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Crack Free and Durable Concrete Repairs with the BaenzigerBlock, experiences since 1995

Crack Free and Durable Concrete Repairs with the BaenzigerBlock, experiences since 1995. Heinz Bänziger, Sika Services AG Senior Vice President BU Contractors Head Technical Department Construction Head Market Field Refurbishment & Strengthening.

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Crack Free and Durable Concrete Repairs with the BaenzigerBlock, experiences since 1995

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  1. Crack Free and Durable Concrete Repairs with the BaenzigerBlock, experiences since 1995 Heinz Bänziger, Sika Services AG Senior Vice President BU Contractors Head Technical Department Construction Head Market Field Refurbishment & Strengthening ICRI Convention, October 2010, Pittsburgh

  2. Crack Free Repairs with the BaenzigerBlockPresentation at ICRI Congress October 25, 2001 ICRI Convention, October 2010, Pittsburgh

  3. Crack Free Repairs with the BaenzigerBlockThe basics of successful concrete repair • A concrete repair mortar has to fulfill the requirements which are necessary • to support the existing damaged concrete structure regarding- • Strengths (compressive, flexural, tensile) • Bond to substrate (> 1.5 MPa) • Durability (a part of sustainability) • Protection • Elastic modulus (e.g mortars with polymeric binder) • Cracking But the most important requirement is: Workability, placement only mortars with excellent processing can reach the high expectations Bad Workability, placement = Bad Quality ICRI Convention, October 2010, Pittsburgh

  4. Crack Free Repairs with the BaenzigerBlockDevelopment: The philosophy Test facility with fastest possible respond of the most important properties! Killing factors visible after 1 day to max 28 days with one single test! 1. Workability Bad placement = bad quality – return to R&D 2. Crack behavior Cracks = reduced protection - return to R&D 3. Adhesion to substrate No adhesion = not usable - return to R&D ICRI Convention, October 2010, Pittsburgh

  5. 3. Adhesion to substrate No adhesion = not usable 2. Crack behavior Cracks = reduced protection 1. Workability Bad placement behavior = bad quality Crack Free Repairs with the BaenzigerBlockDevelopment The philosophyTest facility with fastest possible respond of the most important properties! Killing factors visible in shortest time span as possible! ICRI Convention, October 2010, Pittsburgh

  6. 100% RH 90% RH 80% RH 70% RH 60% RH 50% RH 40% RH 30% RH Free drying shrinkage Restrained shrinkage Tensilestress[N/mm] Shrinkagestrain [mm/m] Strength limit !Cracking! 0%RH 20%RH 40%RH 60%RH 80%RH 100%RH !Drying induced „free“ contraction of the samples! !Free contraction restrained due to mechanical property of substrate! free vs. restrained shrinkage Baenziger Block ICRI Convention, October 2010, Pittsburgh

  7. 1000mm 300mm Crack Free Repairs with the BaenzigerBlock Crack simulation of concrete repair mortars needs • bond to a concrete substrate • specimen sizes which reflects reality • edges • free shrinkage parts • restrained shrinkage parts • connection joints repair to existing • corners • substrate roughness according practice • variable layer thickness • water absorption of substrate concrete • re-produce able climatic conditions Job Site BaenzigerBlock ICRI Convention, October 2010, Pittsburgh

  8. Crack Free Repairs with the BaenzigerBlock Crack simulation of concrete repair mortars needs • bond to a concrete substrate • specimen sizes which reflects reality • edges • free shrinkage parts • restrained shrinkage parts • connection joints repair to existing • corners • substrate roughness according practice • variable layer thickness • water absorption of substrate concrete • re-produce able climatic conditions Job Site ICRI Convention, October 2010, Pittsburgh

  9. Crack Free Repairs with the BaenzigerBlock Crack simulation of concrete repair mortars needs • bond to a concrete substrate • specimen sizes which reflects reality • edges • free shrinkage parts • restrained shrinkage parts • connection joints repair to existing • corners • substrate roughness according practice • variable layer thickness • water absorption of substrate concrete • re-produce able climatic conditions Job Site ICRI Convention, October 2010, Pittsburgh

  10. Crack Free Repairs with the BaenzigerBlock Crack simulation of concrete repair mortars needs • bond to a concrete substrate • specimen sizes which reflects reality • edges • free shrinkage parts • restrained shrinkage parts • connection joints repair to existing • corners • substrate roughness according practice • variable layer thickness • water absorption of substrate concrete • re-produce able climatic conditions Job Site ICRI Convention, October 2010, Pittsburgh

  11. Crack Free Repairs with the BaenzigerBlock Crack simulation of concrete repair mortars needs • bond to a concrete substrate • specimen size which reflects reality • edges • free shrinkage parts • restrained shrinkage parts • connection joints repair to existing • corners • substrate roughness according practice • variable layer thickness • water absorption of substrate concrete • re-produce able climatic conditions Job Site ICRI Convention, October 2010, Pittsburgh

  12. Crack Free Repairs with the BaenzigerBlock Crack simulation of concrete repair mortars needs • bond to a concrete substrate • specimen size which reflects reality • edges • free shrinkage parts • restrained shrinkage parts • connection joints repair to existing • corners • substrate roughness according practice • variable layer thickness • water absorption of substrate concrete • re-produce able climatic conditions Job Site 3cm 6cm ICRI Convention, October 2010, Pittsburgh

  13. Crack Free Repairs with the BaenzigerBlock Crack simulation of concrete repair mortars needs • bond to a concrete substrate • specimen size which reflects reality • edges • free shrinkage parts • restrained shrinkage parts • connection joints repair to existing • corners • substrate roughness according practice • variable layer thickness • water absorption of substrate concrete • re-produce able climatic conditions Job Site Climate Chamber ICRI Convention, October 2010, Pittsburgh

  14. Crack Free Repairs with the BaenzigerBlock The Size of the BaenzigerBlock ICRI Convention, October 2010, Pittsburgh

  15. Crack Free Repairs with the BaenzigerBlock The Preparation of the Block Due to reproducibility reasons we use only one concrete mixture ICRI Convention, October 2010, Pittsburgh

  16. Crack Free Repairs with the BaenzigerBlock Testing, alternative conditions ICRI Convention, October 2010, Pittsburgh

  17. Crack Free Repairs with the BaenzigerBlock Results and Interpretation ICRI Convention, October 2010, Pittsburgh

  18. Crack Free Repairs with the BaenzigerBlock Results and Interpretation ICRI Convention, October 2010, Pittsburgh

  19. Crack Free Repairs with the BaenzigerBlock BaenzigerBlock and practice 15 years ago! Concrete Repair Mortar in practice 15 years ago ICRI Convention, October 2010, Pittsburgh

  20. Mortar 1 “non cracking mortar” Mortar 2 “non cracking mortar” Mortar 3 “low cracking mortar” Crack Free Repairs with the BaenzigerBlock Today Benchmark of so called “Non Cracking Cement Mortars” ICRI Convention, October 2010, Pittsburgh

  21. Crack Free Repairs with the BaenzigerBlock 1. Sample Results “Crack evolution over time” After 2 days After 4 days ICRI Convention, October 2010, Pittsburgh

  22. Crack Free Repairs with the BaenzigerBlock 1. Sample Results “Crack evolution over time” After 9 days After 28 days ICRI Convention, October 2010, Pittsburgh

  23. Crack Free Repairs with the BaenzigerBlock 2. Sample Results “Crack evolution over time” After 28 days After 56 days ICRI Convention, October 2010, Pittsburgh

  24. Crack Free Repairs with the BaenzigerBlock 2. Sample Results “Crack evolution over time” After 90 days The crack development of cement mortars is different! Some mortars are cracking within the first 24 hours others just start to crack after a few days or a few weeks! From our long term experience we know:The cracking behavior of cement concrete repair mortars should be tested up to one year! ICRI Convention, October 2010, Pittsburgh

  25. Crack Free Repairs with the BaenzigerBlock Today Benchmark of “Non Cracking Cement Mortars” It’s possible! No cracks after 1 year! ICRI Convention, October 2010, Pittsburgh

  26. Crack Free Repairs with the BaenzigerBlock Additional Test Methods ICRI Convention, October 2010, Pittsburgh

  27. Crack Free Repairs with the BaenzigerBlock Results “Crack evolution over time” • The BaenzigerBlock enables a lot of additional information: • date when the cracks appears • wideness of the cracks and wideness progress • crack development in length • numbers of cracks and development of cracks over time • type of cracks, e.g. single crack, spider web cracks • sensitivity of crack behavior, at corners, at edges on full surface etc. • loss of bond (de lamination) of the substrate due internal strengths and restricted shrinkage The BaenzigerBlock reflects the reality! But the final approval of the cracking performance Is always the application on a real structure! ICRI Convention, October 2010, Pittsburgh

  28. Crack Free Repairs with the BaenzigerBlock Concrete Repair Mortar development within the last 15 years High quality Concrete Repair under hardest conditions ICRI Convention, October 2010, Pittsburgh

  29. Crack Free Repairs with the BaenzigerBlock Concrete Repair Mortar development within the last 15 years Today it is possible: Architectural Concrete without any Cracks ICRI Convention, October 2010, Pittsburgh

  30. Crack Free Repairs with the BaenzigerBlock Investigations of independent Institutes THE EFFECT OF CONCRETE SUBSTRATE STRENGTH ON THE ADHESION PROPERTIES OF POLYMER MODIFIED REPAIR MATERIALS A.J.C. Jooste Rand Afrikaans University ABSTRACT. It is a known fact that the preparation of the concrete substrate plays an important role on the adhesion properties of polymer modified repair materials. Some uncertainty exist as to the influence of the concrete substrate strength on the adhesion properties of concrete repair materials. This paper reports on research done at the Rand Afrikaans University (South Africa), to investigate the influence of concrete substrate strength on the bonding properties of various repair materials. Different concrete substrate strengths were simulated by using the “Banziger test block” (20, 30 and 40 MPa). On these blocks seven different repair materials, from three different manufacturers, were placed. The placing specifications of the manufacturers were strictly followed. The samples were fully cured for 28 days, during which the crack behaviour was observed at 1, 7 ,14 and 28 days. The influence of concrete substrate strength on crack behaviour was experimentally investigated. By determining the bonding strength between repair material and concrete after 28 days, the influence of concrete strength on bonding strength was investigated. To compare practise with laboratory work a trial repair was done on a part of the R.A.U. complex. This repair was evaluated in the same manner as the “Banziger test blocks”. An important conclusion drawn from the observations, is that the actual method of substrate preparation plays an important role in determining bond strength. In substrates of low strengths, micro-cracks are easily formed. These cracks lead to reduced bonding strengths. 1999 ICRI Convention, October 2010, Pittsburgh

  31. Crack Free Repairs with the BaenzigerBlock Investigations of independent Institutes 2004 ICRI Convention, October 2010, Pittsburgh

  32. Crack Free Repairs with the BaenzigerBlock Investigations of independent Institutes ICRI Convention, October 2010, Pittsburgh

  33. Crack Free Repairs with the BaenzigerBlock Investigations of independent Institutes ICRI Convention, October 2010, Pittsburgh

  34. Crack Free Repairs with the BaenzigerBlock Investigations of independent Institutes ICRI Convention, October 2010, Pittsburgh

  35. Crack Free Repairs with the BaenzigerBlock Investigations of independent Institutes ICRI Convention, October 2010, Pittsburgh

  36. Crack Free Repairs with the BaenzigerBlock Investigations of independent Institutes ICRI Convention, October 2010, Pittsburgh

  37. Crack Free Repairs with the BaenzigerBlock Investigations of independent Institutes ICRI Convention, October 2010, Pittsburgh

  38. Crack Free Repairs with the BaenzigerBlock Investigations of independent Institutes Ring tests do not simulate reality! ICRI Convention, October 2010, Pittsburgh

  39. Crack Free Repairs with the BaenzigerBlock Investigations of independent Institutes App. 2002 ICRI Convention, October 2010, Pittsburgh

  40. Crack Free Repairs with the BaenzigerBlock Investigations of independent Institutes App 2006 ICRI Convention, October 2010, Pittsburgh

  41. Shrinkage does not correlate with cracking! Crack Free Repairs with the BaenzigerBlockOur investigations: Correlation Cracking - Shrinkage 1400 Mortar 1 Mortar 4 Mortar 3 1200 Mortar 5 1000 800 free - 21°C - 60% R.H.) Shrinkage (µm/m) (EN 12617-4 600 Mortar 2 Mortar 6 400 200 0 0 1 2 3 4 5 6 7 Ranking of cracking on Bänziger Block Bench mark at same age of specimens No cracks Full of cracks ICRI Convention, October 2010, Pittsburgh

  42. t = 28 d t = 55.5 d t = 56 d t = 59 d relative humidity [-] Crack Free Repairs with the BaenzigerBlockOur investigations: Moisture conditions in concrete and mortar before and during the repair process Development of internal moisture content during hardening and mortar application Of course a block of steel would not show similar behavior and the results would be different! ICRI Convention, October 2010, Pittsburgh

  43. Crack Free Repairs with the BaenzigerBlockOur investigations: Alternative Crack Testing Method based on our experiences Target: smaller, less weight, reliable, reproducible Correlation • Measuring cracking time on different devices Steel Ring Test does not simulate the site conditions: Steel has no surface roughness, does not breath and does not absorb water of the repair mortar = 100 % moist in contact zone mortar/steel ICRI Convention, October 2010, Pittsburgh

  44. Crack Free Repairs with the BaenzigerBlockConclusion oflaboratory investigations, Alternative Crack Testing Method based on our experiences • Based on fundamental research of Technology Center Improved lab test equipment • Possibility to identify directly which formulation parameters impact cracking • Final laboratory testing will still involve BaenzigerBlock • The final market release of a concrete repair mortar is still pending on the performance of selective applications on job site! ICRI Convention, October 2010, Pittsburgh

  45. Crack Free Repairs with the BaenzigerBlockSummary of over 15 years experience • During the past 20 years we made big improvements and gained more knowledge regarding cracking behavior of cement mortars! • Cracking of mortars is influenced by different parameters • Shrinkage of mortar • Environmental conditions • Concrete Substrate • Application and placement quality • Relaxation properties of the mortar • We have learned to formulate low (no) cracking mortars • We introduced the BaenzigerBlock in all development centers around the globe • It is our best tool for benchmarking different formulations; or comparisons with competitor’s products • The BaenzigerBlock is one of the best tool to test the mortar due to the close simulation of a real of concrete repair! ICRI Convention, October 2010, Pittsburgh

  46. Crack Free Repairs with the BaenzigerBlockOutlook 2020 • Due to high investments in infrastructures over the past decades, costs for maintenance and refurbishment of all (concrete) structures will increase dramatically! • The costs have already exceeded the budgets of many states! • Lack of maintenance is reality • Examples of collapses we see every day in the news • Functioning infrastructures are the backbone of every economy • New structures must have high sustainability and durability • The repair and protection of existing structures requires long lasting and sustainable methods • Sustainability is like a plant, it starts very small and is more important and more powerful with the age! • only if all components of a system meet the requirements of sustainability and durability, the overall system can meet this requirement also! • It is one of our main tasks to invest in products which align with Sustainability! ICRI Convention, October 2010, Pittsburgh

  47. Thanks for Attention! ICRI Convention, October 2010, Pittsburgh

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