Understanding Concrete, Cement, and Mortar | Ask This Old House

Host Kevin O'Connor explains the differences between three popular masonry materials. (See steps below.)

Steps for Understanding Concrete, Cement, and Mortar:
1. Portland cement is a fine gray powder that hardens when mixed with water. It's seldom used by itself but is an important ingredient in many other masonry products.
2. Concrete is a mixture of portland cement, sand, and an aggregate, such as gravel or coarse stone.
3. Concrete is mixed with water, then poured or pumped to create foundation walls, footings, piers, slab floors, driveways, steps, and sidewalks.
4. Once fully cured, concrete can support immense structural loads.
5. Mortar is a mixture of cement, lime, and sand, and is commonly used to hold together bricks, concrete blocks, and stones.
6. Masons use a wide variety of trowels to apply, spread, pack, and tool mortar.
7. When cured, mortar is somewhat softer than concrete, which allows it to accommodate a small amount of movement in a wall without cracking or crumbling.
8. Concrete, cement, and mortar are available in various strengths and mixtures, so be sure to get the right one for your job.

About Ask This Old House TV:
Homeowners have a virtual truckload of questions for us on smaller projects, and we're ready to answer. Ask This Old House solves the steady stream of home improvement problems faced by our viewers—and we make house calls! Ask This Old House features some familiar faces from This Old House, including Kevin O'Connor, general contractor Tom Silva, plumbing and heating expert Richard Trethewey, and landscape contractor Roger Cook.

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Understanding Concrete, Cement, and Mortar | Ask This Old House

[greencello]

You gotta hand it to Kevin. He isn't a professional in the trades, but rather the everyman that looks at a home improvement project with a lot of questions. Those questions are what we need answers to, whether it's the basics of masonry, carpentry, painting, gardening, and many other jobs. Kevin is the go between for us the viewers and the professionals. Along the way, he has learned some things and imparts what he know just like Tommy, Roger, Jenn, and the others.

[songofyesterday]

Almost bought a bag of cement and then realized I needed mortar. Thanks video!

[MatthewChenault]

This is also relevant when doing repair work in historic cemeteries. Marble is a sensitive stone that requires materials specifically designed to deal with stonework.

[derekplus]

Extremely useful and straight to the point.

[skymasterever]

The first 15 seconds was me at homedepot. The reason i am here exactly.

[geomodelrailroader]

This is good to know. With concrete you need to get it right. Too much water will turn it into slurry which will crack, too much sand will turn it into mortar which will creep before it cracks, and too much gravel will make it bumpy and it will chip. If everything is placed in the right order you will have the right mixture and it will last for decades.

[nxtkppo]

Concrete "can sustain heavy structural loads" however only in compression. That is why they put rebar into concrete which will be under a tension load.

[figgiefigueroa]

I love that TV show. Always great information for us the first timers.😂😂

[fuyu]

Thanks for ur explanation. It cleared up some confusion. Will aid me in selecting the right material for my DIY projects instead of guessing n possibly unsuccessful results. Kudos for ur video. New subscriber to ur videos. Anticipating ur next one.

[网中人]

i never know that until now thanks for showing this video.

[joelsantiagovalentin]

Best explainable practised ever thanks

[redcarpetofhollywood]

Thank you! this was my biggest dilemma today, what to chose, no one in home Depot will help anymore

[robertkoch]

😮 Right to the point! 😂 Great video.🎬 I was looking for this exact info.

[alphacentauri]

I learned something today thank you very much

[Doris-yv]

you didnt mention what cement is used for, and why they are different types for.

[PearlsAnneHeels]

This was SUPER helpful. Apparently I accidentally got the right thing (concrete) for my project 😅

[Apolac]

I should've watched this before trying to fix a wall footing!

[yosim]

Hi. Great video. Im building an outside patio with porcelain tiles. They will be laying on 4 inch cement slab. The question I can’t get an answer to is what should I use to join the tile to the concrete. Unfortunately I’m getting a lot of different answers. Seems like everyone guesting and I’d love to have a correct answer. Please keep in mind that I’m in NJ. Cold in the winter and raining in the summer. Thank you.

[SunFlower-hhvd]

Hello Sir, can you please give me an advice? What should I use to make a flower pot, garden decor? Which one is the best to use? Thank you and God bless.

[MisterBrauer]

Now if only we could teach people the difference between asphalt and bitumen.