The potential of ground clay brick to mitigate Alkali–Silica Reaction in mortar prepared with highly reactive aggregate Kaveh Afshinnia ⇑ , Amir Poursaee Glenn Department of Civil Engineering, Clemson University, Clemson, SC 29634, USA highlights  A brief study has been done to evaluate the pozzolanic reactivity and ASR mitigation performance of ground crushed brick.  A brief study has been done to evaluate the effect of ground crushed brick fineness on ASR mitigation performance.  Microscopic analysis has been conducted to evaluate the microstructure of the mortar containing ground crushed brick.  A comparison has been made to investigate the pozzolanic reactivity of ground crushed brick using XRD analysis. article info Article history: Received 1 March 2015 Received in revised form 9 July 2015 Accepted 15 July 2015 Keywords: Ground crushed brick (GCB) Alkali–Silica Reaction (ASR) Pozzolanic reactivity Concrete expansion Cementitious material XRD abstract The objective of this work was to study the effect of ground clay brick on mitigating the Alkali Silica Reaction (ASR) in mortar bars prepared with highly reactive aggregates. To evaluate the potential of ground crushed clay brick to mitigate ASR distress in mortar, mortar bars and mortar cubes were cast with combination of different dosages of ground clay brick (partial replacement of portland cement). The pozzolanic reactivity of ground clay brick was also evaluated using strength activity index test. In addition, the Scanning Electron Microscopy (SEM) and the Energy-Dispersive X-ray Spectroscopy (EDS) were conducted to evaluate the microstructure and location of the ASR gel and its chemical composition. The results from this study indicated satisfactory level of pozzolanic reactivity when cement was partially replacement by the ground clay brick. Also, it was found that replacing 25% of cement with ground clay brick (by weight) could significantly decrease the ASR expansion by 67% at the age of 14 days. However, this study suggested that the compressive strength values of the specimens containing higher dosages of ground crushed brick (i.e. 50% replacement level) were significantly lower than that of the control specimens. Ó 2015 Elsevier Ltd. All rights reserved. 1. Introduction Alkali Silica Reaction (ASR) is a chemical reaction occurs between the specific source of silica from aggregate and the hydroxyl ions that are usually available in the alkaline environ- ment of the pore solution. The product of this reaction is a hygroscopic ASR gel, which by itself does not cause any problem for the concrete. However, at the presence of moisture, the ASR gel swells and consequently causes significant pressure through the surrounding concrete matrix. Typically, Supplementary Cementitious Materials (SCMs) such as fly ashes [1–5], slag [6–8], meta-kaolin [9–12], silica fume [13,14] and other SCMs derived from waste materials such as glass [15–19] have been used successfully to mitigate the ASR distress in concrete. Depletion of alkali loading in concrete mixture due to the replacement of portland cement (dilution effect), better alkali binding provided by modified C–S–H (Calcium–Silicate–Hydrate) gel (particularly, where the calcium to silica ratio are low), higher strength provided by pozzolanic reaction of SCMs and decreasing the rate of silica dissolution from aggregate surface [20] are some of the main causes by which the SCMs can mitigate ASR distress in concrete mixtures. Moreover, the SCMs may refine the pores’ dis- tribution in concrete paste; therefore, the reactive aggregates have less access to the external moisture compared to the conventional concrete (without SCMs) [21,22]. Even though the beneficial influ- ence of typical SCMs such as fly ash, meta-kaolin, slag and silica fume have been well investigated in different studies, the use of pozzolans derived from waste materials such as ground clay brick needs further investigations. In addition, due to the different envi- ronmental agency reports, alternative methods of recycling waste http://dx.doi.org/10.1016/j.conbuildmat.2015.07.155 0950-0618/Ó 2015 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. E-mail addresses: kafshin@clemson.edu (K. Afshinnia), amire@clemson.edu (A. Poursaee). Construction and Building Materials 95 (2015) 164–170 Contents lists available at ScienceDirect Construction and Building Materials journal homepage: www.elsevier.com/locate/conbuildmat