Journal of Building Engineering 32 (2020) 101732 Available online 30 August 2020 2352-7102/© 2020 Elsevier Ltd. All rights reserved. Prediction of mechanical properties of lightweight basalt fber reinforced concrete containing silica fume and fy ash: Experimental and numerical assessment Ashkan Saradar a, * , Parisa Nemati a , Ali Shadmani Paskiabi b , Mohammad Mohtasham Moein c , Hossein Moez d , Elaheh Hassanzadeh Vishki e a Department of Civil Engineering, University of Guilan, Rasht, Iran b Department of Civil Engineering, Institute of Higher Education Deylaman, Lahijan, Iran c Department of Civil Engineering, Allameh Mohaddes Nouri University, Mazandaran, Noor, Iran d Department of Civil Engineering, Rasht branch, Islamic Azad University, Rasht, Iran e Department of Architecture, Lahijan Branch, Islamic Azad University, Lahijan, Iran A R T I C L E INFO Keywords: Lightweight concrete Mechanical properties Basalt fber Fly ash Adaptive neuro-fuzzy inference system ABSTRACT As a building material, concrete has its own advantages and disadvantages. One of the weaknesses of concrete is its very low tensile strength and strain as well as brittleness under fexural or compressive loading, which results in sudden failure of the concrete structures during earthquakes. On the other hand, low strength of lightweight aggregates and their fragility lead to poor performance of the lightweight concrete against ductility. Therefore, this study investigated mechanical properties of the lightweight structural concrete containing expanded clay aggregate and different amounts of basalt fbers (0–0.5%). Hence, pozzolanic materials of silica fume and fy ash were used to modify some of the concrete properties in lightweight concrete mixtures as a substitute of part of the cement weight. In total, 21 mix designs were made and their fresh and hardened properties were tested at different ages of 7, 28, and 90 days. Results indicated that the presence of basalt fbers reduced slump and compressive strength by 37% and 13%, respectively. It was also found that all mixtures had a “good” level of water absorption quality and thus were placed in the category of “structural concrete”. Results also indicated that addition of fbers improved tensile, fexural strength, and shrinkage. In order to predict empirical results, an adaptive neuro-fuzzy inference system (ANFIS) was used as a reliable method for evaluating and estimating the results and numerical analysis outputs showed accurate estimation of the empirical results. 1. Introduction The widespread and increasing need of societies for building and housing and consequently the necessity of the use of modern systems to accelerate construction, lightning, and strengthening the buildings against the earthquake has become an inevitable issue. Lightning the concrete structures is one of the important issues in the construction industry and civil projects attracted by engineers and re- searchers. Reduction of the building weight with the lightweight ma- terials saves money, time, and energy, reduces damages caused by natural events such as earthquake, and minimizes damages due to the building overload. Nowadays, lightning the concrete structures using different types of lightweight concrete and applying them to various parts of the structure such as non-bearing members (non-structural members) or beams and columns (bearing members) have decreased the overall weight and size of the structure [1–4]. Lightweight concrete is produced by light aggregates or by light cement matrices [2,5]. The most common method of obtaining lightweight concrete is to use light aggregates, including artifcial aggregates or natural aggregates [4,6]. A plethora of research has been done worldwide on a large number of natural aggregates (e.g., diatomite, pumice, scoria) or artifcial aggre- gates (e.g., shale, slag, perlite, and expanded clay aggregate) as concrete aggregates [7–12]. Fig. 1 depicts specifcations of different types of lightweight concrete in terms of construction and strength. As a building material, concrete has its own advantages and disad- vantages. One of the weaknesses of concrete is its very low tensile strength, strain, and brittleness under fexural or compressive loading, * Corresponding author. E-mail address: ashkan.saradar@gmail.com (A. Saradar). Contents lists available at ScienceDirect Journal of Building Engineering journal homepage: http://www.elsevier.com/locate/jobe https://doi.org/10.1016/j.jobe.2020.101732 Received 5 April 2020; Received in revised form 5 August 2020; Accepted 5 August 2020