New ecosustainable cement from ceramic waste

The aim of the work is to reuse ceramic waste, in order to allow the production of Pozzolanic cement also in the regions where natural pozzolan or artificial pozzolan, like fly ash, are not available. This possibility, beyond the higher durability of the concrete in the environment in which the pozzolanic properties are required, allows a saving of high percentages of clinker in cement production, reducing in a proportional way the needs of raw material from quarrying and the issues related to the waste disposal of Construction and Demolition waste (CDW). All these issues are of fundamental interest for European research and environmental policy, as well as finding direct application in the industry of building and constructions. This research investigates the possibility to use ceramic waste in the preparation of cement or in concretes as Supplementary Cementitius Material, through the determination of the chemical and mechanical behaviors. The research starts from the sampling of ceramic waste from construction and demolition landfills or from the disposal sites of the ceramic industry. The study of the behavior of these materials was carried out checking the match of the required chemical properties of the each materials for its eligibility as pozzolanic materials, or addition, in accordance to European and American standards. After that, several experimental Pozzolanic cements were produced in laboratory, using the ceramic wastes in a variety of different percentages, in replacement of the Portland cement type I 52,5 R, containing over 95 % clinker Portland. The new experimental Pozzolanic cements were characterized about chemical and mechanical properties in comparison to 4 reference commercial cements, which are produced with the same kind of clinker Portland in the same factory, the mentioned Portland cement type I 52,5 R, also used as in the production of all experimental Pozzolanic cements, a Pozzolanic cement type IV/A (P) 42,5R, a Pozzolanic cement type IV/B (P) 32,5 R and a Composite Portland cement type II/B-LL 32,5 R. The new experimental Pozzolanic cements were also tested in the production of concrete, in order to evaluate the actual mechanical performances in the building works, from which depends dosage and convenience of the cement and the possibility to produce high strength classes of concrete. Over 30 different experimental Pozzolanic cements, were produced and tested about the pozzolanicity and in concrete production, each at several different water/cement ratios, obtaining an excellent mechanical strength, especially in the production of concrete with low water/cement ratio and high mechanical performance. The results indicate, first of all, the possibilities to produce Pozzolanic cement through different types of ceramic wastes. The waste from bricks and tiles permits to assure the necessary high level of pozzolanicity at 8 day for its classification as Sulphate Resistant Pozzolanic cement in accordance to EN 197-1: 2011. This kind of ceramic waste shows behavior and performances very similar to the common natural pozzolans usually quarried and used in central Italy for cement production. The second kind of ceramic waste, from porcelain stoneware production process, named hard ceramic, thanks to the high pozzolanic activity, assures the possibility to produce Sulphate Resistant Pozzolanic cements in accordance to European Norm, with very little contents of ceramic waste and obtaining mechanical performances in the standard mortar similar or better than those of the pure Portland cement type I 52,5 R. Also, the possibility of using ceramic waste in the cement production, depending on the type of cement required, can reach the maximum quantity of pozzolanic material allowed in cement in accordance with the EU norms. Moreover, the results in concrete at low water/cement ratio indicate very interesting opportunities for using these cements for the production of very high performance concretes, showing the possibilities to obtain mechanical strengths at 28 days of maturation higher than those of the commercialized Portland cements type I, having the maximum strength class 52,5 R. The higher increasing of mechanical strength of the concrete made with Pozzolanic cement, not only those containing ceramic waste [...] but also with the natural pozzolans used as reference, highlights the benefit of the use of Pozzolanic cements, which appear to be less advantageous just from the point of view of the standard mortar, as well as in concretes with w/c ratio higher than 0.5. To the better mechanical performance in concrete at low w/c ratio it must be added the lower heat of hydration due to the reduction of the clinker Portland content and the higher durability. This research work is described in 5 chapters, with the following main contents: Chapter 1- Introduction - A short history of the use of pozzolan and ceramic waste in the production of water resistant concrete. In the chapter are also indicated modern applications, standards on the cement production and environmental implication of the use of ceramic waste in the cement. Chapter 2 Materials e methods - The materials involved in the experimentation (raw materials, ceramic wastes, commercial cements, experimental cement mixes) are reported and described in this chapter, together with methods and tests applied in the experimentation. Even if the great part of the used tests are in accordance to Standard norms, they are described in order to indicate, for each of them, the actual meanings of the results and the difference between results of test having apparently similar scope. Chapter 3 Results - The chapter reports and describes the results of the characterization of each ceramic waste, together with the results of the different tests used to characterize the properties of the new experimental cements, in comparison to 4 reference commercial cements. Particular attention was taken in the evaluation of the behavior of the new cement in concrete. Chapter 4 Discussion - In this chapter, the behavior of different kinds of ceramic waste and the applicability for the cement production are displayed, as a result of the very high chemical and mechanical potential performances obtained. The interesting properties of a new pozzolanic cement are evidenced and compared to those of the common Portland cement and Pozzolanic cement. The data are discussed also in terms of their impact on the environmental issues related to the cement industry. Chapter 5 Conclusions In this chapter a summary of the most important results obtained in the study is reported, with a discussion on the applications of the experimental cements produced and the industrial implications. The possible classification of 2 new ecosustainable pozzolanic cements produced through two different kinds of ceramic waste are reported, in accordance to the European Norm about cement production EN 197-1:2011.