Concrete Basic 101: Properties, Additive Ratios and Quality Control

Concrete ranks among the most extensively utilized construction materials globally. In fact, it ranks as the second most consumed material globally, second only to water. Virtually every type of construction project involves concrete in some form. For example, highways and bridges to skyscrapers and parking lots. Its versatility, durability, and longevity make it a vital choice for the construction industry.

 

 

 

1. Basic Properties of Concrete

Concrete is comprised of three key ingredients: fine and coarse aggregates (such as sand, rocks, or gravel), portland cement, and water. These materials each play distinct chemical roles in the formation of concrete due to cement being hydraulic cement. Its strength derives from a chemical reaction with water. When portland cement and water combine, a chemical reaction called hydration occurs. Through this process, a cementitious paste envelops the aggregates. Bonding them together and gaining strength as they harden. Resulting in the formation of concrete.

 

Concrete Manufacturing

When producing concrete, you have the flexibility to adjust the mix. For example, varying the ratio of fine to coarse aggregates. Fine aggregates can increase concrete volume. In contrast, coarse aggregates provide the necessary strength to support heavy loads. Additionally, various concrete admixtures can be introduced into the concrete mix.

 

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2. Additives of Concrete

In recent years, new construction methods have emerged. This involves high-rise buildings, large-span structures, and various construction techniques. For example, large-volume concrete, shotcrete, and slip-form construction. As a result, concrete has been subjected to a wide range of performance requirements.

 

Balancing Concrete Performance

The proportions of its key ingredients determine the performance of concrete. They are cement, sand, aggregates, and water. Aiming to enhance a specific aspect of concrete’s performance. It is possible to adjust the ratio of these raw materials. But, this approach often results in trade-offs. For instance, increasing water content to improve concrete’s flowability may compromise its strength.

 

plasticizers vs superplasticizer

 

 

3. Concrete Mix Ratio

 

3.1 The Role of Concrete Additives

Concrete additives, like those offered by WOTAIchem, are engineered to address these challenges. They enable the improvement of concrete’s performance without sacrificing other critical properties. For example, incorporating a mere 0.2% to 0.3% of a water reducer into the concrete mix. It is possible to significantly increase the slump without adding more water. Similarly, adding 2% to 4% of calcium formate into the mix without increasing cement content. It can boost early strength by 60% to 70% and enhance long-term strength.

 

3.2 How to Calculate the Concrete Mix Design?

Precision in weighing concrete components ensures quality and resource efficiency. Generally, weight-based tolerances of ±2% for cement, water, and admixtures apply. Aggregate weighing permits ±3% tolerance due to material variations. Considering differences in moisture and density. The weight-based mix design can prove more accurate than volume-based methods.

 

3.3 The Quality of Water Used in Concrete

The concrete water content is a big matter. Water with industrial impurities is unsuitable for concrete mixing. For example, fats, vegetable oils, sugars, and acids. These impurities diminish the bonding strength of cement. Finally, this leads to reduced concrete strength. So, high salt content in mineral water can impair cement’s resistance to water intrusion. Mineral water must meet specific chemical composition standards or pass strength tests against regular potable water before use.

 

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4. Why Is the 28 Days Compressive Strength of Concrete Generally Specified?

Concrete gains compressive strength through the binding action of cement and the process of hydration. The cement hardens progressively over time, reaching optimal strength. Under normal curing conditions, compressive strength increases rapidly in the first seven days. And a slower growth between days 7 and 14. Beyond 28 days, strength development slows considerably. Making it the standard strength benchmark for design and construction quality assessment.

 

In brief, using a strength standard lower than 28 days would limit concrete’s performance. Setting a strength standard higher than 28 days can lead to longer construction schedules and delays.

 

 

 

5. How to Properly Cure Concrete?

 

5.1 Natural Curing

Concrete can be cured by exposing it to environmental conditions where the temperature remains above +5°C. And the humidity levels range between 90% to 100%. But, it’s important to note that concrete’s strength development is quite slow under these conditions.

 

Within the initial seven days, concrete typically reaches only 30% to 70% of its 28-day strength. Achieving the necessary strength for formwork removal and factory standards may take a considerable amount of time. It can result in extended production cycles. Necessitating significant investments in formwork equipment and consuming substantial production space. As a result, overall infrastructure costs may increase.

 

5.2 Steam Curing

For faster concrete strength development, steam curing can be employed. In this method, concrete is subjected to steam. It can accelerate the hardening process. It is achieved by maintaining higher temperatures. It is usually within the range of 70°C to 90°C. Ensuring elevated humidity level around 90% or more. Steam curing is especially valuable when time-sensitive projects demand quicker strength gain.

 

5.3 Climate Considerations

In regions characterized by consistently warm and sunny climates, natural curing remains a cost-effective and efficient choice. This approach can reduce expenses related to specialized equipment.

 

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6. Conclusion&WOTAIchem

The choice of concrete components, measurements, and admixtures can make all the difference in performance. It’s essential to remember that concrete’s strength doesn’t stop at its initial setting. The decision between natural and steam curing depends on various factors. For example, timelines and environmental conditions.

 

At WOTAIchem, we recognize the role concrete additives play in enhancing concrete performance. We provide a range of high-quality additives to meet your construction needs. With our concrete additives, you can achieve the desired flowability, early strength, and other properties without compromising on durability.

 

– Concrete fibers(PET, PVA, PPF, PAN Fibers).
Superplasticizers(PCE, SM).
Calcium formate.
Antifoaming agents.

 

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The SOE group backs us. This background boasts substantial R&D and production facilities. With over two decades of experience in construction additives, we are committed to providing various additive OEM solutions. Our team can offer you customized formulations with technical support. Ensuring that your construction projects receive the individualized attention they deserve.

 

With WOTAIchem, you’re not just a customer; you’re a partner in achieving exceptional results. If you’re looking to elevate your projects, consider incorporating our additives into your mix! Contact us today to explore how our additives can take your projects to the next level.

 

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Posted by Isabel

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