Mortar

Mortar and Cement Basics

Mortar makes up 7 to 15 percent of a wall's total area. Although thats a small percentage, the role it plays is not minor. Everyone knows that it holds the unit masonry together so it forms a stable structure. But it also does a lot more. It protects masonry from water damage and weathering, so it lasts longer. It gives stone, brick or block work a clean, finished, uniform look. The key properties you need are workability, water retention, bond strength and durability. Since each of these depends on the others, you cant change just one. If, for example, you add more water to improve workability, you'll decrease it's strength. Changing one changes the others, often in ways you can't predict. Be careful when customizing a mortar mix.

QUIKRETE Mortar Mix is a blend of masonry cement and graded sand , designed to meet ASTM C 270 for Type N Mortar. Just add water.

Mortar Components

Mortar is made of four basic ingredients:

1. Portland Cement

2. Hydrated Lime

3. Sand

4. Water

We'll also take a good look at masonry cement. This is a manufactured, premixed, packaged combination of Portland cement, hydrated lime and optional admixtures. Masonry cement is so much easier to use that you don't often find anyone mixing mortar from scratch at a job site anymore.

Portland Cement

The binding agent is Portland cement. It was named after the Isle of Portland in the English Channel.

Type I Normal This is a general purpose cement. It's usually the only type you'll need. It comes in three varieties; regular, air-entrained and white. Regular Portland cement is gray in color and costs less than the white variety.

Type II Modified This type of Portland cement generates less heat than type I as it cures, and makes concrete that's moderately resistant to sulfate damage.

Type III High Early Strength Use this when you want concrete to set and cure as soon as possible. Here is an example. Let say you are on a job near Chicago. It's early October and the job's running behind schedule. Then a cold front rolls in. You can't stop work and wait out the weather. But you can mix concrete using type III Portland cement. This concrete will cure in just three days instead of seven needed to cure concrete made with type I cement.

Type IV Low Heat This generates even less heat than type II as it cures, but it's expensive. That's why it's only used on jobs such as dams that call for very large masses of concrete.

Type V Sulfate Resistant This Portland cement has a higher resistance to sulfate damage than Type II. Use it, instead of Type II, when job site conditions are more extreme. Usually you make mortar with type I, normal Portland cement. Once in a while you will use type III Portland cement to make it set up faster, in near freezing weather for example. The color is the one property that does not change how well it does its job.

Color

This property is the only one that has nothing to do with how well it does it's job. The color has absolutely no effect on a structure's safety or strength. But that doesn't mean you can afford to ignore it or treat it lightly. How something looks is always important to people. It's a big part of customer satisfaction although in this world of fast track construction quality does not always get you the job but is very important to me personally. Most people don't know or care about it's other properties, your work is judged mostly on how it looks. But to get it to look good for a long time you must have quality in your work beyond what the eye can see.

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