Failure modes and shear design of prestressed hollow core slabs made of fiber-reinforced concrete

Hollow core slabs (HCS) are usually precast by extrusion and it is not easy to place stirrups; thus, it is difficult to guarantee shear resistance in some cases. This paper describes an experience using fiber-reinforced concrete (FRC) to produce HCS by extrusion to gain shear reinforcement. An experimental program consisting of 26 HCS was developed. Elements were produced and tested in shear according to the following variables: amount of steel fibers (0, 50 and 70 kg/m(3)) and a shear span/depth (a/d) ratio of 2.3-4.4 and 8.6. Different failure modes took place. Some of the main conclusions drawn were that fibers improve quality of the material for shear, HCS with fibers achieved greater loads than HCS without fiber reinforcement and with a more ductile behavior. (c) 2012 Elsevier Ltd. All rights reserved.The authors of this work wish to thank the research bureau of the Spanish Ministry of Science and Innovation and the Plan E, for the funding of the project "BIA 2009-12722". The collaboration of the precast industry "PREVALESA S.L." is also acknowledged.Cuenca Asensio, E.; Serna Ros, P. (2013). Failure modes and shear design of prestressed hollow core slabs made of fiber-reinforced concrete. Composites Part B: Engineering. 45(1):952-964. doi:10.1016/j.compositesb.2012.06.00595296445

Concrete Early-Age Crack Closing by Autogenous Healing

[EN] Autogenous healing is mainly produced by continuing hydration or carbonation. The aim of this research is to quantify the crack closing produced by autogenous healing for early-age concrete. This healing was evaluated for two crack size levels, 0.1 mm and 0.4 mm, under three healing conditions: water immersion, a humidity chamber, and wet/dry cycles. Crack closing was evaluated after 7, 14, 28 and 42 days under healing conditions. The internal status of the cracks was verified visually and using phenolphthalein. The results show that specimens stored in the humidity chamber did not experience healing, while specimens under wet/dry cycles and water immersion achieved the complete closing of small-sized cracks (under 0.15 mm). Autogenous healing showed higher speed under wet/dry cycles but higher final efficiency under water immersion. However, the inspection of the interior of the specimens showed that self-closing occurred mostly on the surface, and carbonation in the crack faces was only noticed very near the specimen's surface. Additionally, this study proposes a preliminary strategy to model autogenous healing in concrete in terms of crack closing.Roig-Flores, M.; Serna Ros, P. (2020). Concrete Early-Age Crack Closing by Autogenous Healing. Sustainability. 12(11):1-16. https://doi.org/10.3390/su12114476S1161211De Belie, N., Gruyaert, E., Al-Tabbaa, A., Antonaci, P., Baera, C., Bajare, D., … Jonkers, H. M. (2018). A Review of Self-Healing Concrete for Damage Management of Structures. Advanced Materials Interfaces, 5(17), 1800074. doi:10.1002/admi.201800074Van Tittelboom, K., & De Belie, N. (2013). Self-Healing in Cementitious Materials—A Review. Materials, 6(6), 2182-2217. doi:10.3390/ma6062182Yuan, L., Chen, S., Wang, S., Huang, Y., Yang, Q., Liu, S., … Zhou, Z. (2019). Research on the Improvement of Concrete Autogenous Self-healing Based on the Regulation of Cement Particle Size Distribution (PSD). Materials, 12(17), 2818. doi:10.3390/ma12172818Gagné, R., & Argouges, M. (2012). A study of the natural self-healing of mortars using air-flow measurements. Materials and Structures, 45(11), 1625-1638. doi:10.1617/s11527-012-9861-ySuleiman, A. R., & Nehdi, M. L. (2018). Effect of environmental exposure on autogenous self-healing of cracked cement-based materials. Cement and Concrete Research, 111, 197-208. doi:10.1016/j.cemconres.2018.05.009Qian, S., Zhou, J., de Rooij, M. R., Schlangen, E., Ye, G., & van Breugel, K. (2009). Self-healing behavior of strain hardening cementitious composites incorporating local waste materials. Cement and Concrete Composites, 31(9), 613-621. doi:10.1016/j.cemconcomp.2009.03.003Yıldırım, G., Khiavi, A. H., Yeşilmen, S., & Şahmaran, M. (2018). Self-healing performance of aged cementitious composites. Cement and Concrete Composites, 87, 172-186. doi:10.1016/j.cemconcomp.2018.01.004Rajczakowska, M., Habermehl-Cwirzen, K., Hedlund, H., & Cwirzen, A. (2019). The Effect of Exposure on the Autogenous Self-Healing of Ordinary Portland Cement Mortars. Materials, 12(23), 3926. doi:10.3390/ma12233926Roig-Flores, M., Pirritano, F., Serna, P., & Ferrara, L. (2016). Effect of crystalline admixtures on the self-healing capability of early-age concrete studied by means of permeability and crack closing tests. Construction and Building Materials, 114, 447-457. doi:10.1016/j.conbuildmat.2016.03.196Yang, Y., Lepech, M. D., Yang, E.-H., & Li, V. C. (2009). Autogenous healing of engineered cementitious composites under wet–dry cycles. Cement and Concrete Research, 39(5), 382-390. doi:10.1016/j.cemconres.2009.01.013Yang, Y., Yang, E.-H., & Li, V. C. (2011). Autogenous healing of engineered cementitious composites at early age. Cement and Concrete Research, 41(2), 176-183. doi:10.1016/j.cemconres.2010.11.002Liu, H., Huang, H., Wu, X., Peng, H., Li, Z., Hu, J., & Yu, Q. (2019). Effects of external multi-ions and wet-dry cycles in a marine environment on autogenous self-healing of cracks in cement paste. Cement and Concrete Research, 120, 198-206. doi:10.1016/j.cemconres.2019.03.014Van Tittelboom, K., Gruyaert, E., Rahier, H., & De Belie, N. (2012). Influence of mix composition on the extent of autogenous crack healing by continued hydration or calcium carbonate formation. Construction and Building Materials, 37, 349-359. doi:10.1016/j.conbuildmat.2012.07.026Huang, H., Ye, G., & Damidot, D. (2014). Effect of blast furnace slag on self-healing of microcracks in cementitious materials. Cement and Concrete Research, 60, 68-82. doi:10.1016/j.cemconres.2014.03.010Wiktor, V., & Jonkers, H. M. (2011). Quantification of crack-healing in novel bacteria-based self-healing concrete. Cement and Concrete Composites, 33(7), 763-770. doi:10.1016/j.cemconcomp.2011.03.012Snoeck, D., & De Belie, N. (2012). Mechanical and self-healing properties of cementitious composites reinforced with flax and cottonised flax, and compared with polyvinyl alcohol fibres. Biosystems Engineering, 111(4), 325-335. doi:10.1016/j.biosystemseng.2011.12.005Ferrara, L., Van Mullem, T., Alonso, M. C., Antonaci, P., Borg, R. P., Cuenca, E., … De Belie, N. (2018). Experimental characterization of the self-healing capacity of cement based materials and its effects on the material performance: A state of the art report by COST Action SARCOS WG2. Construction and Building Materials, 167, 115-142. doi:10.1016/j.conbuildmat.2018.01.143Zhong, W., & Yao, W. (2008). Influence of damage degree on self-healing of concrete. Construction and Building Materials, 22(6), 1137-1142. doi:10.1016/j.conbuildmat.2007.02.006Sisomphon, K., Copuroglu, O., & Koenders, E. A. B. (2013). Effect of exposure conditions on self healing behavior of strain hardening cementitious composites incorporating various cementitious materials. Construction and Building Materials, 42, 217-224. doi:10.1016/j.conbuildmat.2013.01.012Argiz, C., Menéndez, E., Moragues, A., & Sanjuán, M. Á. (2014). Recent Advances in Coal Bottom Ash Use as a New Common Portland Cement Constituent. Structural Engineering International, 24(4), 503-508. doi:10.2749/101686613x1376834840051

Método para la formulación de hormigones de fibras metálicas

In the work we are presenting, we have set ourselves the target of determining a practical method for ascertaining the dosage of fibrous concrete. To do this, as in any problem regarding dosage, we shall start from the possibilities of supply, which will be conditioned by the nature of the aggregates to be used, of certain technical restrictions imposed by the admixtures and of the carrying out requirements which will set the concrete workability. The first part of our study amounts to determining the optimal percentages for each aggregate and the water-cement ratio, starting with the dosage of cement established initially and for each fibre content proposed. In the second part, we shall develop the study of acceptable limits of fibre content, in order to prevent 'balls of fibre' from forming.En los trabajos que presentamos nos hemos planteado el objetivo de determinar un método práctico de dosificación de hormigones de fibras. Para ello partiremos, como en cualquier problema de dosificación, de unas posibilidades de suministro que nos condicionarán la naturaleza de los áridos a utilizar, de unas limitaciones técnicas impuestas por los aditivos, y de unas necesidades de puesta en obra que nos fijarán la trabajabilidad del hormigón. La primera parte de nuestro trabajo se reduce a determinar, a partir de la dosificación en cemento fijada inicialmente, y para cada contenido en fibras propuesto, los porcentajes óptimos de cada uno de los áridos y la relación agua/cemento. En la segunda parte desarrollaremos el estudio de los límites admisibles del contenido en fibras, para evitar la formación de "pelotas de fibras"

Tensile behaviour of reinforced UHPFRC elements under serviceability conditions

[EN] Tension stiffening is an essential effect that influences the behaviour of concrete structures under serviceability conditions, mainly regarding crack control and deflection behaviour. Serviceability conditions can be studied experimentally by running the so-called uniaxial tensile test. This paper reports an extensive experimental research conducted to study the tensile behaviour of reinforced Ultra-High Performance Fibre-Reinforced Concrete (R-UHPFRC) under service conditions by uniaxial tensile testing. The parameters studied were the reinforcement ratio and the steel fibre content in a experimental programme including 36 specimens. Special testing equipment and methodology to measure the post-cracking deformation of R-UHPFRC ties were developed, and special attention was paid to the shrinkage effect. The tensile elements' axial stiffness was approximately parallel to the bare bar response after microcracking formation showing a full tension-stiffening response. The average tensile capacity of the reinforced elements (tension stiffening response) was achieved. Concrete's contribution in the R-UHPFRC ties with the tensile properties deriving from four-point bending tests (4PBTs) on non-reinforced UHPFRC specimens was also compared. The experimental results revealed a slight increase in concrete's contribution with the higher reinforcement ratio. Moreover, the concrete's contribution in the tensile elements was higher than the characteristic tensile properties deriving from 4PBTs.This study forms part of Project BIA2016-78460-C3-1-R, supported by the Ministry of Economy and Competitiveness of Spain.Khorami, M.; Navarro-Gregori, J.; Serna Ros, P. (2021). Tensile behaviour of reinforced UHPFRC elements under serviceability conditions. Materials and Structures. 54(1):1-17. https://doi.org/10.1617/s11527-021-01630-zS117541Burns C (2012) Serviceability analysis of reinforced concrete based on the tension chord model, PhD thesis no. 19979, Institute of Structural Engineering, Swiss Federal Institute of Technology, Zurich, SwitzerlandHonfi D (2013) Design for Serviceability-A probabilistic approach. Lund University, SwedenSahamitmongkol R, Kishi T (2011) Tension stiffening effect and bonding characteristics of chemically prestressed concrete under tension. Mater Struct 44(2):455–474Gribniak V et al (2015) Stochastic tension-stiffening approach for the solution of serviceability problems in reinforced concrete: Constitutive modeling. Comput-Aided Civil Infrastruct Eng 30(9):684–702Muhamad R et al (2012) The tension stiffening mechanism in reinforced concrete prisms. Adv Struct Eng 15(12):2053–2069Model Code 2010 (2012), Final Complete Draft, Fib Bull: No.65 and 66, March 2012-ISBN 978-2-88394-105-2 and April 2012-ISBN 978-2-88394-106-9AFGC S (2002) Bétons fibrés à ultra-hautes performances–Recommandations provisoires. AFGC, FranceCommittee JC (2008) Recommendations for design and construction of high performance fiber reinforced cement composites with multiple fine cracks. Japan Society of Civil Engineers, Tokyo, JapanCahier Technique SIA 2052 (2014) Béton fibré ultra-performant (BFUP)-Matériaux, dimensionnement et exécution. ProjetBelarbi A, Hsu TT (1994) Constitutive laws of concrete in tension and reinforcing bars stiffened by concrete. Structural Journal 91(4):465–474Yankelevsky DZ, Jabareen M, Abutbul AD (2008) One-dimensional analysis of tension stiffening in reinforced concrete with discrete cracks. Eng Struct 30(1):206–217Stramandinoli RS, La Rovere HL (2008) An efficient tension-stiffening model for nonlinear analysis of reinforced concrete members. Eng Struct 30(7):2069–2080Collins MP, Mitchell D (1991) Prestressed concrete structures, vol 9. Prentice Hall Englewood Cliffs, NJKaklauskas G (2001) Integral constitutive model for deformational analysis of flexural reinforced concrete members. Statyba 7(1):3–9Hsu TT (2017) Unified theory of reinforced concrete. Routledge, UKFields K, Bischoff PH (2004) Tension stiffening and cracking of high-strength reinforced concrete tension members. Structural Journal 101(4):447–456Patel K, Chaudhary S, Nagpal A (2016) A tension stiffening model for analysis of RC flexural members under service load. Comput Concrete 17(1):29–51Lee SC, Cho JY and Vecchio FJ (2013) Tension-Stiffening Model for Steel Fiber-Reinforced Concrete Containing Conventional Reinforcement. ACI Structural Journal 110(4)Bischoff PH (2003) Tension stiffening and cracking of steel fiber-reinforced concrete. J Mater Civ Eng 15(2):174–182Amin A, Foster SJ, Watts M (2016) Modelling the tension stiffening effect in SFR-RC. Mag Concrete Res 68(7):339–352Deluce JR, Vecchio FJ (2013) Cracking Behavior of Steel Fiber-Reinforced Concrete Members Containing Conventional Reinforcement. ACI Struct J 110(3):481–490Bernardi P et al (2016) Experimental and numerical study on cracking process in RC and R/FRC ties. Mater Struct 49(1–2):261–277Baby F et al (2013) UHPFRC tensile behavior characterization: inverse analysis of four-point bending test results. Mater Struct 46(8):1337–1354Lee S-C, Kim H-B, Joh C (2017) Inverse Analysis of UHPFRC Beams with a Notch to Evaluate Tensile Behavior. Advances in Materials Science and Engineering 2017:1–10Baby F et al (2013) Identification of UHPFRC tensile behaviour: methodology based on bending tests. UHPFRC 2013-International Symposium on Ultra-High Performance Fibre-Reinforced Concrete: 649–658Baby F et al (2012) Proposed flexural test method and associated inverse analysis for ultra-high-performance fiber-reinforced concrete. ACI Mater J 109(5):545López JÁ et al (2015) An inverse analysis method based on deflection to curvature transformation to determine the tensile properties of UHPFRC. Mater Struct 48(11):3703–3718López JÁ (2017) Characterisation of The Tensile Behaviour of UHPFRC by Means of Four-Point Bending Tests. PhD Thesis, Universitat Politècnica de ValènciaKhorami M, Navarro-Gregori J, Serna P (2020) Experimental methodology on the serviceability behaviour of reinforced ultra-high performance fibre reinforced concrete tensile elements. Strain 56(5):e12361Khorami M et al (2019) A testing method for studying the serviceability behavior of reinforced UHPFRC tensile ties. in IOP Conference Series: Materials Science and Engineering. IOP Conference Series 596:12–22Lee N, Chisholm D (2005) Reactive Powder Concrete, Study Report SR 146. Ltd, Judgeford, New ZealandBeigi MH et al (2013) An experimental survey on combined effects of fibers and nanosilica on the mechanical, rheological, and durability properties of self-compacting concrete. Mater Des 50:1019–1029Li VC (2002) Large volume, high-performance applications of fibers in civil engineering. J Appl Polym Sci 83(3):660–686Edgington J (1973) Steel fibre reinforced concrete. University of Surrey, GuildfordLópez J et al (2015) Comparison between inverse analysis procedure results and experimental measurements obtained from UHPFRC Four-Point Bending Tests. in Seventh International RILEM Conference on High Performance Fiber Reinforced Cement Composites (HPFRCC7): 185–192Löfgren I (2005) Fibre-reinforced Concrete for Industrial Construction-a fracture mechanics approach to material testing and structural analysis. Chalmers University of Technology, GothenburgAfroughsabet V, Biolzi L, Ozbakkaloglu T (2016) High-performance fiber-reinforced concrete: a review. J Mater Sci 51(14):6517–6551Buttignol TET, Sousa J, Bittencourt T (2017) Ultra High-Performance Fiber-Reinforced Concrete (UHPFRC): a review of material properties and design procedures. Revista IBRACON de estruturas e materiais 10(4):957–971Fehling E et al (2014) Ultra-high performance concrete UHPC: Fundamentals, design, examples. Wiley, NYMakita T, Brühwiler E (2014) Tensile fatigue behaviour of Ultra-High Performance Fibre Reinforced Concrete combined with steel rebars (R-UHPFRC). Int J Fatigue 59:145–152Rauch M and Sigrist V (2010) Dimensioning of Structures made of UHPFRC. in IABSE Symposium Report. 34th International Association for Bridge and Structural Engineering 97(34):39–46Sigrist V and Rauch M (2008) Deformation behavior of reinforced UHPFRC elements in tension. Anonymous Tailor Made Concrete Structures. CRC Press: 405–410Redaelli D (2006) Testing of reinforced high performance fibre concrete members in tension. in Proceedings of the 6th Int. Ph. D. Symposium in Civil Engineering, Zurich 2006. 2006. Proceedings of the 6th Int. Ph. D. Symposium in Civil Engineering, ZurichInstitution BS (2004) Eurocode 2: Design of concrete structures: Part 1–1: General rules and rules for buildings. British Standards Institution, UKGribniak V, Kaklauskas G and Bačinskas D (2007) State-of-art review of shrinkage effect on cracking and deformations of concrete bridge elements. The Baltic Journal of Road & Bridge Engineering 2(4):183-193Torst H (1967) Auswirkungen des superpositionsprinzips auf kriech-und relaxationsprobleme bei beton und spannbeton. Beton-und stahlbetonbau 10(230–238):261–269Bazant Z (1972) Predictions of concrete effects using age adjusted effective modulus method. J Am Concrete Institute 69:212–217AFGC (2013)  Ultra high performance fibre-reinforced concretes, recommendations. Documents scientifiques et techniques, ParisGowripalan N, Gilbert R (2000) Design guidelines for RPC prestressed concrete beams. School of Civil and Environmental Engineering, University of New South Wales, Sydney, AustraliaOstergaard L, Walter R and Olesen J (2005) Method for determination of tensile properties of engineered cementitious composites (ECC). Proceedings of ConMat'05, Vancouver, CanadaKanakubo T (2006) Tensile characteristics evaluation method for ductile fiber-reinforced cementitious composites. J Adv Concrete Technol 4(1):3–1

Experimental methodology on the serviceability behaviour of reinforced ultra-high performance fibre reinforced concrete tensile elements

[EN] Design codes include serviceability limit state (SLS) provisions for stress, crack, and deflection control in concrete structures, which may limit the structural design. When drawing on reinforced ultra-high performance fibre-reinforced concrete (R-UHPFRC), the process of cracking differs significantly from traditional concretes. Thus, it remains unclear whether the traditional provisions are applicable to R-UHPFRC or should be reviewed. Uniaxial tensile tie test is an excellent option to analyse and review these criteria. This work proposes a novel test methodology to study the behaviour of R-UHPFRC under serviceability conditions, which lets the study of the global and local deformation behaviour by using different measurement equipment. Two different types of R-UHPFRC ties with variant fibre content were tested. The global average tensile stressstrain curve, cracking behaviour, number, and width of cracks were obtained. Promising preliminary results admitted that this methodology can be useful to propose design criteria of R-UHPFRC under SLS.State Research Agency of Spain, Grant/Award Number: BIA2016-78460-C3-1-RKhorami, M.; Navarro-Gregori, J.; Serna Ros, P. (2020). Experimental methodology on the serviceability behaviour of reinforced ultra-high performance fibre reinforced concrete tensile elements. STRAIN. 56(5):1-13. https://doi.org/10.1111/str.12361S11356

A Study of the Flexural Behavior of Fiber-Reinforced Concretes Exposed to Moderate Temperatures

[EN] The use of synthetic fibers in fiber-reinforced concretes (FRCs) is often avoided due to the mistrust of lower performance at changing temperatures. This work examines the effect of moderate temperatures on the flexural strengths of FRCs. Two types of polypropylene fibers were tested, and one steel fiber was employed as a reference. Three-point bending tests were carried out following an adapted methodology based on the standard EN 14651. This adapted procedure included an insulation system that allowed the assessment of FRC flexural behavior after being exposed for two months at temperatures of 5, 20, 35 and 50 °C. In addition, the interaction of temperature with a precracked state was also analyzed. To do this, several specimens were pre-cracked to 0.5 mm after 28days and conditioned in their respective temperature until testing. The findings suggest that this range of moderate temperatures did not degrade the behavior of FRCs to a great extent since the analysis of variances showed that temperature is not always a significant factor; however, it did have an influence on the pre-cracked specimens at 35 and 50 °C.This research was funded by Spanish Ministry of Science, Innovation and Universities, grant number FPU18/06145.Caballero-Jorna, M.; Roig-Flores, M.; Serna Ros, P. (2021). A Study of the Flexural Behavior of Fiber-Reinforced Concretes Exposed to Moderate Temperatures. Materials. 14(13):1-18. https://doi.org/10.3390/ma14133522S118141

Time-dependent evolution of strand transfer length in pretensioned prestressed concrete members

For design purposes, it is generally considered that prestressing strand transfer length does not change with time. However, some experimental studies on the effect of time on transfer lengths show contradictory results. In this paper, an experimental research to study transfer length changes over time is presented. A test procedure based on the ECADA testing technique to measure prestressing strand force variation over time in pretensioned prestressed concrete specimens has been set up. With this test method, an experimental program that varies concrete strength, specimen cross section, age of release, prestress transfer method, and embedment length has been carried out. Both the initial and long-term transfer lengths of 13-mm prestressing steel strands have been measured. The test results show that transfer length variation exists for some prestressing load conditions, resulting in increased transfer length over time. The applied test method based on prestressing strand force measurements has shown more reliable results than procedures based on measuring free end slips and longitudinal strains of concrete. An additional factor for transfer length models is proposed in order to include the time-dependent evolution of strand transfer length in pretensioned prestressed concrete members. © 2012 Springer Science+Business Media Dordrecht.Funding for this experimental research work has been provided by the Spanish Ministry of Education and Science and ERDF (Projects BIA2006-05521 and BIA2009-12722). Tests have been conducted at the Institute of Concrete Science and Technology (ICITECH), at the Universitat Politecnica de Valencia (Spain).Caro Forero, LA.; Martí Vargas, JR.; Serna Ros, P. (2013). Time-dependent evolution of strand transfer length in pretensioned prestressed concrete members. Mechanics of Time-Dependent Materials. 17(4):501-527. doi:10.1007/s11043-012-9200-2S501527174ACI: ACI 318-11 Building code requirements for reinforced concrete. ACI Committee 318. American Concrete Institute, Farmington Hills, MI (2011)AENOR: UNE 36094:1997 Alambres y cordones de acero para armaduras de hormigón pretensado. Asociación Española de Normalización: Madrid (1997)Balevicius, R.: An average stress strain approach to creep analysis of RC uncracked elements. Mech. Time-Depend. Mater. 14, 69–89 (2010)Barnes, R.W., Grove, J.W., Burns, N.H.: Experimental assessment of factors affecting transfer length. ACI Struct. J. 100(6), 740–748 (2003)Base, G.D.: Some tests on the effect of time on transmission length in pretensioned concrete. Mag. Concr. Res. 4, 73–82 (1957)Base, G.D.: An investigation of transmission length in pretensioned concrete. Cement and Concrete Association, Research Report n∘ 5 (1958)Bruce, R.N., Russell, H.G., Roller, J.J., Martin, B.T.: Feasibility evaluation of utilizing high-strength concrete in design and construction of highway bridge structures. Louisiana Transportation Research Center. Report n $^{\rm{o}}$ FHWA/LA-94-282. Baton Rouge, LA (1994)Buckner, C.D.: A review of strand development length for pretensioned concrete members. PCI J. 40(2), 84–105 (1995)CEN: European standard EN 197-1:2000: Cement. Part 1: Compositions, specifications and conformity criteria for common cements. Comité Européen de Normalisation, Brussels (2000)Cousins, Th.E., Johnston, D.W., Zia, P.: Transfer length of epoxy-coated prestressing strand. ACI Mater. J. 87(3), 193–203 (1990)Deatherage, J.H., Burdette, E., Chew, Ch.K.: Development length and lateral spacing requirements of prestressing strand for prestressed concrete bridge girders. PCI J. 39(1), 70–83 (1994)den Uijl, J.A.: Bond modelling of prestressing strand. In: Bond and Development of Reinforcement (SP 180-7), pp. 145–169. ACI International, Farmington Hills (1998)Dorsten, V., Hunt, F.F., Preston, H.K.: Epoxy coated seven-wire strand for prestressed concrete. PCI J. 29(4), 100–109 (1984)Evans, R.H.: Research and developments in pre-stressing. Proc., Inst. Civ. Eng. 35, 231–261 (1951)Evans, R.H., Robinson, W.R.: Bond stresses in prestressed concrete from X-ray photographs. Proc., Inst. Civ. Eng. 6(14), 212–235 (1955)FIB: Model Code 2010 (First complete draft). FIB Bulletin n∘55. International federation for structural concrete. Lausanne (2010)Floyd, R.W., Howland, M.B., Hale, W.M.: Evaluation of strand bond equations for prestressed members cast with self-consolidating concrete. Eng. Struct. 33, 2879–2887 (2011)Girgis, A.F., Tuan, Ch.Y.: Bond strength and transfer length of pretensioned bridge girders cast with self-consolidating concrete. PCI J. 50(6), 72–87 (2005)Grace, N.F.: Transfer length of CFRP/CFCC strands for double-T girders. PCI J. 45(5), 110–126 (2000)Guyon, Y.: Béton Précontrainte. Étude Théorique et Experiméntale. Eyrolles, Paris (1953)Holmberg, A., Lindgren, S.: Anchorage and prestress transmission. National Swedish Building Research, Document D1/1970 (1970)Issa, M.A., Sen, R., Amer, A.: Comparative study of transfer length in fiberglass and steel pretensioned concrete members. PCI J. 38(6), 52–63 (1993)Kaar, P.H., LaFraugh, R.W., Mass, M.A.: Influence of concrete strength on strand transfer length. PCI J. 8(5), 47–67 (1963)Kahn, L.F., Dill, J.C., Reutlinger, C.G.: Transfer and development length of 15-mm strand in high performance concrete girders. J. Struct. Eng. 128(7), 913–921 (2002)Kose, M.M., Burkett, W.R.: Formulation of new development length equation for 0.6 in prestressing strand. PCI J. 50(5), 96–105 (2005)Krishnamurthy, D.: Influencia del procedimiento de destesado sobre las tensiones en las zonas de anclaje y sobre la longitud de transmisión, en elementos de hormigón pretensado con armaduras pretesas. Traslation of paper published in The Indian Concrete Journal 44(3). Hormigón y Acero June, 49–65 (1970)Lane, S.N.: A new development length equation for pretensioned strands in bridge beams and piles. Federal Highway Administration. Research FHWA-RD-98-116, Mclean, VA (1998)Larson, K.H., Peterman, R.J., Esmaeily, A.: Bond characteristics of self-consolidating concrete for prestressed bridge girders. PCI J. 52(4), 44–57 (2007)Logan, D.R.: Acceptance criteria for bond quality of strand for pretensioned prestressed concrete applications. PCI J. 42(2), 52–90 (1997)Lu, Z., Boothby, Th.E., Bakis, Ch.E., Nanni, A.: Transfer and development lengths of FRP prestressing tendons. PCI J. 45(2), 84–95 (2000)Mahmoud, Z.I., Rizkalla, S.H., Zaghloul, E.R.: Transfer and development lengths of carbon fiber reinforcement polymers prestressing reinforcing. ACI Struct. J. 96(4), 594–602 (1999)Martí-Vargas, J.R., Serna-Ros, P., Fernández-Prada, M.A., Miguel-Sosa, P.F., Arbeláez, C.A.: Test method for determination of the transmission and anchorage lengths in prestressed reinforcement. Mag. Concr. Res. 58(1), 21–29 (2006a)Martí-Vargas, J.R., Arbeláez, C.A., Serna-Ros, P., Fernández-Prada, M.A., Miguel-Sosa, P.F.: Transfer and development lengths of concentrically prestressed concrete. PCI J. 51(5), 74–85 (2006b)Martí-Vargas, J.R., Serna-Ros, P., Arbeláez, C.A., Rigueira-Victor, J.W.: Bond behaviour of self-compacting concrete in transmission and anchorage. Mater. Constr. 56(284), 27–42 (2006c)Martí-Vargas, J.R., Arbeláez, C.A., Serna-Ros, P., Navarro-Gregori, J., Pallarés-Rubio, L.: Analytical model for transfer length prediction of 13 mm prestressing strand. Struct. Eng. Mech. 26(2), 211–229 (2007a)Martí-Vargas, J.R., Arbeláez, C.A., Serna-Ros, P., Castro-Bugallo, C.: Reliability of transfer length estimation from strand end slip. ACI Struct. J. 104(4), 487–494 (2007b)Martí-Vargas, J.R., Serna, P., Navarro-Gregori, J., Bonet, J.L.: Effects of concrete composition on transmission length of prestressing strands. Constr. Build. Mater. 27, 350–356 (2012a)Martí-Vargas, J.R., Serna, P., Navarro-Gregori, J., Pallarés, L.: Bond of 13 mm prestressing steel strands in pretensioned concrete members. Eng. Struct. 41, 403–412 (2012b)Martí-Vargas, J.R., Caro, L.A., Serna, P.: Experimental technique for measuring the long-term transfer length in prestressed concrete. Strain. doi: 10.1111/str.12019 (2012c)Marshall, G.: End anchorage and bond stress in prestressed concrete. Mag. Concr. Res. 1, 123–127 (1949)Mayfield, B., Davies, G., Kong, F.K.: Some tests on the transmission length and ultimate strength of pretensioned concrete beams incorporating Dyform strand. Mag. Concr. Res. 22(73), 219–226 (1970)Mitchell, D., Cook, W.D., Khan, A.A., Tham, Th.: Influence of high strength concrete on transfer and development length of pretensioning strand. PCI J. 38(3), 52–66 (1993)Nanni, A., Utsunomiya, T., Yonekura, H., Tanigaki, M.: Transmission of prestressing force to concrete by bonded fiber reinforced plastic tendons. ACI Struct. J. 89(3), 335–344 (1992)Oh, B.H., Kim, E.S.: Realistic evaluation of transfer lengths in pretensioned, prestressed concrete members. ACI Struct. J. 97(6), 821–830 (2000)Peterman, R.J.: The effects of as-cast depth and concrete fluidity on strand bond. PCI J. 52(3), 72–101 (2007)Pozolo, A.M., Andrawes, B.: Transfer length in prestressed self-consolidating concrete box and I-girders. ACI Struct. J. 108(3), 341–349 (2011)Ramirez, J.A., Russell, B.W.: Transfer, development, and splice length for strand/reinforcement in High-Strength Concrete. NCHRP Report 603. National Cooperative Highway Research Program (2008)Russell, B.W., Burns, N.H.: Measured transfer lengths of 0.5 and 0.6 in strands in pretensioned concrete. PCI J. 41(5), 44–65 (1996)RILEM: RPC6 Specification for the test to determine the bond properties of prestressing tendons. Réunion Internationale des Laboratoires et Experts des Matériaux, Systèmes de Constructions et Ouvrages, Bagneux., France (1979)Roller, J.J., Martin, B.T., Russell, H.G., Bruce, R.N.: Performance of prestressed high strength concrete bridge girders. PCI J. 38(3), 34–45 (1993)Shahawy, M., Issa, M., Batchelor, B.: Strand transfer lengths in full scale AASHTO prestressed concrete girders. PCI J. 37(3), 84–96 (1992)Shing, P.B., Frangopol, D.M., McMullen, M.L., Hutter, W., Cooke, D.E., Leonard, M.A.: Strand development and transfer length tests on high performance concrete box girders. PCI J. 45(5), 96–109 (2000)Soudki, K., Green, M., Clapp, F.: Transfer length of carbon fiber rods in precast pretensioned concrete beams. PCI J. 42(5), 78–87 (1997)Staton, B.W., Do, N.H., Ruiz, E.D., Hale, W.M.: Transfer lengths of prestressed beams cast with self-consolidating concrete. PCI J. 54(2), 64–83 (2009)Swamy, R.N., Anand, K.L.: Losses in transmission length and prestress in high alumina cement concrete. Proc., Inst. Civ. Eng. 59, 293–307 (1975)Tabatabai, H., Dickson, Th.: The history of the prestressing strand development length equation. PCI J. 38(5), 64–75 (1993)Tadros, M.K., Baishya, M.C.: Discussion of a review of strand development length for pretensioned concrete members. PCI J. 41(2), 112–127 (1996)Trent, J.: Transfer length, development length, flexural strength, and prestress loss evaluation in pretensioned self-consolidating concrete members. MS Thesis, Virginia Polytechnic Institute and State University, Blacksburg, VA (2007)Weerasekera, I.: Transfer and Flexural Bond in Pretensioned Prestressed Concrete. UMI Dissertation Services, University of Calgary (1991). Dissertation, ISBN 0-315-71095-5William, G.W., Shoukry, S.N., Riad, M.Y.: Development of early age shrinkage stresses in reinforced concrete bridge decks. Mech. Time-Depend. Mater. 12, 343–356 (2008)Zia, P., Mostafa, T.: Development length of prestressing strands. PCI J. 22(5), 54–65 (1977)Zou, P.X.V.: Long-term properties and transfer length of fiber-reinforced polymers. J. Compos. Constr. 7(1), 10–19 (2003

Prestress losses evaluation in prestressed concrete prismatic specimens

This paper presents an experimental research work to evaluate prestress losses in pretensioned prestressed concrete. An experimental program including variables such as concrete mix design, specimen cross-section size and concrete age at the prestress transfer was carried out. Several pretensioned prestressed concrete prismatic specimens were made and tested using the ECADA+ test method, based on measuring prestressing reinforcement force. In addition, specimens were instrumented to obtain the longitudinal concrete strains profiles at any time. Measurements from both techniques were taken over 1 year. Measured prestress losses included elastic shortening losses and time-dependent losses due to concrete shrinkage and creep. A coefficient to account for the relationship between the prestress losses from the measured prestressing forces and the actual prestress losses from concrete compressive strains is proposed. The experimental results were compared with the predicted prestress losses using methods from several codes.Funding for this experimental research work has been provided by the Spanish Ministry of Education and Science and ERDF (Project BIA2006-05521 and Project BIA2009-12722). Tests have been conducted at the Institute of Concrete Science and Technology (ICI-TECH), at the Universitat Politecnica de Valencia (Spain).Caro Forero, LA.; Martí Vargas, JR.; Serna Ros, P. (2013). Prestress losses evaluation in prestressed concrete prismatic specimens. Engineering Structures. 48:704-715. doi:10.1016/j.engstruct.2012.11.038S7047154

Interfacial Transition Zone in Mature Fiber-Reinforced Concretes

[EN] The interfacial transition zone (ITZ) in concrete is the region of the cement paste that is disturbed by the presence of an aggregate or fiber. This work focuses on the ITZ around silica and dolomite grains and steel fibers. The analysis performed is based on: the macroscale properties of the specimens; petrographic analyses with polarized microscopy; and qualitative and quantitative SEM analyses. The following types of concrete were tested: standard quality (SQ); high-quality with steel fibers (PFRC); and ultra-high-performance fiber-reinforced concrete (UHPFRC). The most important parameters affecting ITZ are the properties of the disturbing elements and the mixture composition of the concrete. In PFRC, a differentiated zone of thickness 20 ¿m (787.40 ¿in.) was observed around a dolomite grain, showing a preferential growth of Ca-based compounds. In UHPFRC, SEM-EDS analysis revealed C-S-H of lower Ca/Si ratios in the proximity of fibers and aggregates.Roig-Flores, M.; Simicevic, F.; Maricic, A.; Serna Ros, P.; Horvat, M. (2018). Interfacial Transition Zone in Mature Fiber-Reinforced Concretes. ACI Materials Journal. 115(4):623-631. https://doi.org/10.14359/51702419623631115

Characterization of Glass Powder from Glass Recycling Process Waste and Preliminary Testing

[EN] This work studies the possibility of incorporating different proportions of glass powder from the waste glass (rejected material called fine cullet) produced during the glass recycling process into the manufacturing of mortar and concrete. For this purpose, the material is characterized by its chemical composition and pozzolanic activity, and the shape and size of its particles are studied. It is then incorporated as a substitute for cement into the manufacturing of mortar and concrete at 25% and 40% of cement weight, and its effect on setting times, consistency, and mechanical strength is analyzed. Its behavior as a slow pozzolan is verified, and the possibility of incorporating it into concrete is ratified by reducing its cement content and making it a more sustainable material.This research was funded by Agencia Valenciana de la Innovacio (AVI) grant number INNEST/2020/85.Gimenez-Carbo, E.; Soriano Martinez, L.; Roig-Flores, M.; Serna Ros, P. (2021). Characterization of Glass Powder from Glass Recycling Process Waste and Preliminary Testing. Materials. 14(11):1-15. https://doi.org/10.3390/ma14112971S115141