Hi our pavers have started to lose the grouting between them and when we did a section using M3 mortar from Bunnings the colour was inconsistent. The next section is in a prominent position so we are reluctant to use the same product. The pavers have an 8mm+ gap between them. What product would you suggest and what process would you use ?
Welcome to the Bunnings Workshop community, @Susiegot. It's fantastic that you've joined us, and thanks for your question.
Keen to hear more about your projects around the house and garden.
I apologise for the delay in my reply. Are you referring to a colour inconsistency of the new mortar to itself or between the new and old mortar? If you are mixing batches of mortar from the same bag, it should be identical. It looks like you have some residual white stains on some of the areas, and scrubbing them back with a stiff bristle brush and cleaning up the area should resolve them. You'll also find the joints will age eventually to a more consistent colouring.
If you are referring to the difference in colour between the new and old mortar, then there will be differences, which results from patching the area. I'd suggest the first thing you do is to use a high-pressure cleaner and either Chemtech 5L Concrete And Driveway Cleaner or Bondall 5L Hydrochloric Acid to clean the old mortar joints. Please wear appropriate PPE gear when using these chemicals, including gloves, goggles and respirator if in a confined space. By cleaning the old mortar, it will restore it to its original light grey colouring.
If you are still having issues matching the older soiled mortar, you can add oxides to the new mortar to tone the colour down. Please bear in mind that the new mortar will age naturally over the next six months and end up much darker than it is now through natural weathering and grime build-up regardless of adding oxides. If you add oxides to make it the same colour as the older mortar, in 12 months and through natural ageing, it will be darker than the old mortar causing another issue.
It would be my opinion that the mortar you have used looks almost identical to the old mortar colour-wise. It just needs to go through a similar ageing process.
Please let me know if you need further assistance or have questions.
The white stains were part of the new grouting replaced recently, that was why I said the colour was inconsistent. Even in a replaced long strip the colour varied. Is the M3 mortar the right product for the grouting replacement?
These photos are of the original paving. We had the grouting fixed about 18 years ago and that grouting doesn't seem to be as stained with age as the original grouting. Should we just use the M3 mortar and see how it goes?
M3 is a mortar class used for general block laying around homes and should be suitable for this purpose. If you've used one of our mortars, I would be happy to contact the manufacturer to ensure it is the correct product.
The type of sand used in the mortar changes the colouring. Since mortar supplied from various localities uses different sand in manufacturing, the colouring can vary dramatically. However, new mortar is always going to be much lighter in colouring than old mortar. In some of your photos, the old mortar is quite stained and aged, appearing almost dark grey. I am not aware of any pre-packaged mortar that is dark grey. It would likely be best to add Avista Oxide 1kg Jet Black Cement Colouring to the mortar, toning the white down. As I previously mentioned, pressure washing the old mortar should lighten it. Hopefully, by darkening the new mortar with an oxide and cleaning the old mortar, you should meet somewhere in the middle and get a reasonable transition.
Thanks for trying to solve our paver issues. We are planning to clean the old mortar. If you look back at the first photo I sent, the areas of replaced grouting have white colour in the grouting. Could this be from too much water in the mix (I didn't mix it myself) or water getting into the grout when wiping away the grout that spreads onto the adjoining pavers?
Welcome to Bunnings Workshop. I suspect what you are seeing is a phenomenon called cement surface mottling. It often occurs in certain conditions.
Too much water in the cement mix
Inconsistent turnover of product with water.
The grout was worked over too much while in the drying process.
Too much water in the sponge and was trapped on top of the grout.
( giving you that lighter finish.)
The grout was overheated while curing.
Water got trapped at the bottom of the mix while grouting.
Don't feel bad, even professional tilers and cement specialist run in to this issue no one is spared.
To avoid mottling I advise working only in the cooler part of the day. Once the grout is laid do not rework it with the grout tool. Overworking is not good as well. Cover fresh grout with black builders plastic and keep cool by spraying with garden hose on top do not get grout wet. What we are trying to do is achieve a uniform drying finish. Uniformity in depth and laying is paramount as inconsistent levels also produce the effect your seeing. These are my best suggestions for this particular issue. I suggest using a light detergent and a stiff brush to see if you can salvage your fresh work. You can also try using a rubbing stone to scratch the surface of the grout to get a uniform finish. You may have to modify the stone so that it's the same width as the grout line. Good luck and stay safe.
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As @redracer01 has mentioned, it could be because of several reasons. It does look like excess water on the surface has allowed the cement to creep out of the joins through the brick's pores. However, after the mortar replacement has been completed, a clean-up process needs to be done. Have you tried scrubbing the white areas down with a stiff bristle brush? It could just be a very fine coating of lighter mortar on the surface that needs to be brushed back. Some Chemtech 1L Brick Tile And Paver Cleaner will assist in this process as it is designed to help remove mortar slurry stains from bricks.
Thanks Red. What do you do for consistency when you are basically patching the paving grouting like in my case? There will be variations in the missing grout depth unless the grout is all removed and also old vs new grouting will vary. Are you saying the variations in depth of the repair sections will cause the colour of the grouting in the repair grouting to vary due to the depth differences? What product would you use?