This research describes a series of laboratory tests performed to characterize the mechanical properties of plastic concrete. The mechanical properties of plastic concrete are studied using a series of compression tes...This research describes a series of laboratory tests performed to characterize the mechanical properties of plastic concrete. The mechanical properties of plastic concrete are studied using a series of compression tests. Stress relaxation and controlled rate of loading tests are also performed to investigate the rate sensitivity and time-dependency of plastic concrete. An important requirement for the plastic concrete in such applications is adequate strength for the design loads. The replacement of cement content of plastic concrete by micro silica does not result in any significant decrease in workability of plastic concretes and hence, unlike the case for normal concretes, plasticizers or super plasticizers are not required to rectify the adverse effect of micro silica on workability. The aim of the experimental research was to investigate the effects of various levels of cement replacement by micro silica, including 0%, 3%, 6%, 9%, 12% and 15% on strength of plastic concrete. Obtained results show that the effect of micro silica on strength enhancement of plastic concretes is substantial and a replacement level of 15% resulted in 70%-180% increase in strength compared to the control mix. For normal concretes, the increase in strength due to incorporation of micro silica was generally reported as 30%-50%.展开更多
Plastic concrete is an engineering material,which is commonly used for construction of cut-offwalls to prevent water seepage under the dam.This paper aims to explore two machine learning algorithms including artificia...Plastic concrete is an engineering material,which is commonly used for construction of cut-offwalls to prevent water seepage under the dam.This paper aims to explore two machine learning algorithms including artificial neural network (ANN)and support vector machine (SVM)to predict the compressive strength of bentonite/sepiolite plastic concretes.For this purpose,two unique sets of 72 data for compressive strength of bentonite and sepiolite plastic concrete samples (totally 144 data)were prepared by conducting an experimental study.The results confirm the ability of ANN and SVM models in prediction processes.Also,Sensitivity analysis of the best obtained model indicated that cement and silty clay have the maximum and minimum influences on the compressive strength,respectively.In addition, investigation of the effect of measurement error of input variables showed that change in the sand content (amount)and curing time will have the maximum and minimum effects on the output mean absolute percent error (MAPE)of model, respectively.Finally,the influence of different variables on the plastic concrete compressive strength values was evaluated by conducting parametric studies.展开更多
HyperCoal was prepared from low-rank coal via high-temperature solvent extraction with N-methylpyrrolidone as an extraction solvent and a liquid-to-solid ratio of 50 mL/g in a high-temperature and high-pressure reacto...HyperCoal was prepared from low-rank coal via high-temperature solvent extraction with N-methylpyrrolidone as an extraction solvent and a liquid-to-solid ratio of 50 mL/g in a high-temperature and high-pressure reactor. When HyperCoal was used as a binder and pulverized coal was used as the raw material, the compressive strength of the hot-pressed briquettes(each with a diameter of 20 mm and mass of 5 g) under different conditions was studied using a hot-pressing mold and a high-temperature furnace. The compressive strength of the hot-pressed briquettes was substantially improved and reached 436 N when the holding time period was 15 min, the hot-pressing temperature was 673 K, and the HyperCoal content, was 15 wt%. Changes in the carbonaceous structure, as reflected by the intensity ratio between the Raman G-and D-bands(IG/ID), strongly affected the compressive strength of hot-pressed briquettes prepared at different hot-pressing temperatures. Compared with cold-pressed briquettes, hot-pressed briquettes have many advantages, including high compressive strength, low ash content, high moisture resistance, and good thermal stability; thus, we expect that hot-pressed briquettes will have broad application prospects.展开更多
Loess and laterite distributed widely in the northern and southern China cannot be directly used as the natural barrier to isolate the solid waste because of their high hydraulic conductivity. In this paper, they are ...Loess and laterite distributed widely in the northern and southern China cannot be directly used as the natural barrier to isolate the solid waste because of their high hydraulic conductivity. In this paper, they are enhanced by bentonite to improve their hydraulic performance. The impact of bentonite content and water content on compressive strength of the compacted soil was investigated. The effects of bentonite content, water content, dry density and hydraulic gradient on the hydraulic conductivity were studied in detail. For the laterite and the laterite with 8% of bentonite, the experimental results of hydraulic conductivity can be applied in the engineering design. However, for the loess and the bentonite enhanced loess, those of hydraulic conductivity can not be directly applied in the engineering design because their hydraulic performance does not comply with the Darcy's law. These experimental results have to be carefully modified before application.展开更多
Densification of agricultural residues into briquettes as the alternative renewable feedstock can improve their physico-mechanical and storage properties as solid fuels.This paper presents the physico-mechanical prope...Densification of agricultural residues into briquettes as the alternative renewable feedstock can improve their physico-mechanical and storage properties as solid fuels.This paper presents the physico-mechanical properties of the composite briquettes made from corncob and rice husk.Raw samples of corncob and rice husk were collected,sorted and pulverised into fines of 0.25,1.00 and 1.75 mm particle sizes.The fines were blended at mixing ratios of 80꞉20,70꞉30,60꞉40,and 50꞉50,bonded with 5%starch on weight percentage basis and compressed at compaction pressures of 25,50,and 65 kPa to produce the briquette samples.The briquette made from 80:20 ratio of corncob to rice husk,0.25 mm particle size and 65 kPa pressure exhibited the highest compressive strength of 111 kN/m2 and the least of 39 kN/m^(2) from briquette with 50꞉50 ratio of corncob to rice husk,1.75 mm particle size and 25 kPa pressure.The briquette made from 50꞉50 ratio of corncob to rice husk,0.25 mm particle size and 65 kPa pressure had the highest water resistance capacity,and the least from briquette of 80꞉20 ratio of corncob to rice husk,1.75 mm particle size and 25 kPa pressure.The resulting physico-mechanical qualities of the produced corncob and rice husk briquettes suggested that they could be used as the solid fuels for domestic and industrial applications.展开更多
文摘This research describes a series of laboratory tests performed to characterize the mechanical properties of plastic concrete. The mechanical properties of plastic concrete are studied using a series of compression tests. Stress relaxation and controlled rate of loading tests are also performed to investigate the rate sensitivity and time-dependency of plastic concrete. An important requirement for the plastic concrete in such applications is adequate strength for the design loads. The replacement of cement content of plastic concrete by micro silica does not result in any significant decrease in workability of plastic concretes and hence, unlike the case for normal concretes, plasticizers or super plasticizers are not required to rectify the adverse effect of micro silica on workability. The aim of the experimental research was to investigate the effects of various levels of cement replacement by micro silica, including 0%, 3%, 6%, 9%, 12% and 15% on strength of plastic concrete. Obtained results show that the effect of micro silica on strength enhancement of plastic concretes is substantial and a replacement level of 15% resulted in 70%-180% increase in strength compared to the control mix. For normal concretes, the increase in strength due to incorporation of micro silica was generally reported as 30%-50%.
文摘Plastic concrete is an engineering material,which is commonly used for construction of cut-offwalls to prevent water seepage under the dam.This paper aims to explore two machine learning algorithms including artificial neural network (ANN)and support vector machine (SVM)to predict the compressive strength of bentonite/sepiolite plastic concretes.For this purpose,two unique sets of 72 data for compressive strength of bentonite and sepiolite plastic concrete samples (totally 144 data)were prepared by conducting an experimental study.The results confirm the ability of ANN and SVM models in prediction processes.Also,Sensitivity analysis of the best obtained model indicated that cement and silty clay have the maximum and minimum influences on the compressive strength,respectively.In addition, investigation of the effect of measurement error of input variables showed that change in the sand content (amount)and curing time will have the maximum and minimum effects on the output mean absolute percent error (MAPE)of model, respectively.Finally,the influence of different variables on the plastic concrete compressive strength values was evaluated by conducting parametric studies.
基金financially supported by the NationalNatural Science Foundation of China (No. 51574023)the National Key Research and Development Program ofChina (No. 2016YFB0600701)
文摘HyperCoal was prepared from low-rank coal via high-temperature solvent extraction with N-methylpyrrolidone as an extraction solvent and a liquid-to-solid ratio of 50 mL/g in a high-temperature and high-pressure reactor. When HyperCoal was used as a binder and pulverized coal was used as the raw material, the compressive strength of the hot-pressed briquettes(each with a diameter of 20 mm and mass of 5 g) under different conditions was studied using a hot-pressing mold and a high-temperature furnace. The compressive strength of the hot-pressed briquettes was substantially improved and reached 436 N when the holding time period was 15 min, the hot-pressing temperature was 673 K, and the HyperCoal content, was 15 wt%. Changes in the carbonaceous structure, as reflected by the intensity ratio between the Raman G-and D-bands(IG/ID), strongly affected the compressive strength of hot-pressed briquettes prepared at different hot-pressing temperatures. Compared with cold-pressed briquettes, hot-pressed briquettes have many advantages, including high compressive strength, low ash content, high moisture resistance, and good thermal stability; thus, we expect that hot-pressed briquettes will have broad application prospects.
文摘Loess and laterite distributed widely in the northern and southern China cannot be directly used as the natural barrier to isolate the solid waste because of their high hydraulic conductivity. In this paper, they are enhanced by bentonite to improve their hydraulic performance. The impact of bentonite content and water content on compressive strength of the compacted soil was investigated. The effects of bentonite content, water content, dry density and hydraulic gradient on the hydraulic conductivity were studied in detail. For the laterite and the laterite with 8% of bentonite, the experimental results of hydraulic conductivity can be applied in the engineering design. However, for the loess and the bentonite enhanced loess, those of hydraulic conductivity can not be directly applied in the engineering design because their hydraulic performance does not comply with the Darcy's law. These experimental results have to be carefully modified before application.
文摘Densification of agricultural residues into briquettes as the alternative renewable feedstock can improve their physico-mechanical and storage properties as solid fuels.This paper presents the physico-mechanical properties of the composite briquettes made from corncob and rice husk.Raw samples of corncob and rice husk were collected,sorted and pulverised into fines of 0.25,1.00 and 1.75 mm particle sizes.The fines were blended at mixing ratios of 80꞉20,70꞉30,60꞉40,and 50꞉50,bonded with 5%starch on weight percentage basis and compressed at compaction pressures of 25,50,and 65 kPa to produce the briquette samples.The briquette made from 80:20 ratio of corncob to rice husk,0.25 mm particle size and 65 kPa pressure exhibited the highest compressive strength of 111 kN/m2 and the least of 39 kN/m^(2) from briquette with 50꞉50 ratio of corncob to rice husk,1.75 mm particle size and 25 kPa pressure.The briquette made from 50꞉50 ratio of corncob to rice husk,0.25 mm particle size and 65 kPa pressure had the highest water resistance capacity,and the least from briquette of 80꞉20 ratio of corncob to rice husk,1.75 mm particle size and 25 kPa pressure.The resulting physico-mechanical qualities of the produced corncob and rice husk briquettes suggested that they could be used as the solid fuels for domestic and industrial applications.
