Hva slags AAR-krav i framtida? Begrunnelse for Felt/Lab Performance. COIN fagdag 20. mai 2008 Terje F. Rønning, Norcem AS

Transkript

1 Hva slags AAR-krav i framtida? Begrunnelse for Felt/Lab Performance COIN fagdag 20. mai 2008 Terje F. Rønning, Norcem AS

2 Rilem forslag til CEN Level of Precaution P2: A normal level of precaution against AAR damage is employed. This can take the form of one of the following precautionary measures: M1: Measures to restrict the alkalinity of the pore solution [BINDER] M2: Measures to ensure the use of non-reactive aggregate combination M3: Measures to reduce the access of moisture and maintain the concrete in a sufficiently dry state M4: Measures to modify the properties of any gel such that it is non-expansive Level of Precaution P3: At least 1 of the measures + resist additional aggravating factor Level of Precaution P4: At least 2 of the measures.

3 Rilem TC 191-ARP Proposal Table 4 Alkali limits and Aggregate Reactivity : Includes Safety margin (Lab/Field sample deviations, Testing uncertainties (leaching), Constituents declaration limits, ) Aggregate reactivity Alkali limit (kg/m 3 Na 2 Oeq). Low None required Medium Typically 3 or 3.5 kg/m 3 High Lower limit eg 2.5 kg/m 3 Mange norske tilslag? Avhenger av prøvekriterier

4 Table 5 Recommended minimum proportions Rilem TC 191-ARP Proposal Aggregate reactivity Low lime fly ash (<8% CaO) (<5% Na 2 O-Eq.) Medium lime fly ash (8 to 20% CaO) Ground granulated blastfurnace slag % by mass of total cementitious material Low any any any Medium High 40 not recommended 50

5 Rilem, CEN, Nasjonalt..

6 Prøvning skjer ved o C

7 AAR Svært ulik geologi i ulike land Ulike løsninger internasjonalt Svært ulik grad av helhetlig forståelse Ulike interesse for grad av fleksibilitet i løsninger Bestrebelser for økt normativ oppførsel Dagens løsning i Norge ingen selvfølge historisk eller fremover!

8 Greywacke coarse aggregate and pit sand from Lower Notch OPC Lower Notch Dam Built ~ Lower Notch dam, Ontario - Byggd ca Høy-alkalisk sement, ca 20% FA, lokalt reaktivt tilslag har ikke gitt skader etter 25 år - Andre damkonstruksjoner i området med samme tilslag og sement har gitt store skader => FA har forhindret skadelig AAR

9 Prøvning av tilslag i betong v/ o C

10 Prøvning av tilslag i 1 N NaOH v/ 80 o C

11 Prøvning av tilslag i betong v/ o C

12 Effect of slag on alkalinity relative OH - -concentration in % CEM I 20 m.-% S 40 m.-% S 80 m.-% S storage period in days ECRA / VDZ 2004

13 Effect of fly ash on alkalinity relative OH - -concentration in % CaO < 5 m.-% CEM I 20 m.-% V 40 m.-% V 60 m.-% V ECRA / VDZ storage period in days

14 Rilem : Mye må sjekkes.

15 Objective (sp 4.4) Provide improved understanding of the accelerated AAR effects when concrete i subjected to elevated temperature and moisture regimes during various laboratory (performance) testing, compared to field conditions. Such knowledge is essential for a future performance testing concept, enabling flexible solutions for the stakeholders. SINTEF Building and Infrastructure 15

16 Objectives (PhD study Jan Lindgård; 1rst stage) To evaluate accelerated ASR effects when concrete is subjected to elevated temperature and moisture regimes during various laboratory performance testing, compared to field conditions. To produce a state-of-the art paper covering the key parameters that may influence the speed and extent of alkali aggregate reactivity of a concrete. Research needs on important parameters will also be addressed. To summarize and evaluate the performance testing performed in Norway during the last ten years. SINTEF Building and Infrastructure 16

17 Objectives (PhD study Jan Lindgård; 1rst stage) To document and evaluate the influence of the selected issues / parameters for study on the results and outcome from the performance testing with the various test methods selected. To give input to the RILEM TC ACS-P sub-group as basis for the development of a future international agreed performance testing concept for evaluation of the alkali reactivity of binders/aggregate/mix design combinations. SINTEF Building and Infrastructure 17

18 Grunnlagsarbeid for retningslinjer Det må gjøres en jobb på sammenstilling av data fra felt OG (modifiserte ;) lab-tester. Det må gjøres noe undersøkelser av prøvemetodikk og mekanismer i Felt-perspektiv : Det må forstås bedre kvantitativt hva vi gjør når vi tar ting inn i laboratoriet Mulige endringer i retningslinjer mht. innhold av flyveaske/slagg/silika

19 Rilem / CEN Konsekvenser Vi får på CEN-nivå Rammer for regime (flytskjema) Konvensjon for bestemmelse av [Alk.] i bindemiddel Kanskje en tilnærmelse for vurdering av tilslagsreaktivitet (Kriterier : place in use ) Vi må nasjonalt Fastsette kategorier/kriterier tilslag & tiltak Sette grenseverdier for [Alk.] og Slagg/Pfa/Silika + Videreutvikle (int.sm.arb.) basis Performance testing Bruke dette til justering av tiltaks-spekteret