The Experts below are selected from a list of 33 Experts worldwide ranked by ideXlab platform
Timothy D Murphy - One of the best experts on this subject based on the ideXlab platform.
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compressive strength and microstructure of alkali activated fly ash slag Binders at high temperature
Cement & Concrete Composites, 2018Co-Authors: Zhu Pan, Zhong Tao, Yifang Cao, Richard Wuhrer, Timothy D MurphyAbstract:Abstract This paper reports the results of the compressive strength and microstructure of various alkali-activated Binders at elevated temperatures of 300 and 600 °C. The Binders were prepared by alkali-activated low calcium fly ash/ground granulated blast-furnace slag at ratios of 100/0, 50/50, 10/90 and 0/100 wt.%. Specimens free of loading were heated to a pre-fixed temperature by keeping the furnace temperature constant until the specimens reached a steady state. Then the specimen was loaded to failure while hot. XRD, SEM and FTIR techniques were used to investigate the microstructural changes after the thermal exposure. The fly ash-based specimen shows an increase in strength at 600 °C. On the other hand, the slag-based specimen gives the worst high-temperature performance particularly at a temperature of 300 °C as compared to ordinary Portland Cement Binder. This contrasting behaviour of Binders is due to their different Binder formulation which gives rise to various phase transformations at elevated temperatures. The effects of these transformations on the compressive strength are discussed on the basis of experimental results.
Jianzhuang Xiao - One of the best experts on this subject based on the ideXlab platform.
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recycled geopolymer aggregates as coarse aggregates for Portland Cement concrete and geopolymer concrete effects on mechanical properties
Construction and Building Materials, 2020Co-Authors: Sara Mesgari, Ali Akbarnezhad, Jianzhuang XiaoAbstract:Abstract The available literature on recycling of geopolymer concrete is currently limited to application of recycled geopolymer aggregates as coarse aggregates for new geopolymer concrete. This paper highlights an alternative waste management strategy for geopolymer concrete construction and demolition waste by illustrating the suitability of recycled geopolymer aggregates for full or partial replaCement of coarse natural aggregates in the widely used Portland Cement concrete. The properties of Portland Cement concrete and geopolymer concrete made with varying contents of coarse geopolymer recycled aggregates (0%, 20%, 50% and 100% coarse natural aggregates replaCement) are investigated and compared with those of Portland Cement concrete containing recycled Portland Cement concrete aggregates. The results indicate that up to 20% replaCement of coarse natural aggregates with recycled geopolymer concrete aggregates results in only insignificant reductions in the modulus of elasticity, flexural strength and volume of permeable voids as well as a moderate reduction in compressive strength of Portland Cement concrete. The negative effects of varying amounts of recycled geopolymer concrete aggregates on the properties of Portland Cement concrete is however found to be slightly more significant than those caused by same proportions of recycled aggregates produced from Portland Cement concrete waste. Furthermore, incorporation of coarse recycled geopolymer concrete aggregates is found to lead to more significant negative effects on properties of Portland Cement concrete than geopolymer concrete. These include respectively 21%, 8.3% and 3.4% further reductions in compressive strength, modulus of elasticity and flexural strength of RAGC compared to RAG at 100% coarse aggregate replaCement ratio, highlighting a higher compatibility between geopolymer recycled aggregates and geopolymer Binder than Portland Cement Binder.
Shan Li - One of the best experts on this subject based on the ideXlab platform.
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physical and mechanical properties and micro characteristics of fly ash based geopolymer paste incorporated with waste granulated blast furnace slag gbfs and functionalized multi walled carbon nanotubes mwcnts
Journal of Hazardous Materials, 2021Co-Authors: Faping Li, Zheming Yang, Shan LiAbstract:Abstract Geopolymers are highly durable and have favorable mechanical properties, and are thus regarded as an eco-friendly alternative to traditional ordinary Portland Cement Binder. In this study, MWCNTs are obtained through a modification method using a compound of nitric acid and sulfuric acid, and are then dispersed using three types of dispersants. Fly ash-based geopolymers are prepared to validate the effectiveness and feasibility of adopting 0.05 wt.%, 0.10 wt.%, and 0.15 wt.% functionalized MWCNTs and substitution ratios of 10 %–40 % of fly ash with GBFS. The structure and dispersity of the functionalized MWCNTs in aqueous solutions are characterized using FT-IR and TEM, respectively. Then, the setting time, water absorption capacity, and mechanical behaviors are evaluated. In addition, SEM-EDS, FT-IR, TG-DSC, 29Si NMR, and XRD are employed to investigate the morphology, elemental components, mineralogical phases, and geopolymerization degree of the gel products. The experimental results show that the functionalized MWCNTs comprise −COOH and −OH groups and can be uniformly dispersed in aqueous solution containing SDS dispersant. Furthermore, geopolymer paste incorporated with 0.1 wt.% functionalized MWCNTs and having 30 % substitution of fly ash with GBFS exhibits a higher compressive and flexural strength and a lower water absorption capacity compared with all other geopolymer pastes.
Jana Kukutschova - One of the best experts on this subject based on the ideXlab platform.
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metakaolinite tio2 composite photoactive admixture for building materials based on Portland Cement Binder
Construction and Building Materials, 2012Co-Authors: Vlastimil Matějka, Petra Matějkova, Pavel Kovař, Jozef Vlcek, J Přikryl, P Cervenka, Zdenek Lacný, Jana KukutschovaAbstract:Abstract Novel latent hydraulic and photoactive admixture metakaolinite/TiO 2 was prepared, characterized and evaluated as a partial replaCement for the Portland Cement in mortars. The main component of this novel composite material is metakaolinite containing the anatase nanoparticles anchored on its surface. The values of the compression strength measured for the mortars containing metakaolinite/TiO 2 composites reached higher values in comparison to the mortar without this admixture. Photodegradation activity of the mortars with given amount of the metakaolinite/TiO 2 admixture against nitric oxide (NO) was tested using the modified ISO standard. The results showed that the conversion of NO increases with the increasing content of TiO 2 . The synergistic effect of the photodegradation activity and the latent hydraulicity in this material can be utilized in building industry to decrease concentration of selected air pollutants e.g. in areas affected by traffic pollution.
Zhu Pan - One of the best experts on this subject based on the ideXlab platform.
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compressive strength and microstructure of alkali activated fly ash slag Binders at high temperature
Cement & Concrete Composites, 2018Co-Authors: Zhu Pan, Zhong Tao, Yifang Cao, Richard Wuhrer, Timothy D MurphyAbstract:Abstract This paper reports the results of the compressive strength and microstructure of various alkali-activated Binders at elevated temperatures of 300 and 600 °C. The Binders were prepared by alkali-activated low calcium fly ash/ground granulated blast-furnace slag at ratios of 100/0, 50/50, 10/90 and 0/100 wt.%. Specimens free of loading were heated to a pre-fixed temperature by keeping the furnace temperature constant until the specimens reached a steady state. Then the specimen was loaded to failure while hot. XRD, SEM and FTIR techniques were used to investigate the microstructural changes after the thermal exposure. The fly ash-based specimen shows an increase in strength at 600 °C. On the other hand, the slag-based specimen gives the worst high-temperature performance particularly at a temperature of 300 °C as compared to ordinary Portland Cement Binder. This contrasting behaviour of Binders is due to their different Binder formulation which gives rise to various phase transformations at elevated temperatures. The effects of these transformations on the compressive strength are discussed on the basis of experimental results.