If you don't have enough portland cement, your concrete will be weak and not very sturdy. If you have too much, it can lose its desired shape since the bond between particles is so strong. 1 part cement to 2 parts aggregate by volume, with 5 parts water.
The Right Mix of Materials Cement and water act as the paste of the concrete. If you don't have enough paste, the concrete will dry with a honeycombed surface and may be too porous. If you have too much paste, the concrete will be easy to spread but more likely to crack when it dries.
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.
How thin can you pour concrete over concrete? Your new layer needs to be at least 2 inches thick. If it's any thinner than that, it'll easily crack under pressure and won't adequately bond to your surface.
When too little water is used or if water evaporates out too quickly, the cement never reaches a full chemical cure, causing a weakened product.
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. Too little water leads to structurally weak concrete, and too much will disrupt effective curing and cause flaking, shrinking, divots or cracks.
Although dry pouring of concrete might be fine for filling fence-post holes, it should be avoided as a placement method for concrete slabs if you want the concrete to look good and last for the long term.
The strength of concrete increases when less water is used to make concrete. The hydration reaction itself consumes a specific amount of water. Concrete is actually mixed with more water than is needed for the hydration reactions. This extra water is added to give concrete sufficient workability.
Too much water added to the mix means that excess water is retained inside the concrete after the curing process has finished. This will often result in the formation of small cracks as the water eventually evaporates over time, which reduces the compressive strength of the concrete.
The thinnest that is usually used when pouring concrete, in general, is about 2 to 2 ½ inches. That also applies to this pouring new concrete over old concrete. Any thinner than 2 inches would be too thin.
Adding more water to the concrete increases workability but more water also increases the potential for segregation (settling of coarse aggregate particles), increased bleeding, drying shrinkage and cracking in addition to decreasing the strength and durability.
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.
Technically, concrete never stops curing. In fact, concrete gets stronger and stronger as time goes on.
Unsound concrete can be identified through various signs such as visible cracks, micro-cracks, spalling, scaling, blisters, and delamination. Multiple factors lead to different types of damages, and as a result, a specific repair strategy may be required for each type of concrete damage.
Applied-load cracking.
In residential concrete, 4 inches is the minimum thickness for walkways and patios. Garage slabs and driveways should be 5 to 6 inches thick if any heavy truck traffic is anticipated, otherwise 4 inches is adequate.
When a concrete mixture is too wet, it causes a greater amount of shrinkage during the drying process than is needed. As a result, the concrete has a great likelihood of cracking and for those cracks are likely to be a fairly good size.
SSS or sweating slab syndrome is a phenomenon where moisture intermittently develops on the surface of an interior concrete slab. When warm air comes into contact with a colder temperature concrete slab, the condensation will build up on the surface and can commonly be defined as concrete sweating.
“If the surface of a floor slab is colder than the dew point temperature of the ambient air above the slab, moisture will condense on the surface of the slab. This condition, commonly called “sweating,” typically occurs when warm, moist air flows into a building that has relatively cool floors.”
DO spray new concrete with water. One of the most common methods for curing concrete is to hose it down frequently with water—five to 10 times per day, or as often as you can—for the first seven days. Known as “moist curing,” this allows the moisture in the concrete to evaporate slowly.
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.
Water containing bicarbonate ions and carbon dioxide causes a reaction known as carbonation in concrete. This often happens in the presence of salts and acid rain. As the acidic substances lower the concrete's pH, the calcium carbonate within the aggregates dissolves and reduces the concrete's strength.
Yes, you can pour fresh concrete over existing concrete. As long as your concrete is in mint condition, this task is doable. If you decide to pour a new mixture over an old slab, be sure it is at least 2 inches thick.
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.
Patching is the simplest and most common way to fix concrete. To patch a surface, you simply apply a new layer of concrete over the old one. This new layer can be textured or smooth, depending on your preference. Patching is ideal for small areas that are damaged or cracked.