Can glass be used as aggregate in concrete?
Glass aggregate can replace part or all of the sand and gravel in concrete, for effects that range from colorful terrazzo, to granite- or marble-like finishes, to concrete that reflects light like a mirror. Glass aggregate can even be used to produce concrete that literally glows.
What happens to the concrete when the alkali silica reaction occurs?
This hygroscopic gel swells and increases in volume when absorbing water: it exerts an expansive pressure inside the siliceous aggregate, causing spalling and loss of strength of the concrete, finally leading to its failure.
What causes alkali silica reaction in concrete?
The primary cause of ASR is a reaction between the alkaline cement’s hydroxyl ions and some aggregate’s reactive forms of silica. This produces a hygroscopic gel which expands on the absorption of water, imposing pressure on the surrounding concrete and weakening it in a way similar to a freeze-thaw action.
What is the major limitation of using waste glass in concrete?
Note that using waste glass aggregates will significantly reduce the concrete mixture’s workability. The glass cullets’ angular shapes negatively affect the concrete mixture’s workability.
Does glass react with cement?
alkali-silica reaction – asr – in a glass tube. I’m often asked: “Does cement react with glass?” Yes, it does, it results in asr. Firstly, fly ash and slag are largely composed of glass; obviously, these react with Portland cement as that is the purpose of adding them to the concrete mix.
Which promotes the alkali aggregate reaction?
The alkali-aggregate reaction is greatly promoted by a relative humidity of 80 % or more. Like all chemical reactions, AAR is affected by temperature. In general the rate of reaction and formation of gel will increase as the temperature rises.
How will the alkali aggregate reaction effect the concrete properties?
The effects of alkali–aggregate reaction (AAR) on concrete and structures start at the microstructural level, that is, at molecular and microscopic levels, such as the formation of reaction products in concrete and associated microcracking, which ultimately leads to macro-level effects such as visual cracking.
What does silica react with?
In ASR, aggregates containing certain forms of silica will react with alkali hydroxide in concrete to form a gel that swells as it adsorbs water from the surrounding cement paste or the environment. These gels can induce enough expansive pressure to damage concrete.
What is alkali concrete?
Alkali–silica reaction is a chemical reaction between the available reactive silica in certain types of aggregates and the alkali hydroxides in the pore fluid of the concrete. The alkalis in concrete are mainly supplied by the cement and, in some cases, by admixtures, aggregates, or the external environment.
How can alkali aggregate reaction in concrete be controlled?
It can be controlled using proper portions of supplementary cementitious materials like silica fume, fly ash, and ground granulated blast-furnace slag. Lithium compounds can be used to decrease alkali-silica reactions.
Why do they put glass bottles in concrete?
The use of empty vessels in construction dates back at least to ancient Rome, where many structures used empty amphorae embedded in concrete. This was not done for aesthetic reasons, but to lighten the load of upper levels of structures, and also to reduce concrete usage.