Modeling and statistical assessments to evaluate the effects of fly ash and silica fume on the mechanical properties of
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(2020) 5:26
RESEARCH ARTICLE
Modeling and statistical assessments to evaluate the effects of fly ash and silica fume on the mechanical properties of concrete at different strength ranges Serwan Kh. Rafiq1 Received: 14 June 2020 / Accepted: 24 July 2020 © Springer Nature Switzerland AG 2020
Abstract The main objective of this research is to quantify the effect of fly ash content (FA) and silica fume content (SF), water/cement ratio (w/c), and curing time (t) on the compressive strength (CS), flexural strength (FS) and tensile strength (TS) of normal strength concrete (NSC) high strength concrete (HSC) up to 90 days of curing. More than 1000 experimental data were collected from different research studies. Statistical analysis and modeling were performed on the collected data. The w/c ratio for concrete modified with fly ash (up to 90%) and the concrete modified with silica fume (up to 45%) was ranged between 0.19–0.87, 0.25–0.55, and 0.2–0.80, respectively. The compressive, flexural, and tensile strengths ranges for concrete were 10.5–81.9 MPa, 2.6–9.9 MPa, and 0.41–6.1 MPa, for concrete modified with FA were 13.8–79.9 MPa, 2.53–10.4 MPa, and 0.30–6.5 MPa and for concrete modified with SF were 2.9—99.3 MPa, 3.8–11.9 MPa, and 1–6.6 MPa respectively. The compressive strength was correlated very well to the flexural and tensile strength. Based on the coefficient of determination (R2) and root mean square error (RMSE) the compressive strength, flexural strength, and tensile strength of concrete as a function of w/c ratio, FA content, SF content and curing time quantified very well using nonlinear (NLM) relationship. Based on the NLM parameters, the effect of FA and SF were less than w/c ratio and curing time on the mechanical strength of modified concrete in different strength ranges. Keywords Water/cement ratio · Fly ash · Silica fume · Mechanical properties · Statistical analysis · Modelling
1 Introduction Concrete is a commonly used construction material for different types of structures due to its strength and structural stability [1]. Based on the compressive strength, the concrete can be divided into two major parts NSC and HSC (ACI363-2R-11). HSC is defined as a concrete that having an identified compressive strength of 55 MPa and less than 55 MPa of compressive strength the concrete will be classified as an NSC [2–4]. Several cementitious materials were used to enhance the mechanical properties of concrete, such as metakaolin, fly ash, ground granulated blast furnace slag, silica fume, and natural pozzolan [5, 6]. Fly ash and silica * Serwan Kh. Rafiq [email protected] 1
College of Engineering, Department of Civil Engineering, University of Sulaimani, Sulaymaniyah, Kurdistan Region, Iraq
fume were considered as the most popular two cementitious materials which were used to improve the properties of concrete. Using fly ash and silica fume as a partial replacement is not only energy-saving and environmental desired, but also enhance the mechanical properties and durability of concrete [7]. Man
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