ICRI Convention, October 2010, Pittsburgh 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 BaenzigerBlock Presentation at ICRI Congress October 25, 2001

ICRI Convention, October 2010, Pittsburgh 3 Crack Free Repairs with the BaenzigerBlock The 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 3. Adhesion to substrate No adhesion = not usable - return to R&D 2. Crack behavior Cracks = reduced protection - return to R&D 1. Workability Bad placement = bad quality – return to R&D Crack Free Repairs with the BaenzigerBlock Development: 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!

ICRI Convention, October 2010, Pittsburgh 5 2. Crack behavior Cracks = reduced protection 3. Adhesion to substrate No adhesion = not usable 1. Workability Bad placement behavior = bad quality Crack Free Repairs with the BaenzigerBlock Development The philosophy Test 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 Restrained shrinkage Tensile stress [N/mm] 100% RH 90% RH 80% RH 70% RH 60% RH 50% RH 40% RH 30% RH 0%RH20%RH40%RH60%RH80%RH100%RH Free drying shrinkage Shrinkage strain [mm/m] Baenziger Block !Drying induced „free“ contraction of the samples! !Free contraction restrained due to mechanical property of substrate! free vs. restrained shrinkage Strength limit !Cracking!

ICRI Convention, October 2010, Pittsburgh 7 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 300mm 1000mm

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 Crack Free Repairs with the BaenzigerBlock Today Benchmark of so called “Non Cracking Cement Mortars” Mortar 1 “non cracking mortar” Mortar 2 “non cracking mortar” Mortar 3 “low cracking mortar”

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! Ranking of cracking on Bänziger Block Shrinkage (µm/m) (EN free - 21°C - 60% R.H.) No cracks Full of cracks Mortar 2 Mortar 5 Mortar 4 Mortar 6 Mortar 3 Mortar 1 Crack Free Repairs with the BaenzigerBlock Our investigations: Correlation Cracking - Shrinkage Bench mark at same age of specimens

ICRI Convention, October 2010, Pittsburgh 42 relative humidity [-] t = 28 d t = 56 dt = 55.5 d t = 59 d Crack Free Repairs with the BaenzigerBlock Our 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 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 Crack Free Repairs with the BaenzigerBlock Our investigations: Alternative Crack Testing Method based on our experiences Cracking time of mortarsMortar 1Mortar 2 Steel Ring Test32 days5-6 days BaenzigerBlock10-17 days9-11 days Alternative Laboratory Test Method of Sika 14 days9-11 days

ICRI Convention, October 2010, Pittsburgh 44  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! Crack Free Repairs with the BaenzigerBlock Conclusion of laboratory investigations, Alternative Crack Testing Method based on our experiences

ICRI Convention, October 2010, Pittsburgh 45  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! Crack Free Repairs with the BaenzigerBlock Summary of over 15 years experience

ICRI Convention, October 2010, Pittsburgh 46  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! Crack Free Repairs with the BaenzigerBlock Outlook 2020

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