Leandro Sanchez

University of Ottawa · Department of Civil Engineering

Currently, the C3A content of binders is considered the most important factor contributing to external sulphate attack (ESA) deterioration. However, portlandite is also deemed to play a major role in ESA development. Yet, there are very few researches on this topic. This paper evaluates physical (i.e., induced expansion and mass variation, ultrason...

Nanoparticles (NPs) of titanium dioxide (TiO2) are highly efficient mineral additives which modify the hydration reaction of white Portland cement (WPC) by creating additional nucleation sites. Particle size and specific surface area influence on promoting nucleation sites has been proven to be the main factor affecting hydration kinetics since the...

The urgent need to develop sustainable and durable alternatives to Portland cement (PC) concrete has been a major drive for research on alkali-activated materials (AAMs). Amongst AAMs, hybrid alkaline binders appear to be the most industry-ready option, as their manufacturing process is similar to that of PC binders, they use milder doses of alkali...

The alkali–silica reaction (ASR) is one of the most harmful distress mechanisms affecting concrete infrastructure worldwide. The reaction leads to cracking, loss of material integrity, and consequently compromises the serviceability and capacity of the affected structures. In this study, a modeling approach was proposed to simulate ASR-induced expa...

It is widely accepted that Alkali-Silica Reaction (ASR)-induced expansion and deterioration may be prevented by the appropriate use of supplementary cementing materials (SCMs). Nevertheless, the correlation between microscopic/macroscopic damage degree and features of SCMs-made concrete is still not fully understood. Moreover, more research needs t...

Internal swelling reactions (ISR) are amongst the most harmful deterioration mechanisms affecting the durability, serviceability, and overall performance of critical concrete infrastructure around the globe. Over the years, several approaches have been developed worldwide to assess the condition and manage ISR-affected structures. However, several...

Alkali-aggregate reaction (AAR) is among the most harmful deterioration mechanisms affecting concrete infrastructure worldwide, impacting more than 50 countries. Over the last decades, numerous laboratory tests have been developed to evaluate the reactivity of aggregates and the effectiveness of supplementary cementitious materials (SCMs) to mitiga...

Among the ways to counter the effects of concrete cracking, self-healing appears to be very promising. This research aims to appraise the effect of autogenous and autonomous self-healing on the condition recovery of mechanically loaded concrete specimens proportioned with distinct raw materials. A commercially available crystalline admixture (CA),...

The concrete industry needs to find cost-effective technologies to reduce the carbon footprint of its products. At the same time, these technologies should not reduce the concrete performance, including long-term durability. The great demand for concrete and the expected shortages of high-quality aggregates (e.g., ASR resistant) in the coming years...

An efficient method to produce ecoefficient cementitious mixtures is using particle packing models (PPMs) combined with limestone fillers (LF). Yet, key outcomes obtained in the fresh and hardened states, including slump and compressive strength, are variable and remain mostly not fully understood. Therefore, in this work, the concept of interparti...

The effect of two superplasticizers (SPs) with various equivalent (eq.) alkali contents (i.e., with 0.00009% and 4.1% of Na 2 O eq , respectively) on the development of an alkali-silica reaction (ASR) was investigated through the use of multilevel assessment. This testing protocol showed promising results for evaluating concrete damage due to ASRs...

The multi-level approach coupling of mechanical (i.e., Stiffness Damage Test -SDT) and microscopic (i.e., Damage Rating Index -DRI) testing procedures, was found to be promising for evaluating the condition of ASR-affected concrete elements under unconfined and internally confined conditions. Yet, only a few studies investigated the effect of exter...

Abstract: Fresh and hardened state performance of eco-efficient concrete mixtures incorporating soil waste Most contaminated soils are destined for landfills without treatment before burial, exposing the surrounding environment to secondary contamination. Air quality, groundwater quality, and land availability for economic and social development ar...

Correlating short-term expansion of concrete specimens in the laboratory and long-term expansion of concrete in the field is crucial to evaluate the reliability of laboratory test methods and essential for the prognosis of alkali-silica reaction (ASR) in concrete infrastructures. In this study, a novel semi-empirical approach is proposed for foreca...

The Bridge, a highway bridge structure, was built using a suspected alkali-silica reactive aggregate in the 1960’s in a city in central Canada. Its concrete elements experienced rapid deterioration resulting in the need for costly increased repairs and rehabilitations. Alkali-silica reaction (ASR) is one of several damage mechanisms which might be...

Two concrete deck slabs extracted from a Canadian bridge have been evaluated using non-destructive testing (NDT), followed by destructive testing. Throughout its service life, the bridge experienced harsh environmental conditions with frequent freeze-thaw cycles, hot and humid summers, and the use of de-icing salts during winters. This study presen...

Deterioration signs were observed on the concrete surface of the exterior columns of the SITE building located at the University of Ottawa, Ottawa (Ontario, Canada) which demonstrated the potential presence of a concrete damage mechanism, suspected to be alkali-silica reaction (ASR). To investigate the root cause of this deterioration, a visual ins...

The ever-growing urgency to combat climate change has led the civil construction industry to develop and adopt sustainable construction materials and methods. The so-called recycled concrete aggregate (RCA) emerges as an alternative to decrease the carbon footprint of new concrete construction, the disposal of waste concrete, and the use of non-ren...

Recently, many signs of distress were developed on the various columns of the School of Information Technology and Engineering (SITE) building constructed in the early 2000 s, located on the University of Ottawa campus (Ontario, Canada). Thus, a visual inspection was performed to select four columns showing the highest deterioration signs to extrac...

Freeze-thaw damage is one of the main deleterious processes of concrete in cold climates. This study intends to detect the ongoing freeze-thaw (FT) deterioration in concrete specimens through the use of the global assessment combining the results of the mechanical and microscopic evaluation, pressure tension (PT) and compressive strength test as we...

The Robert-Bourassa/Charest (RBC) overpass was built in 1966 and demolished in 2010/2011 due to numerous signs of distress developed mostly due to alkali-silica reaction (ASR). Cores were extracted prior to RBC's demolition, which enabled a thorough condition assessment of the structure, mainly using the Dam-age Rating Index (DRI). The DRI is a sem...

Modeling damage generated by distress mechanisms like alkali-silica reaction (ASR) and reinforcement corrosion in reinforced concrete structures is very complex, yet necessary to correctly assess the current (diagnosis) and future structural response (prognosis) of affected concrete members. The situation is even more complex when more than one dis...

Over the last decades, different techniques with the aim of assessing the actual damage of aging concrete infrastructure have been proposed around the world. A method that has increasingly been used in North America is the Damage Rating Index (DRI). This microscopic and semi-quantitative petrographic tool was developed to provide a reliable charact...

Robert-Bourassa/Charest (RBC) overpass (Quebec, Canada) was a concrete structure severely affected by alkali-silica reaction (ASR) due to the use of a highly reactive coarse aggregate (local siliceous limestone) in the concrete construction. Over the years, RBC overpass was monitored, and several laboratory test procedures were conducted on cores e...

Alkali silica reaction (ASR) is a widely known chemical reaction in concrete that can cause premature distress and leads to loss of serviceability of affected structures. Since its identification in the late 1930s, extensive research has been carried out for a better understanding of the mechanisms involved in the reaction, while also developing wa...

The constant effort to develop sustainable and durable alternatives to Portland cement (PC) concrete has been a major drive for research on alkali-activated concrete (AAC). Although AACs are known for their high chemical resistance, their potential for deleterious induced expansion and deterioration caused by alkali-silica reaction (ASR) remains un...

The Damage Rating Index (DRI) has proven to be a quite reliable microscopic technique enabling the condition assessment of concrete affected by internal swelling reactions (ISR). Yet, very few research has been conducted on the use of the DRI to appraise induced deterioration caused by physical salt attack (PSA) and external sulfate attack (ESA). T...

Although 28-day concrete compressive strength is often used as a quality control indicator, early-age mechanical properties are becoming more critical to optimize construction scheduling. Electrical resistivity (ER) and maturity can be used to appraise mechanical properties’ gain over time. Although these methods are well-defined for conventional c...

Recycled concrete aggregates (RCA) have been adopted as one of the most efficient methods to reduce the carbon footprint of the concrete industry. However, the performance of recycled concrete mixtures made of Alkali-silica reaction (ASR)-affected RCA is primarily unknown. In this work, two types of RCA were produced from ASR-affected concrete with...

Among arising sustainable civil construction practices, recycling of unused/demolished concrete as the so-called recycled concrete aggregates (RCA) has been receiving increased attention. However, contaminated/deteriorated materials, such as alkali-silica reaction (ASR)-affected concrete, may be present in some RCA sources. In recent years, a numbe...

Over the past decades, a wide number of research programs were conducted and demonstrated the efficiency of supplementary cementing materials (SCMs) to mitigate alkali-silica reaction (ASR)-induced expansion and deterioration. However, the anticipated depletion in the coming years of some of the most common SCMs used in concrete makes imperative th...

Conventional visual inspection techniques are generally qualitative and therefore unable to provide accurate information on the extend of alkali-silica reaction (ASR)-induced damage development in concrete. Therefore, improving and finding more accurate visual procedures is extremely important for a better condition assessment and development of ma...

Most of the previous research on recycled concrete aggregates (RCA) has focused on coarse RCA (CRCA), while much less has been accomplished on the use of fine RCA particles (FRCA). Furthermore, most RCA research disregards its unique microstructure, and thus the inferior performance of concrete incorporating RCA is often reported in the fresh and h...

The pressure to use sustainable materials and adopt practices reducing the carbon footprint of the construction industry has risen. Such materials include recycled concrete aggregates (RCA) made from waste concrete. However, concrete made with RCA often presents poor fresh and hardened properties along with a decrease in its durability performance,...

Periodic visual inspections are typically the primary means by which the existing condition of most infrastructure assets is assessed. The results of these inspections are inherently qualitative and subjective, and unfortunately, the recent catastrophic collapse of structures such as De La Concorde overpass in Canada have underscored the need for q...

The multi-level assessment, combining microscopic (i.e., Damage Rating Index) and mechanical (i.e., Stiffness Damage Test) techniques, has been effectively used to appraise the deterioration cause by alkali-silica reaction (ASR) in unconfined concrete. However, the impact of restrainment on ASR-induced deterioration originated from reactive fine an...

The Stiffness Damage Test (SDT), a mechanical and cyclic test procedure, has been successfully used to appraise alkali-silica reaction (ASR) deterioration under unrestrained conditions. However, the effects of confinement on ASR-induced mechanical damage have not been fully investigated. This work aims to understand the influence of confinement on...

Reducing Normal Portland Cement (NPC) has been a major concern of concrete industry and research community over the last 2-3 decades. As much as 8% of the global CO2 emissions stem from clinker production. Hence, a wide number of research projects have been focusing on reducing NPC in cementitious materials using numerous strategies such as the use...

Recycled concrete aggregates (RCA) have gained popularity over the last few decades as a potential sustainable alternative for natural aggregates. Research has shown promising hardened state performance when residual mortar (RM) is accounted for in the mixture proportioning. Yet, most of the successful results reported in the literature highlighted...

Although the 28-day concrete compressive strength is often used as a quality control indicator, early-age mechanical properties are becoming more critical to optimize construction scheduling. Numerous advanced techniques have been proposed in this regard and among those, electrical resistivity (ER), a non-destructive and inexpensive technique able...

Several techniques and procedures were developed over the last decades to perform the condition assessment of concrete infrastructure affected by alkali-aggregate reaction (AAR). Among them, structure health monitoring techniques are deemed as one of the most reliable methods to understand the expansion rate over time and thus the potential of furt...

Modeling the expansion and damage generated by alkali-aggregate reaction (AAR) in reinforced concrete structures is quite complex, yet necessary to obtain accurate predictions of the structural response of distressed members. Several AAR models have been developed to predict expansion and damage at the material (microscopic) or the structural (macr...

Concrete has been largely used in civil engineering due to its interesting fresh and hardened state properties. The 28-day compressive strength is the most important concrete property, being frequently used as an indicator of the material’s quality. In this context, early-age mechanical properties (e.g., compressive strength) are becoming more crit...

The Damage Rating Index (DRI), a semi-quantitative microscopic procedure, has been successfully used to describe alkali-silica reaction (ASR) damage development of concrete under “free expansion” conditions. Yet, the confinement impact on ASR-induced cracks' generation and propagation has not been fully investigated. This work aims to understand th...

Alkali-silica reaction (ASR) is one of the most detrimental distress mechanisms leading to early deterioration of concrete infrastructure, creating large amounts of construction and demolition waste which however can be transformed into recycled concrete aggregates (RCA). Yet, as ASR is an ongoing distress mechanism, its potential of reoccurrence i...

Alkali silica reaction (ASR) is a harmful distress mechanism which results in expansion and reduction of mechanical properties of concrete. The latter may cause loss of serviceability and load carrying capacity of affected concrete structures. Influences of ASR on concrete are known to be complex in nature, for which the traditional empirical and c...

Alkali-silica reaction (ASR) is one of the most damaging mechanisms affecting concrete structures worldwide. ASR effects on the durability and serviceability of damaged concrete are widely known and fairly well understood. However, the structural implications are still unclear, and a number of contradictory data are found in the literature, especia...

Describing alkali-aggregate reaction (AAR) induced expansion is a very complicated task, yet very useful to forecast and understand the potential of further deterioration of affected concrete. Back in the 90s, Larive developed an empirical model to describe AAR-kinetics in the laboratory. Although relatively well accepted by AAR community, Larive’s...

A large amount of research has been conducted on the reuse of construction and demolition waste (CDW) inconcrete. Yet, CDW may display pre-existing damage which raises concerns on its use. In this work, coarse recycled concrete aggregate (RCA) is reclaimed from distinct members of an alkali-silica reaction (ASR) affected overpass. RCA mixtures inco...

This test method covers the laboratory determination of the swelling potential and the residual free expansion of concrete extracted from structures affected by alkali-silica reaction.

Two test procedures are recommended as per Laval University Method.

An indication about the expansion of the concrete can be derived from the crack-index [1]. The crack-index is determined by measuring the crack width along pre-drawn lines, Fig. 2.1 and is expressed as crack-width per measured length. However, it has to be kept in mind that the formation of the cracks may not be attributable solely to AAR. Still, t...

This part of the document discusses a number of techniques used to quantify the in concrete affected by alkali-aggregate reaction (AAR). The principal points of each technique (similarities and differences) are presented and an overall discussion is addressed.

Alkali-silica reaction (ASR) is one of the most harmful distress mechanisms affecting concrete infrastructure worldwide. ASR is a chemical reaction that generates a secondary product, which induces expansive pressure within the reacting aggregate material and adjacent cement paste upon moisture uptake, leading to cracking, loss of material’s integr...

Recycled concrete aggregates (RCA) are deemed an efficient approach to reduce waste yet, the presence of previous alkali-silica reaction (ASR) causes reservations towards its use in new construction. In this work, RCA specimens are manufactured in the laboratory incorporating RCA displaying distinct ASR past deteriorations (i.e. slight and severe)....

The Damage Rating Index (DRI) has been increasingly used in North America since it answers interesting questions on the cause and extent of damage in concrete. Currently, the DRI is mostly used to appraise alkali-silica reaction (ASR) affected concrete and there is very few research on the evaluation of other distress mechanisms through this method...

The use of recycled concrete aggregate (RCA) has substantially grown over the last several decades. RCA is a composite material composed of original virgin aggregates (OVA) and residual mortar (RM); it has been found that accounting for RM as part of the total mortar volume in the design of RCA concrete can improve its mechanical and durability-rel...

Various numerical models have been developed to appraise alkali-silica reaction (ASR) induced expansion and to predict its potential to generate further damage. A previous work proposed a finite element approach that does not oversimplify nor overcomplicate the reaction analysis, while still being capable of representing the anisotropic expansion a...

The articles presented in this special issue are focused on the state-of-the-art techniques, methods, and applications employed in aging, deterioration, and damage analysis and assessment in concrete structures and infrastructures. Overall, 17 submissions were received by the editorial team, and 8 manuscripts have been accepted for publication.

External sulphate attack (ESA) is a term used to describe various chemical reactions between sulphate ions and hydrated cement compounds. Thus, the chemical composition of the binder is extremely important on the durability of concrete struc- tures and structural members exposed to sulphate environments. This paper aims to evaluate physical (i.e. i...

RBC overpass was a highway bridge structure that was built using an alkali-silica reactive aggregate. Over nearly 5 decades, many signs of distress were developed on the various RBC structural members mainly due to alkali-silica reaction (ASR). In 2010/2011, RBC overpass was demolished and thus a number of cores from the various structural members...

The damage rating index (DRI) is among the most promising microscopy methods for condition assessment of concrete infrastructure. However, it requires experts to perform time-consuming petrographic microscopy of samples. The article discusses a study aimed at automating DRI assessments using machine learning (ML). It is expected that ML will reduce...

Various studies on the use of recycled concrete aggregate (RCA) were developed in the past decades. Yet, very often direct replacement techniques are adopted to proportion RCA concrete, which leads to inferior performance of the recycled material when compared to conventional concrete. RCA is a multi-phase material comprised of original virgin aggr...

Alkali-Aggregate Reaction (AAR) is one of the most harmful distress mechanisms affecting the durability and serviceability of concrete infrastructure worldwide. Over the years, a number of comprehensive testing protocols have been developed to appraise the amount of damage, expansion attained to date and mechanical properties reductions of concrete...

Pressure is mounting in the construction industry to adopt more environmentally sustainable methods to reduce CO2 emissions. One of the most efficient methods in this regard is the use of low cement systems, the so-called low cement concrete (LCC). Although eco-efficient, the use of structural LCC is somewhat new and its performance and long-term b...

The production of Portland cement (PC) clinker is responsible for about 6.5% of the total carbon dioxide (CO2) emissions worldwide. Therefore, recent studies have been focusing on alternatives to decrease PC content and thus reduce the carbon footprint of concrete construction. Although guidelines suggest a minimum cement content of approximately 2...

Modeling alkali-silica reaction (ASR) induced expansion and damage in reinforced concrete structures is quite complex, yet necessary to obtain accurate predictions of the structural responses of distressed concrete members. In order to predict the expansion and damage at the structural (macroscopic) scale, a new simple yet reliable finite element (...

Concrete, the major construction material used in the construction industry worldwide, presents a huge environmental impact producing about 7% of the global carbon dioxide. Given the concerns related to global warming, studies have been focusing on distinct approaches aiming to reduce the amount of Portland cement (PC), which is the least sustainab...

Robert-Bourassa/Charest (RBC) overpass was a highway bridge structure (Quebec, Canada) that was built us-ing an alkali-silica reactive limestone aggregate. Over nearly 5 decades, many signs of distress developed on the various structural members of the structure mainly due to alkali-silica reaction (ASR), freeze-thaw (FT) cycles, as well as steel c...

Modeling the expansion and damage generated by alkali-silica reaction (ASR) in reinforced concrete structures is quite complex, yet necessary to obtain accurate predictions of the structural responses of distressed concrete members. Several ASR models have been developed over the past decades to predict expansion and damage at the material (microsc...

Over the past decades researchers have tried to develop protocols to assess the current condition (diagnosis) and the potential for further expansion/distress (prognosis) of aging critical infrastructure. Among promising techniques, particular attention was given to quantitative microscopic procedures such as the Damage Rating Index (DRI). However,...

Recent works propose the use of a comprehensive management tool for assessing concrete damage due to alkali-silica reaction (ASR) based on a series of mechanical and microscopic laboratory test procedures, mainly the Stiffness Damage Test (SDT) and the Damage Rating Index (DRI). However, the use of these procedures for assessing other distress mech...