Concrete additives are always used in concrete production to improve its mechanical properties and workability. According to the definition in Chapter 9 of the National Building Regulations, an additive is a chemical substance, other than Portland cement, aggregates, and water, that is added in powder or liquid form to modify one or more properties of fresh or hardened concrete. This addition occurs shortly before mixing or during the mixing process.
The amount of concrete additives used is generally small and is not accounted for in the standard mixing ratios. These materials are typically added as a percentage of the cement content in the mix. As specified in Chapter 9 of the National Building Regulations, the maximum amount allowed is 5% of the cement’s weight used in the mixture.
Additives are classified as single-purpose if they affect only one property of concrete, or multi-purpose if they influence multiple properties. Based on the type of material, concrete additives are divided into two categories: chemical additives and mineral additives. According to ASTM C-494, additives are classified into eight types:
The most commonly used concrete additives include air-entraining agents (foam concrete), water-reducing agents, retarders, and accelerators. Although additives are not considered the primary components of concrete, they are so effective and widespread that producing concrete without additives is considered an exception today.
These additives play a vital role in improving the performance and workability of concrete for different construction projects.
Parsman Chemical is a leading manufacturer of concrete additives, utilizing the latest techniques and cutting-edge laboratory equipment from around the world. The company produces a wide range of concrete additives, including superplasticizers, high-range water reducers, normal plasticizers, and products designed to control setting times and foam concrete.
Parsman Chemical is committed to producing specialized products tailored to the specific needs and conditions of various construction projects. The company aims to meet the demands of the construction industry and ensure maximum customer satisfaction.
For consultation and purchasing Parsman Chemical’s products, please contact our experts today.
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Microsilica enhances the adhesion between cement particles and aggregates, thereby reducing the permeability of the concrete. Microsilica particles, which are much finer than cement, fill the pores in the concrete, increasing its strength and reducing permeability.
Neutral mineral additives in concrete do not affect the concrete’s strength but do improve workability and adhesion. These materials typically meet the aggregate requirements for concrete and are used as aggregates in the concrete mix.
Pigments are another type of neutral additive used to change the color of concrete. These color additives come in three forms: powder, granules, or liquid. The powdered form, which has been used the longest, consists of microscopic particles about one-tenth the size of cement particles. These pigment particles are inert, meaning they do not react with the cement but only change the color of the cement during the hydration process.
ASTM C979 is the standard for integrally colored concrete, specifying the amount and type of pigments to be used. The dosage of color additives typically ranges from 1 to 7% of the cement’s weight and should not exceed 10%, as higher amounts can affect the concrete’s strength. Iron oxide is the most commonly used pigment in concrete due to its stability, as it does not fade or wash away over time. The main colors produced by iron oxide pigments are yellow, red, and black, which can be mixed to create a wide range of colors.
Other pigments, such as green (from chromium oxide) and blue (from cobalt), are available but are used less frequently due to their higher cost. Colored concrete has a variety of applications, including decorative structures that require high-end finishes, such as bridges, pavements, and road surfaces, which can help differentiate vehicle lanes or even building facades.
Cementitious-like additives also have latent hydraulic properties. When properly activated, they exhibit cement-like behavior. These additives react similarly to Portland cement only in an alkaline environment with water and, compared to pozzolans, are more similar to ordinary cement. The most common type of this additive is ground granulated blast-furnace slag (GGBFS).
According to **ASTM C-494**, chemical additives for concrete that only reduce water content are classified as **Type A**. If they also have retarding properties, they fall under **Type D**, and if they have accelerating properties, they are classified as **Type E**, though these are less commonly used than Type A. Water-reducing agents with stronger effects are classified as **Type F**. One of the primary uses of water-reducing agents is to increase the workability of the concrete mix for better handling, which is why these agents are often referred to as **plasticizers** or **superplasticizers** when they have strong water-reducing properties.
**Plasticizers** and **superplasticizers** serve three main purposes in concrete mixes:
1. To improve workability without changing the water and cement content, making the concrete easier to pour and place.
2. To reduce the water content in the mix, thus lowering the **water-to-cement ratio (W/C)**, leading to higher strength and greater durability at the same workability.
3. To reduce both cement and water consumption at the same workability level, allowing for cost savings in cement usage.
These additives are compatible with various types of cement, and studies show that their effects are even more pronounced in the presence of **pozzolans**. The difference between plasticizers and superplasticizers lies not in their function but in their intensity of action. **Superplasticizers** can reduce water content by 21 to 31% at a constant slump, whereas **plasticizers** typically reduce water by 5 to 12% for the same slump.
Increasing the dosage of plasticizers can enhance water reduction, but it may also negatively affect the concrete’s setting time, air content, and strength. Typically, plasticizers are used at a dosage of 1.2 to 1.4% of the dry cement weight, while superplasticizers are used at around 1.1 to 1.2%. However, these dosages vary depending on the type of chemical additive and the active substance, and are usually specified by the manufacturer.
From a compositional standpoint, plasticizers are quite different from superplasticizers. The main components of superplasticizers are **synthetic water-soluble polymers**, such as:
– **Sulfonated Melamine Formaldehyde** (SMF)
– **Sulfonated Naphthalene Formaldehyde** (SNF)
– **Acrylic Polymers**, such as **Carboxylic Acrylic Acid Copolymers**.
On the other hand, the primary components of plasticizers are **organic compounds**, which can be classified into four groups:
1. The first group includes **lignosulfonate salts**, which can also be modified to function as superplasticizers.
2. The second group includes **hydrocarboxylic acid salts**.
3. The third group includes **carbohydrates**.
4. The fourth group contains miscellaneous compounds such as **glycerol**, **polyvinyl alcohol**, and others.
Figures 1 to 4 illustrate the chemical structures of some common plasticizers.
Concrete additives, as one of the significant innovations in the construction industry, offer numerous benefits that enhance the quality and performance of concrete. Below are some of the key advantages of using concrete additives:
Increased Concrete Strength
Additives such as polycarboxylate ether improve the compressive strength of concrete. By reducing the water-to-cement ratio while maintaining the mix’s workability, the final strength of the concrete is increased, resulting in more durable structures.
Improved Workability and Flowability
The use of plasticizers and superplasticizers makes the concrete easier to work with and pump. This is especially important in large and complex projects where high workability is essential.
Reduced Water Consumption
One of the most important advantages of concrete additives is reducing the water required in the mix. This reduction not only saves resources but also increases the density and quality of the concrete.
Reduced Shrinkage and Cracking
Some additives help reduce concrete shrinkage and prevent cracking during drying. This leads to increased durability and longevity of concrete in various weather conditions.
Increased Durability and Resistance to Environmental Conditions
Specific additives make concrete more resistant to environmental factors such as moisture, freeze-thaw cycles, chemicals, and corrosive conditions. This is particularly crucial for projects exposed to harsh environments.
Time and Cost Savings
By improving the properties of concrete and reducing curing time, construction projects can save time and reduce overall construction costs.
Extended Lifespan of Structures
Additives improve the mechanical properties and durability of concrete, thus extending the lifespan of structures and reducing the need for repairs and maintenance over time.
These benefits make concrete additives essential for modern construction, contributing to more efficient, durable, and cost-effective projects.
While concrete additives offer numerous benefits in improving the performance and efficiency of concrete, like any product, they may present certain challenges in specific conditions. For example, improper or excessive use of these materials can alter the setting time of the concrete or lead to issues like incompatibility with other materials. However, Parsman Chemical minimizes these concerns by providing high-quality additives and leveraging its team of specialists. With proper guidance and precise usage, our products can be used in your projects without any issues. Selecting the right additives and carefully controlling the dosage is key to achieving optimal results.
While some may point out the potential drawbacks of concrete additives, Parsman Chemical addresses all related concerns by offering advanced and optimized concrete additives. Our products are developed using the latest technologies to deliver the best performance without negative impacts on setting time or compatibility with other materials. Moreover, our expert team provides precise solutions and specialized consultations to assist you in using additives correctly and managing dosage with accuracy. With Parsman Chemical products, you can be confident that all your project needs will be met with the highest quality and efficiency.
Using concrete additives in construction projects not only improves the quality and performance of concrete but also helps save costs, increase structural durability, and enhance resistance to environmental conditions. Parsman Chemical offers a wide range of high-quality additives, making us your reliable partner in achieving excellent results in your construction projects. For consultation and purchasing, contact us today to benefit from our expertise and experience.
