This paper describes an experimental study of an enhancement of pre-formed foamed concrete, 1300-1900 kg/m3, by utilising two types of additives, silica fume and fly ash, to partially replace Portland cement and fine sand. It focuses on consistency, mechanical and thermal properties as well as presenting a comparison with normal weight, lightweight and foamed concretes from the literature. In addition to conventional foamed concrete mixes (FC), foamed concrete mixes with high flowability and strength (FCa) were also manufactured in this study. The FC mixes had 28-day compressive strengths from 6 to 23 MPa and corresponding thermal conductivities in the dry state from 0.475 to 0.951 W/mK, whereas for the same density range, the FCa mixes gave 19-47 MPa and 0.498-0.962 W/mK, respectively. Compared to other studies on foamed concrete, the results from the mixes investigated in this study showed higher strengths (for a given density), higher tensile to compressive strength ratios and higher moduli of elasticity

Grouted macadam, a material that consists of a porous asphalt skeleton with 25–35% voids, filled with a cementitious grout, has traditionally been used as a specialist surfacing with excellent resistance to both deformation and fuel spillage. However, the actual engineering properties of the material have rarely been investigated in depth and design of pavements incorporating grouted macadam has relied heavily on past experience. The purpose of this study was to assess the consequences of applying analytical pavement design methods to pavements incorporating grouted macadam layers. Two different design methodologies were tested: (1) a conventional approach based on the traditional fatigue criterion used for bituminous materials; and (2) an iterative approach, which took realistic account of the actual damage accumulation within the material. For both methodologies, a comparison was made between a grouted macadam and a conventional bituminous mixture. The main conclusion drawn from this study is that extended fatigue life can be obtained from pavements incorporating grouted macadam although this advantage will be overlooked if design is carried out using the traditional fatigue failure criterion.

Many factors impact on the sustainability of road maintenance, including the organization of road authorities, contract forms used, financing structure and, unfortunately, political interference and corruption. However, this paper reviews the opportunities to increase sustainability by utilizing less environmentally damaging material sources, and also the associated challenges. It is a field that has seen advances in recent decades, for example in the effectiveness of cold-mix asphalt binders. Nevertheless, the opportunities are not being taken up in many countries, and this reflects uncertainty in predicting performance. This paper reviews the different design methods available, developed in both temperate and tropical climates, and highlights the lack of agreement with regard to non-conventional materials. The different sources of uncertainty and risk are then discussed, together with ways of limiting them. It is found that, while advances in performance prediction are highly desirable, the key to encouraging recycling and the use of inexpensive but non-conventional materials lies in development of the right contractual arrangements, specifically partnering and risk/reward sharing. The paper concludes with a discussion on approaches to partnering in the construction industry and the prerequisite climate of trust without which innovation is almost inevitably stifled.

The aggregate in an asphalt mixture is coated with mastic consisting of bitumen (dilute phase) and filler (particulates phase). The interaction of bitumen and filler and packing of filler plays an important role in the properties of mastics. The micromechanics models from composite rheology can be used to predict the stiffening effect of a suspension. In this research, the stiffening effect of fillers was investigated based on the rheology of mastic. The frequency sweep tests in a dynamic shear rheometer at different temperatures were performed within a linear viscoelastic range to construct the master curves. The volume fractions were expressed as compositional volumes of filler in mastic. The particle shape and surface texture are determined through microscopy. We used six micromechanics-based models to predict the stiffening potential of fillers in mastics. The models include Maron–Pierce, Lewis Nielsen, Mooney, Krieger–Dougherty, Chong, Robinson, and Hashin Models. The results show that the same volume content of filler has a different effective volume. The fillers increase the stiffening effect of the composite, especially at high temperatures. The behaviour of fillers with similar effective volume and packing is identical. The filler type affects the stiffening of mastics. Micromechanics modelling results show that most models show an accurate stiffening effect at lower concentrations with the exception of the Chong Model. The Maron–Pierce Model under-estimates the stiffening potential for granite mastic at higher concentrations beyond the 30% filler content fraction. The value of maximum packing fraction (ϕ_m) and Einstien coefficient (K_E) in the Mooney model are significantly different from other models for limestone and granite, respectively. The line of equality graph shows good agreement of measured and predicted stiffness. It is difficult to precisely model the mastic data with any single model due to the presence of complex stiffening effects beyond volume filling.