The European Calcium Silicate Masonry Unit Industry – Building on its past, ready for the future

At the beginning of the 19th century there were certainly less than two dozen industrial sand-lime brick manufacturing sites in Europe, if not worldwide. But already by the 1930s the sector had become an important industry. According to Warren E. Emley [3] by 1913 the industry in the United States of America had grown to 68 operating plants, with a total output of more than 200 million bricks. The Journal of the Royal Society of Arts [4] reports in 1934 annual production volumes of 320 million sand-lime bricks in the United States as well as 100 million each in the United Kingdom and Switzerland. Furthermore, the article [4] places the output in Germany at that time in the neighbourhood of 1 billion bricks, which probably underestimated the output in Germany. The German calcium silicate association’s [2] records indicate a peak volume of 2.5 billion bricks in 1936 produced by close to 300 factories at that time in the territory of the German Reich.

Today the reported and estimated annual production figures in Europe sum up to a total annual volume of approximately 7 million m³. For comparison with the afore mentioned historic figures: this volume corresponds approximately to 3.6 billon German RF standard sized bricks and is being produced by approximately 130 factories in Europe, more than 80 % of them represented by ECSPA [1], either directly or via national associations, as shown in the map. Beyond the sites shown in the map, ECSPA has basic, indirect knowledge about the presence of calcium silicate factories in Australia, Canada, China, Korea, South Africa, the CIS countries, the middle East and South America. ECSPA therefore welcomes any information which may contribute to completing today’s picture of the calcium silicate masonry industry worldwide, publishing it only upon prior approval.

Considering that the calcium silicate pioneers had to conquer markets with their new products against the resistance of well-established building and product traditions, it is impressive how good and fast they succeeded. The way forward was convincing architects, contractors and investors of the excellent performance of the new product and its quality, if necessary, with practical and often impressive demonstrations [5]. In the early days of the industry, when calcium silicate manufacturers were competing amongst each other and against competitors of other product sectors, quality was not only a sales argument but in fact a corner stone of the calcium silicate industry’s success story. In 1901, long before authorities thought about minimum performance levels, German calcium silicate unit manufacturers founded an association and agreed upon compliance with a minimum compressive strength of the products as condition for membership. Two years later the association established a quality mark allowing only those manufacturers demonstrating compliance with the agreed minimum compressive strength to label their products accordingly. A clear commitment to quality and a strong signal to the market, setting a mark also for competitors from other sectors, who soon had to follow the example. The quality criteria agreed by the founders of the association formed the basis for the first German industry standard for calcium silicate masonry units DIN 106, first published in 1927. While quality criteria can no longer be a condition for membership in an association, quality remains at the heart of the calcium silicate industry in Europe

Innovation has been a driving force since the early days. Calcium silicate innovations contributed considerably increasing the efficiency on construction sites. At first, in the 1950s, formats with up to 24 cm height were introduced to the market, the so-called block formats. To be workable by hand (two-handed), the gross density of the blocks was reduced by formed voids and in addition the blocks had ergonomic lifting holds. Masons not only required less work cycles to fabricate the same square meters of wall, but also saved time on laying the mortar, especially when the headers of the blocks were equipped with tongues and groves which needn’t be filled with mortar. In the 1970s the next step in size followed with the introduction of elements with 50 cm height to the market, which together with using thin layer mortar once more boosted processing speed and masonry strength. These new dimensions required the parallel development of new technologies supporting market launch of these new products and allowing handling them in safe work conditions.

Of course, the term “brick” did no longer fit to the new formats, which why European standards refer to calcium silicate masonry units instead, encompassing brick, blocks and elements. At present the largest calcium silicate units are elements of 65 cm height and 1 m length. Due to different market conditions and traditions figures differ from country to country, but overall, the share of large-sized calcium silicate elements in Europe today is in the order of 40 - 50 %, whereas small sized formats for one-handed laying – including brick sized formats – have a market share of less than 20 %. The next step on the size ladder are prefabricated calcium silicate masonry segments and wall, which are known since the 1990 in Germany, but got a little forgotten and are returning into focus in some European countries where shortage of skilled work force and a continuously high demand for affordable housing prevail.

In the beginning, the load bearing capacity of calcium silicate masonry walls as well as their resistance to weathering and to fire were the main characteristics of interest to architects and engineers. Starting in the 1970s and 1980s, building physics became increasingly important. To meet the different demands in end use, the industry developed a system of calcium silicate products and solutions. Today this system approach allows architects and engineer choose just with the perfect solution for each situation and makes calcium silicate masonry structures a champion in all disciplines.

Beside the evolution on the product side, also production technologies and processes have constantly evolved and continue evolving. In this area developments were originally driven by raising output, ensuring the quality promise and supplying the market with new products. Later, competition was the driving factor for increasing automation and improving efficiency. In recent years environmental aspects have become more and more focal. As calcium silicate masonry units are predominantly made of sand, lime and water, one has a hard time measuring any emission of critical substances into soil and groundwater or into indoor air environment. Optimisation of the sand grading curve, reduction of lime content as well as improvements in the process regarding energy efficiency and management have and continue contributing to positioning calcium silicate masonry units among the most healthy and environmentally friendly construction products. This is an excellent starting point for coping with circular economy, resource efficiency and climate change challenges ahead, but no reason for the industry to rest of its laurels of the past.

[1] European Calcium Silicate Producers Association,

www.ecspa.org

[2] 100 Jahre Kalksandstein Industrie. Bundesverband

Kalksandsteinindustrie eV.,

Entenfangweg 15, 30149 Hannover. 1994

[3] Warren E. Emley (1917). Manufacture and

properties of sand-lime brick. Department of

Commerce, Technologic Papers of the Bureau

of Standards, No. 85

[4] Sand-Lime Bricks – The Growing Popularity of a

Modern Product. Journal of the Royal Society

of Arts Vol. 82, No. 4247 (April 13th, 1934), pp.

596-598. JSTOR, www.jstor.org/stable/41360106

[5] https://www.kalksandstein.de/bv_ksi/geschichte