Cement in Sand for Block Paving: Do You Really Need It?

There’s absolutely no use of cement in the complete process from preparation to laying the block paving except to make mortar for laying the edge course and installing a drainage system (linear channel).

But for some reason, I’ve seen people using or advising mixing cement in the sand. Let’s see what’s the purpose of using cement in the sand and do you really need it.

There are two different cases when you can use cement in the sand and I’ve heard about both of them that’s using cement in the sharp sand while screeding and also in kiln-dried sand at the time of filling the joints between the blocks. Let’s see what are the reasons for recommending using cement in both cases and whether you should use or not.

Cement in Sharp Sand for Block Paving Bed (Dry Mix)

I heard about this inside a landscaping community when a guy posted about it saying how can there be so conflicting ways for doing the exact same thing. The story was he was looking to block pave his 120m2 driveway and the people he asked to quote had different ways to do the same thing.

Some said it needs the same preparation as most people do and the standard way of doing block paving like type 1 (100-150mm), sharp sand (30-40mm) and them comes blocks on top of it.

However, some said that the sub-base and sand bed needs thicker which isn’t the problem and it’s better if you’ve clayey soil but they’ve also said about using cement in the sand to prevent the blocks from sinking. This brings up a lot of questions so, let’s find out do you really need sand and cement mix laying course for your block paving or will it sink.

Reasons why it will not work

To lay block pavers, you need a flexible bed under them. Hence, for this reason, sharp sand is thrown and wacked to create a suitable bed to lay the block pavers. But when you use cement in the sharp sand you’re going in totally opposite direction to what your paving needs.

There’re other little-little things that you can take care of and get right during the job like using a membrane to support the sub-base from getting pushed into the soil, getting the correct depth for the sub-base, or proper wacking. All these tiny things combine up and decide whether the block paving will sink or not instead of using such a non-standard method of mixing cement in the sand.

If you are a DIYer doing block paving yourself, see the DIYers Cheat Sheet for Block Paving here, there’s a lot more you need to know during the process to give paving a better chance for success and longevity.

Cement in Kiln Dried Sand for Block Paving Joints

I’ve written a series of articles on block paving and covered various aspects of it including sanding or re-sanding and sealing. By the way, if you’re in the process of doing block paving you should really check out the previous post for some useful information.

One thing that I saw while doing it is after brushing in the sand, it washes out too quickly from the block paving joints is a common problem. So, I’ve seen people recommending using cement in the kiln-dried sand instead of using only kiln-dried sand to fill block paving joints.

Also, it was advised to mix cement in kiln-dried sand to prevent weed growth into the joints which you should never ever do if you want to follow the professional way of doing the block paving.

Reasons why it will not work

Firstly, the cement will create a lot of mess and will stain the pavers which can ruin the look of the entire block paving as you’ve to deal with a lot of things to get rid of the stains, or sometimes they even won’t go.

The most important reason is block paving is a flexible installation and it needs to be flexible as we saw earlier, while the cement is rigid when dried. If the surface is flexible the joints also need to be flexible that’s why just the kiln-dried sand is the best option.

It would be an absolute horror show. Cement wouldn’t go into the gaps. It would stain the paving, would need water to set and even if managed all that, the cement would crack and eventually come out of the joints through minute movement in blocks. Other than that, no problem 🙂

The cement will literally pop out after cracking when there will be a movement in the pavers and you will end up re-sanding your driveway or block paving again but in a correct way as you’ve learned a lesson this time.

Sealing the driveway (which also means sealing the sanded joints) is by far the best and only way to prevent the sand in the joints from washing out. There’re are also other benefits of sealing a block paving but with a high-quality sealer so, it’s always recommended to seal a driveway every 2-3 years after you sand the joints.

Take a look at this post here Cost to Clean & Seal a Block Paved Driveway to know what is the typical cost of sealing block paving with a high-quality sealer.