Effects of Fly Ash, Silica Fume, and Ground-Granulated Blast Slag on Properties of Self-Compacting High Strength Lightweight Concrete

Sherif Yehia, Sharef Farrag, Kareem Helal, Shahinaz El-Kalie


In this paper, the effect of utilizing Fly ash (FA), Silica fume (SF), Ground granulated blast slag (GGBS), and various combinations of them is assessed. Their effect on the fresh stage and mechanical properties of Self-compacting Lightweight Concrete (SCCLWC) is investigated and compared to a control mix without Supplementary Cementitious Materials (SCMs). Flowability, compressive strength, and flexural strength were the main criteria considered in the evaluation. Moreover, the applicability of the ACI 318 reduction factor (λ) for flexural strength was assessed for all mixes to capture the effect of various SCMs based on the lower and upper limits of the proposed ACI 318 equation. Results from the evaluation show that SF greatly improved the compressive strength and GGBS increased flexural strength of SCCLWC. However, SF reduces the flowability of SCCLWC. Equally important, FA achieved the lowest increase in compressive strength compared to the control mix. Furthermore, the λ value of 0.85 proposed by ACI 318 for sand-lightweight provides a good estimate of LWC properties even when different SCMs are utilized. However, fly ash can affect the λ value at early age.


Lightweight aggregate, Lightweight concrete, Supplementary cementitious materials, Mechanical properties, SCCLWC

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