Aglime (CLS42)

CLS42 is a crushed chalk horticultural lime, 5mm down, which can be used as a mortar addition in particular conditions or for agriculture to modify soil Ph levels.

Key Benefits

  • Crushed chalk 5mm down horticultural lime
  • Suitable to raise the pH of soil and counter acidity
  • Suitable as an addition to mortar with sand or for use with hot mixed mortars
  • Available in mini and bulk bags



5% discount on orders over £500 (Excluding Vat & Delivery). For larger projects visit our pricing page.

Product Variations

Product OptionPrice (Ex VAT)
mini-bag: £3.78 £4.54 inc VAT
bulk-bag: £78.72 £94.46 inc VAT
SKU: 1041421.
990 kg
Categories: . Manufacturer:
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Not ideally suited as a mortar sand on its own because of the high fines content, however, when added to a suitable sand it can enhance the performance characteristics of  the mortar.

In Agriculture/Horticulture use Aglimes are added to soils to modify pH levels.

Aglime (CLS42) is available in 25 Kg & 1 Tonne bags. We have deliberately separated it from the other sands listed on the website as it has very different characteristics and isn’t necessarily suitable for most general building work.

It has the following uses:

Agricultural Lime

Aglime is a soil pH modifier, it is used to raise the pH of soil and counter any acidity present. Acidic soils can develop from the source rock like granites, from degradation of organic material, or even from acid rain; it can reduce crop yields as well as prevent some flower types from growing. It also helps to reintroduce calcium and a small amount of magnesium back into the soil, which are elements often absorbed by various plant types and washed out by rain.

Addition rate depends on how acidic and how coarse the soil is but a guide of 0.6-1Kg per square meter is usually a good starting point. For very highly acidic areas with clay-like soil, addition rates can be up to 2Kg a square meter. Aglime needs to be mixed through and turned into the soil in order to get the best effect.

Mortar Addition

Limestone aggregates can be used as part of a mortar to increase the calcium carbonate content of a mortar increasing the vapour permeability, capillary action and flexibility of a mortar. The limestone also acts as a catalyst to carbonation as a porous particulate.

Due to the high fines content it is very dependent on the sand it’s being blended with as to an appropriate addition rate, but blends done here at Cornish Lime have indicated anywhere between a 5 and 20% replacement of standard aggregate with the CLS42 is effective whilst limiting additional shrinkage. Putty mortars are able to take higher replacement rates as they can be re-tempered if there is any additional latent shrinkage.

Hot Mixed Mortars

The notable exception for use as a mortar aggregate is using the CLS42 as a sole aggregate in hot mixed mortars. Hot mixes need a higher fines content to mop up the extra free lime to limit shrinkage and our research has shown that the CLS42 works extremely well giving a good mortar with limited to no shrinkage. In our test it gave a very light off-white coloured mortar with a  coarse texture when finished with a beaten back face.


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A worthwhile addition serving as a porous particulate in lime mortars as well as a seed to carbonation (Testing carried out in our laboratory validates what many assume as anecdotal)

This aggregate can be used as a mortar addition, particularly in hot mixed mortars and in agriculture/horticultural as a soil pH modifier.

The grading is predominantly 5mm down, but is not an ideal grading for most uses as building sand due to the high fines content that comes from the crushing process.

Each project is unique, always seek professional advice before undertaking a project.


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