You can add more Portland cement to bagged concrete to make it stronger. You can also add hydrated lime. To make the strongest concrete, the sand should be sourced from volcanic lava that has a high silica content.
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.
Beyond a certain point, it also acts negatively. Since major force transfer in a concrete/mortar matrix is from sand-sand interaction, excess cement will turn the mortar very brittle since cement particles cannot transfer normal contact force - they are good at providing shear strength.
The compressive strength of concrete can be increased by:
- Including admixtures.
- Adjusting the cement type and quantity.
- Reducing the water/cement ratio.
- Utilizing supplementary cementitious materials (SCMs)
- Altering the aggregates - type and gradations.
Pozzolans, such as fly ash and silica fume, are the most commonly used mineral admixtures in high-strength concrete. These materials impart additional strength to the concrete by reacting with portland cement hydration products to create additional C-S-H gel, the part of the paste responsible for concrete strength.
Strong Concrete Mix Ratio
In making concrete strong, these ingredients should usually be mixed in a ratio of 1:2:3:0.5 to achieve maximum strength. That is 1 part cement, 2 parts sand, 3 parts gravel, and 0.5 part water.
The higher the number, the stronger the concrete. Strength is the result of multiple factors, but is primarily the outcome of the concrete's composition—the ratio of cement, water and aggregate. Pounds per square inch are measured via several methods in labs or, in some instances, on-site.
Add too much water and you'll ruin the concrete. You can add more Portland cement to bagged concrete to make it stronger. You can also add hydrated lime. To make the strongest concrete, the sand should be sourced from volcanic lava that has a high silica content.
Making concrete lighter is possible, though, simply by replacing the aggregate with a lighter material such as pumice. The substitute mixture, known as Pumice-Crete, uses the porous crushed volcanic rock to create a lighter concrete that even acts as a moderate insulator.
Water/Cement Ratio
The ratio of the weight of water to the weight of cement is called Water/Cement ratio. It is the most important factor for gaining the strength of concrete. The lower w/c ratio leads the higher strength of concrete. Generally, the water/cement ratio of 0.45 to 0.60 is used.
Concrete is a very brittle material. If it were not able to relieve its internal stresses by creep, almost all concrete would crack. The stronger the concrete, the greater these internal stresses and the lower the creep capacity.
If too little cement is used, the aggregate mix will not cohere and the concrete will crumble under pressure.
The secret is in the mix. A new concrete mix replaces 40 percent of cement with plentiful materials and byproducts. This formula reduces brittleness and “bounces back” more than traditional concrete. Using non-cement fillers may reduce environmental impact.
If you're not doing a commercial-level project but still want some additional reinforcement for your concrete, a wire mesh is a great (and cheaper) alternative to rebar. Wire mesh use is becoming much more common for projects like a home driveway.
Four-two-one and the Seven Part Mix Ratio
The safest bet for any concrete mix is four-two-one: four parts crushed rock; two parts sand; and one part cement.
Concrete is made from cement, sand, gravel and water.
In making concrete strong, these ingredients should usually be mixed in a ratio of 1:2:3:0.5 to achieve maximum strength. That is 1 part cement, 2 parts sand, 3 parts gravel, and 0.5 part water.
Ultra-High Performance Concrete (UHPC) is a cementitious, concrete material that has a minimum specified compressive strength of 17,000 pounds per square inch (120 MPa) with specified durability, tensile ductility and toughness requirements; fibers are generally included in the mixture to achieve specified requirements ...
Concrete footings and slabs on grade typically require a concrete of 3,500 to 4,000 psi. Suspended slabs, beams, and girders (as often found in bridges) require 3,500 to 5,000 psi. Traditional concrete walls and columns tend to range from 3,000 to 5,000 psi, while 4,000 to 5,000 psi is needed for pavement.
What is this? The tensile strength of concrete is between 10% and 15% of its compressive strength. So, a 6” thick concrete slab with a compressive strength of 3000 to 4000 psi on a prepared base has a tensile strength between 300 and 600 psi.
Steel is the most common material used as reinforcement, but other materials such as fiber-reinforced polymer (FRP) are also used. The reinforcement must be of the right kind, of the right amount, and in the right place in order for the concrete struc- ture to meet its requirements for strength and serviceability.
One 94 lb. bag of Portland Cement makes 4.5 cubic feet of concrete. For thicknesses less than 2 inches and toppings, use: 1 part of Portland Cement with 3–4 parts of concrete sand or general purpose sand.
A piece of concrete in the open air usually shrinks during hardening. This shrinkage is due to the evaporation of part of the water contained in the concrete. Cracking occurs when shrinkage forces become greater than the strength of the concrete.
Flexible concrete is different than traditional concrete in that it has polyvinyl alcohol fibers and very fine silica sand instead of course aggregate. Other fibers such as silica fibers, glass fibers, steel fibers, and asbestos fibers can be used. These micro-fibers give the new concrete its flexibility.