Concrete 101: Understanding Admixtures & Additives

When most people think of concrete, they picture the basic mix — cement, water, sand, and gravel. But did you know that what goes into a mix can be adjusted depending on the job? That’s where admixtures and additives come in.

These are ingredients added in small amounts that change how concrete behaves. A few common ones include:

Plasticizers (Water Reducers): Make the mix easier to work with without adding extra water. Great for tight rebar work or decorative pours.
Accelerators: Speed up set time — handy for cold weather pours.
Retarders: Slow down set time, giving crews more working time in hot weather.
Air-Entraining Agents: Add tiny air bubbles that protect against freeze-thaw damage. Perfect for driveways and sidewalks in cold climates.
Fibers: Tiny reinforcements that help reduce cracking and add durability.

Why it matters: Admixtures help tailor the concrete to the job’s specific needs, saving time, money, and reducing potential problems. Whether it’s finishing a slab faster, keeping cracks at bay, or pouring in tough weather, additives make the mix smarter.

👉 Next time you see a truck backing up, remember — there’s more science in that drum than meets the eye!

⚠️ Legal Disclaimer:
This blog post is intended for informational purposes only and should not be taken as professional, legal, or construction advice. Every project is unique, and conditions may vary. RLW Concrete LLC is not liable for any actions taken based on this information. Always consult with a qualified professional or attorney for your specific needs.
License #PA65009

Comments

Why It Matters Wednesday: Why Pozzolans Matter

Why Pozzolans Matter Concrete is more than just cement, water, and stone. One of the most important ingredients used to improve concrete performance is something called a pozzolan . Pozzolans play a critical role in making concrete stronger, more durable, and longer lasting. What is a Pozzolan? A pozzolan is a material added to concrete that reacts chemically with calcium hydroxide during the curing process. This reaction strengthens the internal structure of the concrete and improves its overall performance. Common pozzolans include: Fly ash Silica fume Slag cement Natural volcanic materials These materials enhance concrete beyond what cement alone can achieve. Why Pozzolans Matter Pozzolans significantly improve concrete quality in several ways: Increased Strength Pozzolans strengthen the internal bond within the concrete, resulting in a stronger final product. Improved Durability Concrete with pozzolans is more resistant to weather, moisture, and wear....

Concrete 101: A Brief History of Concrete

Concrete 101: A Brief History of Concrete RLW: The Mixer Minute Concrete is one of the most widely used building materials in the world today—but it’s not a modern invention. Its history stretches back thousands of years, proving just how reliable and versatile it is. Here’s a quick look at concrete through the ages. ✅ 1. The Ancient Origins The earliest forms of concrete date back to ancient civilizations. The Egyptians used a mixture of mud and straw for bricks and later developed a lime and gypsum mortar. But it was the Romans who perfected the use of concrete, mixing volcanic ash with lime and water to create structures that still stand today. ✅ 2. Roman Concrete Marvels The Romans built roads, aqueducts, and massive structures like the Colosseum and the Pantheon dome using concrete. Their formula allowed the material to resist cracking and even grow stronger over time when exposed to seawater. ✅ 3. Concrete Disappears—and Returns After the fall of the Roman Empire, ...

FAQs: Why Does Concrete Crack?

FAQs: Why Does Concrete Crack? One of the most common questions we hear at RLW Concrete LLC is: “Why does concrete crack?” The short answer? All concrete cracks. The important part is why it cracks and how it’s managed. Let’s break it down 👇 ❓ Is cracking normal in concrete? Yes. Concrete is extremely strong, but it is not flexible. As it cures, settles, and reacts to its environment, some cracking is completely normal and expected . ❓ What causes concrete to crack? 1. Shrinkage During Curing As concrete dries and hardens, water evaporates. This causes the concrete to shrink slightly , which can lead to surface cracking. This is the most common cause and usually cosmetic. 2. Temperature Changes Concrete expands when it’s hot and contracts when it’s cold. In Pennsylvania’s freeze–thaw climate, this constant movement puts stress on the slab, which can cause cracking over time. 3. Ground Movement or Settling If the soil beneath the concrete shifts, settles, or ...

RLW: The Mixer Minute

Search This Blog