state of the art of shotcrete technologies; experiences...

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

5 Markus Jahn Shotcrete

Tunneling & Mining Process: dense-flow Output: 15-25 m3/h Agg. Size ≤ 12 mm Rebound: < 15 % Accelerator: 25-35 kg/m3

Global Shotcrete Trend

Ordinary Portland cement Blended cement CO2 and cost

500 kg/m3 binder 400 kg/m3 binder CO2 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/mm2 at 2 minutes for building up layers overhead • ≤ 0.2 N/mm2 at 2 minutes for reducing dust and rebound

Source: Testing Gallery Hagerbach, Switzerland

High aggregate surface Compressive strength development

Bonding to the substrate

Smaller hose diameters

High Binder Content – Why?

Challenges in the Future

New Mix Designs Reduced clinker content

• Sustainability (CO2 reduction)

• Tunnel maintenance (sintering)

• Cost reduction (clinker, high costs)

High activities in development of shotcrete admixtures and additives

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-L93 AF 2011 Aluminumsulphate Suspension



Sigunit L-5601 AF 2014 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 L-5711 AF 2016 Aluminumhydroxi-sulphate Solution 13

“…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

Sika MiniShot

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

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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 SiO2 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

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 Superplasticiser

Sigunit Shotcrete Accelerator

SikaTard-930 Long Time Retarder

Sika-PM Shotcrete Spraying System

Aliva TBM-Robotor

SikaPlan Waterproofing Membrane

Sikacrete Fire Protection Mortar

Brenner Base Tunnel, Italy 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

Sigunit-L53 AF Accelerator

Sigunit-LT Accelerator

Sika ViscoCrete SC-305 BBT Superplasticizer

Sika-PM 500 Spraying Equipment

SikaPump-Start 1 Lubrication agent

Aliva FlexoDrain W Drainage System

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 Superplasticizer

SikaTard-930 Retarder

Sigunit-P1 AF Accelerator

Milk Milk Powder

Liquid Accelerator Instant Accelerator

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Sigunit-P1 AF • Extremely long shelf life • No transportation of water • Easy and fast just-in-time production • High performance

Tailor-made Solutions

23

Sweden India Australia

Mixing of Sigunit-P1 AF

Nassau, Germany 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

SikaTard-930 Retarder

Sigunit-L93 AF Accelerator

Aliva-263 Application System

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)

1st at the beginning of the project

2nd 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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https://www.youtube.com/watch?v=_gxF7-6dkZY

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state of the art of shotcrete technologies; experiences...

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