Plain concrete is susceptible to cracking under aggressive environment such as in freezing shaft. And addition of steel fibres in plain high strength concrete is proved to be effective in cracking resistance and brittleness improvement, etc. This paper presents results of experimental investigation carried out to study the mechanical properties of steel fibre-reinforced concrete having volume fractions of 0.38%, 0.51% and 0.64% for two types of fibres respectively. The results of this study revealed that there is an increase for all the mechanical properties such as compressive strength, split tensile strength, modulus of elasticity and flexural strength. Enhancement for split tensile strength and flexural strength is more evident than compressive strength.

Five sewage sludge specimens with different organic contents were prepared by mixing mass ratio 0%, 5%, 10%, 20% and 40% of dry soil powder into raw sewage sludge. The addition of dry soil powder can reduce the organic content of sewage sludge without significantly changing its particle composition. Oedometer tests were conducted, starting from a small effective vertical stress σ v′ = 3 kPa. It is observed that the e-logσ v′ compression curves show an inverse ‘S’ shape due to suction pressure resisting deformation. The suction pressure decreases exponentially with the organic content, a regressed equation for which has been provided. Burland’s concept of intrinsic compression line (ICL) is adopted for correlating the compression curves of sludgewith various organic contents. It is found that the ICL with high organic content lies above the low one, that is, the higher the organic content, the greater the void index. In addition, the shape of the ICL for organic sludges is an inverse ‘S’ rather than slightly concave upwards for inorganic reconstituted clays. An average ICL is provided to normalize the compression curves of sludges with different organic contents. The intrinsic compression parameters e * 100 and C c * can be correlated with the organic content, which increase linearly with the organic content, and the regressed equations for them were provided.

To investigate effects of initial water content on compression behaviour of municipal sewage sludge and clarify its intrinsic compression characteristics. Oedometer tests were performed on sludge with various initial water contents of 0.13-1.48 times the liquid limit. It is observed that the sludge is organic high liquid limit silt, whose e-logσv‘ compression curves are inverse "S" shape due to organic floc structure of sludge potentially. When the effective vertical stress σv‘ > 100 kPa, a clear gap of compression curves of various initial water contents still exists, different from the viewpoint of Burland (1990) that compression curves tend to be consistent. Burland's concept of intrinsic compression line is adopted for correlating compression curves of sludge well, and an intrinsic compression line of the sludge is derived. The intrinsic compression line of sludge is below that of Hong (2010) and Burland (1990) when σv‘ < 100 kPa, due to the difference in initial water contents. A generalized void index is tentatively proposed by introducing generalized intrinsic parameters e*y1 and e*y2, which may be related to the loading history of the soil and the maximum load that the soil may bear in future engineering respectively.