This paper investigates the properties of hydrated binary and ternary blended cements using limestone and calcined clay pozzolan as supplementary cementitious materials. The blended cements were hydrated and their pha...This paper investigates the properties of hydrated binary and ternary blended cements using limestone and calcined clay pozzolan as supplementary cementitious materials. The blended cements were hydrated and their phase compositions were evaluated by thermogravimetric and powder X-ray diffraction at 28 days. The morphology of the samples was also determined. The water demand, setting time, compressive and flexural strengths of mortar and concrete samples were determined up to 365 days. The study concluded that the portlandite [Ca（OH）2] content was considerably reduced whilst ettfingite formation were enhanced as a result of admixture reactions. The water demand and setting times of blended cements were lower than OPC with 5% admixture content but higher with increasing content. The mechanical test results also showed that Class 42.5N and 32.5R cements can be produced from the binary and ternary blends containing up to 10% and 20% admixtures, respectively.展开更多
Limestone calcined clay cement(LC^3),consisting of ordinary Portland cement(OPC)clinker,calcined clay,limestone powder,and gypsum,has been considered a promising solution to current challenges in the cement and concre...Limestone calcined clay cement(LC^3),consisting of ordinary Portland cement(OPC)clinker,calcined clay,limestone powder,and gypsum,has been considered a promising solution to current challenges in the cement and concrete industry,such as high carbon emissions,high energy consumption,and resource shortages.This study carries out a series of experimental investigations of LC^3-based paste,mortar,and concrete,including microstructural analyses(e.g.hydration product characterization and pore structure analysis)and macro-scale testing(e.g.workability and mechanical properties),using raw materials from south China.The results show that,in LC^3 paste,the replacement of clinker by calcined clay and limestone leads to an increased volume of small pores but decreased total volume of pores.The workability of LC^3 mortar and concrete can be readily tailored using conventional superplasticizers.When designed for comparable 28-d compressive strength,the LC^3 mortar and concrete tend to have lower early-age compressive strength,but comparable compressive strength and higher flexural strength than those of the OPC counterparts at late ages.This study also examines the bond-slip behavior between LC^3 concrete and steel bars and finds that the bond strength is comparable to that of OPC concrete with the same 28-d compressive strength,but that the LC^3 concrete-rebar interface exhibits higher bond-slip stiffness.These findings on LC^3 concrete provide fundamental information and guidance for furthering the application of LC^3 binder in structural concrete in the near future.展开更多
Limestone Calcined Clay Cement(LC^(3)) is a newly proposed low-carbon cement,which can effectively reduce energy consumption and carbon emissions of the traditional cement industry without changing the basic mechanica...Limestone Calcined Clay Cement(LC^(3)) is a newly proposed low-carbon cement,which can effectively reduce energy consumption and carbon emissions of the traditional cement industry without changing the basic mechanical properties of cement-based materials.In this study,the degradation process of mortar samples of limestone and calcined clay cementitious material under sulfate attack is studied by both macroscopic and microscopic analysis.The results show that compared with pure Portland cement,the addition of calcined clay and limestone can significantly reduce the expansion rate,loss of dynamic modulus and mass loss of mortar specimens under sulfate attack.The addition of calcined clay and limestone will refine the pore size distribution of mortar specimens,then inhibiting the diffusion of sulfate and formation of corrosive products,therefore leading to a significant improvement of the sulfate resistance.展开更多
文摘This paper investigates the properties of hydrated binary and ternary blended cements using limestone and calcined clay pozzolan as supplementary cementitious materials. The blended cements were hydrated and their phase compositions were evaluated by thermogravimetric and powder X-ray diffraction at 28 days. The morphology of the samples was also determined. The water demand, setting time, compressive and flexural strengths of mortar and concrete samples were determined up to 365 days. The study concluded that the portlandite [Ca（OH）2] content was considerably reduced whilst ettfingite formation were enhanced as a result of admixture reactions. The water demand and setting times of blended cements were lower than OPC with 5% admixture content but higher with increasing content. The mechanical test results also showed that Class 42.5N and 32.5R cements can be produced from the binary and ternary blends containing up to 10% and 20% admixtures, respectively.
基金the National Natural Science Foundation of China(Nos.51708360 and 51978407)the Shenzhen Basic Research Project of China(No.JCYJ20180305124106675)+4 种基金the Key Projects for International Cooperation in ScienceTechnology and Innovation of China(No.2018YFE0125000)the Taipei University of TechnologyShenzhen University Joint Research Program of China(No.2020008)the National Science Foundation of the USA(No.1661609)the Advanced Materials for Sustainable Infrastructure Seed Funding Program at Missouri University of Science and Technology,USA。
文摘Limestone calcined clay cement(LC^3),consisting of ordinary Portland cement(OPC)clinker,calcined clay,limestone powder,and gypsum,has been considered a promising solution to current challenges in the cement and concrete industry,such as high carbon emissions,high energy consumption,and resource shortages.This study carries out a series of experimental investigations of LC^3-based paste,mortar,and concrete,including microstructural analyses(e.g.hydration product characterization and pore structure analysis)and macro-scale testing(e.g.workability and mechanical properties),using raw materials from south China.The results show that,in LC^3 paste,the replacement of clinker by calcined clay and limestone leads to an increased volume of small pores but decreased total volume of pores.The workability of LC^3 mortar and concrete can be readily tailored using conventional superplasticizers.When designed for comparable 28-d compressive strength,the LC^3 mortar and concrete tend to have lower early-age compressive strength,but comparable compressive strength and higher flexural strength than those of the OPC counterparts at late ages.This study also examines the bond-slip behavior between LC^3 concrete and steel bars and finds that the bond strength is comparable to that of OPC concrete with the same 28-d compressive strength,but that the LC^3 concrete-rebar interface exhibits higher bond-slip stiffness.These findings on LC^3 concrete provide fundamental information and guidance for furthering the application of LC^3 binder in structural concrete in the near future.
基金supported in part by grants from National Natural Science Foundation of China(52278259).
文摘Limestone Calcined Clay Cement(LC^(3)) is a newly proposed low-carbon cement,which can effectively reduce energy consumption and carbon emissions of the traditional cement industry without changing the basic mechanical properties of cement-based materials.In this study,the degradation process of mortar samples of limestone and calcined clay cementitious material under sulfate attack is studied by both macroscopic and microscopic analysis.The results show that compared with pure Portland cement,the addition of calcined clay and limestone can significantly reduce the expansion rate,loss of dynamic modulus and mass loss of mortar specimens under sulfate attack.The addition of calcined clay and limestone will refine the pore size distribution of mortar specimens,then inhibiting the diffusion of sulfate and formation of corrosive products,therefore leading to a significant improvement of the sulfate resistance.
