Calorimetric characterization of Portland limestone cement produced by intergrinding V. F. Rahhal • E. F. Irassar • M. A. Trezza • V. L. Bonavetti Received: 17 February 2011 / Accepted: 7 April 2011 / Published online: 22 April 2011 Ó Akade ´miai Kiado ´, Budapest, Hungary 2011 Abstract The calorimetric technique provides continu- ous, direct, and general measurements of the course of coexisting reactions and their interactions during hydration of blended cement at early age. In this article, this tech- nique is used to analyze the inﬂuence of compositional and process variables on the early age hydration of Portland limestone cements (PLC) made by intergrinding in a full size-cement plant. Eight cements, the vertices of 2 3 facto- rial design, were made with a limestone ﬁller content (LF) of 0 and 24%, a gypsum content (GC) of 2.5, and 5.0%; and a ﬁneness, measured as that fraction retained on a 45 lm sieve (R45), of 5 and 18%, to study their effects on the heat released. In addition, a PLC with a composition nearly to the center point of 2 3 designs was analyzed. Measurements were performed on cement pastes (w/ cm = 0.4) using a semiadiabatic differential calorimeter operating at 20 °C during 48 h. At different time, the heat released was determined and it was modeled using a linear mathematical model including the three variables (LF, R45, CG) and their interactions. The signiﬁcance of the model, the variables and the interactions was judged using the analysis of variance. Results of model show that heat released is reduced by LF due to physically dilution phe- nomenon, which is directly proportional to LF content. The R45 exerts its major inﬂuence during the development of second peak (12–21 h) but later its effect declines to null contribution. GC retards and attenuates the hydration reactions moderately until 30 h, and then its increase contributes to Q t due to the formation of ettringite and its transformation. The only signiﬁcant interaction was LF with R45 during the second peak development. Results present good correlation with the isolate measurement of compressive strength at 12, 24, and 48 h. Keywords Portland cement  Hydration  Heat of hydration  Limestone ﬁller  Gypsum  Fineness  Experimental design Introduction The cement hydration begins around the cement clinker particles interacting with dissolved ions in solution and the properties of cement paste, such as heat generation, strength development and shrinkage, are the result of the interrelated chemical, physical, and mechanical processes [1]. The course of hydration (induction, acceleration, and desacceleration) is governed by different laws: dissolution, nucleation/growth, and diffusion. It also produces the change from plastic to rigid state of paste during setting and then the reduction of porosity contributing to increase the strength and to reduce the permeability. During hydration, volume changes are also observed in paste [2]. The factors that exert major inﬂuence on the hydration kinetics of blended cement paste are: the mineralogical composition of clinker [3], the gypsum content [4], the initial water-to-cement ratio (w/cm)[5], the particle size distribution [6], the dispersion/ﬂocculation state of the particles [7], the type and amount of mineral addition used [8, 9], the presence of chemical admixtures [10] and the curing temperature [11]. The production of Portland limestone cement (PLC) rises around the world due to environmental goals required V. F. Rahhal  E. F. Irassar (&)  M. A. Trezza  V. L. Bonavetti Departamento de Ingenierı ´a Civil, Facultad de Ingenierı ´a, Universidad Nacional del Centro de la Provincia de Buenos Aires, B7400JWI Olavarrı ´a, Argentina e-mail: ﬁrassar@ﬁo.unicen.edu.ar 123 J Therm Anal Calorim (2012) 109:153–161 DOI 10.1007/s10973-011-1575-9