Equivalency of Crushed Rock and Three Industrial By-Products Used for Working Platforms During Pavement Construction

Abstract

A study was conducted to define an equivalency criterion for five materials used for working platforms during pavement construction on a poor subgrade: conventional crushed rock (referred to as breaker run) and four alternatives (Grade 2 gravel, foundry slag, bottom ash, and foundry sand). A layer of alternative material was considered equivalent if the total deflection of the alternative material was equal to that of breaker run under the same construction loading. Total deflection data for the equivalency assessment were obtained from a large-scale model experiment (LSME) simulating a prototype-scale pavement structure. Total deflections obtained from the LSME were checked against deflections measured in the field with a rolling wheel deflectometer and with an analytical method developed for unpaved roads. Design charts were developed for selecting the equivalent thickness of alternative working platform materials so that the alternative and a layer of breaker run provided equal deflection.

Deflection of Prototype Geosynthetic-Reinforced Working Platforms over Soft Subgrade

“…Thicknesses required to meet the target maximum deflections are compared in Figure 6 in terms of the thickness ratio (h/h br ), defined as the thickness required to achieve the target deflection for a given type of working platform (h) divided by the thickness required to achieve the same target deflection for a working platform of breaker run stone (h br ). The thickness ratio is greater than 1.0 (1.1-1.2) for all working platforms constructed with Grade 2 gravel without geosynthetic reinforcement because breaker run stone is stiffer than Grade 2 gravel, all other factors being equal (20). By contrast, when reinforcement is added to a working platform constructed with Grade 2 gravel, the thickness ratio is always less than 1.0, with smaller thickness ratios generally corresponding to geosynthetics with lower in situ extensibility.…”

Investigation of alternative ways for recycling waste foundry sand: an extensive review to present benefits

“…However, due to the high costs of such materials, D r a f t searches for alternative materials are on-going. To this end, Tanyu et al (2004) investigated four alternative materials (grade 2 gravel, foundry slag, bottom ash and WFS) to compare their equivalency with crushed rock in terms of cumulative total deflection for a pavement. They indicated thatneglecting other issues such as drainage and weathering -the equivalent thickness of alternative materials obtained when their total deflections were equal to that of conventional crushed rock under the same 1000 cycle load.…”

“…D r a f t Table 5. WFS deflection values of WFS obtained from LSME and equation parameters (Tanyu et al 2004). Table 6.…”

Quantitative Assessment of Environmental and Economic Benefits of Recycled Materials in Highway Construction

“…However, the recycled materials have different engineering properties than the conventional materials, which resulted in differences in the calculated service life. Design parameters for the recycled materials were obtained from recommendations made by Geo Engineering Consulting ( 9), which are based on research findings reported by Li et al (10) and Tanyu et al (11,12).…”