The critical element for sustainable growth in the construction industry is the development of alternative cements. A new technological process called geopolymerization provides an innovative solution, and the presence of aluminum and silicon oxides in fly ash has encouraged its use as a source material. Many previous investigations have involved curing the binder in a heated environment. To reduce energy consumption during the synthesis of geopolymers, the present study investigated the properties of ambient cured geopolymer mortar at early ages. An experimental program was executed to establish a relationship between the activator composition and the properties of geopolymer mortar in fresh and hardened states. Concentrations of sodium hydroxide and sodium silicate were ascertained that are advantageous for constructability and mechanical behavior. Scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffraction techniques were also used to characterize the material. Test results indicate that there is potential for the concrete industry to use fly ash based geopolymer as an alternative to portland cement.

Geosynthetics is a crucial mechanism in which the earth structures can be mechanically stabilized through strength enforcing tensile reinforcement. Moreover, geosynthetic reinforcement stabilizes steep slopes through incorporating the polymeric materials, becoming one of the most cost-effective methods in not only accommodating budgetary restrictions but also alleviating space constraints. In order to explicate on the applicability and widen the understanding of geosynthetic reinforcement technology, a synthesis study was conducted on geosynthetic reinforced steep slope. This study is very important because in not only highlighting the advantages and limitations of using geosynthetic reinforcement but also in investigating the current construction and design methods with a view to determining which best practices can be employed. Furthermore, this study also identified and assessed the optimal condition of the soil, performance measures, construction specifications, design criteria, and geometry of the slope. To further concretize the understanding of these parameters or factors, two case studies were reviewed and a summary of the best practices, existing methods, and recommendations were drawn in order to inform the employment of geosynthetics in reinforcing steep slopes.

This study investigates shear transfer across a definite plane, which must be considered in the formation of the crack opening path as discussed in the companion paper, Part I. Experimental investigation of the shear friction coefficient for a wide density range of 1200-2259 kg/m 3 for normal and lightweight concrete is presented for determination of parameters for the analytical model discussed in Part I, which explains the behaviour of confined concrete. The specimen variables include concrete strength, unit weight, volume percentage of air in the matrix (A/M), and volume percentage of matrix in the concrete (M/T). Test results show that the friction coefficient is dependent on concrete strength. However, shear strength is weakly dependent on the volume percentage of matrix in the concrete and strongly dependent on the volume of air in the matrix.

Part I of this paper presents experimental results for confined concrete in the form of stress–strain relationships. It seeks to determine the behaviour of confined concrete incorporating variable crack angle and void strain to verify the model. Part II presents the investigation of shear transfer across a definite plane which must be considered in the formation of the crack opening path. This paper develops a constitutive model for confined concrete with variable crack angle that is able to show improved correlation with the experimental data. In the case of fibre confined concrete, comparisons of experimental results of specimens with two different concrete strengths are made to determine the effects of selected variables including fibre volume fraction. While existing material models do not adequately represent the behaviour of concrete air voids confined by composite wraps, a new material model is proposed here, which attempts to overcome the shortcomings in the existing material models. An existing stress–strain model for confined concrete was modified to incorporate a variable angle of internal slope, where the angle minimises the normal stress on the slip surface. An additional modification was the introduction of strains due to collapse of internal voids.