Use of Semicircular Bending Test and Cohesive Zone Modeling to Evaluate Fracture Resistance of Stabilized Soils

Abstract

The fracture resistance of a chemically stabilized base or subbase layer is important to the durability and sustainability of a pavement structure. Thus, an appropriate test protocol to characterize the fracture resistance of stabilized bases, subbases, and subgrade soils is essential to the design of pavement materials and structures. This paper proposes a protocol developed on the basis of the semicircular bending test to measure fracture resistance (i.e., fracture energy and fracture toughness) of chemically stabilized material. The effects of three test variables, including specimen thickness, notch length, and loading rate, on fracture properties were investigated, and appropriate values for these test variables were selected for the semicircular bending test protocol. The proposed semicircular bending test method was successful in characterizing the fracture resistance of three chemically stabilized materials. To address fracture properties of the chemically stabilized material more definitively, three-dimensional zone modeling was used and the simulations agreed very well with the experimental results. Both the fracture properties obtained from the experiment and the cohesive zone modeling indicated that polymer-stabilized limestone exhibited a much higher fracture resistance than cement-stabilized limestone and cement-stabilized sand. However, the polymer used demonstrated susceptibility to degradation in the presence of water. Correction of this limitation is the focus of ongoing research on this type of polymer.

Dynamics of Water Intrusion in Polyelectrolyte-Bound Kaolinite: An Insight into Durability Mechanisms via Atomistic Modeling

“…However, a major disadvantage is that these materials are brittle . Significant advantages of polymer-soil composites include mitigation of the erodibility of loose soil particles, , improved compressive strength, fracture toughness, and resistance to fatigue as opposed to the brittle nature of cementitious composites. ,, Furthermore, all these characteristics of polymers develop at low dosages (2 wt %) versus 4 wt % and above, which are typical dosages for traditional stabilizers. However, many polymer species that have been attempted as stabilizers in soils are water-soluble.…”

“…The most significant advantage of traditional stabilizing compounds is the long-term hardening achieved through the formation of hydration products that develop an increasing strength over time within the composite interstices and a level of resistance to environmental factors such as exposure to water due to the dense nature of the stabilized material product. However, a major disadvantage is that these materials are brittle . Significant advantages of polymer-soil composites include mitigation of the erodibility of loose soil particles, , improved compressive strength, fracture toughness, and resistance to fatigue as opposed to the brittle nature of cementitious composites. ,, Furthermore, all these characteristics of polymers develop at low dosages (2 wt %) versus 4 wt % and above, which are typical dosages for traditional stabilizers.…”

“…The advantages are, first, the ease of mixing because water acts as the “carrier” of the polymer chains while simultaneously enhancing the packing ability of soil mineral particles. Second, the curing mechanism for polymer-stabilized composites is simple; it only involves the drying of the interstitial water “breaking away” for the functional groups present in the polymer chains to bind directly to the soil mineral surfaces exposed. ,, Third, the curing time required for polymer-soil composites is not dependent on the kinetics of reactions between stabilizer and native soil minerals, as is needed for most cementitious/pozzolanic stabilizers. Last, because of the commonly nonreactive binding nature (adhesive binding) of many polymer species used, polymers may be less restricted by the availability of soil minerals as raw reactants dictated by the geochemistry of the environment.…”

Experimental investigation of fiber content and length on curing time‐dependent mode‐I fracture behavior and properties of cemented paste backfill and implication to engineering design

“…19,20 Owing to the difficulty in cutting/halving rocks, some scholars manage to use full circular specimens for measuring the fracture toughness of rock. [21][22][23] Compared with other testing methods, SCB tests have several advantages, including simple test procedures and experimental setup, more efficient usage of testing materials, and excellent repeatability, 24 and thus have been widely employed in a routine mix design and quality screening. It should be noted that the compressive stress may develop inside SCB samples and thus complexify the stress field, 25 which inevitably affects the determination of pure mode fracture toughness.…”

Integrity and crack resistance of hybrid polypropylene fiber reinforced cemented soil

“…Qualitative analysis primarily uses various models to simulate soil cracking and calculates parameters such as cracking moisture content, crack initiation time, secondary crack initiation time, crack network curvature, and surface crack spacing. 1–9 Quantitative analysis uses image processing technology to measure crack size (length, width, and depth), 10–13 crack intensity factor, 14–16 surface cracking rate, 17 and crack tip opening angle, 15 which are used to analyze to geometric morphology of soil cracks.…”