How can you improve concrete performance with admixtures?

1 Types of admixtures

There are many types of admixtures available for concrete, but they can be broadly classified into two categories: chemical and mineral. Chemical admixtures are liquids or powders that are added to the concrete mix during or before mixing. They affect the hydration, setting, and hardening of the cement paste, and can improve the workability, strength, durability, and appearance of the concrete. Some examples of chemical admixtures are water reducers, retarders, accelerators, air entrainers, superplasticizers, and corrosion inhibitors. Mineral admixtures are solid materials that are added to the concrete mix as a partial replacement of cement or as an addition. They improve the properties of the concrete by reacting with the cement paste or filling the pores and voids in the matrix. Some examples of mineral admixtures are fly ash, silica fume, blast furnace slag, metakaolin, and rice husk ash.

2 Functions of admixtures

Admixtures for concrete can enhance its performance in various ways, such as improving workability, strength, and durability. For example, water reducers and superplasticizers can reduce the water-cement ratio and increase the slump of the concrete, while accelerators and mineral admixtures can speed up the hydration and strength gain of the cement paste. Air entrainers and mineral admixtures can reduce permeability and shrinkage, while corrosion inhibitors and pozzolanic admixtures can protect the steel reinforcement from rusting and alkali-silica reaction. In addition, admixtures can also make it easier or harder to place, compact, and finish the concrete mix. All of these functions are essential to ensure that the concrete is of high quality and meets the required standards.

3 Benefits of admixtures

Admixtures for concrete can be beneficial in terms of cost-effectiveness, aesthetics, and sustainability. For instance, water reducers and superplasticizers can reduce the amount of cement and water required to achieve a certain strength and workability. Additionally, pigments and fibers can improve the appearance of the concrete, while admixtures that improve the workability and density can reduce surface defects. Furthermore, mineral admixtures can utilize industrial by-products and agricultural wastes as supplementary cementitious materials, while admixtures that enhance durability and service life reduce the need for maintenance and repair. All of these benefits can help to reduce the carbon footprint, waste generation, and resource consumption of the concrete industry.

4 Here’s what else to consider

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