State of the Art of Shotcrete Technologies; Experiences and References Markus Jahn, Corporate Product Engineer, Sika Services AG
Content Global Trends Requirements on Shotcrete Accelerator Development Case Studies Support Troubleshooting
Working mechanism shotcrete Shotcrete A) fills joints and evens out irregularities of the substrate B) its flexural strength prevents blocks from falling out C) seals, that prevents water from washing out fines and small rocks D) supports the rock mass by arching effect E) builds a beam/panel effect with the rock bolts Source: Sprayed Concrete for Rock Support, no. 7, Norwegian Concrete Association
Tunneling & Mining Process: dense-flow Output: 15-25 m 3 /h Agg. Size 12 mm Rebound: < 15 % Accelerator: 25-35 kg/m 3 5 Markus Jahn Shotcrete
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Global Shotcrete Trend Ordinary Portland cement Blended cement CO 2 and cost 500 kg/m 3 binder 400 kg/m 3 binder CO 2 and cost Alkaline Accelerator Alkali free Accelerator EH&S and durability Solutions Suspensions Cost efficient Steel mesh Fibre reinforced Cost efficient Steel fibres Macro synthetic fibres Cost efficient / durability General Solution Customized Solution Sharper optimization Penetrometer / Hilti Ultra sound measurement Reliability
Requirements on Shotcrete Fast setting No negative impact on 28 d compressive strength High durability Few rebound Good bonding to substrate High energy absorbtion Sustainable Cost-performance optimized Austrian Shotcrete Guideline : The compressive strength of shotcrete should fulfill: 0.1-0.2 N/mm 2 at 2 minutes for building up layers overhead 0.2 N/mm 2 at 2 minutes for reducing dust and rebound
High aggregate surface Compressive strength development High Binder Content Why? Smaller hose diameters Bonding to the substrate Source: Testing Gallery Hagerbach, Switzerland
Challenges in the Future New Mix Designs Reduced clinker content Sustainability (CO 2 reduction) Tunnel maintenance (sintering) Cost reduction (clinker, high costs) High activities in development of shotcrete admixtures and additives
13 Product Year Chemical basis Appearance Sigunit Silicate Powder; akaline Sigunit-L Silicate Solution; alkaline Sigunit-L20 1985 Aluminate Solution; alkaline Sigunit-49 AF 1994 Aluminumsulphate Powder Sigunit-L50 AF 1995 Aluminumsulphate Solution Sigunit-L53 AF 1996 Aluminumhydroxi-sulphate Solution Sigunit-P1 AF 2000 Aluminumhydroxi-sulphate Instant Sigunit-L72 AF 2007 Aluminumsulphate Solution Sigunit-L83 AF 2009 Aluminumhydroxi-sulphate Solution Sigunit-L93 AF 2011 Aluminumsulphate Suspension Sigunit-P10 AF 2012 Aluminumhydroxi-sulphate Instant Sigunit-L87 AF 2013 Aluminumhydroxi-sulphate Solution Sigunit L-5601 AF 2014 Aluminumsulphate Suspension Sigunit L-5401 AF 2015 Aluminumsulphate Suspension Sigunit L-2301 AF 2015 Aluminumhydroxi-sulphate Solution Sigunit-39 AF 2015 Aluminumsulphate Powder Sigunit-59 AF 2015 Aluminumhydroxi-sulphate Powder Sigunit L-5710 AF 2015 Aluminumhydroxi-sulphate Solution Sigunit-P20 AF 2015 Aluminumhydroxi-sulphate Instant Sigunit L-5602 AF 2016 Aluminumsulphate Suspension Sigunit L-5711 AF 2016 Aluminumhydroxi-sulphate Solution
Sika MiniShot ultra sound spectrometer which determines the shear modulus as a measure of the strength evolution, non-destructive and continuously.
Sika MiniShot Development of taylor-made shotcrete admixtures Creating cost-performance optimized shotcrete mix designs Quality control for running construction projects
New Shotcrete Accelerator stand for Better cost-performance, due to Optimized production Better logistics New formulations Improved performance No negative impact to durability and final compressive strength Higher stability Tailor-made Perform with local cement types Harmonize with local admixtures and additives More respect in terms of EH&S Do not attack human tissue Environment-friendly Reduced leaching
Products Type Effect Sigunit Accelerator High early strength Sika ViscoCrete Superplasticizer Water reducing SikaTard Retarder Long workability SikaFiber SikaFume Macro fibers Silica fume Energy absorption High final strength SikaPump -Start 1 Lubricant agent Avoids blockages SikaShot-3 Ready mix gunite High accelerated shotcrete SikaTell Colloidal SiO 2 Rebound reduction FlexoDrain Flexible channels Water drainage system Aliva Equipment Rotor machines Application devices Sika-PM Shotcrete pumps Application devices SikaCare Paraffin oil Equipment protection 17
Kiruna Mine, Sweden Requirements: 4 MPa at 4h 28 d strength > 40 MPa Accelerator dosage < 10% Accelerator stability > 6 months Open time > 4h Energy absorption according to ASTM 1550-05 of 490 J Sikament EVO 26S Superplastcizer (HRWR) SikaTard -930 Consistency stabilizer Sigunit -L53 AF (CC) Shotcrete accelerator Sika FastMix 225 HRWR (powder)
Gotthard Base Tunnel, Switzerland Requirements: Early strength: J2 Final strength: B 40/30 Aggregates: 0-8 mm Workability time: 4-8 hrs Exposure class: XA2 Sika ViscoCrete Sigunit SikaTard-930 Sika-PM Aliva SikaPlan Sikacrete Superplasticiser Shotcrete Accelerator Long Time Retarder Shotcrete Spraying System TBM-Robotor Waterproofing Membrane Fire Protection Mortar
Brenner Base Tunnel, Italy Sigunit-L53 AF Sigunit-LT Sika ViscoCrete SC-305 BBT Sika-PM 500 SikaPump-Start 1 Aliva FlexoDrain W Accelerator Accelerator Superplasticizer Spraying Equipment Lubrication agent Drainage System Requirements: SpC 30/37 (28) II/J2 XC2 XF1 GK8 F59 w/c-ratio: 0.50 Open Time: 60 min Compressive Strength after 48 hrs: 10 MPa Compressive Strength after 28 d: C 30/37
Karanjukar, Iceland Requirements: Early strength: J2 Final strength: C 32/40 Aggregates: 0-8 mm Workability time: 2-4 hrs Exposure class: XC2, XF3 Sika ViscoCrete SC-305 SikaTard-930 Sigunit-P1 AF Superplasticizer Retarder Accelerator
Tailor-made Solutions Milk Milk Powder Liquid Accelerator Instant Accelerator Sigunit-P1 AF Extremely long shelf life No transportation of water Easy and fast just-in-time production High performance 22
Mixing of Sigunit-P1 AF Sweden India Australia 23
Nassau, Germany SikaTard-930 Sigunit-L93 AF Aliva-263 Retarder Accelerator Application System Requirements: C 25/30 Early Strength Class: J2 Minimal Working Space: 2 m Open Time: ca. 24h Delivery Distance (thin-flow): 100 300 m Exposition Classes: XC4 / XF1 / XA1
Supplementary Services from the Industry Mix design development Troubleshooting Education / Trainings Quality Management Guidelines Logistics
Troubleshooting of highly optimized systems
Troubleshooting: Who is Guilty?
Quality Management Cement chemistry: Shotcrete performance-testing based on all chemically relevant factors from site: cement, fines (from sand & aggregates), batching water, Sigunit and ViscoCrete (MiniShot) Cement fineness and particle size distribution: Blaine value, specific surface area (BET) and particle size analysis (Laser Granulometry) Chemical analysis of the cement (chemical composition & mineralogy) 1 st at the beginning of the project 2 nd when troubles occur
Sika Academy Shotcrete Training Mix designs Quality management Troubleshooting Supplementary products Nozzleman Training Application according to EFNARC Equipment maintenance EFNARC diploma for experienced nozzlemen
Shotcrete Quality Stop layering / lamination: Well-maintained equipment Don t go to the limit of the machine. Use always a free flowing concrete. Spray only when hopper is more than ¾ full. Place equipment always as horizontally as possible. Clean always the injector holes before spraying. Apply shotcrete according to the spraying rules.
Conclusion 1. Shotcrete is a technology in change regarding mix design and quality measurement. 2. Clients demand for more than only products. They want solutions and support. 3. As more optimized the technology as more sensitive against fluctuating parameters
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