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Fertilizers, chemicals, and de-icing salts can sometimes have bad effects on good concrete. This includes properly cured concrete, low ratios of water-cement, and properly placed ratios. Due to this, neither fertilizers nor de-icing salts ought to be used on concrete in its first year of placement.
De-icing salts might not be good even after the first year as efflorescence is connected to the salts in concrete. It also often shows in concrete that is de-iced.
The bad news is that many cities use up chemicals and salts on concrete more rapidly than they should. People walking on sidewalks or even road vehicles can be tracked into the concrete.
In addition, boots, undercarriages of vehicles and tires easily pick up salt. There needs to be proper care for concrete protection.
When the weather allows, you need to inform snow removal contractors to immediately remove the snow and ice and not just let it melt. Usually, contractors remove the bare ice and snow minimum and then put too much salt before moving on to their next job.
How concrete is made and effects of salt
To understand how damaging freeze-thaw cycles and salt is on concrete, you first need to comprehend the nature in which concrete becomes hardened.
Four components make up concrete. These are cement, water, fine aggregate, and coarse aggregate. The cement and water turn into a paste that reacts with coarse and fine aggregates to form the hardened material we term as ‘concrete’.
The process of curing comes from a chemical reaction called hydration. This is a process that needs a combination of water and cement.
As this combination occurs, the compounds interact with the aggregate material. When properly combined, there is minimum space between the aggregates.
The aggregate gradation is a must for concrete durability to occur. Using many different aggregate sizes, the concrete mix’s voids are filled with aggregate.
Cement manufacturing process
The binder, or the cement, is made from clay and limestone. These are ground and crushed before being heated to three thousand degrees Fahrenheit.
This process makes new compounds that create the cement. The ratio is as follows: fifty percent tricalcium silicate, twenty-five percent dicalcium silicate, ten percent tricalcium aluminate, ten percent tetra-calcium aluminoferrite, and five percent gypsum to control settings. Heat is created as a result of this reaction:
Tricalcium silicate + water = calcium silicate hydrate + calcium hydroxide + heat.
When the hydration process begins and the four components are combined in the concrete mix, much of the water is used up.
The water for mixing that gets unused in the process is left behind and creates small concrete voids. In the end, the less void, the better the concrete.
The lower the water-cement ratio, the stronger your concrete. Lower ratios result in less porosity since there are fewer voids for the chemicals and the water to get into the concrete, thus increasing its durability.
The less the distance between the aggregates and the cement grains, the stronger your concrete.
Curing time
Concrete needs the correct amount of time to gain durable strength and cure. As a chemical reaction takes place, the cement and water paste lock into the aggregates creating a mass that is hard as a rock.
Many people mistakenly believe that when the concrete becomes hardened the next day, it is done. This is far from the truth and hydration is a phase similar to growing plants: the longer the time passes, the stronger the plant (and the concrete) becomes. This takes years.
Good concrete development takes several years to develop and is dependent on many factors. The water in the concrete mix evaporates over time, but the longer it stays in, the stronger the concrete. This process is termed ‘curing times.’ Most mixes of concrete achieve seventy-five percent of their strength in the first twenty-eight days.
Salt and efflorescence
As a superb material for surfaces that are decorative because of its minimal maintenance requirements, durability, and strength, concrete has issues you need to address when it settles or ages.
It’s not new knowledge that concrete discolors or cracks over time. A lesser-known but equally important issue is efflorescence.
This white powder rises to the concrete surface and occurs with both decorative and plain concrete. It is important to know how to remove or prevent it when this situation occurs.
What is efflorescence?
Created out of salt deposits that gather in the concrete surface over time, Efflorescence is an issue you need to know how to address.
Since salt is commonly found in cement along with the aggregates utilized for mixing concrete, unless the concrete is completely sealed on every side, which is virtually impossible when laying ground concrete, water will seep into the material.
As it moves through the concrete, water dissolves the salt it contains and carries it all the way into the surface. Upon exposure to the elements, the water then evaporates and leaves behind a salt residue.
This process becomes more apparent in moist conditions like in regions with high humidity, automatically watered lawns, and rainy climates. When this process continues, this buildup becomes very significant. It can be very visible on colored or patterned surface concrete and destroy the design very significantly.
Efflorescence removal
Many times, efflorescence is a powder that washes off when it rains or can be easily removed using a broom or a hose. If it remains, it eventually gets hard and becomes very hard to clean.
Dissolved salt that has been re-deposited many times can harden and crystallize on surface concrete. This results in an overall whitening of the area of concrete or white patches.
Dried-on or crystallized efflorescence may be removed with scrubbing using a mild soap and a brush, or with power washing.
For hard stains, use a specialty concrete cleaner recommended for touch stains and efflorescence. If these solutions do not work, use an acid solution.
Acid solutions must not be used unless absolutely needed, however since these have a tendency to cause surface deterioration on both the design patterns and the concrete.
If you do use these, you need to neutralize this after using and then reseal the concrete surface. If you utilize an acid solution, wear protective gear and follow all the instructions carefully.
Efflorescence prevention
Proper maintenance and installation of concrete prevent efflorescence from returning and occurring. Effective solutions for drainage are important to keep moisture away from concrete.
This includes drains under the concrete or away from the area. Make sure that no drainage occurs from other sources like from downspouts; empty out on the surface concrete.
Sealers of concrete are quite effective against situations of efflorescence. These prevent moisture from getting into the surface concrete though moisture may come from beneath still.
This causes efflorescence buildup beneath the sealant that is hard to remove. If efflorescence becomes a problem, a sealer for penetration is the ideal choice.
This gives a barrier to surface moisture and flows through the concrete, thus eliminating the paths through which moisture is able to travel.
Conclusion
Efflorescence might be an annoying problem, but it can be protected against. It should not be done only for aesthetics, but also to protect the rebar in the concrete. Salt and water will make it rust and it will cause the concrete around it to weaken and crack.
Freeze thawing is another problem de-icing products cause and you can imagine what happens when water gets to concrete cracks and freeze and melts multiple times. It will widen the cracks.
