Coloured concrete: More than just 50 shades of grey

As the first rays of dawn sweep over the Zebun Nessa Mosque in Ashulia, its dusty pink facade awakens, exuding warmth and quiet dignity. 

Designed in 2023 by architect Saiqa Iqbal Meghna, co-founder of architecture firm Studio Morphogenesis, the mosque epitomises coloured concrete's potential to evoke the past while pushing the boundaries of the present. 

The striking dusty pink facade of the mosque was derived from mixing vibrant pink pigments with concrete during the pouring process. The choice of using pink concrete was not just for aesthetic appeal — it was a conscious decision by Studio Morphogenesis to soften the harsh industrial surroundings and evoke a sense of serenity in people who went there. They also wanted the pink concrete to reference the traditional terracotta tones of Bengal's Mughal architecture while embracing the longevity and practicality of modern materials. 

On the exterior, red cement and locally sourced broken bricks were meticulously arranged to form mosaic-style flooring and ramps, drawing inspiration from the traditional craftsmanship.

In recent years, the architectural landscape of Bangladesh has begun to see the inclusion of coloured concrete in grand projects such as the famous Red Mosque in Keraniganj built by architect Kashef Chowdhury or the Zebun Nessa Mosque.

Concrete is a material that typically looks cold, grey, and drab because of its primary ingredients and the chemical processes involved in its production. 

The most common elements found in concrete — gravel, sand and water — all contribute to its grey colour. However, the main element used in concrete that gives it its colour is cement.

However, coloured concrete, also known as pigmented concrete, is a type of concrete in which pigments are mixed directly into the cement or aggregate during the production process, giving the material a consistent colour throughout its structure. 

These pigments, typically derived from natural or synthetic materials like iron oxides, can produce a wide range of hues, from earthy reds to vibrant blues. Unlike painted surfaces, when pigments such as iron oxide are mixed into the cement, the colour becomes embedded into the material and does not peel, chip, or fade as easily over time.

The dusty tangerine hue of the Nimtali Deuri was acquired by traditional Surki making process using brick dust, lime, betelnut tannin, catechu etc. Photo: TBS

Coloured concrete offers both durability and versatility, allowing architects to create striking designs that combine function with aesthetic. It can be used for various purposes, including decorative flooring, facades, sculptures, and infrastructure, which lends to its growing popularity among architects in Bangladesh.

Marriage of tradition and modernity

Across the river in Keraniganj, the Red Mosque, popularly known as 'Daroga Masjid', built by Kashef Mahbub Chowdhury stands with its bold red concrete facade unapologetically contemporary yet deeply rooted in the traditions of historic Islamic architecture. 

The structure takes a bolder approach, using deep red pigments in its concrete to stand out as a modern reinterpretation of traditional religious structures. It is not just its deep red colour that pulls people in, but the simultaneous renovation of the original version of the historical mosque, Doleshwar Hanafia Jame Masjid right beside it.

The conservation project was undertaken by Dr Abu Sayeed Mostaque Ahmed, architect and architectural conservation specialist, to preserve its cultural legacy. 

"We maintained the mosque's original colour and exterior texture. No artificial colour was used during the renovation. Instead, we used a dyed chalk solution which was mixed with the plaster materials," remarked Mostaque.

The contrast between the new structure, which utilises a deep red-coloured concrete, and the original mosque which has more of an earthen red, perfectly illustrates the bridging of the past with the contemporary.

Mostaque also worked on the conservation project of Nimtali Deuri, where the team tried to incorporate old wall-paint techniques. 

One of the main challenges was to find authentic materials and artisans. Mostaque Ahmed explained, "For example, instead of wall paints, the masons back then used Surki made of brick dust, lime and for good binding, they used natural sticky components like betelnut tannin, catechu, thickened date syrup or even black lentils. From the literature, we learnt about the components but we didn't know the formula. So after several trial-and-error phases, we finally got the perfect ratio of components that we used." 

That is how they managed to acquire the dusty tangerine shades on the walls. 

Future potential

In a country with a rich architectural heritage, from the Sultanate-era red-brick mosques to the stately buildings of the British colonial period, coloured concrete provides a modern medium to carry forward this legacy.

Both the Zebun Nessa Mosque and Red Mosque illustrate how the material can transform religious spaces into symbols of cultural pride. The pink and red tones of these mosques evoke the nostalgia of traditional clay buildings while standing out as architectural landmarks.

Beyond religious structures, coloured concrete also holds potential for enhancing public spaces. 

The contrast between the modern Red Mosque, which utilises a deep red-coloured concrete, and the old Doleshwar Hanafia Jame Masjid which has more of an earthen red, perfectly illustrates the bridging of the past with the contemporary. Photo: TBS

In 2017, the Ministry of Home Affairs began a project to preserve Bangladesh's oldest jail, which served as the central jail historically. Located in Old Dhaka, the jail has long been abandoned due to its dilapidated condition. 

An open design competition was held to determine who would undertake this vast project. It was ultimately awarded to the architecture firm Form.3. The project is set to be designed by Didarul Bhuiyan, the director of Form.3, in collaboration with other experts. "This is a multidisciplinary project of architects, planners, landscape architects, conservation specialists and historians," Bhuiyan remarked.

This project aims to use coloured concrete to create a vibrant and engaging environment while respecting the historical significance of the site. It promises to be a compelling litmus test for the material's potential to blend history with contemporary design while making it accessible to the public in new and exciting ways.

Pros and cons of using coloured concrete

Using coloured concrete is still a novelty in the perspective of Bangladesh, as it can be a bit expensive. However, unlike wall paint, they do not chip or crumble, and as a result, you do not have to paint your surfaces over and over again once you have used this tinted concrete. But like any other building material, it comes with its own set of pros and cons. 

The iron oxide pigments used are known for their resistance to fading and weathering. Studies show that these surfaces can maintain their vibrancy and structural integrity for decades with minimal maintenance.

Unlike other decorative paving materials, this type of concrete does not require regular sealing or intensive cleaning. A simple sweep and occasional wash will keep it looking pristine. This ease of maintenance is a boon for busy homeowners and commercial property managers alike, saving both time and money in the long run.

Some suppliers now offer eco-friendly pigment options, such as those derived from natural earth oxides. Additionally, longevity means less frequent replacement, reducing waste and resource consumption over time.

The addition of pigments and the specialised process involved in its installation often make it more expensive than standard concrete. On average, it can cost anywhere from 10% to 30% more than its plain counterpart. This initial investment might be a significant factor for budget-conscious homeowners or builders.

"In Bangladesh, apart from the traditional grey and white cement, you can get red and black cement. A 50kg bag of normal cement can be priced at an average of Tk500, while the red oxide mixed cement will cost you Tk590-600 per 50kg," Md Jalil Patowary, a local building material seller, informed.   

Moreover, achieving uniform colour can be challenging. Variations in the mix, pigment quality, and application techniques can result in slight inconsistencies in colour.

And the installation is more complex than that of standard concrete. It requires skilled professionals with specific knowledge of colour mixing and application techniques. Finding the right contractor can be a challenge, and the skill level of the installer can greatly influence the outcome.