The properties of polyurethane concrete containing a large amount of fly ash are investigated,and accordingly,a model is introduced to account for the influence of fly ash fineness,water ratio,and loss of ignition(LOI...The properties of polyurethane concrete containing a large amount of fly ash are investigated,and accordingly,a model is introduced to account for the influence of fly ash fineness,water ratio,and loss of ignition(LOI)on its mechanical performances.This research shows that,after optimization,the concrete has a compressive strength of 20.8 MPa,a flexural strength of 3.4 MPa,and a compressive modulus of elasticity of 19.2 GPa.The main factor influencing 28 and 90 d compressive strength is fly ash content,water-binder ratio,and early strength agent content.展开更多
Red mud is a type of highly alkaline waste residue produced in the process of alumina smelting by the Bayer process.Based on the idea of medium calcium content,solid wastes such as red mud and fly ash were used to pre...Red mud is a type of highly alkaline waste residue produced in the process of alumina smelting by the Bayer process.Based on the idea of medium calcium content,solid wastes such as red mud and fly ash were used to prepare non-burnt bricks;and the mass ratio of CaO/SiO2 was selected in the range of 0.88–1.42.Mechanical properties and durability were investigated with a compressive strength test.X-ray diffractometry(XRD),scanning electron microscope(SEM),and Fourier transform infrared spectroscopy(FTIR)techniques were used to characterize the hydration characteristic.The environmental performance was analyzed by Inductively Coupled Plasma Mass Spectrometry(ICP).The results indicated that the mechanical properties and the durability were optimal when the mass ratio of CaO/SiO2 was 1.23.The hydration products were mostly C–S–H gel,ettringite,Na4Ca(Si10All6)O32·12H2O and Ca3Al2(SiO4)(OH)8.They were responsible for the strength development,and the CaO/SiO2 mass ratio of 1.23 had the best polymerized structure.The results of an environmental performance test showed that the heavy metals in the raw materials were well-solidified in the brick.Therefore,this paper provides an effective solution for use of solid wastes in building material.展开更多
To decrease the cement and SF content of RPC by using ultra-fine fly ash (UFFA) and steel slag powder (SS), the effect of these mineral admixtures on compressive strength of RPC were investigated. The experimental...To decrease the cement and SF content of RPC by using ultra-fine fly ash (UFFA) and steel slag powder (SS), the effect of these mineral admixtures on compressive strength of RPC were investigated. The experimental results indicate that the utilization of UFFA and SS in RPC is feasible and has prominent mechanical performance. The microstructure analysis (SEM and TG-DTG-DSC) demonstrated that the excellent mechanical properties of RPC containing SS and UFFA were mainly attributed to the sequential hydration filling effect of the compound system.展开更多
The fly ash occasionally has high content of iron oxide and carbon that are good electrical conducting components. This paper investigates the effect of the fly ash used as mineral admixtures on the electrical conduct...The fly ash occasionally has high content of iron oxide and carbon that are good electrical conducting components. This paper investigates the effect of the fly ash used as mineral admixtures on the electrical conductivity of concretes. The electrical properties of concretes using 3 kinds of fly ash with different iron oxide contents have been studied. Experimental results show that at the same fly ash dosage the resistivity of concrete using fly ash with high content of iron oxide is slightly lower than that with low content of iron oxide. However, the concrete resistivity after 14d increases as fly ash dosage increases regardless of iron oxide content in fly ash.展开更多
Corrosion of embedded rebars is a classical deterioration mechanism of reinforced concrete structures exposed to chloride environments. Such environments can be attributed to the presence of seawater, deicing or sea-s...Corrosion of embedded rebars is a classical deterioration mechanism of reinforced concrete structures exposed to chloride environments. Such environments can be attributed to the presence of seawater, deicing or sea-salts, which have high concentrations of chloride ion. Chloride ingress into concrete, essential for inducing rebar corrosion, is a complex interaction between many physical and chemical processes. The current study proposes two chloride ingress parameter models for fly ash concrete, namely: 1) surface chloride content under tidal exposure condition; and 2) chloride binding. First, inconsistencies in surface chloride content and chloride binding models reported in literature, due to them not being in line with past research studies, are pointed out. Secondly, to avoid such inconsistencies, surface chloride content and chloride binding models for fly ash concrete are proposed based upon the experimental work done by other researchers. It is observed that, proposed models are simple, consistent and in line with past research studies reported in literature.展开更多
We put forward effective methods of increasing the tensile strain of cementitious composites with 2% PVA fiber and high fly ash content. The test results show that curing condition has a significantly effect on the te...We put forward effective methods of increasing the tensile strain of cementitious composites with 2% PVA fiber and high fly ash content. The test results show that curing condition has a significantly effect on the tensile performance. It is approved that the specimens incorporated appropriate volume fraction rubber powder and lightweight aggregate greatly increase the tensile strain of composites at medium-term age, but indefinitely at long-term age. To a certain extent, EVA can limitedly enhance the tensile performance of comentitious composites owing to the formation of polymer membrane and the hindered hydration of cement.展开更多
基金The Second Batch of Industry-University Cooperative Education Projects in 2021(202102113047)Science and Technology Project of Hubei Construction Department[2019(672)].
文摘The properties of polyurethane concrete containing a large amount of fly ash are investigated,and accordingly,a model is introduced to account for the influence of fly ash fineness,water ratio,and loss of ignition(LOI)on its mechanical performances.This research shows that,after optimization,the concrete has a compressive strength of 20.8 MPa,a flexural strength of 3.4 MPa,and a compressive modulus of elasticity of 19.2 GPa.The main factor influencing 28 and 90 d compressive strength is fly ash content,water-binder ratio,and early strength agent content.
基金the financial support from the National Natural Science Foundation of China (No.51574024)Fundamental Research Funds for the Central Universities (FRF-TP-18-005B1)Technological Research and Development Programs of China Railways Corporation (No.2017G006-J)
文摘Red mud is a type of highly alkaline waste residue produced in the process of alumina smelting by the Bayer process.Based on the idea of medium calcium content,solid wastes such as red mud and fly ash were used to prepare non-burnt bricks;and the mass ratio of CaO/SiO2 was selected in the range of 0.88–1.42.Mechanical properties and durability were investigated with a compressive strength test.X-ray diffractometry(XRD),scanning electron microscope(SEM),and Fourier transform infrared spectroscopy(FTIR)techniques were used to characterize the hydration characteristic.The environmental performance was analyzed by Inductively Coupled Plasma Mass Spectrometry(ICP).The results indicated that the mechanical properties and the durability were optimal when the mass ratio of CaO/SiO2 was 1.23.The hydration products were mostly C–S–H gel,ettringite,Na4Ca(Si10All6)O32·12H2O and Ca3Al2(SiO4)(OH)8.They were responsible for the strength development,and the CaO/SiO2 mass ratio of 1.23 had the best polymerized structure.The results of an environmental performance test showed that the heavy metals in the raw materials were well-solidified in the brick.Therefore,this paper provides an effective solution for use of solid wastes in building material.
基金Funded by the Guide Project in National Science & Technology Pillar Program during the 10th Five-Year Plan Period (2003BA652C)
文摘To decrease the cement and SF content of RPC by using ultra-fine fly ash (UFFA) and steel slag powder (SS), the effect of these mineral admixtures on compressive strength of RPC were investigated. The experimental results indicate that the utilization of UFFA and SS in RPC is feasible and has prominent mechanical performance. The microstructure analysis (SEM and TG-DTG-DSC) demonstrated that the excellent mechanical properties of RPC containing SS and UFFA were mainly attributed to the sequential hydration filling effect of the compound system.
基金Funded by the National Natural Science Foundation of China (No.50404005)
文摘The fly ash occasionally has high content of iron oxide and carbon that are good electrical conducting components. This paper investigates the effect of the fly ash used as mineral admixtures on the electrical conductivity of concretes. The electrical properties of concretes using 3 kinds of fly ash with different iron oxide contents have been studied. Experimental results show that at the same fly ash dosage the resistivity of concrete using fly ash with high content of iron oxide is slightly lower than that with low content of iron oxide. However, the concrete resistivity after 14d increases as fly ash dosage increases regardless of iron oxide content in fly ash.
文摘Corrosion of embedded rebars is a classical deterioration mechanism of reinforced concrete structures exposed to chloride environments. Such environments can be attributed to the presence of seawater, deicing or sea-salts, which have high concentrations of chloride ion. Chloride ingress into concrete, essential for inducing rebar corrosion, is a complex interaction between many physical and chemical processes. The current study proposes two chloride ingress parameter models for fly ash concrete, namely: 1) surface chloride content under tidal exposure condition; and 2) chloride binding. First, inconsistencies in surface chloride content and chloride binding models reported in literature, due to them not being in line with past research studies, are pointed out. Secondly, to avoid such inconsistencies, surface chloride content and chloride binding models for fly ash concrete are proposed based upon the experimental work done by other researchers. It is observed that, proposed models are simple, consistent and in line with past research studies reported in literature.
基金Funded by National Basic Research Program of China (973 Program) (No. 2009CB623200)Hong Kong Research Grant Council under CERG 616405
文摘We put forward effective methods of increasing the tensile strain of cementitious composites with 2% PVA fiber and high fly ash content. The test results show that curing condition has a significantly effect on the tensile performance. It is approved that the specimens incorporated appropriate volume fraction rubber powder and lightweight aggregate greatly increase the tensile strain of composites at medium-term age, but indefinitely at long-term age. To a certain extent, EVA can limitedly enhance the tensile performance of comentitious composites owing to the formation of polymer membrane and the hindered hydration of cement.