Knowing how to mix mortar is essential for many DIY construction or masonry projects. Mortar is an essential construction material that binds together bricks, stones, and other building blocks to create one solid and unified structure. Understanding the proper steps in how to mix mortar will ensure strong adhesion, uniformity, and workability. From selecting the right materials to achieving the proper consistency, considering the steps from the beginning to the end will give you the confidence to mix mortar effectively and efficiently.
How to Mix Mortar
Mixing mortar involves several steps to achieve the right consistency. This guide provides the directions for standard mortar mixes, but for specialized mortar, it is vital to follow the manufacturer’s instructions to ensure the ideal consistency.
- Using the Right Mortar Mix
The easiest and most convenient way to buy mortar is in premixed bags. These are pre-portioned for optimum quality and reliability. When you buy the mortar, you need to determine which mortar type you need for the job. Type M and Type S are best for heavy load or structural applications. Though Type N is considered a medium-strength mortar, this works well as a general-purpose mortar. It is suitable for most home construction projects and is also appropriate for load-bearing projects. Type O mortar works well for stone walls and non-load-bearing projects. Type K works for historic restoration projects.
- Gather the Other Materials
Beyond the mortar mix, you will need a mixing container, like a wheelbarrow or a mortar mixing tray, a mixing tool, such as a hoe, a trowel, or a drill with a paddle, and access to water. You may also want safety goggles, a long-sleeved shirt, work gloves, and a respiratory mask.
- Read the Instructions
The pre-mixed mortar bags will have the manufacturer’s instructions on the back of the bag regarding the mortar-to-cement ratio as well as mixing instructions. Read all of these before you begin the process so that you have all the necessary information and can reference it quickly if needed.
- Prepare the Mixing Container
Place the mixing container on a solid and level surface. Make sure that it is clean and clear of any debris that would pollute your mortar mix. You can spray the container down with water, which will help prevent the dry mortar from clinging to the sides of the container. You can also spray the mixing tools.
- Open the Bag
Put on the long-sleeved shirt, safety goggles, and mask if you haven’t done so, and cut open the top of the mortar bag using a utility knife or scissors. Be careful not to cut into the bag too deeply or the contents will spill out. Empty the bag into the mixing container. Some people like to add ¾ of the water amount to the mixing container before adding the dry mix. This method decreases the airborne dust from the mortar mixture. It also helps prevent the dry mortar from sticking to the bottom of the container.
- Add the Water
Follow the manufacturer’s instructions to determine the amount of water you need for the mixture. Most mortar instructions contain the amount of water you need per bag, so calculate the full amount of water you need according to how many bags you are using. Add the water slowly to make a pool in the center of the mortar mix.
- Mix the Mortar
Mix the mortar by folding the dry mix in from the outside and pulling it toward the pooled water using your mixing tool. Work through the mortar, slowly and carefully, to ensure that you don’t have any dry mortar mix left. Continue mixing until the mortar has a smooth and workable consistency. This can take anywhere from 5-10 minutes. If the mortar seems too dry as you are mixing it, you can mix in small amounts of extra water to gain the proper consistency.
For large mixing jobs, a mixing paddle may be more efficient than a trowel or hoe. Operate the mixing paddle at a low speed until the mortar is mixed thoroughly.
- Allow the Mortar to Rest
Once you have achieved the right consistency, you must allow the mortar to rest or “slake” for around 10 minutes. This allows the mixture to hydrate and begin the chemical bonding process. Once the 10 minutes is over, stir the mixture for a few more minutes, but do not add any additional water as this will weaken the mortar mixture.
- Check the Consistency
When you have mixed the mortar sufficiently and allowed it to rest, you can check the consistency of the mix. Using a trowel or a glove-covered hand, scoop up a section of the mortar. Hold the trowel or your hand at a 90-degree angle. The mortar should hold its shape without sagging or excessive crumbling. If the mortar stays on the trowel, it is ready to use.
- Use the Mortar
Mixed mortar will maintain its workability for 90 minutes to 2 hours, yet it can be less if the temperature outside is hot. Avoid mixing more mortar than you can use in this amount of time so that you do not have to waste it if it becomes too dry. In general, one person can apply one cubic foot of mortar per 90 minutes.
Tips for Mixing Thin-Set Mortar
In general, the steps for mixing thin-set mortar are the same as they are for cement mortar, but there are some key differences. Use these tips to help you understand some of the differences in the mixing method.
- Different water-to-cement ratio – Thin-set mortar requires a higher water-to-cement ratio than standard cement mortar. The higher water content contributes to better workability for the placement of tiles.
- Shorter mixing time – Thin-set mortar has a finer consistency than cement mortar, so this leads to a shorter mixing time. On average, thin-set mortar takes between 3-5 minutes to mix. The consistency of thin-set mortar should be the consistency of creamy peanut butter when it is mixed.
- Mixing tools – Many builders use a drill with a paddle attachment to mix thin-set mortar rather than by hand. The paddle helps to blend the fine particles in the mortar’s composition.
- Shorter workability window – Thin-set mortar has a workability window between 30 minutes and 2 hours. This depends on the temperature and humidity conditions surrounding the mortar.
- Read all manufacturer’s instructions – Be sure to look carefully at the manufacturer’s guidelines before you begin as the thin-set may have additional additives that require extra considerations.