br Acknowledgements This study is sponsored by

Acknowledgements This study is sponsored by the Natural Science Foundation of China (grant no. 51178161), 111 Project (grant no. B13024) and the Fundamental Research Funds for the Central Universities (grant no. 2017B00914)
Introduction Highway and pavement engineers are facing concrete pavement damages nowadays due to alkali-aggregate reaction (AAR). AAR is detrimental when it causes significant volume expansion of concrete and results in cracking. There are two types of alkali-aggregate reaction, which are the alkali-silica reaction and alkali-carbonate reaction. The most prevalent form of AAR is the alkali-silica reaction (ASR). An ASR phenomenon is a chemical reaction between the alkali hydroxide coming from hydraulic cement and silica content from aggregate used in concrete. A gel is formed during this chemical reaction, namely ASR gel [1]. When moisture comes in contact with this gel, it swells in volume and exerts pressure in concrete [1], [2]. It leads to the formation of microfractures in concrete, which results in spalling and cracking [3]. Different supplementary cementitious materials (SCMs) such as fly ash, silica fume, and slag can be used to lessen ASR problem. Use of SCMs as partial replacement of cement reduces the alkali content of cement [1]. In addition, the porosity of the concrete can be enhanced by SCMs that will reduce the chances of moisture to initiate deleterious ASR expansion [1]. During pozzolanic activity of SCMs, negatively charged calcium silicate hydrate (C-S-H) is formed with a low calcium to silica ratio. This C-S-H reacts with alkali cations (Na+, K+) and reduces diffusivity of alkali cations into the concrete. In this way, ASR is mitigated by the use of SCMs [4]. About 30% rice hulls are produced during the paddy husking process [5]. It is used as XMD8-92 reviews not only for energy production in paddy milling process but also in various power plants. When rice hull undergoes the burning process, about 20% of it converts into RHA [5], [6]. About 738.2 million tons of paddies are produced in the world each year [7] of which about 70 million tons are RHA [8]. This significant amount of RHA is generally dumped in industrial premises that may cause environmental pollution. Moreover, RHA cannot be naturally degraded due to its siliceous compositions [9]. On the other hand, cement industries are responsible for about 7% of the total equivalent CO2 emissions [9], and one ton of cement production is responsible for about one ton of equivalent CO2 emission [8], [10]. Use of RHA in substitution of cement can reduce the CO2 footprint as well as ecological hazards [11], [12], [13]. Arkansas is the top of all six rice-producing states in the U.S. It contributes about 48% to the total rice production in the U.S. [14]. The largest rice miller in the world, Riceland Foods, Inc., a farmer-family based business that produces 125 million bushels of paddy annually, is situated in Arkansas [15]. Generally, Riceland Foods considers RHA as an agricultural waste product and disposes it to nearby industry premises, which may cause health hazards to the associated workers. Other SCMs such as fly ash and silica fume are expensive and may not be available locally. Hence, locally produced RHA can be used as an alternative SCM due to its high silica content [4]. Akhnoukh et al. [3] reported that Arkansas Department of Transportation (ARDOT) faced concrete pavement and barrier damages at various places across Arkansas in recent years. It may incur ARDOT extra maintenance cost, leading to inflation in the life cycle cost of the project. The factors that contribute to the concrete pavement distress due to ASR in Arkansas are the use of reactive aggregates, the trend of not using SCM in cement and availability of high moisture content in the air. It is suggested to incorporate SCM in highway projects to lessen ASR-related concrete pavement deterioration.