The use of fluvial and marine sediments in the formulation of Roller Compacted Concrete for use in pavements

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1 TENT_A_ fm Page 1 Thursday, May 21, 09 :36 PM Environmental Technology Vol. 00, No. 0, Month 09, 1 7 The use of fluvial and marine sediments in the formulation of Roller Compacted Concrete for use in pavements M. Zdiri a,c *, N. Abriak b and M. Ben Ouezdou a Taylor and Francis a Civil Engineering Laboratory, National Engineering School of Tunis, BP 37, Tunis-Belvedere, 02, Tunisia; b Labo de Génie Civil Environnemental Ecole des Mines de Douai, Rue Charles Boursel, B.P , France; c Laboratoire LAMTI, Université d Artois, F.S.A., Technoparc Futura, 620 Béthune, France In the manufacture of Roller Compacted Concrete (RCC) used for pavement materials, various types of aggregates are used, such as crushed and rolled limestone or siliceous aggregates. The main objective is always to reach the maximum compactness to achieve higher mechanical performances. In the present work, fluvial and marine sediments, resulting from the dredging of harbours and rivers, were introduced as aggregates in the preparation of RCC for pavement construction, with a view to improving the mechanical strength of the RCC. This study included a granulometric, mineralogical and chemical characterization of the aggregates.the work also contains a mechanical characterization of the resulting material. The objective of the study was to find a resistant RCC, by developing materials such as sediments that are often classified as a waste and where their storage is harmful to the environment. The mechanical strengths obtained showed the profitability of using a Roller Compacted Concrete containing sediments. Keywords: Roller Compacted Concrete (RCC); marine sediments; river sediments; mechanical characteristics; Software Rene LCPC 1. Introduction Much research has been done on the formulation and implementation of Roller Compacted Concretes (RCC) for paving manufacture. The main objective is to produce RCC mixtures with optimal compactness. The formulation and the proportioning of the various components allows these mixtures to acquire the best properties in a fresh and hardened state in order to support the loads to which they will be subjected after implementation. Generally, high resistance materials, which are not sensitive to water and are susceptible to being compacted, are sought. The majority of RCC pavements constructed in the world (USA, Canada, Spain etc.) have been manufactured with a hydraulic cement of a total content between 12% and 16% of the mass of the total dry constituents [1]. In the manufacture of RCC for pavement use, various types of materials are used, classically as aggregates, such as crushed and rolled limestone and siliceous aggregates, resulting in concretes with a relative density in the order of 20 to 20 kg/m 3 [2]. In the present work, fluvial and marine sediments, resulting from the dredging of harbours and rivers, are introduced in preparing RCC for pavement use. The accumulation of these mineral and organic sedimentary particles in the harbours, rivers and navigation routes, impeded the clear movement of boats and ships. Several dredging operations of rivers and harbours are regularly carried out. In France, Tunisia and many other countries, these dredging operations generate great quantities of marine and river sediments. Moreover, the special properties (fineness, resistance and density), obtained by the addition of these aggregates to the RCC, are the principle reasons for the use of these marine and river sediments. The marine and river sediments used as aggregates contribute to the mechanical strength and increase the density (exceeding 20 kg/m 3 ) of the RCC. Furthermore, the use of these sediments provides economies in the storage and transport of these materials considered as waste. In this paper the presentation and the characterization of the marine and river sediments and other granular materials, used for RCC manufacture, are presented. Then, the software Rene-LCPC is used for the formulation and the determination of the component proportions. Additionally, the work includes experimental tests of compression on cylindrical specimens of mixtures of marine and river sediments, made by auto- 0 *Corresponding author. zdiri_ms@yahoo.fr ISSN print/issn X online 09 Taylor & Francis DOI:.80/

2 TENT_A_ fm Page 2 Thursday, May 21, 09 :36 PM 2 M. Zdiri et al. matic compaction according to the modified Proctor process. The results of this study show that these concretes develop resistances sufficient for the application of these dredging materials in road engineering. 2. Materials 2.1. Cement In this work, additions such as fly-ash, slag, silica fume and pozzolan were not used. The used binder was a hydraulic Portland cement, which is a key component of RCC manufacture. In this study, the used cement, C.E.M. II/B-M 32. had a relative density equal to 0 kg/m 3 [3] Aggregates Aggregates for this study came from various quarries in the north of France. Different classes of aggregates are necessary to fill the inter-aggregate space to the maximum. Two types of aggregates were used: Boulonnais siliceous sand and Boulonnais crushed gravel. The characteristics and data relative to these aggregates are presented in Table 1 and Figure 1. Figure 1. Grain size distribution of the sediment and the used aggregates Sediments The sediments used are fine particles of organic (humus) and inorganic (minerals) origins. The particles from rivers are termed the river sediments, whereas the elements formed in the harbours are termed the marine sediments [4]. The sediments used in this study are from: - the higher Scarpe river, the town of Brebrières, km from Douai, for the river sediments, - the harbour of Le Havre, for the marine sediments. 3. Formulation by the Compressible Packing Model The proportioning of the various dry materials of the RCC mixtures was chosen in order to obtain a higher strength. To determine the percentages of the components, the Compressible Packing Model (CPM) [] was applied through the software Rene LCPC [6], which was developed at Laboratoire Central des Ponts et Chaussées in France. This model, designed for the formulation of conventional concretes, was adopted for the formulation of the RCC with optimal granular compactness. It allowed the determination of the percentages and the production of RCC mixtures with minimal porosity, i.e. with maximal compactness. On the basis of the various aggregates identified previously, two mixtures were obtained with different combinations of each sediment and the Boulonnais sand and gravel. The results from the model for the components of the two mixtures are presented in Table 3 and Figure 4: Figure 4. Theoretical compactness of the mixture and optimal proportions (%) by the Compressible Packing Model. 4. Preparation of the mixtures and test set-up The mixing of the various components of the RCC was made in a concrete mixer. The specimens were prepared in the minutes following the maxing by the automatic technique of compaction, according to the modified Proctor process [8]. The used specimens were cylindrical with a 0 mm diameter and 0 mm height. The RCC was implemented in the mould in five layers; each layer was compacted with blows as presented in Figures and 6. Figure. 6. Automatic RCC specimens compaction containing of sediments. specimens. In the fresh state, the RCC contains in general many vacuums. It has a low strength and settlements can occur under the effect of loads. To obtain heightbearing capacity, this material should be compacted. The goal of the RCC compaction is to obtain the highest possible dry density. The objective is always to reach a compact configuration of the coarse aggregates [9]. AQ4 The study of the chemical nature of the sediments proved that they will not cause later deterioration in the RCC mixture and that they are compatible with the used cements. The elementary chemical analysis and the characteristics of the sediments are presented in Table 2 and Figures 2 and 3:. Mechanical characterization The setup of the specimens was made according to the modified Proctor process. The specimens were released from the mould after 24 hours and were stored in water at a temperature of about C and hygrometry more than 9%. Compressive tests were made by a AQ Figure Photograph Different used of dried aggregates: sediment. sediment (left), sand (middle) and gravel (right). 0 Table 1. Characteristics of aggregates. Aggregates Type Source Relative density kg/m 3 Flatting ratio % Los Angeles abrasion test Micro-Deval test Boulonnais sand Siliceous sand 0/ Boulonnais 27 Boulonnais gravel 4/ Crushed gravels 4/ Boulonnais Marine sediment marine dredging Le Havre Fluvial sediment fluvial dredging Douai 60 AQ1,1

3 TENT_A_ fm Page 3 Thursday, May 21, 09 :36 PM Environmental Technology Per cent passing Boulonnais Sand. Boulonnais Gravel Sediment Sieve size (mm) Figure 1. Grain size distribution of the sediment and the used aggregates. AQ2 Table 2. Characteristics of the sediments used. Marine Sediments Fluvial sediments Relative density (kg/m 3 ) 60 Relative density after calcination (kg/m 3 ) Content of organic matter (0 C) (%) Loss by fire after 12 h (en %) tensile compression machine of 00 kn capacity at 3, 7, 14 and 28 days of age. The testing equipment is presented in Figure 7 and a photograph of a cracked specimen is shown in Figure 8. Figure Equipment Cracked specimen for compression of RCC containing testing of the sediments. specimens. The compressive strength of the RCC containing sediments is considered its most important property. It gives an overall indication of the quality of a concrete because it is linked directly to the hydrated cement paste structure and the kind of aggregates used. Furthermore, the concrete strength represents the main element for the conception of RCC pavement structures [9]. The curves of the compressive forces versus displacement were plotted for the RCC specimens containing sediments. These graphs give also the stress strain curves for this material. Figure 9 shows that these mixtures have a highest strength of 14 MPa. The results are reported in Figures 9 and. Figure 9.. Force Slope versus of the displacement curve of force of versus three compression displacement tests for one of RCC specimen. containing sediments. The obtained sediment-containing RCC is a noslump concrete which behaves in a fresh state as a soil. In the hardened state it behaves like a concrete and, once implemented in the layers of roadways, is resistant to the action of traffic and atmospheric agents. It also reduces the noise from vehicles wheels because of its strong density. AQ6 0 Figure 2. Photograph of dried sediment. 6. Prediction of the tensile strength The tensile strength represents one of the parameters to be taken into account in designing an RCC pavement, as

4 TENT_A_ fm Page 4 Thursday, May 21, 09 :36 PM 4 M. Zdiri et al. Figure 3. Different used aggregates: sediment (left), sand (middle) and gravel (right). AQ3 Table 3. Example of percentages of the various components determined by Rene LCPC. Cement Fluvial Sediment Boulonnais Sand Boulonnais Gravel 4/ Weight in kg for 1 m Percentage (%) Cement Marine Sediment Boulonnais Sand Boulonnais Gravel 4/ Weight in kg for 1 m Percentage (%) AQ8 AQ9 Compactness Compactness versus the Constituents Sediment Bolonn Sand Bolon Gravel 4/ Proportion ( %) Figure 4. Theoretical compactness of the mixture and optimal proportions (%) by the Compressible Packing Model. for any other rigid concrete pavement. The tensile strength, as for the compressive strength, is influenced by the proportion of cement and water and, consequently, the E/C ratio ; by the compactness value; and by the quality and diameters of the aggregates. To predict the tensile strength, the de Larrard model [ 7, ] was used. It is intended to predict, from the compressive strength F c, the tensile strength by splitting F t of the RCC cylindrical specimen. This model is expressed by the equation: F F t 07. c The objective of the study of the compressive and tensile strengths is to predict the load in the RCC pavement which will cause cracking and rupture. The absence of cracking is extremely significant to ensure the durability of the RCC. It is also necessary to determine the evolution of the tensile strength of the RCC, especially for use in roadways. The RCC pavements were designed based on the flexural strength, which is connected to the tensile strength of this material [1]. 7. Interpretations The study analyses the behaviour and the strength evolution for RCC mixtures containing proportions of dredged sediments. These materials differ from the mixtures containing only limestone and siliceous aggregates. The added sediments present particular characteristics in granulometry and composition. The stress strain curve of the RCC containing sediments presents a weak slope at the beginning of loading whereas this slope becomes stronger as load increases. The compressive strengths (>14 MPa) and the tensile strengths (>1.8 MPa) obtained in this study

5 TENT_A_ fm Page Thursday, May 21, 09 :36 PM Environmental Technology Figure. Automatic compaction of the specimens. Figure 6. RCC specimens containing sediments. 0 Figure 7. Equipment for compression testing of the specimens. Figure 8. Cracked specimen of RCC containing sediments.

6 TENT_A_ fm Page 6 Thursday, May 21, 09 :36 PM 6 M. Zdiri et al Specimen Displacement (mm) Figure 9. Force versus displacement of three compression tests of RCC containing sediments. AQ7 AQ11 Force (N) Force-displacement variation speci Displacement (mm) Figure. Slope of the curve of force versus displacement for one specimen. are sufficient for the material to be put in the base or surface courses of roadways. The strength improvements were due to the very significant resumption of the aggregates of the great part of the loads. The binding part corresponding to the cement paste takes the remaining part of the loads. The paste strength can be weakened by the addition of other fines or sediments. The addition of marine or river sediments to the formulation of RCC mixtures leads to the following gains: a reduction in the hydration heat sufficient compressive and tensile strengths for resisting traffic the possibility of reducing the necessary quantity of cement an increase in the quantity of water required for mixing a high packing of the obtained product. We noted during the mixing that the addition of the sediments provides a higher workability than that of mixtures containing ordinary limestones and siliceous aggregates (without addition of sediments). 8. Conclusion The addition of marine or river sediments in the formulation of the RCC mixtures can act as a partial replacement for ordinary limestone aggregates. This solution is presented as an alternative for the valorization of these sediments and to provide a method of reducing the required quantities of ordinary aggregates. The use of the sediments in the RCC formulation allows for a reduction of hydration heat and improves the workability. These two advantages are very significant for the use of the RCC in dam constructions. 0 Table 4. Example of strength results of the RCC specimen containing sediment. With river sediment With marine sediment Cylindrical specimen (/) Wet relative density (kg/m 3 ) Section (m 2 ) Compressive strength (MPa) Tensile strength (MPa) AQ

7 TENT_A_ fm Page 7 Thursday, May 21, 09 :36 PM Environmental Technology 7 AQ12 AQ13 AQ14 AQ The proportions used vary between 12% and 14.6% and allow the addition of a quantity varying between and 321. kg of sediment per m 3 of RCC. The addition of these sediments also resolves the storage and transport problems of these materials, which are considered to be harmful to the environment. The MEC Model proved to be reliable for the formulation of the RCC mixtures containing the river or marine sediments. This model is based on the principle of maximum compactness and shows that the sediments fill the vacuums remaining in the RCC. However, when the proportion of these sediments is very high it is possible that some quantity of the sediments does not take part in compactness and creates weak points in the RCC structure. The compressive and tensile strengths obtained by the RCC mixtures containing sediments are sufficient to allow the application of this material in road engineering. The sediment fines are not binder elements which can make setting in an autonomous way. Their role in the RCC mixture is hence to increase the compactness of the mixture with basing on a limited proportioning. The sediment properties offer to the RCC mixtures a high compactness which gives sufficient mechanical strength and a pavement surface more closed. References [1] P. Gauthier and J. Marchand, Conception et réalisation de revêtements en béton compacté au rouleau au Québec, Association Béton de Québec, Québec, 04 (In French). [2] P. Gauthier, J. Marchand, L. Boisvert, E. Ouellet, and M. Pigeon, Conception, formulation, production et mise en oeuvre de revêtement en béton compacté au rouleau, Centre de Recherche Interuniversitaire sur le Béton, Université Laval, Québec, 00 (In French). [3] M. Zdiri, J. Neji, M. Ben Ouezdou, and M.R. Elouni, Formulation et simulation des bétons compactés au rouleau: Applications aux matériaux de gisement locaux, CMEDIMAT 0 Conference, Oran, Algeria, 0 (In French). [4] T.N. Thanh, Valorisation des sédiments marins et fluviaux pollués en technique routière, Laboratoire Génie Civil et Environnemental, Ecole des Mines de Douai, Douai, France, 06 (In French). [] F. de Larrard, Concrete Mixture Proportioning: A Scientific Approach, Modern Concrete Technology Series 9, E & F.N. Spon, London, [6] T. Sedran and F. de Larrard, Manuel d utilisation de Rene-LCPC: logiciel d optimisation granulaire, Version 6.1d, (In French), available at result/rene.php. [7] N. Pouliot, T. Sedran, F. de Larrard, and J. Marchand, Prédiction de la compacité des bétons compactés au rouleau à l aide d un modèle d empilement granulaire, Bulletin des Laboratoires des Ponts et Chaussées, 233 (01), pp (In French). [8] M. Zdiri and M. Ben Ouezdou, Compacité et Compactabilité du Béton Compacté au Rouleau (BCR) pour pavages, International Conference SOMAPRO Sols et Matériaux à Problèmes, Hammamet, Tunisia, 07, pp (In French). [9] A.M. Neville, Propriétés des bétons, Centre de Recherche Interuniversitaire sur le Béton, Université Laval, Québec, 00 (In French). [] M. Zdiri, M. Ben Ouezdou, and J. Neji, Theoretical and experimental study of Roller Compacted Concrete strength, Magazine of Concrete Research 60 (08), pp