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Alkali–Silica Reaction in Plain and Fibre Concretes in Field Conditions

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Alkali–Silica Reaction in Plain and Fibre Concretes in Field Conditions Materials and Structures (2019) 52:31 https://doi.org/10.1617/s11527-019-1332-2 (0123456789().,-volV)(0123456789().,-volV) ORIGINAL ARTICLE Alkali–silica reaction in plain and fibre concretes in field conditions Graciela Giaccio . Marı´a Celeste Torrijos . Carlos Milanesi . Rau´l Zerbino Received: 22 August 2018 / Accepted: 5 March 2019 Ó RILEM 2019 Abstract This paper presents an experimental study cracks were observed. While the prisms expansions on the effects of alkali–silica reaction (ASR) in were attenuated after the first 12 months, in the blocks concrete blocks placed outdoors, exposed to weather the damage by ASR continues growing for more than conditions. To promote different reaction kinetics and 3 years. Although the incorporation of macrofibers damage levels, the size of the reactive aggregates, the does not inhibit the development of ASR, it led to alkali content and incorporation of different fibre types benefits such as reduction in cracking and (steel, polymer) were the variables considered. Expan- deformations. sions, crack patterns and air permeability were mon- itored for more than 3 years. In addition, standard Keywords Alkali–aggregate reaction Á Concrete Á expansion, compression and flexion tests were per- Degradation Á Fibre reinforcement Á Mechanical formed. The volume of concrete involved in ASR properties Á Microcracking enhances the development of expansions and crack- ing; in the blocks different expansions were measured Abbreviations in vertical or horizontal directions and important ASR Alkali–silica reaction CMOD Crack mouth opening displacement G. Giaccio E Modulus of elasticity CIC, Commission of Scientific Research, Department of FRC Fibre reinforced concrete Civil Engineering, La Plata National University, La Plata, f Cylinder compressive concrete strength Argentina c fL Limit of proportionality M. C. Torrijos Á R. Zerbino fR1 Residual flexural tensile strength CONICET, National Council of Scientific and corresponding to CMOD = 0.5 mm Technological Research, Department of Civil f Residual flexural tensile strength Engineering, La Plata National University, La Plata, R3 Argentina corresponding to CMOD = 2.5 mm C. Milanesi Cementos Avellaneda S.A., Defensa 113 Piso 6, C1065AAA CABA, Argentina 1 Introduction G. Giaccio Á M. C. Torrijos Á R. Zerbino (&) LEMIT, Commission of Scientific Research, Av. 52, The study of alkali–silica reaction (ASR) has great Hipo´dromo, B1900AYB La Plata, Argentina interest around the world as it is one of the important e-mail: [email protected] 31 Page 2 of 15 Materials and Structures (2019) 52:31 concrete pathologies that can affect diverse types of mineralogy of the rock, the size of the reactive structures. As it is well known, ASR is a chemical aggregates and the kinetic of the reaction, among other reaction between some elements from the concrete variables [18]. Researches on the response of ASR pore solution (mainly OH-,Na?,K?,Ca2?) and damaged concretes under multiaxial loads [19] or the certain siliceous minerals (opal, chalcedony, volcanic relationship between ASR and the compressive glass, strained quartz, micro-crystalline quartz) pre- strength [20] have been recently performed. sent in some aggregates. Under certain conditions of The influence of bars in conventional reinforced humidity and temperature, the reaction products concrete or in prestressed elements affected by ASR (siliceous gel) may absorb water and cause deleterious has been recognized for many years [21–23]. How- expansion and cracking of concrete [1]. The develop- ever, very few studies were made on Fibre Reinforced ment of expansions can promote operational problems Concrete (FRC) elements to evaluate the potential due to the displacement of the structural elements. In contribution of different fibres for mitigating the addition, the appearance of cracks enhances the degradation process and their effects on the mechan- beginning of new mechanisms of deterioration like ical and transport residual properties [24–26]. Most of the corrosion of steel bars or freezing and thawing, these studies were performed with accelerated and which affect concrete mechanical behaviour [2]. The very aggressive conditions as well as artificial reactive study of ASR is also an important issue for Argentina, aggregates to promote the ASR. a country with a large geographic extension and, Lindgard et al. [27] highlighted the need of further consequently, a huge variety of potentially reactive research in FRC as their physical (e.g., permeability) aggregates; a significant number of structures in and mechanical (e.g., strength, toughness) properties service affected by ASR have been observed for over might differ from ordinary concrete. A previous more than 50 years [3, 4]. research was performed on FRC with natural reactive Recent literature shows great interest in the study of aggregates to evaluate if different types of fibres can ASR. Different subjects related to products and kinetic change the rate or the total expansions produced by the of the reaction considering the influence of salts [5], ASR [28]. The incorporation of steel or synthetic powders to promote [6] or inhibit ASR [7], the effects macrofibres decreased the cracks width and density, of polymer action [8] were studied. There are also also a reduction in the coefficient of air permeability many works that use new NDT methodologies for was found, having the steel fibres the best perfor- following ASR [9–13], establish criteria for the mance. Fibre incorporation had no incidence in the characterization and assessment of potentially reactive compressive behaviour. In bending, although the peak aggregates [14], or improve accelerated tests, partic- load decreases, FRC preserved their original residual ularly the impact of alkali leaching on scale effects loading capacity, even though in the case of a severe affecting expansion tests [15]. Recently, Wallau et al. ASR damage. [16] showed that the use of automated expansion The search for a universal testing method that can measuring can contribute to improving validity of reproduce the real behaviour of concrete in service has ASR-testing by excluding additional causes of expan- been the subject of study of many researchers [29]. sion, as cooling–heating cycles, associated to manual The need to obtain relatively fast results in accordance measurements. with project schedules, leads to the use of accelerated The residual mechanical properties of concrete methods that reduce the reliability of the results affected by ASR have been studied by numerous (mortar mixtures, small volume specimens, high researchers [17, 18]; most of whom agree that the temperature, high alkalinity, etc.). In the traditional tensile strength and the modulus of elasticity are the concrete prism test (ASTM 1293) [29] the curing most affected parameters, while the compressive temperature is moderate (38 °C), the particle size strength is less modified. The damage induced by distribution is not significantly modified (no crushing) ASR modifies the shape of the load deformation and the volume of the prism is larger than in the case of curves; it was verified that concrete failure mechanism mortar bar test (ASTM 1260) [30]. However, one is altered both in bending and in compression. As the limitation that can be attributed to this method is the expansion increases the mechanical properties alkali leaching [27, 31] that makes difficult the decrease. Nevertheless, these changes depend on the determination of the content of alkali below which Materials and Structures (2019) 52:31 Page 3 of 15 31 there is no expansion. A fundamental assumption and high alkalis contents were adopted in order to made in concrete prism testing is that there is a relation promote different levels and rates of ASR. between the free expansion of the prisms and the Eight concrete blocks of 0.70 9 0.40 9 0.40 m damaging effect of ASR. However, prism expansion were cast; they were covered with wet clothes during does not solely depend on the reaction extent but also 7 days and then placed outdoors. The meteorological on other mechanisms. Nevertheless, the time depen- conditions recorded during the testing period of La dent prism expansion proved to be linked to the Plata city region were: annual mean temperature damaging effect of ASR, so that the test method is well 17 °C (ranging between 9 and 25 °C), annual mean established for assessing susceptibility of concrete to relative humidity 78% (ranging between 64 and 85%) ASR. Many ASR-modelling approaches infer a time- and annual total rainfall 1150 mm (ranging between dependent reaction extent from concrete prism tests 900 and 1500 mm). It is expected that alkalis in [16]. concrete leach along the time, mainly depending on Nowadays, there is a great interest in the study of the crack development; this fact represents a particular the behaviour of concrete blocks on a larger scale as difference when compared to standard prisms. How- laboratory results may differ from expansion mea- ever, as these are relatively large blocks, stored sured in field cases, mainly due to differences in outside, it can be considered that little leaching will dimensions, mechanical loads and stress development occur. On the block surfaces, the linear deformations induced by ASR [32–36]. Concrete block test allows and air permeability were measured. A crack pattern validating laboratory methods and evaluating the ASR (size and distribution of cracks) survey was also mitigation strategies. In addition, although in the periodically performed to analyse the progress of the prototypes the effects of ASR may become evident reaction and the consequent damage. Figure 1 pre- after many years, they more accurately reproduce the sents a view of the concrete blocks location and the effects of the ambient temperature fluctuation and scheme of the strain measurements. reduce the leaching produced in the laboratory spec- Standard cylinders (100 9 200 mm) and prisms imens. This work presents the results of an experi- (75 9 105 9 430 mm) were also cast with each mental research that studies the development of ASR concrete for the evaluation of the physical and on plain and fibre concrete blocks exposed to the mechanical properties.
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