Cement carbonation is a natural chemical reaction
One of the most significant factors in preparing and pouring cement flooring is the cement to water ratio. It takes a consistent and proportionate combination of concrete and water to produce the most optimal results: minimal porosity and a durable final product. Of course, optimal results will be dependent upon the atmospheric conditions present at the time of the pour. For instance, when cement is poured during the wintertime or in cooler climates, carbon dioxide gases released by fossil fuel heating units can upset the carbon dioxide balance of the curing concrete and negatively affect the finished product.
Natural atmospheric concentrations of carbon dioxide can also negatively affect the curing process. During the spring and summertime, carbon dioxide levels in the atmosphere decline due to photosynthesis - or the process by which trees and other plants convert CO2 into oxygen. And, during the fall and wintertime, CO2 levels are increased due to the dormant plant season induced by the arrival of colder temperatures.
Imbalanced carbonation is not only detrimental to the durability of your cement floors but also their appearance. Discolorations and a perpetual expulsion of calcium carbonate dust can occur, when imbalanced carbonation curing has taken place. The discolorations, depending upon the stains or dyes used to stylize your concrete, may be faint and virtually undetectable. They may also manifest as blatant and bold orange discolorations that cannot be overlooked. The calcium carbonate dust that perpetually appears on the surface of your concrete flooring, regardless of how many times you sweep or mop the affected area, is a result of internal sediments being carried to the surface of the concrete by the excess moisture that is forced from the inside of the cement slab outward, where it evaporates leaving the calcium carbonate dust behind.
Soft and porous concrete will chip easily, and it will not hold a shine, but that doesn't mean that all is lost. Addressing a floor affected by imbalanced carbonation can be accomplished by applying densification chemicals to the concrete. When applied, densifiers are absorbed into the cement and react with the free lime calcium to solidify the concrete and fortify its surface to a level of hardness that is comparable to that of granite. Densification can be achieved in as little as two coats, but the process can sometimes take as many as six applications to reach the point of 'full saturation densification.'
If you are dealing with concrete flooring that has been affected by imbalanced carbonation, get in touch with a few different concrete contractors to discuss the imperfections that have manifested - especially if you are uncomfortable dealing with the contractor that poured your flooring to begin with. A bit of insight into the problem can help you choose the best tradesman to repair your damaged concrete flooring.