Has the mortar crumbled out of the joints of the old stone wall? Cement creates a dense, dark stripe. It traps moisture and pushes out the stone. The solution is pure NHL 3.5 lime. It breathes and matches the old wall. Can be mixed with local sand to your own mortar color. For pointing old stone and brick walls. This is Kerakoll Biocalce Pietra.
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Crumbled joint on old stone wall: breathable lime joint that matches the wall — not dense cement
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Visible, unplastered masonry: fine, 0–1.4 mm grain — beautiful, clean joint appearance on stone and brick walls
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Cement traps moisture: low capillary water absorption (≈ 0.4), high vapor permeability — keeps the wall dry
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Original mortar color required: can be mixed with 1–4 mm local sand (max. 20% by weight) — to match the character of the site
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Monument, protected building: gentle, traditional material — extremely low chloride (≤ 0.002% Cl)
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Healthy interior: radon-free (UNI 10797), antibacterial and antifungal — IAQ Active, EC1 plus
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Exterior and interior: A1 fire resistance class, non-combustible mineral mass — suitable for both facade and interior
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Eco-friendly construction: only natural and recycled mineral raw materials — GreenBuilding Rating 5
| Binder |
NHL 3.5 pure natural hydraulic lime |
| Strength class |
M5 |
| Grain size |
0 – 1.4 mm |
| Capillary water absorption |
≈ 0.4 kg/(m²·min0.5) |
| Chloride content |
≤ 0.002% Cl |
| Material requirement |
≈ 1.7 kg/dm³ |
| Packaging |
25 kg bag |
What is it suitable for?
Masonry elements / walls: Hollow and solid brick, tufa, natural stone, and mixed masonry. Visible, unplastered masonry and joints of old stone and brick walls.
Functions: Pointing of old and new stone and brick walls; creating and bedding visible (unplastered) masonry; pointing and reconstructing visible parts for monument restoration.
Spaces: Exterior and interior visible masonry — facades, stone fences, arches, interior decorative walls where the wall remains visible (Edilizia del Benessere).
Custom option: can be mixed with 1–4 mm locally sourced filler, up to 20% by weight, so the mortar takes on the original character of the site — without changing technical properties.
Not suitable for:
- On dirty, loose, dusty substrates — clean first
- For surfaces with increased interstitial (in-wall) salt content and salt efflorescence — first remove the salt
- Under plaster, as a base coat for smooth surfaces — here Biocalce Intonaco is suitable
- High-strength, load-bearing masonry or reinforcement — here the M10 Biocalce Muratura Fino is the right choice
The Biocalce masonry and restoration system
Biocalce Pietra is the visible wall and joint layer — where the masonry itself remains the finished surface. The complete Biocalce masonry family:
Which Biocalce masonry mortar do you need?
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General masonry, bedding, rubble filling (M5): Biocalce Muratura — coarse grain (0–2.5 mm), Rating 5
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Load-bearing masonry + structural reinforcement (M10): Biocalce Muratura Fino — stronger, also for reinforced plaster (ARV 100 mesh)
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Grouting + visible masonry (M5): Biocalce Pietra — fine grain (0–1.4 mm), low water absorption, can be tinted with local filler — this product
If plaster is applied to the wall after all: for plastered surfaces instead of visible masonry, use the Biocalce plaster system — Rinzaffo base coat, Intonaco body coat, Intonachino Fino / Granello fine plaster, followed by breathable paint.
Frequently Asked Questions
What can be used to re-grout an old stone wall?
Use breathable lime grout mortar, not cement. Cement is dense, traps moisture, and causes the stone to spall. Biocalce Pietra is pure lime — it lets vapor pass and matches the old wall.
Why shouldn’t I grout old stone or brick walls with cement?
Because cement is harder than the old wall and traps moisture. The vapor moves toward the softer stone — resulting in frost damage and flaking. Breathable lime joints protect the stone: low water absorption (≈ 0.4).
What is visible (unplastered) masonry?
Visible masonry remains without plaster — the wall itself is the finished surface. This requires a fine mortar that creates a beautiful joint pattern. Pietra’s 0–1.4 mm grains produce clean joints, suitable for both exterior and interior.
Can it be mixed to match the color of the original mortar on site?
Yes. You can add 1–4 mm local sand, up to 20% of the weight. This way, the mortar takes on the character of the old wall without changing its technical properties.
What does low chloride and radon-free mean?
It introduces chloride salt into the wall, which damages the old structure. Pietra has an extremely low chloride content, ≤ 0.002% Cl — it protects historic buildings. It is radon-free (UNI 10797), making it healthy for indoor use.
Pietra or Muratura — which one do I need?
Muratura is coarser (0–2.5 mm) — for general masonry under plaster. Pietra is finer (0–1.4 mm) with lower water absorption. Pietra is suitable for grouting and visible, unplastered masonry.
How much material and water do I need?
From a 25 kg bag, you get ≈ 14.7 liters of fresh mortar, with ≈ 4.5 liters of mixing water. The amount depends on the joint size and masonry unit. We are happy to help with calculations for larger areas.
When should I NOT use it?
Do not use on dirty, dusty, loose, or salt efflorescence walls — clean first. For plastered, smooth surfaces, use Biocalce Intonaco. For high-strength load-bearing masonry, use Muratura Fino.
Can I grout with it myself?
Yes — it can be applied with a mason’s trowel, putty knife, or machine, and smoothed on a flat wall with a sponge. However, historic and larger visible masonry requires expertise — we also carry out the complete system installation.
