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.
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.
The study used the method of accelerated mortar bar test to study alkali aggregate reaction (ASR) with sandstone aggregate. Both fly ash and slag can inhibit the expansion of mortar bar. Results show that 50% slag can inhibit ASR reluctantly, but 10% fly ash and 20% slag can inhibit ASR very well, and the inhibitory effect of fly ash is far better than slag. Because of the high content of CaO in slag, it has inhibit and promote aspects, when the ASR is fierce, slag can inhibit ASR, otherwise slag can promote ASR.
Based on the analysis of corrosion mechanism, combining with the characteristics of bridge structure, aiming at the existence of corrosive medium and complex physical environment, such as the freezing thawing, corrosion and chlorine salt as well as dry wet, freeze-thaw cycle [, This paper expounds the research and construction practice of the additional anti-corrosion measures of bridge pier caps concrete in Beijing-shanghai high speed railway. It has a certain guiding significance to the similar Bridges in corrosion protection construction.
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