Nondestructive evaluation of internal sulphate f p attack in - PowerPoint PPT Presentation

Non‐destructive evaluation of internal sulphate f p attack in cement‐based materials applying non‐ linear ultrasonic techniques linear ultrasonic techniques José Marcos Ortega, Marina Miró, Pedro Poveda, Antonio José Tenza‐Abril, Jaime Ramis Miguel Ángel Climent Jaime Ramis, Miguel Ángel Climent Departamento de Ingeniería Civil, Universidad de Alicante (Spain) DFISTS, Universidad de Alicante (Spain)

Outline 1 Introduction 1. Introduction 2. Materials and methods 3. Results and discussion 4. Conclusions 4. Conclusions 2

Introduction

Introduction Sulphate attack  It is one of the most harmful aggressive attack to  It is one of the most harmful aggressive attack to which cement‐based materials can be exposed  Complex mechanism → Involves different chemical reactions between components of cement paste microstructure and sulphate ions microstructure and sulphate ions.  Expansive products are formed:  Volumetric strains → Microcracking and loss of pore refinement  Loss of strength and durability in the cement‐based materials 4

Introduction Non‐destructive techniques  Their application for characterizing the  Their application for characterizing the microstructure and properties of cement‐based materials has become an important research field p  Useful for following the development of deleterious processes produced during the attack of aggressive d d d i th tt k f i substances to these cement‐based materials.  Non‐linear ultrasonic (NLU) → Detecting cracks due to steel corrosion in reinforced concrete structures:  DOI: 10.1186/s40069‐020‐00432‐x  DOI: 10 3390/MA12050813  DOI: 10.3390/MA12050813 5

Introduction Objetives To study the possibility of using NLU techniques d h ibili f i h i Non‐destructive evaluation Initial stages of internal sulphate attack in cement based materials cement‐based materials (until 100 hardening days) 6

Materials and methods

Materials and methods S Samples preparation l ti  Materials (cement pastes):  Materials (cement pastes):  Reference specimens → CEM I 42,5 R (100%)  Sulphate specimens → CEM I 42 5 R (90 8%) + gypsum  Sulphate specimens → CEM I 42,5 R (90.8%) + gypsum (9.2%) → To reach in the mixture a SO 3 context of 7% in mass according to ASTM Standard C452‐02 mass according to ASTM Standard C452 02  Water to cement ratio = 0.5  Se�ng → UNE EN 196 3  Se�ng → UNE‐EN 196‐3  Prismatic samples:  25 mm x 25 mm x 285 mm.  Storage in optimum laboratory condition St i ti l b t diti 8

Materials and Methods Experimental techniques  Mercury intrusion porosimetry M i t i i t  Length change due to expansion h h d  Non‐linear ultrasonic technique  Linear ultrasonic pulse velocity 9

Materials and methods M Mercury intrusion porosimetry i i i  Poremaster‐60 GT porosimeter  Total porosity  Pore size distributions  Percentage of Hg retained at the end of the test  Pieces taken from prismatic specimens p p Length change due to expansion  ASTM Standard C452‐02 Linear ultrasonic pulse velocity i l i l l i  Standard UNE‐EN 12504‐4  Proceq Pundit Lab equipment 10

Materials and methods Non‐linear ultrasonic technique N li l i h i  Two transducers → Simultaneously supply two pure tones (f 0 = 20 kHz and f 1 = 200 kHz)  High‐frequency probe signal at an amplitude of 5 V  Low‐frequency pump and acquisition of the frequency modulated signal → 16‐bit ADC resolution I/O device NI‐USB 6361 (sampling frequency 2 MHz) I/O d i NI USB 6361 ( li f 2 MH )  Pump wave signal → Amplifier FS WMA‐100 and then transmitted through a Langevin transducer  Input voltage → 140 V  Transducers IDK09 → Emitting and receiving the high‐frequency signal  Parameter DIFA was studied in this work 11

Results and discussion

Results and discussion >0.1 mm 10 µm-0.1 mm 1-10 µm 100 nm-1 µm 10-100 nm <10 nm 50 1d 28d 100d 28d 100d 1 d Reference 100 S l h t Sulphate 45 me, % 80 ty, % 40 on volum tal porosit 60 35 40 Intrusio 30 30 Tot 20 25 20 0 0 20 40 60 80 100 Reference Sulphate Hardening age, days  Lowest porosity and highest pore refinemement → Reference  Progressive pore refinement with age → Sulphate specimens og ess e po e e e e t t age → Su p ate spec e s  Combined effects of clinker hydration and initial sulphate attack 13

Results and discussion 50 0.20 Reference Sulphate 45 0.15 ned, % 40 on, % Hg retain Expansio 0.10 35 30 H E 0 05 0.05 25 Reference Sulphate 0 00 0.00 20 0 20 40 60 80 100 0 20 40 60 80 100 Hardening age, days Hardening age, days  Hg retained → Overall in keeping with pore size distribu�ons  Expansion for pastes subject to internal sulphate attack pa s o o pastes subject to te a su p ate attac  Expansion would reveal possible microcracking development 14

Results and discussion 80 80 4000 4000 Reference ity, m/s Sulphate 3800 75 75 se veloci IFA, dB 3600 70 DI sonic pul 3400 65 Ultras 3200 3200 Reference Sulphate 3000 60 0 0 20 20 40 40 60 60 80 80 100 100 0 0 20 20 40 40 60 60 80 80 100 100 Hardening age, days Hardening age, days  DIFA → System gradually turned less linear for sulphate pastes DIFA → S t d ll t d l li f l h t t  UPV → Coincided with PIM and not reveal effects of a�ack  NLU technique could be useful for providing information about the deleterious processes due to internal sulphate attack. 15

Conclusions

Conclusions Conclusions  Reference pastes showed an important pore refinement  Reference pastes showed an important pore refinement at 28 hardening days → Microstructure development due to the hydration of clinker y  Pore size distribution of cements pastes exposed to internal sulphate attack gradually became more refined internal sulphate attack gradually became more refined, but lower refinement compared to reference pastes → Simultaneous development of clinker hydration and Simultaneous development of clinker hydration and sulphate attack (silting of pores and later microcracking)  Continuous expansion for pastes subject to internal sulphate attack → Possible presence of pores already silted in which a possible formation of microcracks due silted in which a possible formation of microcracks due to expansion could be produced. 17

Conclusions Conclusions  The tendencies observed for the NLU parameter DIFA p were overall in keeping with the results of the length change due to expansion.  Linear ultrasonic pulse velocity → Progressive reduction of voids with age in the studied samples → No effects of of oids ith a e in the st died samples → No effe ts of sulphate attack in this parameter.  In view of these preliminary results → NLU technique could be useful for providing information about the could be useful for providing information about the deleterious processes due to internal sulphate attack in cement‐based materials → Further research would be needed for confirming this. 18

A k Acknowledgments l d t Project GV/2019/070 Project GV/2019/070 Project BIA2016‐80982‐R Pre‐doctoral fellowship Pre doctoral fellowship FPU16/04078 Cementos Portland V ld Valderrivas, S.A. i S A 19

Non‐destructive evaluation of internal sulphate f p attack in cement‐based materials applying non‐ linear ultrasonic techniques linear ultrasonic techniques José Marcos Ortega, Marina Miró, Pedro Poveda, Antonio José Tenza‐Abril, Jaime Ramis Miguel Ángel Climent Jaime Ramis, Miguel Ángel Climent Departamento de Ingeniería Civil, Universidad de Alicante (Spain) DFISTS, Universidad de Alicante (Spain)