Effect of Basalt Fiber Content and Length on the Strength and Crack Development of Polyvinyl Alcohol/Basalt Hybrid Fiber-Reinforced Cement Soil

Abstract

Polyvinyl alcohol (PVA) fiber is widely used in geotechnical engineering because of its excellent physical and mechanical properties; however, PVA fibers are prone to aging, while basalt fiber has a natural anti-aging ability, which can be added to cement material to effectively eliminate the effects of aging on PVA fiber. Previous experiments identified that the optimum content of PVA fiber is 0.5% (mass fraction, the same below). Based on this, we continued to add basalt fibers of different lengths (3 mm, 6 mm, 9 mm, 12 mm, 18 mm, 30 mm) and different contents (0%, 0.25%, 0.5%, 0.75%, 1%) to study the effect of both length and content of basalt fibers on the strength of cement soil specimens. It was concluded that adding 0.5 % of 9mm basalt fiber results in the greatest increase in unconfined compressive strength (UCS). The UCS reached 12.59 MPa, which was 71% higher than specimens without fiber, and a regression analysis was carried out to obtain the relationship among them. The ratio of cement soil in the highest UCS and the relationship among the UCS, the length, and the content of basalt fiber can be used as a reference for practical projects. In addition, digital image correlation (DIC) technology was used to analyze the surface cracks and horizontal strain field when the peak strain was reached at each content and length of the basalt fiber. Finally, the curing mechanism for hybrid fiber cement soil was analyzed by combining the results of the UCS test, DIC test, and SEM test.

Properties of Concrete Reinforced with a Basalt Fiber Microwave-Absorbing Shielding Layer

“…The compressive strength of the MAB specimen decreased by 2.59 MPa, or about 5.5%, after experiencing microwave freeze-thaw cycles. Afroz and Shu et al [30,31] discovered that basalt fibers exhibit good compatibility with cement. When added to concrete, these fibers can significantly enhance strength and elastic modulus while also increasing toughness and improving durability.…”

The Effect of Different Fiber Reinforcement on Bearing Capacity under Strip Foundation on the Sand Soil: An Experimental Investigation

“…With sufficient content and length, two or more fibers form a good spatial network structure in the soil [30,34]. Due to the differences in fiber diameters, large-diameter fiber forms a large-scale spatial skeleton structure, while small-diameter fiber created a smaller scale spatial structure, and the combination of the two gave better results in soil reinforcement [37,54].…”

“…As a result of the studies, it has been seen that hybrid fibers can improve the toughness, ductility, energy dissipation capacity, and durability performance of concrete [30,34]. When the existing studies on improvement with fiber additives are evaluated, the effects on the soil are examined as a result of the addition of one or more fibers to the soil separately under various varying conditions [35][36][37]. However, studies on the effect of using two or more fibers together in a hybrid form on soil are very insufficient.…”