Cement Energy and Environment

- quantify interlayer water (and hydrogen protons present in other solid components) has been undertaken using white cement. Generally, interlayer water is considered to be more mobile than water incorporated into the mineral solid components and therefore exhibits higher T2 values. Two early studies have reported components with T2 values of 60-100 1-JS that appear after the start of gel pore formation and are continually produced up to 100 h. The appearance of these signal components has been interpreted as either an expansion of the C-S-H interlayer space [30] or as the change in C-S-H morphology from a fibrillar to a sheet-like structure [11]. Recent series of studies [17-19,21 ,27-29] provide a clearer picture of the different hydrogen proton populations and their evolution during hydration in white cement. In these studies, interlayer water has been assigned to a component with a T2 value of -100 1-JS that is produced continuously, and broadly in proportion to the production of the solid fraction containing minerals such as ettringite and portlandite, during hydration (21]. 3.4 Inclusion of interlayer water in hydration products Consideration of the conceptual model provided by Muller et al. [21]. and their proposed T2 value of the interlayer water, highlights the uncertainty in our study as to whether interlayer water was being detected or was part of the IW 06 - 0 G) ai a:: -1 component. Two aspects of the results have led us to conclude that the latter option is correct: 1) the strong correlation between the rate of IW formation and the rate of heat production, as measured by calorimetry (Fig. 7), indicates that the IW fraction accounts for all the water involved in hydration reactions, including the formation of C-S-H (see Section 3.5 for further discussion); and 2) the gel pore component of measurable water, in which the interlayer water would be included if detected, ceases formation and even begins to decrease approximately 40 to 50 h after the start of the acceleration phase of hydration, in line with the behaviour of gel pore water reported by Muller et al. [21]. Based on this reasoning , we will consider that interlayer water is part of IW in further discussion. Furthermore, this discussion will provide additional indirect support to this proposal. The structure and stoichiometry of C-S-H gel have been the subject of intense study over the previous decades with the location and state of water within the hydrate being of particular interest[16,31 ,32]. Water is considered as part of the C-S-H structure, and equivalent to chemically bound water [31], although the water appears to be bound with varying degrees of strength and is liberated progressively over a large range of drying conditions. Most uncertainty exists around physically confined water associated with C- S- H 4 3 2 0 10 20 lO 4.Q. 50 60 10 0 10 20 30 40 50 6Q 10 Time ~ttl} liime ~h) 1111. 7:RAuls(iw~terttmlfbiT1llllon,calb.ll.ktli!d1irth~nl'!,llltl....,~4lvesort~m&11Umbtawat1!11plll~compm!cUotllemaolllleM:grodll«tllll~li!UW1!tlbyi10111emlalll3iilrlmeloyftll' Al nu 11lfan1011~ 8)1(3 g I!& ''rtaron. <tl4ks': "cllnuc.orO) 10'11ll)jg' 'ROtanltrff. NOII!tllOII'UI~ raroo~waanlfbl'lllltlon lt«<lll.all;mw \lie rateorlw ptOIIUI'tltw~. V(nlcal dllshed Unessllaw lhe dmas-~~o IS. atd·l• tl!allsllow.tll~bel1Jlmf11; oftli~ITD< fel pore lbnna\lon. <IIlii <t-S-H dlmlilltcllun ~rospeah~&ljt, 59