Materials Science Forum ISSN: 1662-9752, Vol. 869, pp 106-111 doi:10.4028/www.scientific.net/MSF.869.106 © 2016 Trans Tech Publications, Switzerland
Submitted: 2016-03-18 Accepted: 2016-03-21 Online: 2016-08-31
Hydration and Dehydration of High Initial Strength Portland Cement Type CP V - ARI Aloízio Geraldo de Araújo Júnior1, a, Leandro José da Silva1,b, Túlio Hallak Panzera1,c, Adriano Galvão da Souza Azevedo1,d and Kurt Strecker1,e 1
Universidade Federal de São João del-Rei (UFSJ), Departamento de Engenharia Mecânica, Praça Frei Orlando 170, Centro, CEP: 36307-352, São João del-Rei, MG, Brasil a
[email protected],
[email protected],
[email protected], d
[email protected],
[email protected]
Keywords: Dehydrated cement paste; Cementitious characteristics; Dehydration temperature.
Abstract. It is known that the hydration of cement paste is influenced by a variety of factors, it is also known that some hydration products are gradually dehydrated at elevated temperatures. In doing so, different author studied the dehydration of hydrated cement pastes under different condition. In this work, samples of Hydrated Cement Paste (HCP) were prepared from Portland cement of high initial strength (CP V-ARI) with a water/cement ratio of 0.5. The morphological changes during hydration and dehydration by subsequent heat-treatments were analyzed by X-ray diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR). Thermal Gravimetric Analysis (TGA) was used to study the thermal stability of the HCP. Dehydrated cement powder samples (DCP) were obtained heat treating samples of HCP at 300, 500, 700 and 900°C. After 7 days of curing HCP samples exhibited no significant changes in its structure. HCP dehydrated at 500°C showed the absence of Ca(OH)2 and calcium silicate hydrate. At 700°C the formation of β2CaO.SiO2, 3CaO.SiO2 and CaO is observed. During heat treatment at 900oC the HCP revealed a significant mass loss of 36%. Introduction The hydration of Portland cement paste is influenced by a variety of factors, especially phase composition, fineness, the w/c ratio used, curing temperature and by the presence of additives [1,2, 3]. On microscale (0.1-100 μm), the cement paste is composed of several phases consisting of unhydrated cement clinker and hydration products including especially calcium silicate hydrate (CS-H) and calcium hydroxide (CH). On nanoscale (2-100 nm), C-S-H is formed by a type of gel composed of several cells. At an atomic scale (
