Fly ash and bottom ash are coal combustion by-products (CCBPs) that are generated in large quantities throughout the world. It is often economical to dispose ash as mixtures rather than separately; that notwithstanding, only a few studies have been performed to investigate the behavior of fly and bottom ash mixtures, particularly those with high contents of fly ash. Also, there is very limited data available in the literature on the field performance of structures constructed using ash mixtures. This paper describes the construction and the instrumentation of a demonstration embankment built with an ash mixture (60:40 by weight of fly ash:bottom ash) on State Road 641, Terre Haute, Ind. Monitoring of the demonstration embankment was conducted for a period of 1 year from the start of construction of the embankment. The settlement of the embankment stabilized approximately 5 months after the end of its construction. According to horizontal inclinometer readings, the differential settlement at the top of the...

Mixtures of shredded tyres with sand have become accepted geo-materials in the past decade, especially for use as fill materials. Owing to the large size of tyre shreds commonly used in practice, large-scale direct shear testing equipment is specially fabricated to obtain the shear strength parameters of mixtures. The effect of tyre shred-to-sand mixing ratio on the mechanical response of the mixtures is studied by performing direct shear tests on mixtures prepared at different mixing ratios. Out of the four types of samples tested, three (with mixing ratios of 20/80, 25/75 and 35/65 by weight of tyre shreds to sand) are prepared using 50 to 100 mm long tyre shreds and one (25/75 by weight of tyre chips to sand) using tyre chips with nominal size of 9·5 mm. The end-of-test friction angle of all the tyre shred–sand mixtures considered in this research is in the 30–33° range. Results of direct shear testing from the present study and other studies in the literature show that the shear strength of tyre shred–sand mixtures is greater than that of tyre chip–sand mixtures because the elongated tyre shred pieces are able to provide greater reinforcement effects than are possible with equidimensional (cubical) tyre chips.

The in situ density of compacted layers obtained from sand-cone test is commonly used to assess the quality of compaction of pavement layers. This test is tedious, time consuming, and sometimes not feasible to perform in accordance with specifications. In this study, a lightweight deflectometer (LWD) is used to measure the modulus of deformation, ELWD, of pavement layers and to perform the quality control (QC) of pavement layers. An extensive LWD field testing program was undertaken on 95 test locations of an expressway along the outer ring road located in Hyderabad, India, and the ELWD values of the compacted base and surface layers were commonly found to range from 45 to 60 MPa and 105 to 120 MPa, respectively. The coefficient of variation of the ELWD of base and surface layers was found to range from 4 to 12%. Finite-element analysis was also carried out to study the effect of bottom pavement layers on measured ELWD values from LWD testing. The results showed that the top stiff layer absorbs a ...