Measurement of Bulk Mechanical Properties and Modeling the Load-Response of Rootzone Sands. Part 1: Round and Angular Monosize and Binary Mixtures

Abstract

The bulk mechanical properties of two different types of rootzone sands (round and angular) were measured using a cubical triaxial tester. T wo monosize sands (d 50 = 0:375 mm and 0.675 mm) and their 50:50 binary mixtures (d 50 = 0:500 mm) were studied. T he compression, shear, and failure responses of the above-mentioned six compositions were analyzed, compared, and modeled. T wo elastic parameters (bulk and shear moduli) and two elastoplastic parameters (swelling and consolidation indices) of the six sand compositions were also calculated and compared. T he angular sand was more compressible than round sand during isotropic compression. In addition, the angular sands tended to have lower initial bulk density and high porosity values. Among the three different size fractions, the 0.375 mm mixture was least compressible for both sand shapes. T he failure strength and shear modulus of the angular sand were higher than the round sands. In addition, due to their simplicity, phenomenologica l models were developed to predict the compression and shear behavior of the sands. T he prediction models were validated using subangular and subround sands. Average relative difference values were calculated to determine the effectiveness of the prediction models. T he mean average relative difference values for compression pro® les, i.e., volumetric stress vs. volumetric strain, were from 16% to 39%, except for the initial load-response portion ( < 1% volumetric strain). T he predictive models were effective in reproducing the 145 failure responses: at 17.2 kPa con® ning pressure, the mean of average relative difference was 23%; at 34.5 kPa, the mean difference was 24%.

Critical Review on Engineering Mechanical Quality of Green Compacts using Powder Properties

“…Effect of particle size on compact strength has been well documented (Khan and Pilpel, 1986;McKenna and McCafferty, 1982). In addition, effect of particle shape on a powder system has been investigated in detail, as well (de Bono and McDowell, 2016;Mittal et al, 2001;Yi et al, 2002;Yi et al, 2001). However, study on the relationship between particle shape and compact's properties is scarce, which is thought to be because of the difficulty in quantification of particle shape.…”

Percolation Segregation Model for Similar and Differing Constituents

“…Additionally, Yi et al (2001) stated that (1) irregularly shaped particles can readily lodge in the interstitial void spaces, and (2) void spaces formed from irregularly shaped coarse particles are larger than those for spherically shaped particles.…”

Correlating Particle Shape Parameters to Bulk Properties and Load Stress at Two Water Contents

“…Particle shape has substantial influence on golf course putting green and athletic field root‐zone performance. Research with mono‐sized and mixed‐sized samples has indicated that sands with increasing angularity exhibit lower bulk densities and higher total porosities (Zhang and Baker, 1999; Yi et al, 2001; Puri and Mancino, 2002). Variance in particle shape complexity has also been reported to yield differences in the hydraulic conductivity of sand root‐zone mixes, with more angular and spherical material exhibiting higher permeability than less angular and less spherical material (Zhang and Baker, 1999).…”

“…The influence of particle shape on bulk modulus values has also been shown in mixed‐sized samples. Round, binary sand mixes have a greater resistance to compaction than angular, binary mixes (Yi et al, 2001). The mixes of round particles are able to fill more of the voids than the angular mixes, which results in less volume change under load (Yi et al, 2001).…”

“…In addition to influencing the compressibility of root zones, particle shape also affects root‐zone failure strength and shear modulus (i.e., the resistance to shear distortion or deformation). More angular sand particle shapes give higher shear modulus values and failure strengths than rounded particles (Yi et al, 2001). The increase in root‐zone stability of more complex particle shapes is at least in part provided by improved particle interlocking, indicating that rounded and more spherical particles have less interparticle friction than irregularly shaped sand grains (Yi et al, 2001).…”