The marine structures such as harbour,pier and inshore concrete terrace are exposed in adverse circumstances in a long period of time .Owing to the attack of external corrosive medium,their safety,durability and relia...The marine structures such as harbour,pier and inshore concrete terrace are exposed in adverse circumstances in a long period of time .Owing to the attack of external corrosive medium,their safety,durability and reliability decline.Especially the reinforced concrete(RC) structures in the wave splash area are more likely to be subjected to destruction and the loss is vast. Now the safety ,durability and reliability of structure have become increasingly an important subject to be studied.By way of the soaking and drying cycle test on the different mix proportions oblique section of 10 pieces of RC beams suffered artificial sea water(ASW) corrosion under 0,35,70,105,140 times of dry-wet cycles,the compared results of exerting pressure test of these beams under simply supporting were investigated. The law about the changes of the mechanical performance for RC beams with different mix proportions under different time periods for suffering corrosion of dry-wet cycles is as follows: the resistivity to ASW corrosion of the concrete specimens with various water cement ratio(various initial strength)is different;the characters of oblique section failure for RC beams attacked by sea water are about the same as those for ordinary RC beam; along with the extension of the time for sea water attack, the bearing capacity for oblique section of RC beams varies wave upon wave.The specimens attacked by sea water for about 35 times of corrosion cycle achieve minimum bearing capacity.展开更多
During the hydration process, the Ultra-fine Cements present specific physical and chemical characteristics; they are, very short setting time and high heat release. For special applications, such as rapid hardening a...During the hydration process, the Ultra-fine Cements present specific physical and chemical characteristics; they are, very short setting time and high heat release. For special applications, such as rapid hardening and early high strength mortars or concretes, these characteristics can be considered advantageous. Some commercial products used for concrete reinforcement and repairs are the Rapid Hardening Mortars, these mortars must develop a time of setting up to 3 h and an initial compressive strength of about 3.5 MPa once the hardening of the paste is reached. The objective of the present research work is to use Ultra-fine Cement for the preparation of a series of different Rapid Hardening Mortars （with different percentages of Ultra-fine Cement）, these mortars required the addition of a polycarboxylate-base specification F Superplasticizer. It was observed that the optimum water/cement （W/C） ratio for the hydration of the Ultra-fine Cements is W/C = 0.385. The Ultra-fine Cements were obtained by the High Energy Ball-milling technique at laboratory scale, 90% of the Particle Size Distribution is below 11 μm and the Blaine Specific Surface Area is over 9000 cm^2/g.展开更多
Glass from a light bulb is a waste product that cannot be utilised in a traditional way. This study looks into the possibilities of using lamp borosilicate glass powder as a cement replacing admixture in conventional ...Glass from a light bulb is a waste product that cannot be utilised in a traditional way. This study looks into the possibilities of using lamp borosilicate glass powder as a cement replacing admixture in conventional concrete. Experimental work provides preparation of standard concrete samples and sample testing after seven and 28-day ageing periods in standard conditions. The following glass materials were used for cement replacement： rough ground glass powder, glass dust from filters （both materials were obtained from a glass treatment plant） and additionally ground glass powder. The effect of glass powder on cement setting time was studied. The experimental results indicate that replacement of cement by rough glass powder decreases the compressive strength. Fine glass particles make it possible to replace up to 20% of cement without the loss in strength characteristics. Fine glass powder offers a long-term hardening effect. The best compressive strength results were achieved by using the glass that was additionally ground for 60 minutes. Glass dust obtained from filters shows a less significant effect. Summarising the research findings it may be concluded that ground borosilicate lamp glass may be successfully applied as a micro-filler for concrete as cement replacing material.展开更多
文摘The marine structures such as harbour,pier and inshore concrete terrace are exposed in adverse circumstances in a long period of time .Owing to the attack of external corrosive medium,their safety,durability and reliability decline.Especially the reinforced concrete(RC) structures in the wave splash area are more likely to be subjected to destruction and the loss is vast. Now the safety ,durability and reliability of structure have become increasingly an important subject to be studied.By way of the soaking and drying cycle test on the different mix proportions oblique section of 10 pieces of RC beams suffered artificial sea water(ASW) corrosion under 0,35,70,105,140 times of dry-wet cycles,the compared results of exerting pressure test of these beams under simply supporting were investigated. The law about the changes of the mechanical performance for RC beams with different mix proportions under different time periods for suffering corrosion of dry-wet cycles is as follows: the resistivity to ASW corrosion of the concrete specimens with various water cement ratio(various initial strength)is different;the characters of oblique section failure for RC beams attacked by sea water are about the same as those for ordinary RC beam; along with the extension of the time for sea water attack, the bearing capacity for oblique section of RC beams varies wave upon wave.The specimens attacked by sea water for about 35 times of corrosion cycle achieve minimum bearing capacity.
文摘During the hydration process, the Ultra-fine Cements present specific physical and chemical characteristics; they are, very short setting time and high heat release. For special applications, such as rapid hardening and early high strength mortars or concretes, these characteristics can be considered advantageous. Some commercial products used for concrete reinforcement and repairs are the Rapid Hardening Mortars, these mortars must develop a time of setting up to 3 h and an initial compressive strength of about 3.5 MPa once the hardening of the paste is reached. The objective of the present research work is to use Ultra-fine Cement for the preparation of a series of different Rapid Hardening Mortars （with different percentages of Ultra-fine Cement）, these mortars required the addition of a polycarboxylate-base specification F Superplasticizer. It was observed that the optimum water/cement （W/C） ratio for the hydration of the Ultra-fine Cements is W/C = 0.385. The Ultra-fine Cements were obtained by the High Energy Ball-milling technique at laboratory scale, 90% of the Particle Size Distribution is below 11 μm and the Blaine Specific Surface Area is over 9000 cm^2/g.
文摘Glass from a light bulb is a waste product that cannot be utilised in a traditional way. This study looks into the possibilities of using lamp borosilicate glass powder as a cement replacing admixture in conventional concrete. Experimental work provides preparation of standard concrete samples and sample testing after seven and 28-day ageing periods in standard conditions. The following glass materials were used for cement replacement： rough ground glass powder, glass dust from filters （both materials were obtained from a glass treatment plant） and additionally ground glass powder. The effect of glass powder on cement setting time was studied. The experimental results indicate that replacement of cement by rough glass powder decreases the compressive strength. Fine glass particles make it possible to replace up to 20% of cement without the loss in strength characteristics. Fine glass powder offers a long-term hardening effect. The best compressive strength results were achieved by using the glass that was additionally ground for 60 minutes. Glass dust obtained from filters shows a less significant effect. Summarising the research findings it may be concluded that ground borosilicate lamp glass may be successfully applied as a micro-filler for concrete as cement replacing material.
