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Welcome to Concrete

Welcome to Getting Started With Concrete!

Concrete is everywhere. But, did you know that there's a secret life of concrete beyond your parking garage slab and rectilinear high-rises. Concrete can also be small, rounded, and have a beautiful shiny finish. In this class we'll uncover why concrete is so versatile through making smaller-scale projects that demonstrate why this ancient building material has stood the test of time.

Why Concrete?

It's the most common construction material used, it's inexpensive, can be recycled, and is very strong. Take concrete out of the construction site and into your home with practical projects that highlight the form and function of concrete, but in a less industrial way.

What you'll learn:

This beginner class aims to demystify how and why concrete works (the science is actually really neat!), and familiarize you with core skills about working with concrete that will set the stage for more advanced projects further down the line. You'll learn how to work with with concrete safely, using different molds to make shapes, and techniques to finish your concrete project and really make it stand out. All projects in this class use very basic tools and require no special knowledge.

Skill based projects you will make:


Casting In Pre-Made Molds - Drawer Pulls


Mold with Voids - Garden Planter


Unusual Molds - Balloon Formed Candle Holder


Finishing Concrete - Exposed Aggregate Surface

All culminating in a capstone project:

Capstone Project - Concrete Tabletop Fireplace

Concrete is a great building material and definitely not just for sidewalks or garage slabs. Bring industrial chic into your home with these simple projects that walk you through the basics of working with concrete.


About The Instructor:

Hello. I'm Mike, and I make things.

With hundreds of open-source projects, my aim is to educate, inspire, and entertain. I love learning new things, breaking all the rules, and getting my hands dirty.

My functional prototypes have been included on TV shows and print magazines all over the world, and reprinted in a few art and design books, too. I've compiled 2 books for Instructables and authored my own kids book, 23 things to do before you're 11 ½ - a book for young makers to do with their parents.

I'm originally from Vancouver, Canada, but now cause trouble in San Francisco, California. I work on the Instructables Design Studio, part of the Autodesk Digital Manufacturing Group.

I make all kinds of things aside from concrete projects, like circuit bending electronics and designing my own clothes. You can read more about me here.


What Is Concrete?

In it's simplest form concrete is aggregate mixed with fluid cement. Cement is a gypsum or lime-based binder that hardens over time in the presence of water. This type of cement is called hydraulic cement, as it sets due to a chemical reaction between the dry ingredients and water.

Cement has been used by humans for thousands of years as a building material and has helped shape civilization, as seen in the mortar used to build the Pyramids, aqueducts and structures during the Roman Empire, and castles and canals during the Middle Ages. Over time cement has been refined from ash and burnt limestone to modern day cement which is universally Portland Cement, a dried mix of limestone and small amount of other minerals like calcium, aluminium, and iron which enhance the natural characteristics of cement and regulate the setting time when mixed.

Adding coarse and fine aggregate like gravel and sand add strength to the cement, and allows the mixture to be called concrete.

What's Happening?

The chemical process when water and air are added to concrete is called hydration, which produces crystals that interlock and bind the aggregate together. It's important to know that concrete doesn't dry, it cures. The minerals in the cement hydrate in the presence of water and require proper moisture while hydrating to cure effectively, if hydraulic cement dries out while curing the result can be a very weak product.

So, Concrete Is The Perfect Building Material?

Almost. While concrete is very strong in compression, some mixes supporting 12,000 psi, concrete is weak in tensile strength (more on that in Lesson 3). A common material that's added to concrete that has a high tensile strength is steel, this is commonly called rebar (reinforcing bar). Combined, concrete and steel are a very strong building material and can be seen in many construction sites today.

While concrete is very strong and versatile, it's not perfect.


QUIZ TIME

Put your knowledge to the test, try the quiz below and see how you do!

{
    "id": "quiz-1",
    "question": "Cement and concrete are different names for the same thing",
    "answers": [
        {
            "title": "Yes, they are the same",
            "correct": false
        },
        {
            "title": "No, they are different",
            "correct": true
       }
    ],
    "correctNotice": "Correct! Cement is a binder, concrete is cement mixed with aggregate.",
    "incorrectNotice": "That's incorrect."
}
{
    "id": "quiz-2",
    "question": "What's happening when concrete cures?",
    "answers": [
        {
            "title": "It's hardens by being exposed to air",
            "correct": false
        },
{
            "title": "A chemical process called hydration",
            "correct": true
        },
        {
            "title": "Concrete only cures when it's heated to 50°C",
            "correct": false
        }
    ],
    "correctNotice": "Correct! Cement hydration is a chemical process that produces interlocking crystals that bind together.",
    "incorrectNotice": "That's incorrect."
}
{
    "id": "quiz-3",
    "question": "Concrete is stronger in tension than compression.",
    "answers": [
        {
            "title": "True",
            "correct": false
        },
        {
            "title": "False",
            "correct": true
        }
    ],
    "correctNotice": "Correct! Concrete needs reinforcement in order to be strong in tension.",
    "incorrectNotice": "That's incorrect."
}
{
    "id": "quiz-4",
    "question": "How long can concrete last for?",
    "answers": [
        {
            "title": "10 years",
            "correct": false
        },
        {
            "title": "50 Years",
            "correct": false
        },

        {
            "title": "Thousands of years",
            "correct": true
        }
    ],
    "correctNotice": "Correct! Man made concrete from 6500 BC has been discovered by archaeologists.",
    "incorrectNotice": "That's incorrect."
}
{
    "id": "quiz-5",
    "question": "Select the components of concrete",
    "answers": [
        {
            "title": "Water, cement, Portland cement",
            "correct": false
        },
        {
            "title": "Water, sand, eggs, Portland cement",
            "correct": false
       },

        {
            "title": "Water, aggregate, Portland cement",
            "correct": true
       },
        {
            "title": "Sand, rebar, Portland cement",
            "correct": false
       }
    ],
    "correctNotice": "Correct!",
    "incorrectNotice": "That's incorrect."
}

Concrete is one of mankind's oldest and most used construction material. However, to make anything out of concrete stand the test of time it needs to be mixed and poured correctly. Though it may seem simple. mixing and pouring concrete incorrectly can lead to frustrating results. In the next lesson we'll learn about the proper way to mix and pour concrete for perfect results every time!

CLASS PROJECT

Share a photo of your finished project with the class!

Nice work! You've completed the class project