The Evolution of Cementitious Materials Through History
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DAVID BONEN 1 , MEHMET A. TASDEMIR 2 , AND SHONDEEP L. SARKAR3* 'Northwestern University, Dept. Civil Engng., 2145 Sheridan RD. Eavanston, IL 60208 U.S.A., 2 Istanbul Technical University, Dept. Engng. Materials, 80626 Maslak-Istanbul Turkey, 3 Sherbrooke University, Dept. Civil Engng., Sherbrooke, QC JIK 2R1, Canada
ABSTRACT
The use of cementitious materials dates back to the beginning of the Epipaleolithic period. Examples for ancient cementitious materials from Israel, Egypt, Turkey, and Italy are numerous. Prior to Aspdin's patent of portland cement at the first half of the 19th century, cementitious materials were composed of earth, mixture of earth and limestone, calcium sulfates, and slaked lime with and without pozzolans. The latter comprises pozzolanic materials from volcanic and sedimentary origin, crushed burnt clay brick, and dust brick. Frequently, organic fibers were incorporated for reinforcement. This paper describes the evolution of the cementitious materials through time and highlights the durability of ancient cementitious materials as compares to that of portland cement concrete. Although modem concrete is characterized by its high strength and low permeability, it often faces durability problems. In turn, ancient concretes examined exhibit low strength but have proved to be durable materials. Microstructural examination reveals that the groundmass of the latter has been carbonated and is highly porous. Nevertheless, no specific cracking pattern could be observed. The outstanding performance of ancient concrete structures implies that thermodynamic stability rather that mechanical strength is a key point for a long-term durability. INTRODUCTION
Anthropologists commonly define a prehistoric society according to its remains of material culture, such as, structures, tool forms, and art. The working hypothesis is that the succeeding society is more developed and sophisticated than the previous one, so its remains. Therefore, the progress and skill of a given society can be evaluated by its construction materials. Recent progress in the production of macro defect-free (MDF), densified particle (DSP), and fiber reinforced cements testifies to the advanced state of the present holistic knowledge of cement and concrete. Production and fabrication of cementitious materials with compression strengths of hundreds and thousands MPa are attainable. On the other hand, the growing number of concrete structures that display distress and premature deterioration provoke the question to what extent is portland cement concrete durable? Or in other words, is the main hydrated product of portland cement, the C-S-H capable of withstanding the test of time? This question becomes relevant in the light of the outstanding performance of a few ancient structures, some of which are continuously subjected to sequences of drying and Present Address: S.E.C.A., Inc., Consulting Engineers, 7220 Langtry, Houston, TX 77040 159 Mat. Res. Soc. Symp. Proc. Vol. 370 01995 Materials Research Society
wetting and salt attacks. Besid
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