The influence of the content of matekaolin powder and fly ash in cement on controlling ASR was evaluated using Accelerated Mortar Bar Test (AMBT). Replacing cement with matekaolin powder to the extent of 5%,10%,15%,20%,25%,and with fly ash to the extent of 10%,20%,30%,35%,40%, 45% respectively. The result show that matekaolin powder and fly ash both can control Alkali-aggregate activity but to different degrees. Small amount of metakaolin powder exerts significant influence, whereas only when the proportion of fly ash is up to 35%, can it control ASR effectively. The effect and mechanism of the control of the extension of glass aggregate activity was studied by means of SEM analysis.
The study on metakaolins inhibit effect to alkali-silica reaction (ASR) of slate aggregate by the way of accelerated mortar-bar test (AMBT),the results show that when the gel contains 15% metakaolin,the 14d expansion ratio is less than 0.03%,the inhibit reach the wear goal. But when we add the content of metakaolin, the expansion ratios are similar at every age.
Slate has high alkali activity.When broken as aggregate, it produce high content of slate powder.In order to study the effect of slate powder on fly ash in suppressing alkali activity of slate aggregate and the possibility of making full use of the powder,we carried the experiment on rapid mortar bar method.The experimental results show that:1. When the content of slate powder is less than 15% , it has no adverse effect on fly ash in suppressing alkali activity of slate aggregate. When the content of slate powder is greater than 15%,it can increase the effect of suppression.2. For alkali-silica reaction,what really suppress it is the active SiO2 that comes from slate powder or fly ash.As long as the mineral admixture containing active SiO2 grinds fine to the fineness of cement particle, it can increase the effect of suppression on fly ash in suppressing alkali activity of slate aggregate, rather than reduces the suppressive effect.
In order to prepare SCC (self-compacting concrete) which is used as the packing layer in CRTS III type track system this paper primary researched the influence of sand ratio on its performance through experiments of the design of mix proportion. Test results show that when sand ratio is too small, the fluidity of SCC will be bad and the concrete will generate segregation and weeping. If sand ratio is too great, the workability of SCC will not be good either, but segregation will not occur again. The optimum range of sand ratio is 0.56 to 0.58 in this paper, while the range proposed by China Academy of Railway Sciences is 0.50 to 0.55.
In order to improve workability of manufactured-sand mortar, limestone manufactured-sand mortar mixed with bentonite, and discussed the role of different dosage of bentonite that had played on mortar fluidity, consistency, layered degree ,mortar compressive and flexural strength. The results show that, mortar water demand increases, fluidity, consistency, stratification decreases with increasing bentonite dosage. Bentonite can be good to improve the water retention properties of the mortar. Doped bentonite mortar strength improved, when doped with 0.9%, mortar has best water retention, flexural, compressive strength also reached maximum.
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