WASTES: Solutíons, Treatments and Opportunities 2 nd Intemational Conference September 11 th - 13 th 2013 ONE-PART GEOPOL YMERS VERSUS ORDINARY PORTLAND CEMENT (OPC) Mortars: DURABILlTY ASSESSMENT Z. Abdollahnejad", C. JeSUS 2 , F. Pacheco-Torqar' and J. B. Aquiar" 1 Department of Civil Engineering, University of Minho, Guimaraes, Portugal. tolumahvash@gmail.com 2 Departmentof Civil Engineering, Universityof Minho,Guimaraes, Portugal. cjesus@civil.uminho.pt 3 C-TAC Research Centre, Department of Civil Engineering, University of Minho, Guimaraes, Portugal.torgal@civil.uminho.pt 4 C-TAC Research Centre, Department of Civil Engineering, University of Minho, Guimaraes, Portugal.aguiar@civil.uminho.pt ABSTRACT Investigations on the field of geopolymeric binders, state that this new material is likely to have high potential to become an alternative to Ordinary Portland cement (OPC). Recent results on the Life Cycle Analysis (LCA) of geopolymers they have a lower impact on global warming than OPC but on the other side they have a higher environmental impact regarding other impact categories. Lower COSRQPONMLKJIHGFEDCBA 2 emissions geopolymers are therefore needed. Classical two part geopolymers could be made more eco-efficient with a lower carbon dioxide footprint if the use of sodium silicate is avoided. Besides current geopolymeric mixes can suffer from efflorescence originated by the fact that alkaline and/or soluble silicates that are added during processing cannot be totally consumed during geopolymerisation. Therefore new and improved geopolymer mixes are needed. One-part geopolymers (sodium silicate free) were described by the first time in 2008 still a lot of issues remain unexplained about them. This paper compares the durability performance of one-part geopolymers with OPC mortars. The obtained results revealed that replacing 70% Portland cement by 58.3% Fly ash, 4% calcined stuff and 7.7% calcium hydroxide results in satisfactory and promising results in durability tests. Keywords: Geopolymers; ordinary Portland cement; fly ash; durability performance. INTRODUCTION With an annual production of almost 3 Gt Ordinary Portland cement (OPC) is the dominant binder of the construction industry [1]. The production of one tonne of OPC generates 0.55 tonnes of chemical CO 2 and requires an additional 0.39 tonnes of CO 2 in fuel emissions for baking and grinding, accounting for a total of 0.94 tonnes of CO 2 . Other authors [2] reported that the cement industry emiUed in 2000, on average, 0.87 kg of CO 2 for every kg of cement produced. As a result the cement industry contributes about 7% of the total worldwide CO 2 emissions [3]. The projections for the global demand of Portland cement show that in the next 40 years it will have a twofold increase reaching 6 Gt/year. The urge to reduce carbon dioxide emissions and the fact that OPC structures which have been build a few decades ago are still facing disintegration problems points out the handicaps of OPC. Portland cement based concrete presents a higher permeability that allows water and other aggressive media to enter leading to carbonation and corrosion problems. The early deterioration of reinforced concrete structures based on ordinary Portland cement (OPC) is a current phenomenon with significant consequences both in terms of the cost for the rehabilitation of these structures, or even in terms of environmental impacts associated with these operations. Research works [4-8] carried out so far in the development of geopolymers showed that much has already been investigated and also that an environmental friendly alternative to Portland cement is rising. Besides the durability of geopolymers is still a subject of some controversy [9]. While Duxon et aI. [10] state this is the most important issue on determining the success of these new materiais and other authors [11] mention that the fact that samples from the former Soviet Union that have been exposed to service conditions for in excess of 30 years showing liUle degradation means that geopolymers do therefore appear to stand the test of time. Sut since those materiais were of the (Si+Ca) type that conclusion cannot be extended to geopolymers defined as "alkali aluminosilicate gel, with aluminium 115