Admixtures are extra materials – natural or artificial added to a concrete mix during or before mixing to change concrete’s properties as required for the project.
Functions of concrete admixtures
- To delay initial setting time during long-distance concrete pumping.
- To enhance strengthen development stage at early ages. The widely used accelerator is calcium chloride.
- To enhance workability without any changes in the water content. Generally, Pozzolana is used.
- To escalate resistance towards thawing or freezing. For this purpose, the vinyl resin is used.
- To accelerate water tightness.
- To lessen heat evolution.
- To lower capillary water flow.
- To decrease bleeding & segregation rate.
Concrete admixture types
Chemical admixture types
Bisley International is a leading manufacturer of mineral and chemical admixture types. Chemical admixtures decrease construction cost, modify hardened concrete’s properties, ensure concrete quality during mixing, placing, curing, and transporting. Thus, it helps to overcome specific concrete operation emergencies.
- Accelerating admixtures enhance hydraulic cement’s hydration rate and reduce setting time.
- Retarding admixture delays cement paste’s setting time.
- Water-reducing admixture increases or maintains the work ability of the freshly mixed mortar.
- Super plasticizing admixture offers high flow ability with a large water content decrease.
- Air-entraining admixture entraps air in tiny bubble forms during mixing of the mortar to resist freezing and thawing as well as enhance its work ability.
Mineral admixture types
Mineral admixtures reduce permeability, enhance strength, impact other concrete properties, and are more economical. Use them with any kind of cement or in combination or individually.
- Fly ash makes concrete easy to work with, stronger, and durable.
- Rice husk ash helps to reduce heat hydration and permeability.
- Blast furnace ground granulated slag is used as a supplementary cementitious material. The aggregate has low thermal conductivities and is beneficial in applications like frost tapers or pavement bases over the frost susceptible soils.
- Silica fumes for early-stage strength and decreases permeability.
The processing procedures used for preparing concrete mixture includes –
Raw material -> Drying -> Pre-crushing & Grinding -> Sorting -> Storing -> Transporting
Grinding & sorting is the main feature of concrete admixture processing. There are two types of processing equipment used for concrete admixture production – the drying-ball mill powder selection system and the vertical mill system. The former traditional mill has a small area and low processing cost advantages. The latter system incorporates drying, grinding, and powdering options.
The equipment to choose for concrete admixture processing will depend on the blended raw material nature, particle size, and finished product’s fineness.
How good concrete admixture is produced?
Choose high-quality raw materials
The raw materials have to undergo a radioactivity test. It needs to have a high level of helpful components and less harmful substances like soil, moisture, and chloride ions.
Select a mill with low power consumption
Raw materials with low moisture like slag can use the vertical mill with energy consumption 55% to 77% of the dry ball milling process.
Reduce admixture’s raw material cost
Use nearby waste materials like limestone carving waste, marble scraps, broken ceramic glass, and more to reduce the transportation and purchase costs of raw materials.
Control the admixture processing
Raw materials already exposed to severe heat like steel slag, blast furnace, and broken glass-ceramics carry huge fine grinding cost.