In order to examine the resistance to acidic solution of the different concrete compositions, an accelerated degradation test was carried out employing the apparatus developed by De Belie et al. (2002). The accelerated test procedure was based on the combination of a chemical action (wetting in an acid solution and drying in air) and a mechanical action (brushing).
Three toroid specimens were casted in a special mould for testing each concrete batch. The mould presented an internal diameter of 40 mm, an external diameter of 270 mm and a height of 70 mm.
In addition, the mould contained the anchoring mechanisms needed for the attachment of the specimen into one axle of the apparatus and for the metallic piece serving as the trigger for the beginning of the laser measurements.
The testing machine (Figure 3.42a) consisted of four horizontal rotating stainless steel axles, each one able to contain two sets of three samples turning through their own container and covered by a shared case to avoid evaporation. A switch gear manually actioned made possible the variation in the rotating speed between 1.04 and 24.41 revolutions per hour. The equipment also permitted the coupling of the brushing device (Figure 3.42b) and laser device (Figure 3.42c) to a fixed position on the frame of the apparatus by use of two stop pieces and two bolts. A more detailed description of the apparatus can be found in De Belie et al. (2002).
115 Figure 3.42: TAP apparatus
After 28 days of curing, the concrete specimens were installed into the accelerated degradation tests (TAP) apparatus with two clamping rings, and a stainless steel angle (10x10 mm) was screwed by means of two bolts into each sample. Each test container was filled with two litres of acid solution composed of 30 g/l of acetic acid and 30 g/l lactic acid, which affected only to the outer bottom part of each specimen.
One accelerated degradation cycle consisted of the immersion of the samples in a fresh acid solution during 7 days, followed by a 2 hours air-drying period before 3 brushing steps - in alternate direction of rotation - to remove the degraded concrete weakened by the chemical attack. Whilst the low rotating speed was selected during the acid immersion, the brushing step was performed with the samples rotating at high speed by means of three rotary brushes with 20 mm long white nylon hairs turning at 394 rpm. This testing sequence was repeated until 6 attack cycles were completed. Previous to the testing procedure and after each attack cycle, the distance between the samples and the laser sensors was determined by means of optical triangulation and registered as a means to evaluate the change in radius due to the degradation process. All the measurements - 4 contour parallel lines separated 0.50 mm per specimen - were performed in steps of 0.24 mm with the samples turning at high speed. In addition, the evolution of the degradation was evaluated visually and the pH of the solution was measured at the beginning and at the end of each attack cycle.
(a)
(b) (c)
116
The laser measurements were employed to calculate the degradation depth by comparing the radius change through the experiment. Moreover, the surface roughness (3.37) was calculated as the arithmetical average value of the departure y(x) (mm) of the profile above and below the centre line throughout a prescribed sample length, based on ISO 4287 (1997).
Ra= 1
SL∙ SL|y x |dx
0
(3.37)
with Ra the surface roughness [mm], SL the prescribed sampling length [mm] and y(x) the profile height function [mm]. Given that a 50 mm sampling length was chosen (De Belie et al., 2002), thirteen Ra values were obtained per contour profile.
7. REFERENCES
Abbas, A., Fathifazl, G., Isgor, O.B., Razaqpur, A., Fournier, B., Foo, S., 2008. Proposed method for determining the residual mortar content of recycled concrete aggregates. Journal of ASTM International 5 (1): 12.
Abell, A.B., Willis, K.L., Lange, D.A., 1999. Mercury intrusion porosimetry and image analysis of cement-based materials. Journal of Colloid and Interface Science 211 (1): 39–44.
ASTM C88-13, 2013. Test method for soundness of aggregates by use of sodium sulfate or magnesium sulfate. ASTM International, Pennsylvania.
ASTM C457-12, 2012. Test Method for Microscopical Determination of Parameters of the Air-Void System in Hardened Concrete. ASTM International, Pennsylvania.
ASTM C577-07, 2014. Test method for permeability of refractories. ASTM International, Pennsylvania.
ASTM C666M-03, 2008. Test method for resistance of concrete to rapid freezing and thawing.
ASTM International, Pennsylvania.
ASTM C1585-13, 2013. Test method for measurement of rate of absorption of water by hydraulic-cement concretes. ASTM International, Pennsylvania.
ASTM D4404-10, 2010. Test method for determination of pore volume and pore volume distribution of soil and rock by mercury intrusion porosimetry. ASTM International, Pennsylvania.
Bermejo, E.B., Moragues, A., Gálvez, J.C., Fernández Cánovas, M., 2010. Permeability and pore size distribution in medium strength self-compacting concrete. Materiales de Construcción 60 (299): 37–51.
Callister, W.D.J., 2007. Materials science and engineering: An introduction. John Wiley & Sons, Hoboken, New Jersey.
Carcasses, M., Abbas, A., Ollivier, J.-P., Verdier, J., 2002. An optimised preconditioning procedure for gas permeability measurement. Materials and Structures 35 (1): 22–27.
Davies, G., Oberholster, R.E., 1987. An interlaboratory test programme on the NBRI accelerated test to determine the alkali reactivity of aggregates (Special Report No. BOU 92-1987).
National Building Research Institute, Council for Scientific and Industrial Research, Pretoria.
117 De Belie, N., Monteny, J., Taerwe, L., 2002. Apparatus for accelerated degradation testing of
concrete specimens. Materials and Structures 35 (7): 427–433.
Deslattes, R.D., Kessler, E.G., Indelicato, P., de Billy, L., Lindroth, E., Anton, J., 2003. X-ray transition energies: new approach to a comprehensive evaluation. Reviews of Modern Physics 75 (1):
35–99.
Diamond, S., 2000. Mercury porosimetry: An inappropriate method for the measurement of pore size distributions in cement-based materials. Cement and Concrete Research 30 (10):
1517–1525.
Diamond, S., 2003. A discussion of the paper “Effect of drying on cement-based materials pore structure as identified by mercury porosimetry: a comparative study between oven, vacuum, and freeze-drying” by C. Gallé. Cement and Concrete Research 33 (1): 169–170.
Duan, Z.H., Poon, C.S., 2014. Properties of recycled aggregate concrete made with recycled aggregates with different amounts of old adhered mortars. Materials & Design 58: 19–29.
EN 206-1, 2005. Concrete. Part 1: Specification, performance, production and conformity. CEN, Brussels.
Freiesleben Hansen, P., Pedersen, J., 1977. Maturity computer for controlled curing and hardening of concrete. Nordisk Betong 1: 19–34.
Fultz, P.D.B., Howe, P.D.J., 2013. Diffraction and the x-ray powder diffractometer, in: Transmission Electron Microscopy and Diffractometry of Materials. Springer Berlin Heidelberg, 1–57.
Gallé, C., 2001. Effect of drying on cement-based materials pore structure as identified by mercury intrusion porosimetry: A comparative study between oven, vacuum, and freeze-drying.
Cement and Concrete Research 31 (10): 1467–1477.
Gallé, C., 2003. Reply to the discussion by S. Diamond of the paper “Effect of drying on cement-based materials pore structure as identified by mercury intrusion porosimetry: a comparative study between oven, vacuum and freeze-drying.” Cement and Concrete Research 33 (1): 171–172.
Giesche, H., 2002. Mercury porosimetry, in: Schüth, F., Sing, K.S.W., Weitkamp, J. (Eds.), Handbook of Porous Solids. Wiley-VCH Verlag GmbH, 309–351.
Grosse, C.U., Reinhardt, H.W., 2000. Ultrasound technique for quality control of cementitious materials. Presented at the Proceedings of the 15th Conference on Nondestructive Testing.
Gruyaert, E., 2011. Effect of blast-furnace slag as cement replacement on hydration, microstructure, strength and durability of concrete. Ghent University, Ghent, Belgium.
Gruyaert, E., Maes, M., De Belie, N., 2013. Performance of BFS concrete: k-value concept versus equivalent performance concept. Construction and Building Materials 47: 441–455.
Hilsdorf, H., Kropp, J. (Eds.), 2004. Performance criteria for concrete durability, RILEM Report. CRC Press.
ICDD, 2015. International Centre for Diffraction Data [http://www.icdd.com/].
ISO 4287, 1997. Geometrical Product Specifications (GPS). Surface texture: Profile method. Terms, definitions and surface texture parameters. ISO, Geneva.
Jacobsen, S., Arntsen, B., 2007. Aggregate packing and void saturation in mortar and concrete proportioning. Materials and Structures 41 (4): 703–716.
118
Janssens, K., 2003. X-ray fluorescence analysis, in: Gauglitz, G., Vo-Dinh, T. (Eds.), Handbook of Spectroscopy. Wiley-VCH Verlag GmbH & Co. KGaA, 363–420.
Jenkins, R., 2001. X-ray fluorescence spectrometry, in: Günzler, H., Williams, A. (Eds.), Handbook of Analytical Techniques. Wiley-VCH Verlag GmbH, 753–766.
Klockenkämper, R., Bohlen, A. von (Eds.), 2014. Fundamentals of x-ray fluorescence, in: Total-Reflection X-Ray Fluorescence Analysis and Related Methods. John Wiley & Sons, Inc., 1–
78.
Kollek, J.J., 1989. The determination of the permeability of concrete to oxygen by the Cembureau method—a recommendation. Materials and Structures 22 (3): 225–230.
Konecny, L., Naqvi, S.J., 1993. The effect of different drying techniques on the pore size distribution of blended cement mortars. Cement and Concrete Research 23 (5): 1223–1228.
Kristiansen, K., 1997. Scanning electron microscope with energy-and wavelength-dispersive spectrometry, in: Brune, D., Hellborg, R., Whitlow, H.J., Hunderi, O. (Eds.), Surface Characterization. Wiley-VCH Verlag GmbH, 111–128.
Kumar, R., Bhattacharjee, B., 2003. Study on some factors affecting the results in the use of MIP method in concrete research. Cement and Concrete Research 33 (3): 417–424.
Kurz, J.H., Grosse, C.U., Reinhardt, H.-W., 2005. Strategies for reliable automatic onset time picking of acoustic emissions and of ultrasound signals in concrete. Ultrasonics 43 (7): 538–546.
Leng, Y., 2013a. X-Ray diffraction methods, in: Materials Characterization. Wiley-VCH Verlag GmbH
& Co. KGaA, 47–82.
Leng, Y., 2013b. Scanning electron microscopy, in: Materials Characterization. Wiley-VCH Verlag GmbH & Co. KGaA, 127–161.
Maes, M., Gruyaert, E., Belie, N.D., 2013. Resistance of concrete with blast-furnace slag against chlorides, investigated by comparing chloride profiles after migration and diffusion. Mater Struct 46 (1-2): 89–103.
Marchand, J., Pigeon, M., Bager, D., Talbot, C., 1999. Influence of chloride solution concentration on de-icer salt scaling deterioration of concrete. ACI Materials Journal 96 (4).
NBN B 05-201, 1976. Resistance of materials to freezing - Water absorption by capillarity. NBN, Brussels.
NBN B 15-278, 1976. Testing of concrete. Creep [in French]. NBN, Brussels.
NT BUILD 480, 1997. Cement. Heat of hydration. NORDTEST, Espoo.
NT BUILD 492, 1999. Concrete, mortar and cement-based repair materials: Chloride migration coefficient from non-steady-state migration experiments. NORDTEST, Espoo.
Oberholster, R.E., Davies, G., 1986. An accelerated method for testing the potential alkali reactivity of siliceous aggregates. Cement and Concrete Research 16 (2): 181–189.
Permanent Commission on Concrete, 2008. Code on Structural Concrete (EHE-08) [in Spanish].
Spanish Ministry of Public Works, Madrid.
Reinhardt, H.W., Grosse, C.U., 2004. Continuous monitoring of setting and hardening of mortar and concrete. Construction and Building Materials, 3rd Kumamoto International Workshop on Fracture, Acoustic Emission and NDE in Concrete (KIFA-3) 18 (3): 145–154.
Reinhardt, H.W., Grosse, C.U., Herb, A., Weiler, B., Schmidt, G., 2001. Method for examining a solidifying and/or hardening material using ultrasound, receptacle and ultrasound sensor for carrying out the method. Patent no 09/857, 536.
119 RILEM TC 107-CSP, 1998. Measurement of time-dependent strains of concrete. Materials and
Structures 31: 507–512.
Robeyst, N., 2009. Monitoring setting and microstructure development in fresh concrete with the ultrasonic through-transmission method. Ghent University, Ghent, Belgium.
Robeyst, N., Grosse, C.U., De Belie, N., 2009. Monitoring fresh concrete by ultrasonic transmission measurements: Exploratory multi-way analysis of the spectral information. Chemometrics and Intelligent Laboratory Systems 95 (1): 64–73.
Rübner, K., Fritz, T., Jacobs, F., 2002. Precision of porosity measurements on cementitious mortars, in: F. Rodriguez-Reinoso, B.M. J. Rouquerol and K. Unger (Ed.), Studies in Surface Science and Catalysis, Characterization of Porous Solids VI Proceedings of the 6th International Symposium on the Characterization of Porous Solids (COPS-VI). Elsevier, 459–466.
Scheu, C., Kaplan, W.D., 2012. Introduction to scanning electron microscopy, in: Dehm, G., Howe, J.M., Zweck, J. (Eds.), In-Situ Electron Microscopy. Wiley-VCH Verlag GmbH & Co. KGaA, 1–
37.
Thomas-García, C., Polanco-Madrazo, J.A., Setien-Marquínez, J., 2013. Flow meter for the gas permeability determination of a material [in Spanish]. Patent no ES2400592B1.
Thomas-García, C., Polanco-Madrazo, J.A., Setien-Marquínez, J., 2014. System for the gas permeability determination of a material [in Spanish]. Patent no ES2406386B1.
Trtnik, G., Gams, M., 2013. The use of frequency spectrum of ultrasonic P-waves to monitor the setting process of cement pastes. Cement and Concrete Research 43: 1–11.
UNE 83981, 2008. Concrete durability. Test methods. Determination to gas permeability of hardened concrete [in Spanish]. AENOR, Madrid.
UNE 83982, 2008. Concrete durability. Test methods. Determination of the capillar suction in hardened concrete. Fagerlund method [in Spanish]. AENOR, Madrid.
UNE 83988-1, 2008. Concrete durability. Test methods. Determination of the electrical resistivity.
Part 1: Direct test (reference method). [in Spanish]. AENOR, Madrid.
UNE 83993-1, 2013. Durability of concrete. Test method. Measurement of carbonation penetration rate in hardened concrete. Part 1: Natural method [in Spanish]. AENOR, Madrid.
UNE 112011, 2011. Corrosion of concrete reinforcement steel. Determination of the carbonatation depht for in-service concrete [in Spanish]. AENOR, Madrid.
UNE EN 196-9, 2011. Methods of testing cement. Part 9: Heat of hydration - Semi-adiabatic method [in Spanish]. AENOR, Madrid.
UNE EN 932-1, 1997. Test for general properties of aggregates. Part 1: Methods for sampling [in Spanish]. AENOR, Madrid.
UNE EN 932-2, 1999. Tests for general properties of aggregates. Part 2: Methods for reducing laboratory samples [in Spanish]. AENOR, Madrid.
UNE EN 933-1, 2012. Tests for geometrical properties of aggregates. Part 1: Determination of particle size distribution - Sieving method [in Spanish]. AENOR, Madrid.
120
UNE EN 933-2, 1996. Test for geometrical properties of aggregates. Part 2: Determination of particle size distribution. Test sieves, nominal size of apertures [in Spanish]. AENOR, Madrid.
UNE EN 933-3, 2012. Tests for geometrical properties of aggregates. Part 3: Determination of particle shape - Flakiness index [in Spanish]. AENOR, Madrid.
UNE EN 933-8, 2012. Tests for geometrical properties of aggregates. Part 8: Assessment of fines - Sand equivalent test [in Spanish]. AENOR, Madrid.
UNE EN 933-11, 2009. Tests for geometrical properties of aggregates. Part 11: Classification test for the constituents of coarse recycled aggregate [in Spanish]. AENOR, Madrid.
UNE EN 1097-2, 2010. Tests for mechanical and physical properties of aggregates. Part 2: Methods for the determination of resistance to fragmentation [in Spanish]. AENOR, Madrid.
UNE EN 1097-6, 2014. Tests for mechanical and physical properties of aggregates. Part 6:
Determination of particle density and water absorption [in Spanish]. AENOR, Madrid.
UNE EN 1339, 2004. Concrete paving flags - Requirements and test methods [in Spanish]. AENOR, Madrid.
UNE EN 12350-1, 2009. Testing fresh concrete. Part 1: Sampling [in Spanish]. AENOR, Madrid.
UNE EN 12350-2, 2009. Testing fresh concrete. Part 2: Slump-test [in Spanish]. AENOR, Madrid.
UNE EN 12350-6, 2009. Testing fresh concrete. Part 6: Density [in Spanish]. AENOR, Madrid.
UNE EN 12350-7, 2010. Testing fresh concrete. Part 7: Air content. Pressure methods [in Spanish].
AENOR, Madrid.
UNE EN 12390-1, 2013. Testing hardened concrete. Part 1: Shape, dimensions and other requirements for specimens and moulds [in Spanish]. AENOR, Madrid.
UNE EN 12390-3, 2009. Testing hardened concrete. Part 3: Compressive strength of test specimens [in Spanish]. AENOR, Madrid.
UNE EN 12390-4, 2001. Testing hardened concrete. Part 4: Compressive strength - Specification for testing machines [in Spanish]. AENOR, Madrid.
UNE EN 12390-5, 2009. Testing hardened concrete. Part 5: Flexural strength of test specimens [in Spanish]. AENOR, Madrid.
UNE EN 12390-13, 2014. Testing hardened concrete. Part 13: Determination of secant modulus of elasticity in compression [in Spanish]. AENOR, Madrid.
UNE EN 12504-4, 2006. Testing concrete - Part 4: Determination of ultrasonic pulse velocity [in Spanish]. AENOR, Madrid.
Valenza II, J.J., Scherer, G.W., 2007. A review of salt scaling: I. Phenomenology. Cement and Concrete Research 37 (7): 1007–1021.
Wang, Y., Petrova, V., 2012. Scanning electron microscopy, in: Padua, G.W., Wang, Q. (Eds.), Nanotechnology Research Methods for Foods and Bioproducts. Wiley-Blackwell, 103–126.
Washburn, E.W., 1921. Note on a method of determining the distribution of pore sizes in a porous material, in: Proceedings of the National Academy of Sciences of the United States of America. 115–116.
121 Winslow, D.N., Diamond, S., 1970. A mercury porosimetry study of the porosity in Portland
cement. Journal of Materials (ASTM) 5 (3): 564–585.
123
1. INTRODUCTION
The emergence of the use of recycled materials in the construction industry, specifically in the production of concrete, has met with varying degrees of success due to the barriers that the market for recycled products has still to overcome. Since to a large extent, the quality of the concrete mixture depends upon the properties of the raw materials used in its manufacture; the quality of the recycled aggregates is perceived as an obstacle in the recycling of construction and demolition wastes (CDW) as secondary aggregates for concrete. Nonetheless, numerous scientific studies show that it is possible to obtain good quality, economic and environmentally friendly building materials when the coarse fraction of CDW recycled aggregates is used appropriately.
This chapter presents an overview of the significant characteristics of the different constituents to be used in the conventional and recycled concrete mixtures. From a quality point of view, special attention was paid to the recycled coarse aggregates since their heterogeneous nature strongly affects their quality. Thus, a thorough physical, mechanical and microstructural characterization was carried out in order to assess the suitability of their use in the concrete manufacture in accordance with the requirements set for natural aggregates in the current Spanish legislation.
Nevertheless, note that the Spanish Code on Structural Concrete (EHE-08) (Permanent Commission on Concrete, 2008) does not take into account the use of mixed recycled aggregates in the concrete manufacture, not even in a non-structural capacity.