Chemicals Used in Concrete
| Chemical Name | Formula | Abbreviation | Purpose/Property |
|---|---|---|---|
| Tricalcium Silicate | 3CaO·SiO₂ | C₃S | Early strength development |
| Dicalcium Silicate | 2CaO·SiO₂ | C₂S | Later strength development |
| Tricalcium Aluminate | 3CaO·Al₂O₃ | C₃A | Rapid reaction, contributes to heat of hydration |
| Tetracalcium Aluminoferrite | 4CaO·Al₂O₃·Fe₂O₃ | C₄AF | Color + minor strength gain |
| Calcium Hydroxide | Ca(OH)₂ | Hydration byproduct, affects durability | |
| Gypsum (Calcium Sulfate) | CaSO₄·2H₂O | Controls setting time | |
| Fly Ash | SiO₂, Al₂O₃ | Pozzolanic, improves strength & workability | |
| Silica Fume | Amorphous SiO₂ | Increases strength, lowers permeability | |
| GGBS (Ground Granulated Slag) | CaO, SiO₂, Al₂O₃ | Improves durability | |
| Superplasticizer | Polycarboxylate Ether | PCE | Enhances flow without water increase |
| Plasticizer | Lignosulfonates | Improves workability | |
| Retarder | Sugar, Citric acid | Delays setting | |
| Accelerator | Calcium Chloride | CaCl₂ | Speeds up setting |
| Air Entraining Agent | Vinsol resin, sulfonates | Freeze-thaw resistance | |
| Corrosion Inhibitor | Calcium Nitrite | Ca(NO₂)₂ | Protects steel rebars |
| Waterproofing Agent | Silanes, Siloxanes | Reduces water absorption | |
| Shrinkage Reducing Admixture | Polyethylene glycol | PEG | Minimizes shrinkage cracks |
| Lithium Nitrate | LiNO₃ | Prevents Alkali-Silica Reaction | |
| Curing Compound | Paraffin-based emulsions | Retains moisture for curing | |
| Form Release Agent | Vegetable or mineral oils | Eases mold removal | |
| Bonding Agent | Styrene-Butadiene Rubber (SBR) | Enhances old-to-new concrete bonding | |
| Epoxy Grout | Bisphenol-A Epoxy Resin | High-strength repair bonding | |
| Microbial Agents (Self-healing) | Bacillus subtilis capsules | Cracks heal with bacteria-induced CaCO₃ | |
| Nano-silica | SiO₂ nanoparticles | Fills pores, strengthens matrix |
