for total absorption measurement. Results indicated that geopolymer concrete exhibits better strength in marine environments than in those of potable water. Results also showed that crushed marble (CMA) exhibits higher compressive strength and durability.展开更多
基金Funded by the Environment and Conservation Fund, the WooWheelock Green Fund andthe Hong Kong Polytechnic University
文摘The effects of fly ash on the compressive strength, pore size distribution and chloride-ion penetration of recycled aggregate concrete were investigated. Two series of concrete mb:tures were prepared. The concrete mixtures in series I had a water-to-binder ratio and a cement content of 0.55 and 410 kg/ m^3 , respectively. The concrete rnixtures in series II had a water-to-binder ratio and a cement content of 0.45 and 400 kg/ ml respectively. Recycled aggregate was ased as 20% , 50% , and 100% replacements of natural coarse aggregate in the concrete mixtures in both series. In cutdition, fly ash was used as 0% , 25% and 35% by weight replacements of cement. The results show that the compressive strengths of the concrete decreased as the recycled aggregate and the fly ash contents increased. The total porosity and average porosity diameter of the concrete increased us the recycled aggregate content increased. Furtherrruore , an increase in the recycled aggregate content decreased the resistance to chloride ion penetration. Nevertheless, the replacement of cement by 25% fly ush improved the resistance to chloride ion penetration and pore diameters and reduced the total porosity of the recycled aggregate concrete.
文摘Low-grade fly ash (rejected fly ash,rFA),a significant portion of the pulverized fuel ash (PFA) produced from coal-fired power plants and rejected from the ash classifying process,remains unused due to its high carbon content and large particle size (>45μm).But it is thought that the rejected ash may have potential uses in chemical stabilization/solidification (S/S) processes which need relatively lower strengths and a lower chemical reactivity.Flue Gas Desulphurisation (FGD) sludge is a by-product of air pollution control equipment in coal fired power plants whose chemical composition is mainly gypsum.As there is no effective usage of both of these two materials,it is of interest to research on the possible activation of rFA using FGD.This paper presents experimental results of a study on the properties of rFA activated by the FGD in rFA-cement pastes.Different percentages of FGD were added into the mix to study the effects of the FGD on the reaction of the rFA blended cement pastes.The results show that FGD takes effect as an activator only at late curing ages.Adding Ca(OH) 2 enhances the effect of FGD on activating the hydration of rFA.Also,10% FGD by weight of rFA is the optimal addition in the rFA-cement pastes.The results of the compressive strength measurements correlate well with the porosity results.
基金Funded by the High-Tech Research and Development Program (863 National Program) of China(No.2009AA11Z106)
文摘For lack of laboratory and field performance data on stabilization of reclaimed asphalt pavement (RAP) aggregate and stabilized soil (S) for road bases and subbases construction, the influences of RAP/S ratio, cement and fly ash content, modifying agent (MA) on the compact, unconfined compressive strength, indirect tensile strength and water stability of the CIR mixtures were investigated. The experimental results showed that the maximum dry density and the optimum moisture content of the mixture changed significantly with the RAP/S ratio and cement-fly ash content. Unconfined compressive strength, indirect tensile strength and water stability were improved significantly by the addition of MA, and the water stability was improved by nearly 20% on average. Scanning electron microscopy(SEM) images indicated that MA accelerated the hydration of cement-fly ash system. Needle-like AFt and fibrous C-S-H gel were observed in the mixtures, which resulted in the cementation effect among the CIR mixture particles and a more compact microstructure. All these could be the cause of high strength of the CIR mixtures with MA.
基金This work was supported by the National Natural Science Foundation of China(No.52009045)National Key Research and Development Program of China(No.2018YFC0406902).
文摘Pervious concrete is recommended,which is of great benefit to the ecological environment and human living environment.In this paper,the influences of five water-cement ratios and four fly ash contents to replace the cement by mass with a water-cement ratio of 0.30 on the properties of Recycled Aggregate Pervious Concrete(RAPC)were studied.Following this,based on the Grey relational-Technique for Order Preference by Similarity to an Ideal Solution(TOPSIS)optimization method,the strength,permeability,abrasion loss rate,and material costs of RAPC were adopted as evaluation indices to establish a mix proportion optimization model.The results show that the increase of water-cement ratio and fly ash replacement level of RAPC leads to decreased compres-sive strength while an increase in the permeability and abrasion loss rate.According to test results based on the optimal model 0.30 was identified as the best mix proportion.In addition,ecological-economic analysis of RAPC raw materials was carried out by comparing different natural aggregates.The results of EE(embodied energy)and ECO 2e(embodied CO_(2) emission)pointed out that the combination of recycled aggregate and fly ash leads to sig-nificant ecological and economic benefits.
文摘In order to seek the effective method of increasing the coal combustion effi-ciency and to obtain the dcsign data for a certain kind of coal in fluidized bed combustors(FBCs),the experiments of coal combustion characteristics were conducted in a FBC facil-ity with the cross-section of 0.3m×0.3m and 6m in height.The variations of carbon con-tent of particles with recycle ratio,particle diameter,sample location and flow direction,the effects of bed temperature and fluidizing velocity on combustion efficiency and the va-riations of the temperature characteristic and combustion fraction in freeboard were inves-tigated.The experimental results indicate that using fly ash recycle not only can increasethe combustion efficiency,but also can improve the operation performances obviously.
基金Funded by the National Natural Science Foundation of China(Nos.51208370,51172164)the Specialized Research Fund for the Doctoral Program of Higher Education(Nos.20110072120046,20090072110010)of China
文摘The feasibility of utilization of flue gas desulfurization (FGD) gypsum and Class-C fly ash (CFA) to prepare CFA-based geopolymer were studied. The results showed that geopolymer made from 90% CFA and 10% FGD gypsum (FGDG) which was thermally treated at 800 ℃ for 1 h obtained the better compressive strength of 37.0 MPa. The micro characteristics and structures of the geopolymer samples of CFA and CFA-FGDG were tested by XRD, FT-IR, and SEM-EDXA after these samples cured at 75 ℃ for 8 h followed by 23 ℃ for 28 d. Both the geopolymer samples of CFA and CFA-FGDG have significant asymmetric stretching of A1-O/Si-O bonds and Si-O-Si / Si-O-A1 bending band. In geopolymer sample of CFA-FGDG, a small quantity of lathy products probably being the ettringite wrapped over the spherical fly ash particle, and the concentration of sulfur is much more than that in geopolymer sample of CFA. It is indicated that FGD gypsum may react during alkali-activated and geopolymeric process.
基金This work was funded by the Israel National Coal Ash Board(INCAB)Grant#39477.The authors wish to express their deep gratitude to the late Mr.Omri Lulav,Head of the INCAB.
文摘A tool for calculating the economic and environmental impacts of the use of byproducts of industrial processes that can substitute for perishable resources was presented.This was exemplified by fly ash(the fine fraction of ash originating from coal burned to generate electricity and collected by filtering exhaust gases leaving the furnace),added to soil as a component of sewage sludge stabilized with fly ash and lime(NVS).Application to soil of NVS has potential agricultural and environmental advantages and disadvantages.The costs and benefits of such application were calculated using both a database and expert opinions.The calculations assumed a representative assemblage of soils and crops,with weights assigned to each crop type and soil characteristic.The annual weighted benefits(additional income for the farmer)and costs per hectare reached 324$/ha and 131$/ha respectively.Major potential benefits include:Chemical fertilizer replacement,159$/ha;Improvement to the soil’s physical properties,75$/ha;Supply of vital trace elements,33$/ha.Major potential costs were:Regulatory limitations on marketing of crops pending proof of absence of risk of heavy metals or radionuclides accumulation in these crops,(17$/ha and 36$/ha respectively);Application and incorporation cost,50$/ha.The presented estimates of the costs and benefits refer to the array of soils and conditions typical to Israel.It is possible to maximize potential benefits by applying fly ash only to the most suitable agricultural soils while improper use of fly ash will increase the costs incurred from its use.
基金financially supported by the National Natural Science Foundation of China (Nos. U1360202, 51472030, 51672024 and 51502014)the Fundamental Research Funds for the Central Universities (No. FRF-TP-16-027A3)the Innovation Project of Yunnan Province New Material Preparation and Processing Key Laboratory (No. 2016cx05)
文摘Municipal solid waste incineration(MSWI) fly ash is a by-product from municipal waste incineration.According to incomplete statistics, each year more than one million tons MSWI fly ash was produced in China. Owing to high heavy elements content, widely used disposal methods of landfill are not suitable for MSWI fly ash treatment. In this study, by using MSWI fly ash as raw materials, glassceramics was synthesized for the solidification of heavy metals and waste recycle. Process parameters, including composition, heat treatment temperature and time, were studied and optimized. Under optimizing conditions, the product has good properties of density of 3.42 g·cm^(-3) and Vickers hardness of 6.91 GPa. Moreover, the leaching concentration of heavy metal elements meets allowable values of toxicity characteristic leaching procedure(TCLP).This study offers an alternative for MSWI fly ash recycle.
基金supported by the National Natural Science Foundation of China(No.22178328,No.52006200)the Henan Science and Technology Research Project (No.222102320059)+1 种基金the Nanyang Collaborative Innovation Project (No.21XTCX12002)the Program of processing and efficient utilization of biomass resources (No.GZS2022007).
文摘Coal fly ash(CFA)is the main combustion residue of fine ground coal in the process of coal-fired thermal power generation,and crude glycerol(CG)is the byproduct of biodiesel production.The novel polyurethane/CFA(PU/CFA)foam composites were prepared from CFA and CG.Two kinds of CFA,CFAI and CFAII were used as fillers for the property enhancement of PU/CFA composites,and the effects on foaming behavior and the reinforcement for the PU/CFA composites were investigated.It was found that the addition of CFA can prolong the rising time and tack-free time,and the maximum rising time and tack-free time increased to 40 s and 42 s.Meanwhile,the maximum compressive strength of PU/CFAI and PU/CFAII increased to 0.2186 MPa and 0.2284 MPa with the addition of CFA.The thermogravimetric analysis showed that the PU/CFA composites underwent three stages of thermal decomposition,and the amount of carbon residue increased from 23.11%to 67.91%with increasing CFA dosage.Moreover,the values of the limit oxygen index increased from 21.5%to 23.7%with the incorporation of CFA into the PU foam matrix,indicating that CFA improved the thermal stability and flame retardant performance of the composites.This study provided a new method for the recycling and high-value utilization of CG and CFA.
文摘Recycled concrete is a material with the potential to create a sustainable construction industry.However,recycled concrete presents heterogeneous properties,thereby reducing its applications for some structural purposes and enhancing its application in pavements.This paper provides an insight into a solution in the deformation control for recycled concrete by adding supplementary cementitious materials fly ash and blast furnace slag.Results of this study indicated that the 50%fly ash replacement of Portland cement increased the rupture modulus of the recycled concrete.Conversely,a mixture with over 50%cement replacement by either fly ash or slag or a combination of both exhibited detrimental effect on the compressive strength,rupture modulus,and drying shrinkage.The combined analysis of environmental impacts and mechanical properties of recycled concrete demonstrated the possibility of optimizing the selection of recycled concrete because the best scenario in this study was obtained with the concrete mixture M8(50%of fly ash+100%recycled coarse aggregate).
文摘This research studies the impact of different types of coarse aggregate on the behavior of geopolymer concrete based on both fly ash (FA) and ground granulated blast furnace slag (GGBFS) in different marine environments. Aiming to solve the problems caused by the construction and demolition waste and the depletion of natural aggregates, in the present study coarse recycled aggregates is used to produce new green concrete with a fly ash-slag based geopolymer. By this examination, the research seeks to improve the quality and productivity of concrete used in construction and hydraulic projects. For this research, four mixtures containing different types of coarse aggregate in two different water environments were used. The utilized mixtures contained natural aggregate concrete (NAC) such as basalt and crushed marble. Also, recycled coarse aggregate concrete (RAC), which totally replaced natural aggregate, was presented in this paper such as crushed concrete and crushed ceramic. For this study, in the sieve analysis;specific and unit weights, was recorded. Furthermore, the mechanical properties were determined, using a compressive test that was conducted on the 7th, 28th, 56th and 90th days at different water environments;potable water (PW) and sea water (SW). Durability test was also performed for total absorption measurement. Results indicated that geopolymer concrete exhibits better strength in marine environments than in those of potable water. Results also showed that crushed marble (CMA) exhibits higher compressive strength and durability.