Reasons for Carbonization of Grouting Materials:

Carbonization of carbonation-proof grout is a form of chemical corrosion that concrete carbonation-proof grout encounters. CO2 gas in the air permeates into the concrete, reacts with its alkaline substances to form carbonates and water, causing the concrete's alkalinity to decrease. This process is known as concrete carbonization, also referred to as neutralization, with the chemical reaction being: Ca(OH)2 + CO2 = CaCO3 + H2O. During hydration, cement generates a large amount of calcium hydroxide, filling the voids in the concrete carbonation-proof grout with a saturated solution of calcium hydroxide. This alkaline medium has a good protective effect on steel bars, causing the surface to form an insoluble Fe2O3 and Fe3O4 film, known as the passivation film.

The alkalinity of concrete carbonation inhibitor grout decreases after carbonization. When carbonation exceeds the maintenance layer of the concrete carbonation inhibitor grout, under the presence of water and air, it causes the concrete carbonation inhibitor grout to lose its protective effect on the steel reinforcement, leading to the beginning of rust formation on the steel.

Importance of Grouting Material Curing

The rushed project schedule has led to an overly fast construction pace, resulting in inadequate curing of the grouting material and subsequent cracking.
2. Failure to use grouting material as instructed, resulting in improper usage of the grouting material.
The initial curing time of the grouting material is crucial for controlling early shrinkage cracks in the product. Water curing should be applied within a few hours after the grout starts to set.
4. The curing of grout material is also related to the properties of the grout mixture, as well as climate, temperature, and humidity. Appropriate curing should be conducted based on the actual environmental conditions.