PSI - Issue 64

Abbas S.A. Al-Hedad et al. / Procedia Structural Integrity 64 (2024) 1386–1393 Abbas S. A. Al-Hedad and Muhammad N. S. Hadi / Structural Integrity Procedia 00 (2019) 000 – 000

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Fig. 1. Triaxial geogrid.

2.2. Test Matrix

Two groups of concrete beam specimens, called specimens hereafter, with 150 mm × 150 mm cross-section and 550 mm length were tested. For the geogrid reinforced specimens, the geogrid reinforcement was placed at a depth of 55 mm from the bottom of the specimens. Table 2 lists details of the specimens adopted in this study. The first group of specimens included six specimens (Group ST). Two specimens of Group ST were unreinforced (Specimens US) and taken as control specimens. The second two specimens of Group ST were reinforced with one layer of geogrid (Specimens GS) placed at a depth of 55 mm from the bottom of the specimens. The last two specimens of Group ST were reinforced with two layers of geogrid (Specimens 2GS) which were coincidingly placed. The specimens of Group ST were tested under static four-point bending loads at a loading rate of 1 MPa/min until failure (Australian Standard 1012.11, 2014). The second group of specimens (Group CY) consisted of nine specimens, as listed in Table 2. Three specimens of Group CY were unreinforced and undertaken as control specimens (Specimens UC). The second three specimens of Group CY were reinforced with one layer of geogrid (Specimens GC). The last three specimens of Group CY were reinforced with two layers of geogrid (Specimens 2GC). The specimens of Group CY were tested under cyclic four-point bending loads at a frequency of 7 H z . At the middle of the span of the specimens, a notch with a width of 3 mm and a length of 40 mm was made. The notch was made in the middle of the span of the specimens to localize the propagation of cracks during the testing. The localization of the propagation of crack facilitated monitoring and evaluating the effect of geogrid reinforcement on the flexural behavior of the specimens.

Table 2. Test matrix.

Label of specimens

Size of specimen (mm)

Details of Group

Remarks

Label of group

Number of specimens

2 2 2 3 3 3

Specimens US Specimens GS Specimens 2GS Specimens UC Specimens GC Specimens 2GC

Unreinforced concrete specimens Reinforced with one layer of geogrid Reinforced with two layers of geogrid Unreinforced concrete specimens Reinforced with one layer of geogrid Reinforced with two layers of geogrid

Tested under static loads

Group ST

150×150×550

Tested under cyclic loads

Group CY

Normal strength concrete supplied by Syntron Packer (2017) was used in casting the specimens of Groups ST and CY. Ordinary Portland cement at 196 kg/m 3 , coarse aggregate at 801 kg/m 3 with a maximum size of 10.0 mm, coarse and fine sand at 801 kg/m 3 and 1065 kg/m 3 , respectively; were used. Supplementary cementitious materials included fly ash and ground granulated blast furnace slag at 78 kg/m 3 and 118 kg/m 3 , respectively; were added to the ingredients of concrete. Liquid admixtures included water reducer at 1175 ml/m 3 , range water reducer at 391 ml/m 3 ,