In this paper, the effect and mechanism of calcareous stone powder with size less than 0.074 mm are investigated in stone chippings concrete. The results show that the stone powder can participate in hydration reactio...In this paper, the effect and mechanism of calcareous stone powder with size less than 0.074 mm are investigated in stone chippings concrete. The results show that the stone powder can participate in hydration reaction and acts as crystal nucleus in hydration process, namely, it has hydration activity to an extent. The strength of stone chippings concrete is enhanced and the easy-mixing capacity of the concrete mortar is modified when stone chippings contain a proper amount of stone powder. The stone powder has little effect on the wearability of the concrete.展开更多
Traditional metal conductive fillers are expensive and prone to oxidation. Thus, the development of new conductive powders as fillers is urgently needed. A novel gaseous penetration technology was adopted to prepare L...Traditional metal conductive fillers are expensive and prone to oxidation. Thus, the development of new conductive powders as fillers is urgently needed. A novel gaseous penetration technology was adopted to prepare La-doped medical stone powders(La-MSPs), which are inexpensive mesoporous materials, as a new kind of conductive filler material. The prepared La-MSPs attained a resistivity of 450 ?·m and were used as a filler to prepare conductive coatings with epoxy resin as the resin matrix. The influence of the La-MSPs dosage on the resistance and hardness of the coatings was also determined. The resistance and the hardness both decreased with increasing filler dosage. Finally, the optimum recipe of the conductive coatings with the most suitable fillers dosage(55 wt%) was obtained. The hardness and resistance of the coatings with 55 wt% La-MSPs were HV 4 and 5.5 × 10~7 ?, respectively.展开更多
Most of the materials used in engineered cementitious composite are fine in size to achieve ductile nature.Stone slurry powder(SSP)is an inert material obtained from stone industries as by-product which may cause haza...Most of the materials used in engineered cementitious composite are fine in size to achieve ductile nature.Stone slurry powder(SSP)is an inert material obtained from stone industries as by-product which may cause hazardous impact on environment.In this research work,partial replacement of silica sand(SS)and fine sand(FS)by SSP with different contents(25%and 50%each)for making engineered cementitious composite has been explored.The performance was evaluated on the basis of strength,tensile strain,mid span deflection capacity,ultra-sonic pulse velocity and microstructure.Mechanical strength was found to be increased at 25%SSP in both replacements;whereas,strength decreased slightly at 50%replacement.Tensile strain,mid span deflection and quality of concrete were enhanced with increase in SSP content.Using SSP formed denser cementitious composite can help to save the natural resources and contribute in making green cementitious composite.展开更多
Most of the construction materials research now concerns on investigation of construction materials that is locally produced at a rate and cost compatible with the pace of construction. The present paper is concerned ...Most of the construction materials research now concerns on investigation of construction materials that is locally produced at a rate and cost compatible with the pace of construction. The present paper is concerned with investigation of fresh and hardened properties of self-compacting concrete (SCC) produced from local available materials in JORDAN. The produced SCC contains the local stone cut waste powder which is called Al-KHAMKHA in JORDAN with different replacement of (0%, 10%, and 25%) of fine silica aggregate;?the study also investigatesthe effects of SP33 super?plasticizer which is used by different doses (1%, 1.5% and 2%) for cement. The slump flow and the compressive strength of SCC were studied and the experimental results indicate the possibility of using Al-KHAMKHA in the production of SCC as the results showed that the compressive strength of the SCC with 10 % replacement by al-khamkha together with 1% SP33?super plasticizer was higher compared to pure SCC without al-khamkha;?the results also showed that as al-khamkha content increased the slump flow decreased.展开更多
The stone chip resistance performance of automotive coatings has attracted increasing attention in academic and industrial communities.Even though traditional gravelometer tests can be used to evaluate stone chip resi...The stone chip resistance performance of automotive coatings has attracted increasing attention in academic and industrial communities.Even though traditional gravelometer tests can be used to evaluate stone chip resistance of automotive coatings,such experiment-based methods suffer from poor repeatability and high cost.The main purpose of this work is to develop a CFD-DEM-wear coupling method to accurately and efficiently simulate stone chipbehaviorof automotive coatings inagravelometer test.Toachieve this end,an approach coupling an unresolved computational fluid dynamics(CFD)method and a discrete element method(DEM)are employed to account for interactions between fluids and large particles.In order to accurately describe large particles,a rigid connection particle method is proposed.In doing so,each actual non-spherical particle can be approximately described by rigidly connecting a group of non-overlapping spheres,and particle-fluid interactions are simulated based on each component sphere.An erosion wear model is used to calculate the impact damage of coatings based on particlecoating interactions.Single spherical particle tests are performed to demonstrate the feasibility of the proposed rigid connection particle method under various air pressure conditions.Then,the developed CFD-DEM-wear model is applied to reproduce the stone chip behavior of two standard tests,i.e.,DIN 55996-1 and SAE-J400-2002 tests.Numerical results are found to be in good agreement with experimental data,which demonstrates the capacity of our developed method in stone chip resistance evaluation.Finally,parametric studies are conducted to numerically investigate the influences of initial velocity and test panel orientation on impact damage of automotive coatings.展开更多
为了探究单轴受压下石粉-钢渣混凝土的本构关系,根据正交试验方案配制了不同掺量钢渣砂(30%、40%、50%)、钢渣石(30%、40%、50%)、石粉(0%、7.5%、15%)的石粉-钢渣混凝土,对石粉-钢渣混凝土的应力-应变关系进行了实验研究,建立了单轴受...为了探究单轴受压下石粉-钢渣混凝土的本构关系,根据正交试验方案配制了不同掺量钢渣砂(30%、40%、50%)、钢渣石(30%、40%、50%)、石粉(0%、7.5%、15%)的石粉-钢渣混凝土,对石粉-钢渣混凝土的应力-应变关系进行了实验研究,建立了单轴受压下石粉-钢渣混凝土的本构关系模型。实验结果表明:当受到单轴压力时,石粉-钢渣混凝土的破坏模式与普通混凝土相似,表现出斜剪切的特征。石粉-钢渣混凝土峰值应力、峰值应变及弹性模量随着钢渣骨料掺量的增加而提高。为了更好地模拟无量纲应力-应变曲线,本工作采用了Carreira and Chu模型的上升段和过镇海模型的下降段进行了分段拟合。结果表明,实验曲线与分段模型曲线吻合较好。展开更多
研究了不同石粉含量对C60机制砂混凝土徐变的影响,并对现有徐变预测模型进行了对比分析。结果表明:当机制砂石粉含量不超过15%时,各组试件的抗压强度均可满足C60强度等级的要求,各组试件120 d的徐变应变约为(180~230)×10-6,徐变系...研究了不同石粉含量对C60机制砂混凝土徐变的影响,并对现有徐变预测模型进行了对比分析。结果表明:当机制砂石粉含量不超过15%时,各组试件的抗压强度均可满足C60强度等级的要求,各组试件120 d的徐变应变约为(180~230)×10-6,徐变系数在0.41~0.56之间;随着石粉含量的增加,各组试件的徐变应变呈现先减小后增大的趋势,徐变系数呈先增大后减小的趋势;石粉含量对C60机制砂混凝土徐变的影响不显著;现有徐变模型对徐变系数的计算结果均大于实测结果;相比较之下,fib MC 2010模型更适用于高强机制砂混凝土的徐变预测。展开更多
文摘In this paper, the effect and mechanism of calcareous stone powder with size less than 0.074 mm are investigated in stone chippings concrete. The results show that the stone powder can participate in hydration reaction and acts as crystal nucleus in hydration process, namely, it has hydration activity to an extent. The strength of stone chippings concrete is enhanced and the easy-mixing capacity of the concrete mortar is modified when stone chippings contain a proper amount of stone powder. The stone powder has little effect on the wearability of the concrete.
基金financially supported by the Projects of Application Technology and Development of Harbin (No. 2016RAXXJ024)
文摘Traditional metal conductive fillers are expensive and prone to oxidation. Thus, the development of new conductive powders as fillers is urgently needed. A novel gaseous penetration technology was adopted to prepare La-doped medical stone powders(La-MSPs), which are inexpensive mesoporous materials, as a new kind of conductive filler material. The prepared La-MSPs attained a resistivity of 450 ?·m and were used as a filler to prepare conductive coatings with epoxy resin as the resin matrix. The influence of the La-MSPs dosage on the resistance and hardness of the coatings was also determined. The resistance and the hardness both decreased with increasing filler dosage. Finally, the optimum recipe of the conductive coatings with the most suitable fillers dosage(55 wt%) was obtained. The hardness and resistance of the coatings with 55 wt% La-MSPs were HV 4 and 5.5 × 10~7 ?, respectively.
基金Project(F1-17.1/2017-18/MANF-2017-18-HAR-78129)supported by the University Grants Commission New Delhi,India。
文摘Most of the materials used in engineered cementitious composite are fine in size to achieve ductile nature.Stone slurry powder(SSP)is an inert material obtained from stone industries as by-product which may cause hazardous impact on environment.In this research work,partial replacement of silica sand(SS)and fine sand(FS)by SSP with different contents(25%and 50%each)for making engineered cementitious composite has been explored.The performance was evaluated on the basis of strength,tensile strain,mid span deflection capacity,ultra-sonic pulse velocity and microstructure.Mechanical strength was found to be increased at 25%SSP in both replacements;whereas,strength decreased slightly at 50%replacement.Tensile strain,mid span deflection and quality of concrete were enhanced with increase in SSP content.Using SSP formed denser cementitious composite can help to save the natural resources and contribute in making green cementitious composite.
文摘Most of the construction materials research now concerns on investigation of construction materials that is locally produced at a rate and cost compatible with the pace of construction. The present paper is concerned with investigation of fresh and hardened properties of self-compacting concrete (SCC) produced from local available materials in JORDAN. The produced SCC contains the local stone cut waste powder which is called Al-KHAMKHA in JORDAN with different replacement of (0%, 10%, and 25%) of fine silica aggregate;?the study also investigatesthe effects of SP33 super?plasticizer which is used by different doses (1%, 1.5% and 2%) for cement. The slump flow and the compressive strength of SCC were studied and the experimental results indicate the possibility of using Al-KHAMKHA in the production of SCC as the results showed that the compressive strength of the SCC with 10 % replacement by al-khamkha together with 1% SP33?super plasticizer was higher compared to pure SCC without al-khamkha;?the results also showed that as al-khamkha content increased the slump flow decreased.
基金supported by the National Key R&D Program of China(No.2017YFE0117300)the Science and Technology Planning Project of Guangzhou(No.201804020065)the Innovation Group Project of Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)(No.311021013).
文摘The stone chip resistance performance of automotive coatings has attracted increasing attention in academic and industrial communities.Even though traditional gravelometer tests can be used to evaluate stone chip resistance of automotive coatings,such experiment-based methods suffer from poor repeatability and high cost.The main purpose of this work is to develop a CFD-DEM-wear coupling method to accurately and efficiently simulate stone chipbehaviorof automotive coatings inagravelometer test.Toachieve this end,an approach coupling an unresolved computational fluid dynamics(CFD)method and a discrete element method(DEM)are employed to account for interactions between fluids and large particles.In order to accurately describe large particles,a rigid connection particle method is proposed.In doing so,each actual non-spherical particle can be approximately described by rigidly connecting a group of non-overlapping spheres,and particle-fluid interactions are simulated based on each component sphere.An erosion wear model is used to calculate the impact damage of coatings based on particlecoating interactions.Single spherical particle tests are performed to demonstrate the feasibility of the proposed rigid connection particle method under various air pressure conditions.Then,the developed CFD-DEM-wear model is applied to reproduce the stone chip behavior of two standard tests,i.e.,DIN 55996-1 and SAE-J400-2002 tests.Numerical results are found to be in good agreement with experimental data,which demonstrates the capacity of our developed method in stone chip resistance evaluation.Finally,parametric studies are conducted to numerically investigate the influences of initial velocity and test panel orientation on impact damage of automotive coatings.
文摘为了探究单轴受压下石粉-钢渣混凝土的本构关系,根据正交试验方案配制了不同掺量钢渣砂(30%、40%、50%)、钢渣石(30%、40%、50%)、石粉(0%、7.5%、15%)的石粉-钢渣混凝土,对石粉-钢渣混凝土的应力-应变关系进行了实验研究,建立了单轴受压下石粉-钢渣混凝土的本构关系模型。实验结果表明:当受到单轴压力时,石粉-钢渣混凝土的破坏模式与普通混凝土相似,表现出斜剪切的特征。石粉-钢渣混凝土峰值应力、峰值应变及弹性模量随着钢渣骨料掺量的增加而提高。为了更好地模拟无量纲应力-应变曲线,本工作采用了Carreira and Chu模型的上升段和过镇海模型的下降段进行了分段拟合。结果表明,实验曲线与分段模型曲线吻合较好。
文摘研究了不同石粉含量对C60机制砂混凝土徐变的影响,并对现有徐变预测模型进行了对比分析。结果表明:当机制砂石粉含量不超过15%时,各组试件的抗压强度均可满足C60强度等级的要求,各组试件120 d的徐变应变约为(180~230)×10-6,徐变系数在0.41~0.56之间;随着石粉含量的增加,各组试件的徐变应变呈现先减小后增大的趋势,徐变系数呈先增大后减小的趋势;石粉含量对C60机制砂混凝土徐变的影响不显著;现有徐变模型对徐变系数的计算结果均大于实测结果;相比较之下,fib MC 2010模型更适用于高强机制砂混凝土的徐变预测。
