In the present study physicochemical characterization of slate sample was carried out which was collected from slate mine in Lasbela District, Baluchistan. Slate was evaluated for its effectiveness as partial replacement of ordinary Portland cement (OPC) in the production of Portland Pozzolana cement (PPC). The grain size analysis of crushed slate sample using ball mill revealed that maximum fraction retained on 44 μm was about 72.8 %. Sum of the major oxides (SiO2 + Al2O3 + Fe2O3) is about 90.09 % that meet the requirement as per ASTM C 618 (minimum 70.0 %). Other oxides including SO3 (<0.05), CaO (4.04), MgO (1.66), K2O (0.10), Na2O (0.16), TiO2 (0.35), MnO (<0.02) and Cl (0.12) also meet the international standard of ASTM C 618 for PPC. OPC without and with using slate sample in a ratio of 5 % and 10 % with clinker was tested to measure compressive strength, physical tests and setting time. The results showed that after 5 % and 10 % replacement, insignificant effect was observed on the physical properties, setting time and compressive strength in 2-, 7- and 28-days curing. Hence, slate can be used as natural pozzolan for manufacturing PPC. It is cost effective for the production of cement as well as to sustain the resources of limestone for long time and reducing emission of CO2 in the environment. It can also be used in the sulfate rich environment, coastal areas especially for the construction of dams and bridges.
This paper presents the historical background of the 20th-century technology of geopolymers in light of a literature research of the 15th to 19th centuries and offers a hypothesis on why this historical knowledge was forgotten when Portland cement appeared. The recapitulation of the different cementitious calcareous matters returns all the way to the Bible builders; Ancient Vitruvius Pollio’s work "Ten Books of Architecture". These books were not only read but practically proven in pre-Portland times and especially at the beginning of 19th century. The long-term stability of Roman mortars and constructions was studied from the perspective of the cementitious materials, and the cited literature demonstrates the historical evolution of calcareous cements, then the reasons for the interruption of progress and return to the historical experience in the 1980s., Tomáš Hanzlíček, Ivana Perná, Zdenek Ertl and Sean M. Miller., and Obsahuje bibliografii