Inheritance of Cement and Concrete A.K. Jain, Technical Advisor, UltraTech Cement Ltd.

Introduction: Cement and concrete have changed the face of the earth. In last 150 years human race has succeeded in leaving its indelible imprints on this globe with the help of cement and concrete. Both cement and concrete have been in forefront in amazing progress of civilization during the 20th Century along with other

epoch

transportation,

making

technological

communication,

developments

medicine,

nuclear

in

the

science,

fields

of

energy,

computers and digitization. Cement and concrete have touched every individual on this planet directly or indirectly and enriched their life beyond their imagination. Be infrastructure, housing, industrial, irrigation, social facilities, energy or any other sector of human endeavor, cement and concrete are integral part of it. It is fascinating that both these materials within a short span of 150 years have contributed so much to the human progress. In this paper an effort has been made to trace the history of these wonderful materials from the beginning and to pay homage to those who have contributed to bring them to the present level. Ancient Developments: The ancient Mediterranean cultures knew how to make lime mortars hydraulic by means of pozzolans. The Greek knowledge of the use of highly siliceous, volcanic santorim earth goes back to 500-300 BC (1). Half a millennium later, Vitruvius had found that “there is also a kind of powder, which due to its nature gives excellent results”. He called this powder “pulvis puteolanis” because it was found at the town putcoli now Pozzuoli, in the bay of Naples(2). This pozzolan was likely first used to make hydraulic mortar for marine concrete in North of Rome (3). Its ability to produce concrete of 1

higher strength and durability than pure lime made ‘Roman Concrete’ unique building and construction material for imperial development from Northern England to Turkey, Syria, Israel and Egypt and further west to Spain and Southern France (3). The Colosseum provides important evidence of the superior engineering competence of the Romans. It was built by the Emperor Vespasian in 72-80 AD over an elliptical base with a 187.77m long and 156.64m short axis, the external walls reaching to height of 50m(4). The foundations consisted of a 6m thick concrete slab covering the whole area of the building. A 6m thick ring was cast on the bottom slab, which supports the pilasters for the superstructure.

Another

living

example of excellence in concrete construction is Pantheon, which in still used for ‘divinc service’. It was built by Emperor Hadrian (120-125 AD). It is 6m

thick mass concrete cylinder

covered with a concrete dome. The height and diameter of which is 43.3m. The height of dome is exactly half of entire height and its curve is a perfect sphere, which just touches the floor. The weight of the dome is carefully reduced as it travels upwards by reducing thickness and using light aggregates. No other dome of such free large span was constructed before the nineteenth century. Romans cleverly made use of compressive strength of the materials in their structural system. They did not use any reinforcement for separate transfer of tensile and flexural stresses but learned by trial and error to cast mass concrete and masonry into magnificent structural shapes of sizable magnitude.

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After the fall of Roman Empire in 5th Century, the period of feudal chiefs, anarchy and devastation ruled Europe for almost next 1000 years. This period is generally called ‘dark centuries’. The knowledge of pozzolanic materials for improvement of lime mortar was for centuries

confined

to

the

catholic

monks who could read Vitruvius Latin. Lime

mortars

applications knowledge

sufficed and

of

the hydraulic

for

most

inherited mortars

containing pozzolans was good enough for special purposes such as prestigious building

for

the

aristocracy. It was

church

and

the

only during

the

Rennaissance period (15th to 17th century) when progress in science was recognized as decisive factor for man’s understanding of nature and future development. It was only during this period after the fall of Roman Empire that some progress was made in this field (5). Developments prior to Portland cement: Danish writer L. Holbery wrote in 1749 that on the island of Bormholm in the Baltic sea, a coal and cement plant had been built and that the cement was roughly 10% better than Dutch cement(6). The source material for this cement was an argillaceous limestone and the cement was in itself a hydraulic lime. It was a revolutionary innovation, although it did not receive much attention, may be due to limited international interaction of the time. It was a cement of excellent quality as it had been used in Denmark as “Roman Cement” throughout the nineteenth century. In 1756, John Smeaton was commissioned to build the third lighthouse on the Eddy-stone skerry in the English Channel off the coast of Plymouth (7, 8).

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For the construction with hewn stones set in mortar, he wanted a stronger cement than slaked lime. By experimenting he obtained very strong cement by burning an argillaceous limestone and made very strong mortar by mixing this cement with a pozzolan, which he obtained from north of Rome. He claimed to have developed a product as strong and durable as ‘the best Portland stone’ the building stone from the island of Portland which was used extensively in London. Almost at the same time in 1778, M. Faujas de Saint-Fond, a French geologist published a thorough study of pozzolanic materials, their properties and effects and referred to concrete works, for instance at the naval port of Toulon (9). He mentioned the Swedish production of a pozzolan by two-times calcinations of an alum schist and referred to its use in the Troldhattan lock. However, these developments remained in isolation due to very limited facilities of interaction and communication during that period. Entry of Portland Cement: In 1824, Joseph Aspdin was granted British patent No. 5022 for the manufacture

of

Portland

cement.

Portland

cement

became

the

indispensable material for making mass concrete suitable for large scale ports, docks and marine construction Very soon in 1843, other applications of concrete were found in building houses. The samples of Apsdin’s concrete of 1847 confirms that this cement possessed the potentials we are familiar with today. They show the existence of same clinker components in the cement as we have in a modern standard Portland cement. However, Apsdin did not know about the clinker minerals or how they reacted, and also not much about how to get the same product batch after batch in the cement kiln. The prototype of modern cement in a plant was made in 1845 by Issac Johnson, who burnt a mixture of clay and chalk until clinkering, so that the reactions necessary for the formation of strongly cementitious compounds 4

took place (10). The production of Portland cement in Europe and North America on industrial scale started only around 1880. The world cement production in the year 1900 was about 20mt which increased to about 35mt by 1914 at the beginning WWI. It further increased to about 95mt in 1939 at the time of WWII. After WWII, cement production has been continuously increasing at a very fast pace and it has now reached to about 3200mt per annum. Developments in later half of 19th Century: The developments in improving Portland cement were accelerated due to advancements in emerging inorganic chemistry which was applied to explore the nature of the cement calcination process and the hydration of cement with water. The French Chemist I. J. Vikat had as early as, 1818, found that lime and silica were the primary reactants and that specified mix proportion

was

essential

for

proper

reactions. The German chemist, W. Michailis studied the hydration reaction. The French chemist H. le Chatelier introduced petrographic examination of cement clinker in 1883, and the Swede chemist A.E Toemebohm confirmed his observation fifteen years later. He introduced in 1897, the names elite, belite, celite and felite for the four crystalline components which he found in clinker thin section (11). Cement chemistry was therefore well prepared for the tremendous developments which took place during the twentieth century in the field of industrial production

of

cement.

In

contrast

to

the

scientific

research

and

development in cement technology, the use of concrete largely remained within the domain of mason’s knowledge of the craft until the advent of reinforced concrete, which started in the last decade of the nineteenth century and appreciably developed during first few decades of the 20th Century. 5

Developments in first half of 20th century: The first conference on Chemistry of cement was held in London in 1918 by the prestigious Faraday Society. The cement industry by now had learnt to manufacture Portland cement of sufficient uniformity and to make comparisons between the quality of different cements produced at different plants and at different times(12). The basic chemical science knowledge has reached a stage that the chemistry of Portland cement and its hydration could be used to predict the properties of concrete. This knowledge synchronized well with civil engineering development of reinforced concrete and helped in formulating the regulatory requirements and test methods to control cement quality. The conference reviewed the state-of-the-art of composition and hydration chemistry and the setting process of Portland cement. The famous French chemist, H.le Chatatelier presented his investigations on the microcrystalline nature of cement hydration products which were otherwise perceived as amorphous gel substances. Cement research during first quarter of 20 th century was mainly advanced in the Continent, especially in France and Germany, though Portland cement was discovered in England. The establishment of British Building Research Station in 1921, started its basic research into the chemistry of cement and cement hydration and made important contributions. The British studies by wet chemistry of the different reaction systems of the individual and the complex cement oxides hydration reactions and the American development of the ‘Bouge calculation system’ for mineral clinker composition as derived from the oxide analyses of the raw meal for the cement burning process in early 1930s were of historic importance. During 1930s, Swedish researchers including J.A. Hedvall, silicate chemist, G. Assarson and N. Sundius, geologists and mineralogists and L. Forseen and S.Giertz Hedestrom, chemical physicists had gained international reputation for scientific research on cement mineralogy and cement hydration. In 1938 the second symposium on chemistry of cement was held in Sweden(13). In 6

this meeting, the ‘Bogue calculation’ from 1931 was universally accepted as a means of cement plant monitoring and for development of cements with special properties like setting time, strength, sulphate resistance, etc. The optical microscopy was applied for control of the mineral composition of the clinker. The other important issues like energy consuming calcination and grinding processes for the making of cement and on the energy releasing hydration process of cement were discussed. The visionary contributions concerning the porous structure of cement paste and the pore liquid as a saturated Ca(OH)2 and ettrinigite as secondary component in ordinary cement paste were made. The new basic research at Portland Cement Association of the USA was presented by TC Powers. First time retarders and accelerators as chemical additives to fresh concrete were mentioned. During the first half of the 20th Century the cement chemistry had been fully understood,

the

subsequent

developments

mainly

relate

to

the

modernization of cement plant technology and developments in the field of reinforced concrete. Development Concrete: Many

of

people

Reinforced think

that

Reinforced Concrete has been in use for a very long time, but that is not the case. Effective use of RC in Civil Engineering construction is less than 150 years old. Joseph Monier, the owner of a nursery in Paris is credited to make first practical use of reinforced concrete during 1849-1867. He acquired first French patent in 1867 for iron reinforced concrete tubs, then followed by pipes and water tanks in 1868, flat plates in 1869 and bridges in 1873, stairways in 1875. He had no quantitative knowledge regarding its behavior or any method of making design calculations. During the same period, Joseph Lambot in France constructed 7

a RC small boat and received a patent in 1855. Another Frenchman, François Coignet published a book in 1861describing many applications and uses of reinforced concrete. In

the

United

states

the

pioneering work was done by Thaddeus Hyatt who conducted experiments concrete

on

reinforced

beams

in

1850s,

however his experiments were unknown

upto

published

his

1877

work

when

privately.

Emest L. Ransome was the first to use and patent in 1884 the deformed (twisted) bar. In 1890, Ransome built first RC building, a museum in San Francisco two stories high and 95m long. Since that time, development of reinforced concrete in the United States had been very rapid. During 1891-1894 various investigators in Europe published theories and test results, among them were professor Molier system (Germany), A. Wayss the first engineer who made theory, and then furnished formula and methods for design. Francois Hannebique (France) received patent in 1892 and was the first engineer to use stirrups and bent up bars in RC beams against shear. However the practical use of reinforced concrete in Europe was less extensive than in United States. From 1890 onwards, the RCC in

building

construction

was

extensively used in USA and CAP Turner, Morton

Arthur

Talbot,

O.Whitney

WA

and

Stater, Federick

Tumeaure played significant role. Throughout the entire period 18501900, relatively little was published as

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the

engineers

working

in

the

reinforced

concrete

field

considered

construction and computational methods as trade secrets. The first publications that might be classified as text book on reinforced concrete was that of Armand Coroidere (France) in 1899. In 1903 a joint committee was formed in the

United

representative organizations

States of

of all

interested

in reinforced concrete for uniform

application

of

knowledge in design and constructions.

This

joint

committee is now known as American Concrete Institute. The earliest text book in English was that of Frederick. E.Tumeaure and Mourer published in 1907 in US entitled ‘Principles of Reinforced concrete constructions’. In the first decade of 20 th century, progress in reinforced concrete was very rapid. Extensive testing to determine beam behavior, compressive strength of concrete and modulus of elasticity was conducted by Arthur N. Talbot at the University of Illinois, by Frederick E. Tumeaure and Morton O. whitney at the University of Wisconsin and by Bach in Germany. In 1912, Ernest L Ramsone and Alexis Saubrey co-authored “Reinforced Concrete Buildings”(14). In1906 major earthquake struck San Francisco, California (magnitude 7.9) and in the aftermath, engineers conducted extensive research and revised the method of design. From about 1916 to the mid-1930s, research centered mainly on axially loaded column behavior. In the late 1930s and 1940s, eccentrically loaded columns, footings, and the ultimate strength of beams received attention. The elastic methods of analysis, the working stress method (also called allowable. Stress Design or straight-line design) was adopted almost universally by codes throughout the world as the best method for designs. The first modifications of the elastic working stress method resulted from the study of axially loaded 9

columns in the early 1930s. By 1940s, the design of axially loaded columns was based on ultimate strength. In 1942 Charles S. Whitney, an American Engineer presented a paper that a probable stress-strain curve with reasonable accuracy is a parabola with rectangular stress block for simplification. The 1956 ACI-318 code permitted ultimate strength Design (USD) as an alternate to working Stress Design (WSD). The 1963 ACI-318 code gave both methods equal standing. Since the mid-1950s, reinforced concrete design has made the transition from that based on elastic method to ultimate strength. With the possibilities of producing high strength concrete of M-60 and above grade at very low water to cement

ratio

with

the

use

of

chemical and mineral admixtures and improved quality of cement, new uses of concrete were found in high-rise buildings, long span bridges, tall chimneys, industrial buildings and many other applications where traditionally steel had been used in the past. The development of pre-stressed concrete in 1930s and 1940s further helped use of concrete in critical applications. From the second half of 20th Century, concrete has emerged as the most important construction material in all types of civil engineering works. It is estimated that the use of concrete per year has reached to a level of 15 billion tons worldwide or nearly 2t per head. It is second most widely used material after water at present. Cudos to cement and concrete. Conclusion: The discovery of Portland cement and its use in reinforced concrete have immensely contributed to the social, economic and industrial development during the 20th Century. The progress of modern society is unthinkable in absence of cement and reinforced concrete. No doubt cement and concrete have enriched the life of each individual on the globe, but they 10

have also caused degradation due to mining of aggregates and other minerals and emission of green houses gases in atmosphere. Cement alone is responsible for emission of about 6.5% of green house gases and production and transportation of concrete will further add to this figure. The use of industrial by products like fly ash, ggbs silica fume, etc in concrete and alternate fuels in production of cement are some of the modern initiatives to mitigate this problem. However, ever increasing use of cement and concrete will require extensive research as how to conserve use of minerals, energy and fuel in production of these indispensible materials and how to make them better performing and more durable. References: 1. Estathiadis E. Greek Concrete of three millenniums. Public works Research Centre, 31 pp Athens, 1978. 2. Vitruvius, P De architeeture, English translation by J. Gwilt, London 1826. 3. McCann, A-M. The Roman Port of Cosa, Scientific American pp-84-91, March 1988. 4. Manzione, E. The colosseum, 94 pp, 1982. 5. Adams, F-D. 6. Idom GM ‘Zement and Beton’ No. 18, April 1960. Danish Edition. 7. Smeaton, J, ‘Narration of the building and description of the construction of Eddystone light-house’, London 1813. 8. Stanley CS ‘Highlights in the history of concrete’, 44pp, Cement and Concrete Association, Slough 1979. 9. M. Faujas de Saint-Fond, ‘Researches sue le pozzolanes’, 125 Grenoble, et Paris, 1778. 10. Gunnar M.I.dron, ‘Concrete progress from Antiquity to the third Millennium’ pp 22-23, Thomson Telford, London 1997. 11. Tornebohm, A-E, “Ueber die Petro graphic des Portland Cement” Portland Cement Fabrikanten, 34stockholm- 1897. 12. First symposium on the Chemistry of Cement 1918, Transactions of the Faraday society VOL XIV, pp1918-19.

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13. Second International symposium on the Chemistry of cement, 1938. A general discussion on the setting of cement. Proceedings published by Royal Swedish Institute pp1939. 14. Website www.engineer’soutlook.com. History of Reinforced concrete and structural design. 15. The author thankfully acknowledge the text material from various chapters of the book written by Gunnar Idorn ‘concrete progress from Antiquity to the third Millennium’, published by Thomson Telford, London in 1997.

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