The Value Of Readymix Concrete Admixtures

The Value Of Readymix Concrete Admixtures

by

Maria Tirrasas

In discussing the value of readymix concrete admixtures, it could be appropriate to first analyze the qualities of readymix concrete per se. (RMC) Readymix concrete is concrete that is produced for delivery to a customer\’s building site. Concrete is a mixture of Portland cement, water and aggregates, like mashed stone or gravel and sand. RMC is created in line with a set recipe, and after that transported to a work site by truck mounted transit mixers, to keep the readymix concrete from going -off. The time span before going-off in between batching and placing (ten minutes) can be modified by means of plasticizers allowing an elevated time span, according to the type and level of additive included with the mix.

Readymix concrete admixtures differs from RMC, in that, either chemical or mineral based components are added onto RMC, which creates different traits and properties to the mix, such as dictated by the project style and specs. Chemical admixtures are generally powder based or fluid based ingredients included with RMC to obtain features not possible with plain concrete. Although adding chlorides will increase the moisture of concrete, it has a corrosive effect on any steel used as reinforcement in concrete structures and nitrates are thus preferred. In the event where retardation of the hydration procedure is needed, due to large pours as an example, sugar, tartaric acid or citric acid (polyols) is put into the mix. If the specifications demand a pigmented concrete design, colors may be added to get a new color of concrete, while the inclusion of plasticizers will boost the workability of fresh concrete. Other forms of admixtures will inhibit corrosion, while yet others can provide bonds typically between new and old concrete pours. Mineral based materials (inorganic materials) may be added to standard RMC mixes to boost the properties of concrete. They may also be used to save on the usage of Portland cement as a cost saver or as a more environmentally friendly substance. Commonly used mineral based materials added to RMC are fly ash – developed during the burning of coal -ground granulated blast furnace slag, silica fume – this material is a lot like fly ash but has a smaller particle size and is therefore more potent as a pozzolanic, boosting the power of cement – and metakolin (HRM) while having the same qualities as silica fume has a color advantage, being white, and thus more desirable in architectural structures. By using pozzolans the use of Portland cement can be reduced by as much as 40% when producing concrete, without substantially reducing the final toughness of the product. It is also much more beneficial to our environment than cement, while being less expensive to use than cement. The earliest readymix factory was built in the 1930s, but the industry did not begin to expand considerably until the 1960s. After that the use of readymix concrete has exploded immensely to the extent where there is almost not a medium to large construction site, today, that is not characterized by transit mixers delivering readymix concrete admixtures.

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