PSI - Issue 30

A.A. Vasilieva et al. / Procedia Structural Integrity 30 (2020) 186–192 Vasilieva A.A. et al. / Structural Integrity Procedia 00 (2020) 000–000

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In this paper, we study the moisture saturation of basalt fiber reinforced rebar with an anhydride curing agent after climate aging in a cold climate. A feature of the studied BFRP rebar is a low porosity and a high degree of the binder curing. 2. Material and Methods 2.1. Material and Experimental tests Specimens of BFRP rebar with diameters of 6 mm and with a height of 5, 10, 30, 50, 70, 100 mm were manufactured (see Fig. 1a). The main stages of manufacturing BFRP rebar: continuous basalt roving (bundled thin basalt fibers with a diameter of 9 ... 13 microns (see Fig. 1b)) impregnated with thermosetting epoxy resin; the impregnated roving is pulled through a heated forming extrusion nozzle with subsequent curing; the resulting rod is wrapped with a bundle of polyamide yarns (see Fig. 1c) to increase the adhesion of rebar with mating materials (concrete, lime, cement mortars, etc.). According to the purpose of the work, some of the BFRP rebar specimens were kept at open (atmospheric) stands for 54 months in Yakutsk (Northern Russia). Some of the specimens from this series were stored in warehouse. After which the specimens were exposed to moisture under conditions simulating a humid tropical climate according to the method Startsev et al. (2002). Namely, the specimens were previously dried in a Binder ED53 oven

Fig. 1. (a) Specimens of BFRP rebar; (b) Microstructure of the BFRP rod; (c) BFRP rebar winding scheme.

(Germany) over silica gel at a temperature of 333±1 K for 14 days prior to its constant weight. After that, moisture uptake of specimens was performed at the same temperature and relative humidity 98±2% in a desiccator above the water surface. At the same time, the specimens mass was periodically measured on an Ohaus analytical balance (USA) sensitive to 0.1 mg, the measurement range was from 0.01 to 210 g, accuracy class I, GOST 9.707-81.

2.2. Fickian moisture diffusion

Consider the simplest moisture transport in an infinite plane-parallel plate with a width l : diffusion occurs in one direction perpendicular to the plane of the absorbing material; molecular diffusion is the only way of absorbing moisture in the material. Then the moisture transport is described by Fick's law of diffusion

2

c x t

( , )

 

(1)

, D c t

0, 0    x l

,



2

t

x

