Zr-rich basalt continuous fibers with increased alkali resistant properties

• Zr-rich basalt continuous fiber with record values of alkali resistance were obtained. • By adding lanthanum oxide to t the production temperature range increases. • The tensile strength of Zr-rich basalt continuous fibers increases by 15–20%. Zirconium-rich basalt continuous fibers with zirconium oxide content from 5.1 to 8.1 wt% with the addition of 1% lanthanum oxide were obtained in a laboratory facility. The production temperature range were measured. It was shown that lanthanum oxide addition allows to decrease production temperature by 50° and to make wider the production temperature range by 10°. Weight loss and tensile strength loss of fibers after refluxing in alkali solution were determined. The weight loss after boiling in 1 M NaOH and 0.5 M Na2CO3 solution is comparable to the weight loss of zirconium-rich glass fibers (AR glass). The addition of lanthanum oxide leads to an increase in the tensile strength of Zr-rich basalt continuous fibers by 15–20%. Based on the obtained data, it can be concluded that the presented approach will not only improve the alkali resistance of basalt continuous fibers for reinforcing cements and concretes, but also significantly reduce their cost.