Does phosphorus affect the industrial Portland cement reactivity? Sonia Boughanmi a,⇑ , Islem Labidi a , Adel Megriche a , Houssine Tiss b , André Nonat c a Université de Tunis El Manar, Faculté des Sciences de Tunis, UR11ES18 Chimie Minérale Appliquée, Campus Universitaire Farhat Hached, 2092 Tunis, Tunisia b Laboratoire de Production, les Ciments de Bizerte, 7000 Bizerte, Tunisia c Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303 CNRS-Université de Bourgogne Franche, Comté, BP 47870, 21078 Dijon Cedex, France highlights  Study of properties of industrial clinkers with 0.5 < P 2 O 5 < 1.1%  No direct relation between reactivity and mineralogy.  Compressive strength is not affected in the range 0.5 < P 2 O 5 < 1.1% article info Article history: Received 28 September 2017 Received in revised form 15 July 2018 Accepted 11 August 2018 Keywords: Industrial clinkers Phosphorous Mineralogy Reactivity abstract The effect of phosphorous on the mineralogy and reactivity of Portland cement has been investigated through an industrial clinkers series. The samples were collected from the same Tunisian cement plant and classified according to the content of P 2 O 5 from 0.5% to 1.1%. All samples were manufactured at the same thermal and cooling conditions as well as possible. The specimens were characterized by X-ray fluorescence spectrometry and optical microscopy techniques and their mineralogy was deter- mined by X-ray powder diffraction coupled to the Rietveld analysis. The cements reactivity prepared from the clinkers was followed by means of isothermalcalorimetry. The compressive strength of the cement pastes was measured. The results revealed that the content of phosphorous in this range has not a significant influence on the clinkers mineralogy cement reactivity and concrete performance. Ó 2018 Elsevier Ltd. All rights reserved. 1. Introduction Hydration of Portland cement remains a subject of a lot of researches because of its complexity, the needs to improve its envi- ronmental footprint and the properties of the final materials. For example, the presence of minor elements coming from both raw materials and fuels in the clinkering process, may introduce some modifications in the main constituents and modify the kinetics of the hydration reactions. The effects of the impurities on the clinker mineralogy and hydraulic cement reactivity are often complex because many variables are involved which are difficult or impos- sible to control independently. These include chemical composi- tion and polymorphic changes but also inclusion of defects, morphologic and textural modifications such as particle size distri- bution, presence of microcracks etc... [1]. Among these foreign ele- ments, the phosphorous coming from raw materials (marls and limestone) or alternative fuels (meat and bone meals) has been identified as having important effects on the distribution of the main phases in Portland clinker and on the cement reactivity [2–8]. In fact Portland clinker typically contain around 0.2 wt% of P 2 O 5. Most of the studies agree to show that higher phosphorus contents in clinker favors the formation of belite (C 2 S) and free lime to the expense of alite (C 3 S) [1]. As alite is the main hydraulic compound of Portland cement and the most reactive phase, its decrease causes the decrease of the amount of its hydration pro- duct, calcium silicate hydrate (C-S-H) at early age, which leads to the decrease of the development of strength in concrete in the first 28 days. The stabilization of C 2 S by phosphorous is well documented; during the clinkering process phosphorus is firstly fixed by calcium in forms of apatite C 3 P which becomes unstable at higher temper- atures leading to a 0 -C 2 S, a stable solid solution of C 3 P in C 2 S. As a result the C 3 S formation becomes more and more impeded with the P 2 O 5 addition and it results an increase of free lime [9–11]. The decomposition of alite is generally observed above 0.5 wt% P 2 O 5 [4] but in the case of the pure CaO-SiO 2 system, Noirefontaine found that the addition of 0.1 wt% P 2 O 5 is enough to cause a partial https://doi.org/10.1016/j.conbuildmat.2018.08.060 0950-0618/Ó 2018 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. E-mail address: ingenieursonia@gmail.com (S. Boughanmi). Construction and Building Materials 188 (2018) 599–606 Contents lists available at ScienceDirect Construction and Building Materials journal homepage: www.elsevier.com/locate/conbuildmat