It brings together contributions from leading experts involved with the drafting and implementation of ENV and will facilitate discussion on its application. In addition to coverage of the technical aspects of the common Portland cements, the emerging European specification for 'special' cements will be discussed. The availability and requirements for different cement types will be reviewed. The book is derived from a seminar held at the University of Dundee in September ISBN ISBN: X.
File: PDF, 3. The file will be sent to your email address. The impact categories listed in Table 1 and Table 2 have been considered as decision criteria to choose the most sustainable cement powder by mean the AHP method. It consists of decomposition of decision problem what is the best, or most sustainable, cement? Each element of the hierarchy could be referred to any aspect of the decision problem e. Figure 1 represents four levels of analysis. The hierarchical decomposition consists of three criteria criterion A, B and C and five sub-criteria sub-criterion 1 to 5 to be applied to three alternatives.
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Scale of importance by Saaty [ 36 ]. The scale of importance shown in Table 3 allows the decider composing the matrices pairwise comparisons C , whose e ij elements means the preference of i with respect to j and the e ji are reciprocal of e ij Table 4. As consequence of this, such matrices are square and have dimensions equal to the number of variables O i considered elements in the hierarchical level under consideration.
For each hierarchical level, the decision maker generates as many pairwise comparison matrices as elements of the upper level. From each of these matrices, elements of the considered hierarchical level are ordered respect to each involved criterion of the upper level. A pairwise comparison matrix is consistent if any three elements e ij , e ik , e jk satisfies Equation 1 [ 37 ]:. According to the Pareto efficiency, the analysis is based on optimum allocation of available resources [ 38 ].
The hierarchical analysis is mathematically more complex than classic multi-criteria analysis [ 39 ], but it simplifies the work of decision maker, which responds to simple and same type questions, the pairwise comparisons. Subjective elements, as the choice of the relative importance scale, and the definition of the acceptable threshold inconsistency, are present in the hierarchical analysis and they limit the action of decision maker, but the method ensures an inclusive approach to multi-criteria problems.
Indeed, it allows the evaluation of multiple aspects, as happens in construction bids, where legislative, technical, economic and environmental issues should be considered. Jones] on garnet.
This book. This book reviews the implications of the new European standard for cements. It brings together contributions from leading experts. On other hand, the method is decried as being arbitrary in the assignment of the relative weights and influenced in the result by the number of considered alternatives. As regard as the first weak point, the authors interviewed technicians from different backgrounds, experts in the fields of environment, human health and economy i. As regard as the latter weak point, the analysis considers only ten impact categories instead of 26 defined by [ 29 ], and limits human health and economic analysis to the most considered variables at international level [ 40 ].
The study focused on the choice of the most sustainable cement powder to be used for cement bound mixtures e.
The four cement powders are identified by the nomenclature cement n , with n varying from 1 to 4, and they are produced by different plants numbered according to the cement nomenclature i. The hierarchy defined by the authors involves four level of analysis, as represented in Figure Hierarchical decomposition used for the analysis.
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As regard as the priorities relating to the three criteria of level II, pairwise comparisons gave the results shown in Table 5. Thirty two 32 technicians have participated in the AHP analysis: The geometric mean has been used to aggregate individual judgements and obtain pairwise comparison matrices. Each element c ij derives from application of the Saaty method [ 36 ]: Each element x ij of the normalized pairwise comparison matrix for level II N, II is obtained by dividing each element c ij by the sum of each column of pairwise comparison matrix Equation Table 6 allowed the calculation of weights to be related to each criterion of level II.
Weights w ij have been obtained by Equation Random Consistency Index [ 36 ]. The analysis of consistency for level II gave the results listed in Table 9 l max is 3. The results listed in Table 9 satisfy the condition proposed by Saaty [ 36 ]: As regard as the priorities relating to criteria of level III, pairwise comparisons for environment analysis gave the results shown in Table The analysis of consistency of level III, environment analysis gave the results listed in Table For the first one the results are based on the pairwise comparison matrix for level II, shown below in Table As regard as the priorities relating to criteria of level IV, pairwise comparisons for atmosphere analysis gave the results shown in Table The analysis of consistency of level IV, atmosphere analysis gave the results listed in Table At the end of the hierarchical analysis involving all sub-criteria, the cements have been compared.
Table 20 shows the comparison matrix for environmental sub-criteria GWP. Table 21 shows the normalized pairwise comparison matrix for environmental sub-criteria GWP.
Euro-Cements: Impact of Env 197 on Concrete Construction
Weight vector of GWP for the examined alternatives is represented in Table The analysis of consistency of environmental sub-criterion GWP gave the results listed in Table Similar procedure has been applied to all considered sub-criteria of level IV. Performances of cements respect to atmosphere are calculated by mean the hierarchical re-composition of the analysis. In particular, the sorting matrix of alternatives, atmosphere shown in Table 24 should be multiplied by:. The evaluation of the data was made individually for each sample, as well as comparatively for samples having the same limestone content at Fig.
This may be due to the greater insolubility and therefore the greater stability of carbonate. The addition of calcium carbonate does not cause great changes as far as the type of calcium aluminate hydrates is concerned, but it affects their rate of formation.
It must be noticed, however, that it is difficult to distinguish the different forms of C3A hydrates since many of them have similar diffraction patterns. XRD patterns of C3S - 0 and C3S - 35 pastes after 28 days arrows indicate the peaks attributed with the carbosilicate hydrate. CH peaks also increase in relation to hydration time. However, XRD quantitative determination of CH cannot be done, since part of it may not be well crystallized.
There are indications, that small amounts of a type of carbosilicate hydrate probably scawtite, Ca7 Si6O18 CO3? In LC -0 pastes, ettringite is gradually transformed into monosulfate. In LC - 35 pastes, the formation of ettringite is delayed and monocarboaluminate is preferably formed instead of monosulfate. Calcium aluminate hydrates 3CaO? Ettringite is formed during the first 24 h in all samples.
Small quantity of ettringite is probably present up to 7 days, in all samples, but it disappears at 28 days. Pastes with calcium carbonate appear to contain lesser ettringite than in plain cement pastes, even if the dilution of the samples with limestone is taken into account. Monosulfate has already formed in pure cement pastes during the first 24 h and continues to be formed up to 28 days. In pastes with calcium carbonate, monosulfate is formed after 2 days and is still present at 28 days in continually decreased amount. At 2 and 7 days, another form of carboaluminate Ca4Al2O6?
Based on the above observations, it is concluded that calcium carbonate suppresses the conversion of ettringite to monosulfate and favors the replacement of monosulfate by Table 5 Hydration products in samples LC - 0 and LC - 35 1 Day Hydration products Ettringite Ca6Al2 SO4 3 OH 12? The higher content of bound water in the pastes made from limestone cements, indicates that limestone improves the clinker reactivity and exploits its hydraulic potential. This effect may be related to the structure modification of the hydration. The increase of CH content in pastes of limestone cement indicates an acceleration of calcium silicate hydration.
Conclusions The hydration products in C3S and C3A pastes containing CaCO3, as well as in limestone cement pastes, are identified by means of powder diffraction. The effect of calcium carbonate on the hydration procedure is also recorded. It is concluded that, in pastes containing CaCO3, either as a chemical reagent or as a limestone constituent, the ettringite's transformation to monosulfate is delayed, while calcium aluminate monocarbonate is preferably formed instead of monosulfate even at early ages.
In addition, the hydration of calcium silicates is accelerated. References  S. Sarkar, S.
Euro-Cements: Impact of ENV 197 on Concrete Construction
Ghosh, Mineral Admixtures in Cement and Concrete, 1st edn. ABI Books, India, Neville, Properties of Concrete, 4th and final edn. Addison Wesley Longman, England, Baron, C. Schmidt, Cement with interground materials? Dhir, M. Jones, Euro - cements. Schiller, H. Sprung, E. Adams, R.
Euro-Cements | Impact of ENV on Concrete Construction | Taylor & Francis Group
Race, Effect of limestone additions upon drying shrinkage of Portland cement mortar, in: P. Kligger, D. Hooton Eds. Tsivilis, E.