Start by adding dry
Fast-setting concrete is ideal for setting posts because there's no mixing—you simply pour the dry concrete from the bag right into the hole, then add water.
Water facilitates the curing and hardening processes. Without it, the chemical reactions needed to form the hard crystals that give the concrete its strength can't take place.
The water causes the hardening of concrete through a process called hydration. Hydration is a chemical reaction in which the major compounds in cement form chemical bonds with water molecules and become hydrates or hydration products.
Concrete that is not moist-cured at all dries too rapidly, and reaches less than half its potential design strength. It will also have a greater number of shrinkage cracks.
You can mix an appropriate amount of water with just the “portland cement” and let that harden without any sand or rock add. You will get a VERY hard rock-like product.
Many construction specialists recommend watering it down five to ten times per day, for the first week, starting 2-4 hours after it has been poured. The first two to four hours lets the concrete “finish”, which refers to the setting process.
If your concrete mix is too wet it will also be more porous once cured, making it difficult to achieve the desired finish and potentially making it not fit for purpose. In short, a concrete mix that is too wet could seriously impact the durability, longevity and strength of your project.
It is important to keep in mind that dry-pour concrete may not offer the same level of strength and durability as wet-mix concrete. Dry-pour concrete can also be more prone to cracking and shrinkage, which can lead to structural issues and the need for costly repairs over time.
HOW DOES RAIN AFFECT CONCRETE? Rain falling on top of freshly laid concrete can damage the surface and compromise a level and floated finish.
Add enough water to make the mix wet enough to ensure good hydration, but not so wet that the concrete mix becomes soupy. If you've over-poured water just add more dry mix and incorporate it until you achieve a good mix.
Concrete hardens as a result of the chemical reaction between cement and water (known as hydration and producing heat). For every mass (kilogram, pound, or any unit of weight) of cement (c), about 0.35 mass of water (w) is needed to fully complete the hydration reactions.
Measure the recommended water amount (each 80-pound bag of concrete mix will require about 3 quarts of water). Pour approximately 2/3 of the water into the depression. If using liquid cement color, add to the mixing water.
Spraying water on your new concrete is one of the best and oldest ways to cure your concrete. After new concrete is poured and finished the concrete begins its curing process.
As long as the concrete is given 4 to 8 hours after mixing and finishing to set up, rainwater won't affect it nearly as badly as it could. Some concrete mixes will actually benefit from rainwater on the surface because it's beneficial in aiding the hydration and curing process.
When moisture contacts the calcium-rich crystalline material, calcium silica hydrates form, which in turn bond the glass particles in the ash. This reaction is similar to portland cement hydration. “That's why it's often referred to as the 'poor man's portland cement,'” Bergeson says.
Concrete is rated on a system that indicates the strength of the mix after it's cured for approximately a month. To make the concrete stronger, add more cement or less sand. The closer you bring the ratio to an even one-to-one of sand to cement, the stronger the rating becomes.
What is the difference between cement and concrete? Although the terms cement and concrete often are used interchangeably, cement is actually an ingredient of concrete. Concrete is a mixture of aggregates and paste. The aggregates are sand and gravel or crushed stone; the paste is water and portland cement.
Moist curing is a common method of concrete curing. It involves wetting the concrete slab often with water (5-7 times per day) for the first 7 days. This method ensures your concrete slab will be extremely strong and durable, because it allows the moisture to evaporate slowly, preventing cracks and shrinks.
Wet the concrete, then place the plastic sheeting over it. Use bricks, boulders, or stakes to hold the plastic in place and keep small animals out. Once a day, remove the plastic sheet and wet the concrete, then replace the cover. Do this for a week for the best results.
Only pour concrete at a well-prepared job site with a drained and compacted base of soil to start on. Acquire all necessary permits and determine the location of any underground plumbing or wiring. Additionally, prepare all materials for building the concrete forms. A 4- to 6-inch compact base is common.