German Concrete. The Science of Cement from Trass to Portland, 1819-1877.

This book describes for the first time ever, the rise of the modern art of building with concrete in the different German territories stretching from Friesland to Pomerania and southwards from Bavaria to Baden during the first three quarters of the 19th century. Based on careful analyses of historic documents and literature, the book traces an engaging history of master builders, engineers, architects, theoreticians, chemists and inventors tracking the evolution of different building techniques, materials, studies and experiments concerning concrete. It analyses German master builders' consideration for classical building culture and for contemporaneous constructions observed in neighbouring countries. This narration starts at the turn of the 19th century with early scientific studies on cement, examples of rudimentary concrete used as filling material in small hydraulic foundations and attempts at producing mortar-based artificial stones and moulded objects. The account then follows the progression of cement and the abilities of master builders who worked with concrete until crucial evolutionary stages were reached in the 1870s. Early scientific theories about the chemical reactions in the production and hardening of cement were developed; concrete was finally used to build huge underwater foundations as well as entire houses; the production of mortar-based artificial stones and moulded objects became an important manufacturing branch; the first standards for the production and sale of Portland cement were defined and officially implemented.

German Concrete, 1819 - 1877

Salvatore Aprea

This dissertation originates from an investigation about the arising of the modern, German building expertise involving the use of concrete, which develops during the first three quarter of the 19th century against the backdrop of a general modernisation process, and moving from the observation of more advanced building techniques in France, Italy, Holland and the United Kingdom. Early uses of modern concrete in Germany essentially concern the construction of foundations underwater and in marshy soils. Between the end of the 18th and the begin of the 19th century, some traces are to be found in the mixtures of pebbles and mortar that are used as filling materials in the so-called well foundations, which consist of underground circular walls to be filled with rubble masonry work, and among the heads of the timber piles supporting the piers and the abutments of some bridges. From the end of the 1820s, we observe a more mature use of concrete to build underwater foundations, whose bearing capacity essentially depends on concrete itself. This trend further develops in the second half of the 1830s and during the 1840s, when concrete is recognized as an essential material to build underwater. The expertise in building concrete foundations develops along with an increasing interest for the nature and properties of hydraulic binders. This produces consequences on the scientific plan, giving rise to the development of essential chemical studies about lime and mortar, and in the domain of manufacturing, involving the foundation and the enlargement of several hydraulic lime and cement plants. The use of concrete to build above ground appears later than in the domain of the construction of foundations, and it is preceded by the development of a peculiar material, which is known as Kalksand. It is a very lean and lime-base conglomerate, the use of which spreads as of the mid-1840s, mainly in rural domains. Similar to concrete, it is poured in formworks to build walls and, in a few cases, onto centrings to build vaults. Between the mid-1850s and the mid-1860, Kalksand and concrete are recognized as similar materials, and the use of the second one gradually prevails. An important aspect of the use of concrete, or of similar cement-based compounds, concerns the production of moulded artificial stones, tiles, architectural decorations, pipes and other kinds of objects. After several attempts dating back to the first half of the century, this kind of production improves during the 1850s and the 1860s, giving rise to an independent branch of the young German manufacturing. From the second half of the 1860, a number of buildings are entirely built in plain concrete, from the foundations to the roofs, mainly following British examples. At the same time, techniques to build concrete foundations get more advanced and complex, especially for what concerns well foundations, while the study of cement is further developed through chemical analyses and strength tests.

EPFL2015

The Search for Affordable Cement and Concrete in the 18th and 19th Century

Salvatore Aprea

At the turn of the 19th century, the production and use of concrete were limited by the unavailability of raw materials to produce good cement in several places. From that time onwards, the progress of chemistry and a number of empirical discoveries opened new possibilities. Lime, natural cements and volcanic additives - like pozzolana and trass - were analysed on scientific bases, their compositions were ascertained and it became possible to reproduce these substances artificially from raw materials that were affordable and easy to find. This was a fundamental step to reduce the cost of concrete and allow a better spread of it. A second step was the search for affordable mixtures. The key factors were: a reduced use of cement and the provision of aggregates from local and recycled materials. A number of different mixtures were developed and tested. The main components were hydraulic lime, aerial lime - with or without pozzolana or trass - Roman cement, Portland cement and several kinds of aggregates. The paper will analyse the development of modern cement and the evolution of concrete mixtures during the first three quarter of the 19th century, from the rudimental and less-known experiments by Carl August Rydin in Sweden to the compounds by François Coignet in France and the early use of slags in concrete, going through the attempts at using lean conglomerate instead of concrete in several German countries around 1850. The search for affordability will be the interpretation key, based on the hypothesis that the need for affordable concrete mixtures is increasing nowadays - especially in developing countries where economic constraints are significant - and the interest of scientists and entrepreneurs in historic concrete is growing.

Springer2017

German Concrete, 1819 - 1877

Salvatore Aprea

EPFL2015