On the Strengthening of Cement Mortar by Natural Fibers

Abstract

The purpose of this work is to evaluate mechanical behavior of sisal fiber reinforced cement mortar. The composite material was produced from a mixture of sand, cement and water. Sisal fibers were added to the mixture in two different lengths. Mechanical characterization of the composite and the plain mortar was carried out using three point bend, compression and impact tests. Specimens containing parallel sided notches of different root radii were loaded in three point bending in order to determine the effect of the fibers on the material fracture toughness in the presence of discontinuities. According to the results, while fiber reinforcement leads to a decrease in compressive strength, J-integral calculations at maximum load for the different notch root radii have indicated, particularly for the case of long fibers, a significant superiority of the reinforced material in comparison with the plain cement mortar, in consistence with the impact test data.

Behavior of fiber reinforced mortar composites under impact load

“…However, some researches show similar results as in this study (e.g. Pereira et al (2015), Puertas et al (2003), Kruszka et al (2015), Chan and Bindiganavile (2010)). Lower compressive strength of the tested fiber reinforced mortars can be explained by their reduced workability and compaction due to greater amount of fibers and small dimensions of specimens.…”

Charpy Impact Test Methods for Cementitious Composites: Review and Commentary

“…A variety of specimen sizes have been employed for Charpy impact testing of cementitious composites, as listed in Table 1. The most common specimen sizes are equivalent or very close to 10 by 10 by 50 mm [35][36][37][38], which is consistent with standardized methods for metals or 25.4 by 25.4 by 50.8 mm with 40 mm span [42][43][44]51,52]. The largest specimens were used by Al-Oraimi and Seibi [39], measured 100 by 100 by 500 mm, and required extensive modification to the Charpy testing apparatus.…”

“…Impact velocities for typical Charpy apparatus are in the range 3 ≤ v ≤ 6 m/s [31]. The low end of this range corresponds with [35][36][37][38] to 100 by 100 by 500 mm [39]. Most included loading spans of 40 mm, but several reported much longer spans [39][40][41].…”

“…Several different normalization procedures led to results being reported in units of energy, energy per unit length, energy per unit area, and others. A number of studies failed to report significant details including loading span [35][36][37][45][46][47][48][49], aggregate size [46,48], and fiber diameter [35][36][37]39]. These inconsistencies-which will be discussed in greater detail in the pages to come-limit the basis for comparison between studies and demonstrate a need for standardization of test methods and reporting procedures for Charpy impact testing of cementitious composites.…”

“…A majority of the studies that have evaluated the Charpy impact energy absorption of cementitious composites have evaluated fiber-reinforced concrete (FRC). This includes concrete reinforced with steel [39,41,50], ceramic [46], glass [39,49], polymer [42,48], and a variety of natural fibers [35][36][37]39] or fiber meshes [45,47,49]. It should be noted that Radomski [50] actually implemented a rotating impact machine but that study is included in the present discussion because the specimen size and type and the fundamental principles of the test are of interest to this discussion.…”