Bond strength between fibers and concrete is a key factor influencing the physical, mechanical, and performance char-acteristics of fiber-reinforced concrete. This paper analyzes existing methods for determining the pullout strength of fibers within a concrete matrix. Special emphasis is placed on identifying and improving test methods for glass composite fiber, which, in terms of its physical and mechanical properties and pullout strength with the concrete matrix, is not inferior to steel fiber. However, it has lower surface hardness and reduced compressive strength across the glass fibers embedded in the composite. Therefore, testing methods for evaluating the bond of glass composite fiber must account for the structural features of the fiber. Moreover, obtaining reliable results with high accuracy is essential for a more detailed study of the interaction between glass composite fiber and concrete. Experimental data confirms that, for glass composite fiber, the ac-curacy of test results depends significantly on the shape of the test specimen. The refinement of the methodology for deter-mining the bond strength of glass composite fiber to concrete is justified by the increase in accuracy from 6–16% to 4–8%, depending on the fiber type, as well as by a twofold improvement in the reproducibility of results. The result of this refine-ment is a specimen configuration consisting of two halves of a concrete and polymer concrete figure-eight specimen, re-spectively, with an integrated displacement sensor