This paper focuses on seismic evaluation of retrofitted curved RC bridge in two phases. In first phase, seismic performance of piers was evaluated by equivalent static method using two performance objectives and by nonlinear dynamic method using a suit of compatible ground motion records. In this regard, demand capacity ratio and residual displacement were evaluated in static method and base shear and deck displacement were evaluated in dynamic method. High damping rubber bearings were used for isolation retrofitting purpose, replacing the elastomeric bearing of the as-built bridge. In second phase, damage state corresponding to large displacements in the bridge components was assessed in terms of component and system fragility curves. The numerical results show that the isolation-retrofitted bridge experiences less base shear force associated with increased deck displacement compared with the as-built bridge having no collapse damage state for considered hazard levels.

High purity lithium hydroxide and lithium carbonate for use in lithium-ion batteries are produced by the processing of spodumene ore from the Whabouchi mine (Northern Quebec, Canada). The main byproduct of this treatment is an aluminum silicate waste stream, which is produced in very large quantities and should be recycled to avoid its storage in landfills, which is not environmentally friendly. Previous research work by the authors on the characterization of this aluminum silicate waste stream showed its potential as a pozzolanic material and hence that it could be used by the cement and concrete industry, which would contribute to the sustainability of these industries. The purpose of this study was to assess the pozzolanic activity of this new material and its effects on the properties of concrete in its fresh and hardened states in order to evaluate the effects of replacing part of the cement with this aluminum silicate waste stream in various classes of concrete. Series of air-entrained and non-air entrained concrete mixtures were produced and tested in this study. Results from fresh state testing, mechanical and durability properties of the concrete made with this material were similar to those obtained with conventional supplementary cementitious materials and equal or superior to those obtained with reference concrete mixtures made with plain and ordinary portland cement.

Pavement subgrade is an in-situ material upon which the pavement structure is constructed. A soil with a high plasticity index will experience high shrinkage and swell depending upon its moisture content with detrimental impacts on its supported pavement structure. Removing and replacing the weak soil with better-quality soil is an alternative to stabilization of poor subgrade soil and may be a very expensive solution, typically for large road networks. Secondly, stabilization of weak soil -subgrade using conventional cement may not be sustainable due to its high CO₂ footprint. The feasibility of this non-conventional method using blended geopolymer binder for stabilization of weak subgrade soil was investigated compared to the conventional cement stabilization method. Laboratory testing of design mixes included unconfined compression test, maximum dry density, CBR and shrink & swell testing determining its feasibility and optimum extent. This research paper will present the findings on the effectiveness of blended geopolymer (fly ash and slag) as an alternative to conventional cement-based soil stabilizers for weak subgrade and its sustainability potential.

Fireproofing deterioration is widespread in industrial facilities throughout the country. Spalling concrete has potential to damage equipment and harm personnel. Replacing concrete fireproofing like-in-kind, without consideration for proper anchorage or material durability, does not eliminate the hazard as spalls may potentially occur again over time. However, when properly designed and installed, concrete is a durable option for replacing deficient fireproofing in aggressive environments typically present in industrial processing units. This paper presents the results of a case study on a structure in a Midwest industrial complex. Extensive concrete fireproofing repairs were performed on the structure 12 years ago. Design requirements included normal weight concrete with polypropylene fibers which enhance durability by improving cracking resistance. During a fire, the fibers melt forming relief channels for moisture to escape, thus eliminating explosive spalling. Installation methods included welded wire reinforcement (WWR) with positive anchorage to structural steel. WWR was attached to post-installed adhesive anchors between column flanges where existing fireproofing was sound and difficult to remove. After 12 years in service, repairs exhibit no significant defects. This level of durability is attributed to the design and installation methods utilized. Concrete fireproofing is a durable option for fire protection, provided structures are designed to support its weight, its mixture design is properly proportioned, and it is adequately anchored and reinforced.

The current exponential growth in cement demand and the gradual reduction in the availability of the supplementary cementitious materials (SCMs) conventionally employed in the cement sector (fly ash, blast furnace slag, etc.) have brought awareness over the need to find alternative sources of pozzolanic materials. Whereas the use of calcined kaolinitic clays (metakaolinite) could represent an excellent substitute for the traditional SCMs, the environmental and economic cost associated with kaolinite extraction thwarts the development of this course of action. Conversely, the clayey wastes obtained in the coal mining industry could represent an inexpensive and environmentally sound raw material for the production of recycled metakaolinite, promoting at the same time a Circular Economy model.

This work describes the physical and durable properties of binary mortars prepared with different substitution levels (20 % and 50 %) of thermally activated coal mining waste (600 ºC/2 hours), placing emphasis on their chloride resistance. The results show that the differences observed in the pore network and in the mineralogical composition of the blended matrices result in a superior resistance to chloride ingress and, therefore, in a decrease in the risk of corrosion of the subsequent structures and an increase in their service life.