The effects of glass powder on the strength development, chloride permeability and potential alkali-aggregate reaction expansion of lightweight aggregate concrete were investigated. Ground blast furnace slag, coal fly...The effects of glass powder on the strength development, chloride permeability and potential alkali-aggregate reaction expansion of lightweight aggregate concrete were investigated. Ground blast furnace slag, coal fly ash and silica fume were used as reference materials. The re- placement of cement with 25% glass powder slightly decreases the strengthes at ？ and 28 d, but shows no effect on 90 d＇s. Silica fume is very effective in improving both the strength and chloride penetration resistance, while ground glass powder is much more effective than blast furnace slag and fly ash in improving chloride penetration resistance of the concrete. When expanded shale or clay is used as coarse aggregate, the concrete containing glass powder does not exhibit deleterious expansion even if alkali-reactive sand is used as fine aggregate of the concrete.展开更多
Three different methods were applied to study the alkali content of gelpores in cement. In the closed system, the concentration of K＋, Na＋ and OH - have not reduced with the increase of age. In the open system, the ...Three different methods were applied to study the alkali content of gelpores in cement. In the closed system, the concentration of K＋, Na＋ and OH - have not reduced with the increase of age. In the open system, the diffusion and transferring of K＋ and Na＋ towards free space leads to the de-crease of total alkali content. In the micro-analysis system, the contents of K＋ and Na＋ in the first hy- drated layer of ground granulated blastfurnace slag （GBFS） are very low, while the contents of calcium and magnesium are relatively high. This phenomenon shows that the mechanism of GBFS preventing alkali aggregate reaction （AAR） is： when GBFS is dissolved by alkali medium, SiO2 and Al2O3 are dissolved into the cement matrix, then around GBFS particles form reaction rings rich in Ca2＋ and Mg^2＋, and the C-S-H gel of positive charges formed in the area repulses K＋ and Na＋, which are forced to transfer to the mortar＇s matrix, pore or mortar sample surface. The transferred K ^＋ and Na^＋ form alkali gel products with other dissolved ions, then become evenly distributed in the mortar sample and react with Ca（OH）2 in pore solutions to form （Na,K）x-2z·zCa·（SiO2）y·（OH）x gel products; and thus changes the AAR gel products＇ structure. The gel products will not expand, and so they can delay expansion destruction.展开更多
文摘The effects of glass powder on the strength development, chloride permeability and potential alkali-aggregate reaction expansion of lightweight aggregate concrete were investigated. Ground blast furnace slag, coal fly ash and silica fume were used as reference materials. The re- placement of cement with 25% glass powder slightly decreases the strengthes at ？ and 28 d, but shows no effect on 90 d＇s. Silica fume is very effective in improving both the strength and chloride penetration resistance, while ground glass powder is much more effective than blast furnace slag and fly ash in improving chloride penetration resistance of the concrete. When expanded shale or clay is used as coarse aggregate, the concrete containing glass powder does not exhibit deleterious expansion even if alkali-reactive sand is used as fine aggregate of the concrete.
基金Funded by the German Academic Exchange Service (DAAD) for the Project A/09/00743the Science and Technology Project of Wuhan City(No.200860423208)
文摘Three different methods were applied to study the alkali content of gelpores in cement. In the closed system, the concentration of K＋, Na＋ and OH - have not reduced with the increase of age. In the open system, the diffusion and transferring of K＋ and Na＋ towards free space leads to the de-crease of total alkali content. In the micro-analysis system, the contents of K＋ and Na＋ in the first hy- drated layer of ground granulated blastfurnace slag （GBFS） are very low, while the contents of calcium and magnesium are relatively high. This phenomenon shows that the mechanism of GBFS preventing alkali aggregate reaction （AAR） is： when GBFS is dissolved by alkali medium, SiO2 and Al2O3 are dissolved into the cement matrix, then around GBFS particles form reaction rings rich in Ca2＋ and Mg^2＋, and the C-S-H gel of positive charges formed in the area repulses K＋ and Na＋, which are forced to transfer to the mortar＇s matrix, pore or mortar sample surface. The transferred K ^＋ and Na^＋ form alkali gel products with other dissolved ions, then become evenly distributed in the mortar sample and react with Ca（OH）2 in pore solutions to form （Na,K）x-2z·zCa·（SiO2）y·（OH）x gel products; and thus changes the AAR gel products＇ structure. The gel products will not expand, and so they can delay expansion destruction.
