How to make concrete last 100 years

Summary

In this video, Tyler Lai explains how to make concrete last for 100 years or more. He emphasizes the importance of creating high-quality concrete through key practices like controlling the water-cement ratio, consolidating the mix to remove air bubbles, and curing it properly to promote hydration. Tyler also shares tips on using additives like water reducers and air entraining agents, and introduces advanced techniques such as incorporating fly ash, slag, or silica fume to extend concrete’s lifespan. This guide offers both practical tips for DIYers and insights for larger-scale concrete projects.

Takeaways

• 😀 To make concrete last for 100 years, you need to focus on making great concrete, maintaining it well, and ensuring smart design.
• 😀 The key to long-lasting concrete lies in the paste (water + cement), not just the aggregate (rocks and sand).
• 😀 A low water-to-cement ratio is essential for strong, durable concrete. For most DIY projects, aim for a ratio between 0.40 and 0.45.
• 😀 Concrete with a lower water-to-cement ratio has stronger load-bearing capacity and better resistance to water penetration.
• 😀 Ensuring very small cement grain spacing helps to eliminate large voids inside concrete, which can weaken it and allow chemicals or water to penetrate.
• 😀 Use water-reducing admixtures to keep concrete flowable even with a low water content, aiding in the ease of mixing and pouring.
• 😀 Proper consolidation of concrete is vital; using vibrators or tapping the forms helps remove air bubbles and prevent voids that weaken the structure.
• 😀 Proper curing is crucial. Concrete needs to stay moist and warm during the early stages of hydration to form strong bonds.
• 😀 If you're working in freezing conditions, consider adding an air-entraining admixture to your concrete to prevent damage from freezing and thawing.
• 😀 Advanced techniques, such as using fly ash, slag, or silica fume, can further enhance the concrete’s durability and double its service life.
• 😀 Make sure to experiment and learn what works best for your concrete projects, and share strategies with others for the longest-lasting results.

Q & A

What is the main goal of the video?

The main goal of the video is to explain how to make concrete last for 100 years, sharing techniques and best practices for creating long-lasting concrete.

What are the three main steps to ensure concrete lasts a long time?

The three main steps are: 1) Making great concrete, 2) Maintaining concrete, and 3) Using smart designs. This video focuses on the first step—making great concrete.

What is the typical composition of concrete?

Concrete is typically composed of about 75% aggregate (such as sand and rocks) and 25% cement paste (water and cement). The paste binds the aggregate together.

What is the water to cement ratio, and why is it important?

The water to cement ratio is the amount of water divided by the weight of cement in the mix. A lower water to cement ratio creates stronger concrete because it results in more closely packed cement particles, reducing voids and improving durability.

What is the ideal water to cement ratio for typical concrete?

For typical concrete exposed to extreme weather, the ideal water to cement ratio is between 0.45 and 0.35. For DIY projects, a ratio between 0.40 and 0.45 is generally sufficient.

How does the water to cement ratio affect the concrete's strength?

A lower water to cement ratio creates concrete with closely packed cement grains, which makes the concrete stronger by better distributing loads and reducing the likelihood of water and chemicals entering the concrete.

Why is it important to consolidate concrete during the pouring process?

Consolidation is crucial because it removes air voids that can weaken the concrete and create pathways for water and chemicals to penetrate. This is done using tools like vibrators or tapping forms.

What is the role of curing in concrete durability?

Curing helps to maintain moisture and warmth in the concrete, which promotes hydration. Proper curing allows the chemical reactions to complete, resulting in stronger and more durable concrete.

What is an air-entraining admixture, and when should it be used?

An air-entraining admixture is a chemical added during mixing that creates microscopic air bubbles in the concrete. It is particularly important in freezing environments to protect the concrete from damage caused by freezing and thawing cycles.

What are supplementary cementitious materials (SCMs), and how do they enhance concrete durability?

Supplementary cementitious materials, like fly ash, slag, and silica fume, are used as partial replacements for cement. They cause additional chemical reactions that improve concrete's durability, potentially doubling its lifespan.

What are the recommended replacement levels for fly ash, slag, and silica fume in concrete?

The recommended replacement levels are: fly ash can replace up to 20% of the cement, slag can replace up to 40%, and silica fume is usually capped at 5%. These replacements are based on the mass of the cement.

Why is proper consolidation and curing essential for concrete longevity?

Proper consolidation ensures that air voids are removed, which strengthens the concrete. Proper curing ensures the hydration process continues, creating stronger bonds and improving the concrete's durability and resistance to external factors like water and chemicals.