An experimental investigation was conducted to study the efficiency of thermal insulation of composite PCMs （phase change materials） produced by vacuum impregnation process between paraffin （PCMs） and fly ash part...An experimental investigation was conducted to study the efficiency of thermal insulation of composite PCMs （phase change materials） produced by vacuum impregnation process between paraffin （PCMs） and fly ash particles. DSC （differential scanning calorimeter） has been used to determine the thermal properties of latent heat of melting and heat capacity for composite PCMs. Vacuum impregnation pressure of 40 in.Hg, paraffin melting temperature of 90℃, vacuum time and impregnation time of paraffin of 30 min are the optimum condition of composite PCMs productions. The values of latent heat of melting and heat capacity are 74.00 J/g and 15.726 J/g.℃ for composite PCMs that produces by the optimum condition in vacuum impregnation process. Increasing the amount of composite PCMs replacing for cement in mortars causes the compressive strength, flexural strength and tensile strength reduction. Compressive strength, flexural strength and tensile strength of mortar with and without composite PCMs can be increased by the longer time of water curing for mortar specimens. Thermal conductivity （k） of mortar cement is reduced by increasing the amount of composite PCMs which replaced for cement in mortar plate compositions. Composite PCMs have the efficiency for thermal energy insulation when incorporated into the buildings. Therefore, this property of paraffin/fly ash composites PCMs can reduce the energy consumption for temperature control in the buildings.展开更多
In this experimental work, three groups of cement-slag mortars namely OPC, OPC-slag, and slag mortars were made. All were cured in both water and air under room temperature. Strength development was studied up to 90 d...In this experimental work, three groups of cement-slag mortars namely OPC, OPC-slag, and slag mortars were made. All were cured in both water and air under room temperature. Strength development was studied up to 90 days. The mortars were prepared using 0%, 50%, and 100% replacement with slag. The sensitivity for all groups was obtained against the curing regime with the highest being attributed to the slag mortars. The highest and lowest strengths at early ages were attributed to OPC and slag mortars when both were cured in water. The highest and lowest strengths were attributed to OPC-slag and slag mortars at later ages, respectively. The highest strengths for OPC-slag, OPC, and slag mortars were as 72.0, 64.0, and 21.5 MPa at 90 days when the specimens cured in water, respectively. Strength loss was observed for all groups at later ages when cured in air under room temperature. The maximum and minimum, of about 8.0% and 1.3%, occurred at 56 and 90 days for slag and OPC-slag mortars, respectively.展开更多
Cement mortar with sticky rice pulp is an innovative composite material.Investigating its mechanical properties and strength mechanism is essential for the future engineering application.Taking the pulp concentration ...Cement mortar with sticky rice pulp is an innovative composite material.Investigating its mechanical properties and strength mechanism is essential for the future engineering application.Taking the pulp concentration and the mortar ages as the variables,we tested five groups of blocks for the compressive strength and flexural strength,and observed their microstructures with a scanning electronic microscope.The results indicated that the microstructure got dense if the added pulp had a concentration of about 0.3%,and thereby its flexural strength would significantly improve,while the hydration products agglomerated and the microstructure got loose if the added pulp had a concentration of more than 1.0%,which caused a substantial decline in flexural strength.Besides,the hydration reaction was hindered at the early stage due to the addition of the pulp;hence the early strength of the mortar is on the low side.According to the strength mechanism analysis,all the results are mainly attributed to the effects:"water-reduction",agglomeration and retarding,caused by the addition of the pulp.展开更多
文摘采用正交试验法探讨掺入减水剂后各因素对掺电石渣的水泥砂浆强度的影响,确定水泥砂浆强度性能较佳的配方并分析其微观结构.结果表明:掺入减水剂后,对掺电石渣的水泥胶砂试样早期抗压强度的影响从大到小的次序分别为胶砂比、水灰比、电石渣掺量、减水剂掺量、减水剂品种、搅拌时间、减水剂的掺入方式.正交试验法确定的水泥胶砂试样较佳的配方为,电石渣掺量为5%;减水剂为J2,采用后掺方式,其掺量为0.5%;水灰比为0.377;胶砂比为1∶1.5;搅拌时间为9 min.
文摘An experimental investigation was conducted to study the efficiency of thermal insulation of composite PCMs （phase change materials） produced by vacuum impregnation process between paraffin （PCMs） and fly ash particles. DSC （differential scanning calorimeter） has been used to determine the thermal properties of latent heat of melting and heat capacity for composite PCMs. Vacuum impregnation pressure of 40 in.Hg, paraffin melting temperature of 90℃, vacuum time and impregnation time of paraffin of 30 min are the optimum condition of composite PCMs productions. The values of latent heat of melting and heat capacity are 74.00 J/g and 15.726 J/g.℃ for composite PCMs that produces by the optimum condition in vacuum impregnation process. Increasing the amount of composite PCMs replacing for cement in mortars causes the compressive strength, flexural strength and tensile strength reduction. Compressive strength, flexural strength and tensile strength of mortar with and without composite PCMs can be increased by the longer time of water curing for mortar specimens. Thermal conductivity （k） of mortar cement is reduced by increasing the amount of composite PCMs which replaced for cement in mortar plate compositions. Composite PCMs have the efficiency for thermal energy insulation when incorporated into the buildings. Therefore, this property of paraffin/fly ash composites PCMs can reduce the energy consumption for temperature control in the buildings.
文摘In this experimental work, three groups of cement-slag mortars namely OPC, OPC-slag, and slag mortars were made. All were cured in both water and air under room temperature. Strength development was studied up to 90 days. The mortars were prepared using 0%, 50%, and 100% replacement with slag. The sensitivity for all groups was obtained against the curing regime with the highest being attributed to the slag mortars. The highest and lowest strengths at early ages were attributed to OPC and slag mortars when both were cured in water. The highest and lowest strengths were attributed to OPC-slag and slag mortars at later ages, respectively. The highest strengths for OPC-slag, OPC, and slag mortars were as 72.0, 64.0, and 21.5 MPa at 90 days when the specimens cured in water, respectively. Strength loss was observed for all groups at later ages when cured in air under room temperature. The maximum and minimum, of about 8.0% and 1.3%, occurred at 56 and 90 days for slag and OPC-slag mortars, respectively.
基金Supported by the College Students Research Learning and Innovative Experiment Project of Hunan Province(S202012649001)the Natural Science Foundation of Hunan Province(2021JJ30270)。
文摘Cement mortar with sticky rice pulp is an innovative composite material.Investigating its mechanical properties and strength mechanism is essential for the future engineering application.Taking the pulp concentration and the mortar ages as the variables,we tested five groups of blocks for the compressive strength and flexural strength,and observed their microstructures with a scanning electronic microscope.The results indicated that the microstructure got dense if the added pulp had a concentration of about 0.3%,and thereby its flexural strength would significantly improve,while the hydration products agglomerated and the microstructure got loose if the added pulp had a concentration of more than 1.0%,which caused a substantial decline in flexural strength.Besides,the hydration reaction was hindered at the early stage due to the addition of the pulp;hence the early strength of the mortar is on the low side.According to the strength mechanism analysis,all the results are mainly attributed to the effects:"water-reduction",agglomeration and retarding,caused by the addition of the pulp.
