Deliverable D4.2. Field demo of culvert in Italy

Transcription

1 ERA-NET Plus on Infrastructure Innovation SEACON Sustainable concrete using seawater, salt-contaminated aggregates, and non-corrosive reinforcement Start date: 01/10/2015 Duration: 30 months Deliverable D4.2 Field demo of culvert in Italy Main Editor(s) Buzzi Unicem Due Date 30/07/2017 Delivery Date 30/07/2017 Task number 4.1 Dissemination level PU Project Coordinator Antonio Nanni, University of Miami, 1251 Memorial Drive Coral Gables, FL USA Tel: Website:

2 1.1 Objective In the context of WP4, a demonstrator was built in Italy to show the feasibility of SEACON technology in harsh environmental conditions (presence of chloride contamination due to the use of deicing salts during winter). The main goal of the DEMO project was to prove the successful use of seawater as mixing water in concrete if combined with non-corrosive reinforcement (stainless steel and GFRP bars). Carbon steel was also included to better understand the advantages that a non-corrosive reinforcement can offer in terms of durability. Furthermore, the reuse of asphalt was tested, substituting part of the natural aggregate, to investigate the impact that this recycled material has on the concrete properties. Measurement systems were included in the project to allow durability monitoring after the casting. 1.2 Italian DEMO The Italian DEMO consists of a reinforced concrete culvert built along the A1 motorway in Pontenure, Piacenza, in the asphalt production plant of Pavimental, the infrastructure owner which collaborates in the project, Figure 1. The location and the structure type were chosen based on the harsh environmental conditions, created by the outflow waters coming from the motorway, to the culvert, that has the function of providing drainage. The chloride contamination of these waters, due to the use of de-icing salts during winter, is of particular interest for the project. Figure 1- Territorial framing of the Italian DEMO The culvert is 30 m-long, and it was divided into 6 segments in which different concretes and reinforcements were used, Figure 2. In particular: A- Reference concrete and carbon steel Date: 28/07/ (10)

3 B- SEACON concrete and carbon steel C- SEACON concrete and stainless-steel type 304 (austenic) D- SEACON concrete and stainless-steel type (duplex) E- SEACON concrete and GFRP bars F- RAP concrete and carbon steel Figure 2- Scheme of the culvert The specific concrete mixtures for the demo, Table 1, were designed considering the results obtained through laboratory tests performed during the previous WPs and the specific requirements of the structure, made available according to the timing of the project. Table 1- Recipes of the concretes Mix design Reference concrete SEACON concrete RAP concrete CEM II/A-LL 42.5R kg/m Fly ash kg/m Sand 0-5 mm kg/m Gravel 5-7 mm kg/m Gravel 8-15 mm kg/m RAP kg/m Superplasticizer kg/m Retarding agent kg/m Water l/m Seawater l/m The geometry of the cross section is reported in Figure 3. The different types of concretes were used only for the slab. The side walls were constructed in a single common concrete casting using Reference concrete. Date: 28/07/ (10)

4 Figure 3- Cross section geometry In every segment, the reinforcement of the slab has been organized in the form of mesh, the different types have been laid not in contact between each other. In segment B (SEACON concrete + carbon steel), in addition to the reinforcing mesh, an activated titanium mesh has been incorporated in the concrete to allow electrochemical measurements; it has been placed below the armature, but not in contact with it. In each segment, the two reference electrodes and a probe for the measurement of the conductance have been positioned, except in segment E, with GFRP reinforcement, where only the probe and a reference electrode have been used. Table 2 reports the type of reinforcement, concrete and measurement systems for every segment of the culvert. Table 2- Summery of reinforcements, concretes and measurement systems present in every segments Segment A B C D E F Reinforcement Carbon Carbon SS 304 SS Carbon GFRP** steel steel (1.4311)* (1.4362)* steel Concrete Reference SEACON SEACON SEACON SEACON RAP Rebar V V V V - V SSC-Ref V V V V - V Ti-Ref V V V V V V Res-Probe V V V V V V Ti-mesh - V Multi-probe V V V * Supplied by Acciaierie Valbruna ** Supplied by ATP All the reinforcements and probes were connected to an electric box that allows the collection of the data. Date: 28/07/ (10)

5 Figure 4- Acquisition system 1.3 Construction phases The casting was made in two different phases. On November 23 rd, the side walls were cast with Reference concrete, and the next day, November 24th, the slab, divided in six segments, was realized using three concretes, according to the recipes reported in Table 21. The concretes were produced in a concrete batching plant of Buzzi Unicem, about 10 km from the casting site, Figure 5. During the casting of the slab, some tests were performed in order to control the quality of the concretes produced; the slump test was performed first in the concrete batching plant and then repeated at the casting site to check the workability maintenance, so other parameters were determined including, in particular: air content, effective water content and fresh density, Table 3. Table 3- Data measured onsite during the casting Reference concrete SEACON concrete RAP concrete Volume of the batch (m 3 ) Slump in the concrete batching plant (mm) Consistency in the construction site (mm)* n.a. Air content (%) Effective water (l/m 3 ) Fresh density (kg/m 3 ) *estimated by the manometer of the concrete mixing truck Date: 28/07/ (10)

6 Figure 5- Concrete batching plant Figure 6 shows the installation of the reinforcements in mesh form prior to the casting. It is evident that the different types of reinforcement were laid not in contact with each other. Figure 6- Installation of the mesh reinforcement After laying down the reinforcement, the electrodes and probes were installed, and the connections were organized. Date: 28/07/ (10)

7 Figure 7- Positioning of probes and electrodes The concretes were cast through the use of a pump, Figure 8. Figure 8- Concrete casting In Figure 9, the different actions related to the concrete casting are presented, beginning with pumping, then vibration and then finishing. Date: 28/07/ (10)

8 Figure 9- Casting of the concrete, vibration and finishing. 1.4 Complementary laboratory tests During the casting, some samples were taken in order to investigate the concrete properties through laboratory tests, specifically, related to the hardened density, Table 4, and the strength development, Table 5. Table 4- Hardened density measured on the onsite samples Hardened density (kg/m 3 ) Reference concrete SEACON concrete RAP concrete 24h d d d d Table 5- Compressive strength measured on the onsite samples Compressive strength (MPa) Reference concrete SEACON concrete RAP concrete 24h d d d d With regard to compressive strength, Figure 10 shows the comparison of the strength development between the same mixtures cast in laboratory and onsite. Only in the case of Reference concrete, there is a strong difference, in particular, with regard to the medium and long term (90 day). The best result, instead, was presented by SEACON concrete, that shows very similar results in laboratory and onsite. Date: 28/07/ (10)

9 Figure 10- Comparison between onsite and laboratory samples Conclusions on materials: - The feasibility of casting concrete using seawater was demonstrated - Slump loss for seawater concrete was higher compared to reference concrete - Strength development for seawater concrete up to 28 days is higher compared to reference concrete - RAP concrete shows high slump loss and lower strength development 1.5 Evolution of exposure conditions Figure 11- December 19, 2016 T=0 C Date: 28/07/ (10)

10 Figure 12- April 26, 2017 T=15 C Figure 13- June 13, 2017 T=36 C Date: 28/07/ (10)