Project overview

Note: If you only want to see the photos, they are after the text (jump to the gallery).

Murkvalitet Västsverige AB was contacted by SKANSKA, who had heard we’re strong in casting work and material matching.

The assignment concerned the KA4 facility in Gothenburg, where they needed a pair of custom-cast 1940s-style slabs to match the existing slabs on site.

The goal was clear: once installed, the new slabs should blend so well that you couldn’t tell old from new.

Read more about how we work in high-demand settings: older and listed buildings.

Starting point

SKANSKA needed replacement slabs that would disappear into an existing surface of older 1940s slabs. This wasn’t just about “a similar colour”—it was about the whole expression: tone, pores, aggregate, edge profile and how the surface reads in real lighting.

This is exactly the kind of work where standard products rarely work, and where sampling and process control decide the outcome.

Why was this difficult?

Matching older concrete slabs is hard for several reasons:

  • Age and patina: originals change over decades due to wear, cleaning, moisture cycles and UV.
  • Unknown original recipe: 1940s aggregate, cement and pigments can’t be replicated from a standard bag mix.
  • Surface “feel”: small differences in pores, sheen and colour depth stand out when slabs sit side by side.
  • Edges and thickness: details often reveal a replacement faster than the main surface.

That’s why the work needs multiple controlled rounds until the whole system matches.

Solution

We ran a staged sampling process and tuned the key variables step by step:

  • mix and aggregate (speckle and structure)
  • pigmentation (tone temperature and depth)
  • surface treatment (sheen, pores and how the surface reads at angles)
  • edge profile and detailing

In the gallery you can see sample slabs compared side by side, surface checks at an angle, and how the mould and edge details were developed.

Materials and finish

With custom-cast slabs, details decide whether the result feels authentic. We therefore focused on matching:

  • aggregate expression (how the speckle reads in the surface)
  • pore structure (too tight looks new, too open can look wrong)
  • sheen and colour depth (can shift dramatically under different light)
  • edges and corners (profile and finish must align with the original)

This is why we produced multiple samples for side-by-side review before locking the final method.

Function and safety

Beyond appearance, the slabs must perform in real use. We continuously checked against the reference slabs and ensured the solution was stable and durable for the environment where the slabs would be used.

The principle was simple: correct materials + correct surface + controlled process = a result that lasts, not just a good-looking delivery.

Timeline

The timeline was driven by sampling rounds, curing and evaluation between each step. Each sample had to be judged when fully cured and “truly dry”, because concrete can change character from fresh cast to finished surface.

Once the right sample was achieved, we locked recipe and method and proceeded with final production.

Result

The result was a pair of custom-cast 1940s slabs that the project lead described as so well matched that you couldn’t see a difference between the originals and our replacements—which was the main goal.

We also received strong feedback, and the project lead saved our number for future assignments requiring expertise beyond the ordinary.

Location

Gothenburg (KA4).

Want something similar?

Need to match older slabs, stone, render or masonry—and want a result that looks native in its environment? Reach out and tell us about your project (photos help).

We’ll book a free site visit and help you choose the right approach. Contact us here.

From sample to finished 1940s slab

This gallery shows the process behind the custom-cast 1940s slabs for KA4: moulds, test casts, pigmentation, edge detailing and final matching to the existing slabs.

Hand holding a dark custom-cast concrete slab with speckled surface and visible thickness

One of the finished sample slabs held by hand. You can clearly see the colour, aggregate and thickness that had to sit close to the original 1940s slabs.

Rectangular casting mould with a light sample cast placed inside a plastic container

An early test cast in the mould. Before the darker tone was right, we tested geometry, surface behaviour and how the slab released from the form.

Dark sample slab standing on a workbench with a visible blue cast side and exposed edge profile

A side view of one sample slab. This angle shows how we worked on the edge profile and build-up, not only the top surface colour.

Close-up of the corner of a dark sample slab showing the edge and blue form material

A close-up of corner and edge detailing. In a project like this, the finish at the edges is a key part of making the slab feel authentic next to the original.

White rectangular casting mould used to produce a custom concrete slab

The mould prepared for the next casting round. A stable mould and even base make it possible to fine-tune colour and finish with control.

Two dark custom-cast slabs placed side by side for comparison of surface and tone

A comparison between two sample slabs with close but slightly different finishes. Those small differences in tone and surface mattered when matching the existing slabs.

Angled view of two dark sample slabs with different sheen and pore structure

Surface evaluation from an angle. This view shows how sheen, pores and colour depth shift depending on treatment and lighting.

Several custom-cast slab samples laid out on a table for colour and finish comparison

Multiple slab samples laid out for side-by-side review. This made it possible to judge which adjustments were needed to match the existing 1940s slabs.

Two dark concrete slabs side by side with different tone and surface finish

A final comparison between two finished sample surfaces. This kind of control is what allowed Murkvalitet Vastsverige AB to produce convincing matching replacement slabs.

Contact us about custom casting and matching

Need replacement slabs that must blend into an older environment—or a special solution where standard materials won’t work? Tell us about your project (photos help) and we’ll guide you forward. We book a free site visit and provide a quote or cost proposal.

Murkvalitet Västsverige AB
Org. no.: 559296-5544
Hakansgardsgatan 85, 434 36 Kungsbacka
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FAQ

How did you match the original slab?

We ran multiple sampling rounds and compared each sample to the reference slabs. We tuned mix/aggregate, pigmentation, pore structure, sheen and edge profile until the whole expression matched under real lighting—so the replacements visually disappear next to the originals.

Why didn’t standard slabs or a standard mix work?

Older slabs often have patina and wear built up over decades. The original recipe (aggregate, cement type and pigments) is rarely known. Small differences in tone, pores and sheen become obvious when slabs sit side by side.

How many samples are usually needed?

It depends. When visual demands are high, several sampling rounds are often needed to lock tone, speckle/aggregate expression, pore structure and finish. We align continuously before locking the final method.

What do you evaluate when matching the surface?

We look at the whole expression: tone (warm/cool), aggregate/speckle, pores, sheen/colour depth and edge/corner detailing. Surfaces can read differently depending on light and viewing angle, so comparisons are done in relevant conditions.

Can you match edge profile and thickness too?

Yes. Edges, corners and thickness often reveal a replacement faster than the main surface. That’s why we develop moulds, edge details and build-up in parallel with colour and finish.

What affects the price?

Price depends on scope, the number of sampling rounds, materials, requirements and access. After review we provide a clear quote/cost proposal so you know what’s included.

How do you make sure the colour matches in real life?

We evaluate samples after full curing and drying, and compare how the surface reads under different lighting and angles. Concrete can look different when dry vs damp, or in shade vs sun, so we match for the environment where it will be used.

How long does a project like this take?

Timeline depends on how quickly the sampling rounds converge, plus curing and evaluation between steps. Once the right sample is approved, final production is often comparatively fast.

Do you work with contractors and project management?

Yes. We work with contractors, clients and project leads when special solutions and clear sign-offs are required. In this project we delivered on assignment for SKANSKA.

Can I get a quote for similar work?

Yes. Send a short description (photos help) and we’ll book a free site visit and provide a quote or cost proposal.

Kan jag få offert på liknande arbete?

Ja. Skicka en kort beskrivning (gärna med bilder) så bokar vi ett kostnadsfritt platsbesök och tar fram offert eller kostnadsförslag.