Collection: Admixtures

Concrete Admixtures 

Concrete admixtures enhance the characteristics of both fresh and hardened concrete. They are categorised into two main types: chemical and mineral admixtures, each offering distinct qualities that contribute to improved workability, durability, and strength of concrete.

Chemical admixtures affect concrete properties through chemical interactions. They are categorised into five distinct classes based on their functionalities as each chemical admixture achieves different results ranging from decreasing permeability and enhancing flowability to controlling the speed by which concrete sets. Superplasticisers are high-range water reducers that enhance flowability without compromising its structural integrity. Accelerators speed up the setting time and are typically used in cold weather applications. Set retarding admixtures slow down the setting time, making it ideal for hot weather applications or when transportation is extended. Air-entraining admixtures introduce air bubbles into the concrete mixture, improving workability and resistance to freeze-thaw cycles. Water reducers allow for a reduction in the water content of the concrete mix while maintaining its workability, increasing the strength and durability of the concrete while decreasing permeability. Chemical admixtures reduce the cost of construction and modify the properties of hardened concrete to ensure the quality of the concrete admixture is enhanced during transportation, mixing, curing and placing. 

Mineral admixtures are finely ground materials that are added to concrete to alter its physical properties and are often by-products of industrial processes or natural substances. They are used to change the properties of the concrete in hot weather conditions, making the concrete more cohesive, durable and less permeable. This helps concrete to withstand extreme temperatures and minimises the risk of cracking due to thermal expansion. The types of minerals used in concrete include silica fume, fly ash, metakaolin, rice husk ash and granulated blast furnace slag. These admixtures are mostly derived from other substances and are not chemically manufactured.