Abstract
One of the main challenges facing Civil Engineering community is to modify cement quantity in the mix design by admixtures to enhance the mechanical properties. According to more than 1000 data from literature, mechanical characteristics of concrete modified with FA were discussed. The statistical variation with modeling were achieved by set of data. The cement was replaced up to 70% with FA (weight of dry cement) and by cube of concrete testing up to 90 days of curing time and different w/c ratio. The compressive strength of concrete varied from 18-67 MPa, while, for modified concrete with FA, compressive strength ranged from 21-94 MPa, tensile strength ranged from 1-9 MPa and flexural strengths ranged from 3 - 10 MPa. The w/c ratio of concrete modified with FA varied from 0.24-0.53, also the FA content varied from 0-50 %. Vipulanandan correlation model was effective by connecting mechanical properties and compare with Hoek-Brown model. The nonlinear model was used to investigate the effect of FA on properties of normal and high strength concrete. Study results presented a worthy correlation between compressive strength and curing time, w/c ratio and FA content. By using the interactive linked (model) for compressive, tensile, and flexural strengths of concrete quantified well as a function of w/c ratio, curing time and FA content by using a nonlinear relationship.
Highlights
Concrete is defined as a mixture of Portland cement (OPC), fine and coarse aggregate, water and admixture that is used as a material for construction [1]
Concrete without fly ash (FA) According to the data from literature of w/c ratio of 96 for normal and high strength concrete (Table 1), for concrete the w/c ratio ranged of 0.25 - 0.5, mean of 0.35, standard deviation (SD) of 0.035 and coefficient of variation (COV) of 15.2 % which illustrated at Table 3 and Figure 1(a)
Concrete modified with fly ash (FA) According to the data from literature of w/c ratio of 329 for normal and high strength concrete modified with FA (Table 1), for the concrete modified with FA the w/c ratio ranged of 0.24 –0.53, mean 0.34, SD of 0.07 and COV of 19% which illustrated at Table 3 and Figure 1(b)
Summary
Concrete is defined as a mixture of Portland cement (OPC), fine and coarse aggregate, water and admixture that is used as a material for construction [1]. Several experimental researches have shown that the different percent of FA is active to enhancing concrete properties, which decrease the cement content to reduce the costs, enhances the performance, mechanical properties, and durability of normal (NSC) and high strength concrete (HSC) in the hardened state [3 -5]. Based on the literature data the influence of w/c ratio, percent of FA (%FA) and curing time (t) on mechanical properties of NSC and HSC modified with FA were calculated by Nonlinear modeling. (ii) To evaluate and analyze the relations of compressive strength with both tensile strength and flexural strength for normal (NSC) and high strength concrete (HSC) modified with FA. (iii) To establish correlation for the effect of water to cement ratio (w/c), percent of FA (%FA) and curing time (t) on most of mechanical properties of normal NSC and HSC Objectives: objectives were as below: (i) Implement a statistical analysis for w/c ratio, percent of FA and mechanical properties of NSC and HSC modified with FA. (ii) To evaluate and analyze the relations of compressive strength with both tensile strength and flexural strength for normal (NSC) and high strength concrete (HSC) modified with FA. (iii) To establish correlation for the effect of water to cement ratio (w/c), percent of FA (%FA) and curing time (t) on most of mechanical properties of normal NSC and HSC
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