Achieving the proper consistency and durability when working with concrete is crucial for any building project. The plasticizer is one essential component that raises the caliber of concrete. To achieve the best results, however, how much plasticizer should you add to your concrete mix?
Plasticizers are chemical additions that improve the concrete mixture’s fluidity, which facilitates handling and increases the mixture’s ability to flow into molds and forms. This can be especially helpful when working in confined spaces with limited maneuverability or on projects requiring complex designs. Knowing how much is appropriate to use can save time and effort while maintaining the structural integrity of the work.
Numerous factors can affect how much plasticizer you should add to your concrete mix. These consist of the particular kind of plasticizer, the concrete’s composition, and the surrounding circumstances. The manufacturer’s instructions are usually a good place to start. Small tweaks, though, might be required to get the right combination for your specific project.
It’s also crucial to remember that while too little plasticizer might prevent the desired workability, too much plasticizer can weaken the concrete. Before combining large amounts, you can find the ideal proportion by doing a small test batch. You can achieve the ideal balance that will produce concrete that is strong, long-lasting, and simple to work with with some careful measurement and experimentation.
- Why plasticizers are added
- Impact on turnover
- Plastic
- When transporting the mixture for a long time
- Reduced shrinkage
- Frost resistance
- Increasing properties
- Using concrete pumps
- Proportions per cube of concrete
- Calculation per bucket
- Compliance with the instructions of the manufacturer
- Video on the topic
- PLASTICIZER – additive for concrete | My recipe
- Proportions of plasticizer in cement mortar
- Superplasticizer / how to add to the solution
- Plasticizer in concrete is a horror that cannot be changed
Why plasticizers are added
Concrete becomes more elastic and mobile when plasticizer additives are added. Boost the mixture’s technological capabilities. Boost usability. categorized
- By composition:
- polymer-silicone;
- lignosulfonate (with a surfactant);
- polycarboxylate.
- Self-compacting – removes small air bubbles, increasing the density of the composition,
- Catalytic – accelerate hardening;
- Air-entraining – contain foaming agents that increase the porosity of the material, its heat resistance and frost resistance;
- Antifreeze – ensure the interaction of water with the cement mixture in conditions of slower hydration at low ambient temperatures.
Consider the qualities that require improvement when selecting an additive.
Impact on turnover
One factor that is taken into consideration when preparing a solution for a particular kind of work is fluidity, or mobility.
- Shows the ability of a concrete mixture to fill voids in formwork.
- Increases workability.
The typical solution is still usable two hours after it is prepared. The complex superplasticizers Poliplast SP-1 and S-3 extend the properties’ shelf life to six hours, increase fluidity to 22 centimeters (from the initial 4 centimeters), and cut cement consumption by 15%.
Plastic
An indication that shows how simple it is to lay the mixture and how well it compacts without leaving gaps.
Water-repellent complex additives and monoadditives of organic and inorganic origin offer increased plasticity. Their action’s algorithm:
- Entrains air bubbles into the solution.
- Bubbles are evenly distributed in it.
- Reduce the surface tension of the water entering the mixture.
Concrete gets more pliable. Its ability to repel water increases.
When transporting the mixture for a long time
Additives that stabilize are used to keep the composition homogeneous. After adding them, the solution is still mobile for five to seven hours. Pumping, stacking, and long-distance transportation do not cause it to delaminate.
Reduced shrinkage
Concrete shrinks while it is setting. After solidification is complete, linear dimensions keep getting smaller. When plasticizers are added to the mixture, the following is reduced:
- Shrinkage time – 2.5 times;
- Its value is by 0.6-0.7%.
Frost resistance
Concrete’s grade of frost resistance is raised by plasticizing additives. They are separated according to purpose:
- To special ones that increase frost resistance by reducing pore size to a minimum;
- Complex;
- Water repellents that prevent moisture from penetrating into the hardened structure.
The following is used to raise the class of a concrete mixture in terms of resistance to frost:
- Hardening accelerator additives based on calcium nitrate and sodium nitrate;
- Hardening retardant additives, the main component of which is urea;
- Complex superplasticizer for universal use;
- Lignosulfonate additives.
Increasing properties
Modifiers aid in changing the concrete mixture’s composition and enhancing its quality. A basic illustration demonstrates their efficacy. When the modifier additive was introduced, the composition was in line with the M500 brand. Its quality indicators go up one level after hardening. The structure’s condition indicators are on par with those composed of M600.
Strength accelerators are introduced if you need to reach a certain level of readiness quickly. They drastically cut down on how long it takes to pour a monolith.
Using concrete pumps
The concrete solution becomes more mobile with the addition of plasticizer. Its installation is automatable. Use traditional or truck-mounted concrete pumps to feed the modified concrete. This has no effect whatsoever on the structural strength.
Proportions per cube of concrete
The plasticizer’s concentration in the mixture varies according to the application. ranges between 0.25 and 1.5%.
Typically, we take:
- Polyplast PS-1 – 0.4-0.8% by weight of cement or from 400 to 800 g per 100 kg of cement;
- SPF C3 – 0.25-0.7% or 250-700 g.
The water-cement ratio must be accurately calculated in order to produce a high-quality mortar, keeping in mind that the quantity of cement determines the concrete’s class or grade. The higher the grade, the more of it there is in the mixture. Concrete mix M500 with enhanced strength indicators is in demand for private construction. The table displays the amount of components used to prepare one cubic meter of solution with superplasticizer S-3.
Brand | M500 |
---|---|
Ratio cement:sand:crushed stone:water | 1: 1.7: 2.6: 0.4 |
Cement, kg | 405 |
Sand, kg | 675 |
Crushed stone, kg | 1065 |
Water, l | 180 |
C3, kg | 5-9 |
The scheme is used to calculate the amount of plasticizer.
- Requires 0.4% dry matter input.
- 100 kg of cement will require 0.4 kg of additive.
- It is added in liquid form. The concentration of the prepared solution is 35%. It will take X= 100∙0.4/35= 1.142 kg.
- Conversion to liters using the formula V=m/ρ, where:
- V – volume in l,
- m—mass of dry matter in kg,
- ρ—plasticizer density (given in the table of recommendations for the use of complex additive TU5745-001-97474489-2007).
1 and 1.185 equals 0.963 l.
Calculation per bucket
Scales are not always present on construction sites, especially in small-scale construction. In these circumstances, buckets are used to measure dry components. Ratios for twelve-liter buckets:
Component | The number of buckets |
---|---|
Cement | 25, 9 (405, divide by 15.6) |
Sand | 30 large or 39, 7 small |
Crushed stone | 62.6 |
Water | 15 |
0, 037 l of plasticizer is added for every bucket of cement.
Compliance with the instructions of the manufacturer
The mixture is altered by the modified additives added to it.
- Make more plastic and less porous.
- Improve hydration.
- Increase the degree of frost resistance.
- Enhance strength.
This can only be guaranteed by precise adherence to the manufacturer’s instructions.
- Polyfunctional additives are engaged in domestic and foreign companies. They use identical ingredients. But they can differ in density, concentration and other parameters. There will be a dosage of water differently. It is indicated on the package.
- Each plasticizer additive performs its own function and requires strict dosing. Information about this is included in the instructions for use.
- The instructions for use contain requirements for the operating conditions of the mixture.
Plasticizer Type | Recommended Dosage |
General Purpose | 0.2-0.5% of cement weight |
High-Range (Superplasticizer) | 1-2% of cement weight |
Water-Reducing | 0.5-1% of cement weight |
Retarding Plasticizer | 0.3-0.6% of cement weight |
Achieving the appropriate mix consistency and performance in concrete requires knowing how much plasticizer to add. Concrete can be made more workable and durable by carefully measuring and using the prescribed dosage. A balanced mixture is necessary to prevent potential problems like excessive shrinkage or decreased strength.
When it comes to particular plasticizer products, always follow the manufacturer’s instructions. The recommended ratios depending on the type of concrete and the surrounding conditions are given in these instructions. Depending on the particulars of your project, like the ideal setup time and the site’s working conditions, adjustments might be required.
Finding the ideal amount of plasticizer may be accomplished by testing different amounts on small test batches. By following this procedure, the final mix is guaranteed to function as intended, providing long-term durability along with ease of application. You can successfully improve your concrete mix by following these steps, which will result in a more successful and productive building process.
The quantity of plasticizer added to concrete varies on the particular mix and desired qualities, but as a general rule of thumb, use 0.3% to 1% of the cement weight. Without sacrificing strength, this additive increases durability, lowers water content, and improves workability. To get the best results, it’s imperative to adhere to manufacturer recommendations and make adjustments based on the demands of your project.