Issue 78

M. Adel et.al, Frattura ed Integrità Strutturale, 78 (2026) 168-185; DOI: 10.3221/IGF-ESIS.78.10

range. The methodology for facilitating matrix crack formation in the reinforced concrete beam specimens is depicted in Figs. 2(C) and 2(D).

(A)

(B)

(C)

(D)

Figure 2: Matrix crack preparation.

Mixing, casting, and curing The process of mixing concrete is determined by the standard procedures stated in reference [3]. The materials are prepared locally and mixed in a controlled manner to ensure mixture uniformity. Concretes are designed to achieve the desired compressive strength by adding 1.0 percent steel fibers by volume and 5.0% silica fume as a partial replacement for cement. Ordinary Portland Cement (Type I, Grade 52.5N) is mixed with fine aggregate (silicious sand), coarse aggregate (dolomite maximum grading 12.5mm), and silica fume. In addition, superplasticizer (Sicament-R2004) was added to the concrete mixture at 2% of the weight of cement to increase workability and accommodate the addition of steel fibers. All the specimens were cast in lightly oiled molds in order to facilitate demolding. Workability properties of the concrete specimens were tested by a slump test, as shown in Fig. 3, and the results show a reduction in flowability with the incorporation of fibers, with the slump of the normal concrete (NC) being approximately 120 mm and that of the fiber-reinforced concrete (FRC) being 80 mm. The samples were demolded after 24 hours of pouring and then cured for 56 days at 23 °C and 100% RH under controlled conditions to ensure complete hydration and strength development. The long curing period was required to achieve the desired compressive strengths, as confirmed by testing at 56 days in accordance with the specifications of ESS 1658-6/2018 and BS EN 12390/2009. Test procedure Material characterization was conducted to assess the quality of the constituent materials and the properties of the concrete. The normal concrete (NC) samples exhibited a compressive strength of 51.55 MPa, while the fiber-reinforced concrete (FRC) samples achieved a compressive strength of 54.89 MPa. During specimen fabrication, three concrete samples were prepared and cured under the same conditions as the beam specimens. After a curing period of 56 days, the samples were tested for compressive strength, following the ESS standard 1658-6/2018 [16] (refer to Fig. 4). Three cylindrical concrete specimens, each with a diameter of 150 mm and a height of 300 mm, were produced and tested (see Fig. 5). Indirect tests indicated a tensile strength of 4.7 MPa for the normal concrete and 5.1 MPa for the fiber-reinforced concrete following the

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