This paper presents a literature review on the geotechnical behaviour/properties of biosolids and sewage sludge materials, including biodegradation effects, and then focuses on the determination of specific gravity (Gs) for these challenging and difficult geomaterials. For water pycnometry, biodegradation occurring during the course of the test procedure results in apparent higher Gsvalues, leading to erroneous determinations for the solid, liquid and gas phases per unit volume. As demonstrated in the paper, this issue can be addressed by using kerosene or white spirits as the density liquid. Since the pycnometer method is tedious and time consuming, specific gravity is often correlated with total volatile solids (STV), as measured by ignition loss, which is a more straightforward test, having arguably greater reliability. Existing correlations are investigated but found unsuitable for biosolids and sewage sludge materials. Hence, a new Gs–STVrelationship is established specifically for these materials, avoiding the necessity for direct Gsdeterminations in practice. Other issues investigated include the effects of intraparticle voids within the test material and the different specimen oven-drying temperatures of 50 and 105°C specified in different codes. It is concluded that oven drying at 105°C should be consistently used for testing of these materials.

Current permanent ground anchor standards require the use of double-protection systems encapsulating the steel strands, in order to ensure a serviceable design life. In recent years, where steel reinforcement use was restricted due to aggressive ground conditions, carbon-fibre-reinforced polymer (CFRP) reinforcement was successfully used as a durable construction alternative. While CFRP strands have been researched and developed for use in prestressed concrete members such as bridge construction, minimal research has been devoted to developing CFRP strands for use in high-capacity ground anchors. This paper presents research work investigating CFRP strand performance when exposed to extreme aggressive environments. A series of 6-month-long experiments were conducted in an unstressed state, studying the absorption and physical effects as well as the ultimate tensile performance of the CFRPs over a range of accelerated conditions including temperature (30 and 60°C) and aggressive solutions (alkaline, acidic). Based on experimental results, the levels of corrosion protection systems required for CFRP anchor systems are critically assessed. The results highlight the importance of identifying the CFRP strand resin matrix before it can be implemented in a ground anchor system.

This paper presents experimental results on the shear modulus of sand–tyre chip (STCh) mixtures. A series of bender element tests was carried out on specimens of sand mixed with varying proportions of tyre chips (TCh). Tests were carried out on STCh mixtures at a constant initial relative density of 50% for different initial effective confining pressures. The bender element test results indicate that the maximum shear modulus of the STCh mixtures increases with effective confining pressure and decreases with the gravimetric proportion of TCh, which ranged from 23 to 138 kPa and 0 to 40%, respectively. However, the strain-controlled cyclic triaxial test results show that the shear modulus at large shear strains decreases with increasing single-amplitude shear strain as a function of the proportion of TCh in the mixture. The lower the proportion of TCh, the larger the degradation observed. The modified Hardin and Drnevich mathematical formulation adequately captures the variation in shear modulus of the STCh mixtures for a wide range of shear strain amplitudes.

Minimising the maintenance costs of water ingress in transportation tunnels is a significant challenge. Decreasing the overall cost of a ground source heat pump system is equally challenging. An effort to address both issues at once has been made in relation to groundwater ingress in the Glasgow Subway system. Inflowing water is a valuable resource which could be channelled through a water source heat pump (WSHP) to produce heat energy for domestic or public use (heating and domestic hot water). Water flow and water temperature have been recorded for a year at 21 different points within the network of the underground tunnels and platforms. The points of highest water influx were identified, and the heat energy content of each has been calculated. Working from these data, several options were identified for capturing the water and diverting it to a WSHP to recover heat. A final design for a pilot system within the tunnels was developed. The findings of this study are expected to contribute a renewable heat solution through a cost-effective heat pump system design.

The application of landfill containment systems such as cut-off walls could be used effectively as one of the remedial solutions limiting environmental hazards caused by such sites. The complexity and weight of problems concerning remediation works of old sanitary landfills having been considered and interdisciplinary engineering and ecological solutions are recommended. This paper discusses threats to the environment emerging from old landfills and polluted areas and presents examples of engineering solutions used for the remediation of the old, large embankment-type Radiowo landfill located in Warsaw, Poland. The principal remediation problem for the Radiowo landfill was protection systems against leachate migration and groundwater pollution. The research included bentonite vertical barrier quality tests involving both laboratory and on-site hydraulic conductivity tests. Furthermore, a quality assessment based on the groundwater flow and transport modelling and an analysis of monitoring records are presented. The output of the research is the proposal of a dual device employing monitoring and numerical modelling processes for the purpose of controlling the self-purification of soil–water environments after the implementation of containment systems on contaminated sites.

The purposes of this paper are to use the previous authors’ study to investigate the effect of geometrical dimensions on the changes of the failure interfaces and to develop a design procedure for waste placement operations. Four scenarios were selected to conduct analysis so as to find various failure interface changes of the waste depth and also changes of the front and back slopes. The critical liner interface with the minimum factor of safety can vary from one to another with such changes. The curves of FS = 1·0 developed for each case can also be used to evaluate whether the waste mass filled in these landfill cells will possibly fail at a certain waste depth. In addition, a waste-filling sequence was generated so as to maintain FS above a stipulated value during filling operations. It is important to ensure that the minimum FS at the critical interface is always equal to or greater than a targeted value during waste filling, which, in turn, corresponds to different geometric dimensions of the waste.

This paper presents the results of a case study where various methods were used to estimate the frost heave and the thaw settlement of a frozen ground beneath the ice rink facility in Myllypuro, Helsinki. Several undisturbed soil samples were taken from the proximity of the site and characterised for frost susceptibility. Laboratory frost-cell tests were conducted on soil samples from different depths to estimate the possible future frost heave and thaw settlements of the frozen ground. Frost heave and thaw settlement were also calculated from various empirical formulations and compared with the estimations based on the laboratory test results. The thaw settlement estimations from the frost-cell test results was 1·84 m (∼28% of the total frost depth), which was similar to the results from the empirical formulations. The calculated frost depth and frost heave at the end of 30 years were 6·39 m and 622 mm respectively. This was in good agreement with the on-site measurements taken immediately before the renovation, after about 30 years of continuous operation.