Civil Engineering Commons^™

Micromechanical Modeling For Material Design Of Durable Infrastructural Materials: The Influence Of Aggregate And Matrix Modification On Elastic Behavior Of Mortars, Sumanta Das, Amit Maroli, Narayanan Neithalath

International Conference on Durability of Concrete Structures

This paper reports the fundamental difference in microstress distributions in traditional hardened cement paste with quartz inclusions and a cement paste with lightweight aggregate (LWA) inclusions using microstructurebased numerical simulation involving finite element method with periodic boundary conditions. Variation of relative stress distributions under varying component material properties and varying microstructural features in both the systems is elucidated for a comprehensive understanding. The presented microstructure-based numerical technique accurately captures the stress concentrations inside microheterogeneous systems, which is otherwise not detectible using analytical homogenization schemes. Numerical simulations reveal that strengthening and stiffening of matrix and interfacial transition zone (ITZ) with silica …

Research On Concrete Durability Improving For Existing Island-Building And Its Application, Mao Jianghong, Zhu Yaofeng, Xu Fangyuan, Jin Weiliang, Xu Yidong, Chen Xu

International Conference on Durability of Concrete Structures

China’s coastal cities contain a large number of islands with abundant human activities, in which buildings are in a typical marine corrosion environment and the corrosion of reinforced concrete structures is very prominent. This paper makes research work on two aspects: (1) the durability assessment and durability improvement after a thorough investigation of the architecture of Xiangtan County, Ningbo city, on an island and (2) the application research of the bidirectional electromigration rehabilitation (BIEM) technology to enhance the durability of existing island building life. This paper designs a set of BIEM equipment based on solar power supply and develops a …

Chloride Penetration In Surface-Treated Concrete In Natural And Accelerated Environments, Jianfeng Dong, Yuxi Zhao, Shaoliang Pu, Ming Ji

International Conference on Durability of Concrete Structures

This study investigated the chloride penetration of surface-treated concrete in natural and accelerated environments. A part of a real concrete port, including the beams and the columns, was investigated. Concrete specimens cast together with the concrete port were transported to the lab and subjected to wetting and drying cycles for accelerating the ingression of chloride ion. Chloride concentration of the specimens in the lab and the components in situ was tested. The results show that the surface treatments obviously slow down the chloride penetration into the concrete in both lab and in situ. The chloride penetration in situ is …

Hierarchical Life-Cycle Design Of Concrete Structures, Zhujun Wang, Jin Weiliang, Ju Chen

International Conference on Durability of Concrete Structures

Concrete structures’ service life lasts decades. In order to deal with all the probable degradations and deteriorations in the whole life span, the concept of concrete structures’ Life-Cycle Design was introduced into China in the 1980s. However, until this day, Life-Cycle Design is still more of a concept to most structure designers and engineers, rather than a practical method. This paper provides a hierarchical method for concrete structures’ Life-Cycle Design, in which the design process is divided into five levels. Safety should be the fundamental requirements for all concrete structures, so as to guarantee a reliable quality. For structures located …

Study Of Water Permeability Of Lightweight Concrete, Xiaoxiao Xu, Haibin Yang, Hongzhi Cui, Zitao Lin, Tommy Yiu Lo

International Conference on Durability of Concrete Structures

The relationship between water permeability and different levels of the tested layers from the top surface to the bottom surface of the lightweight concrete specimens is determined in this study. It is beneficial to develop the design criteria for a durable lightweight concrete. The water permeability coefficient K of the samples was determined by water permeability test using GWT. It is found that the water permeability coefficient K of the three layers in each set of samples tends to decrease as the level of the tested from the top surface increase. Larger Rebound Number and higher density in the bottom …

Influence Of Sio2@Pmhs On The Water Absorption Of Cement Mortar As A Surface Treatment Agent, Ran Li, Pengkun Hou, Zonghui Zhou, Xin Cheng

International Conference on Durability of Concrete Structures

In this paper, the core–shell structured SiO₂@PMHS hybrid nanoparticles were synthesized with tetraethoxysilane (TEOS) and polymethylhydrosiloxane (PMHS). And SiO₂@PMHS core–shell nanoparticles were first used as a surface treatment agent for cement-based materials. The influence of SiO₂@PMHS nanoparticles on the water absorption of hardened cement mortar with water-to-cement ratio of 0.6 was investigated. Results showed that the water absorption of cement mortar treated with SiO₂@PMHS nanoparticles was decreased by 93.47% in comparison to the control sample.

Edge Detection Of Concrete Mesostructure Based On Dis Operator, Bin Feng, Zicheng Xu, Jin Xia, Shijie Jin, Weiliang Jin

International Conference on Durability of Concrete Structures

Aggregate edge detection is the basis of creating concrete mesoscale model, which is applied to analyze concrete mesoscale characteristics. A concrete digital image edge detection method using DIS operator is presented in this paper. Mean filter, multi-scale filter, and Gaussian filter are compared on the effect of concrete image noise reduction. Based on the result, Gaussian filter is the most optimum method to reduce image noise and remain aggregate edge distinct. Sobel operator, Laplacian operator, and DIS operator are applied respectively to detect the aggregate edge on Gaussian filter processed images. Based on the experiment, DIS operator outperforms other two …

Influence Of The Surface Treatment Of Hardened Cement Mortar With Colloidal Nano-Silica And Teos, Pengkun Hou, Xin Cheng, Zonghui Zhou

International Conference on Durability of Concrete Structures

Two types of silicate material, tetraethoxysilane (TEOS) and colloidal nanoSiO2 (CNS), were applied for surface treatment of hardened cement mortar by exploring their filling and pozzolanic reactivity to make the surface compacter. Results showed that the water adsorption coefficient, the water vapor transmission rate, and the water penetration depth were reduced when CNS and TEOS were applied onto the surface of hardened cement mortar, and TEOS exhibits a superior effect on surface treatment, making the mass-transport rate and extent smaller than CNS does.

Performance Of Concrete Patch Repairs: From A Durability Point Of View, Choorackal Avirachan Eldho, Ominda Nanayakkar, Jun Xia, Steve Jones

International Conference on Durability of Concrete Structures

Chloride contamination in reinforced concrete leads to the corrosion of steel bars. Concrete patch repairs are widely practiced as a remedial measure for the mitigation of such corrosion in reinforced concrete structures. The performance of the patch repairs was studied by various researchers in the past. The structural and material aspects of patch repairs have received more attention than the electrochemical consequences of patch repairs in past studies. But electrochemical changes could be the underlying cause for the failure of many patch repairs. This paper reviews the performance of patch repairs from a durability point of view. It covers the …

Aggregate Shape Effect On Multicomponent Ionic Electromigration In Concrete, Qing-Feng Liu, Long-Yuan Li, Jian Yang

International Conference on Durability of Concrete Structures

This paper presents a numerical study on the mechanism of chloride migration in concrete. Unlike most of existing work, this study utilises multicomponent ionic transport models to reflect the influence of ionic interactions by coupling both mass conservation and Poisson’s equations. A series of 2-D, 3-phase models with different shapes and volume fractions of aggregates are developed to simulate the chloride migration test. Through a comparatively overall numerical exploration that considers external voltage, ionic interactions, heterogeneous nature, ITZ, and ionic binding, some important features about multispecies coupling and aggregate shape effect, which have not been properly reported from existing concrete …

Research On Chloride Penetration Resistance Of Hybrid Fiber Reinforced Self-Compacting Concrete, Wu-Jian Long, Zhe-Ming Mai, Jin-Guang Shi, Tian-Tian Zhao, Wu-Lei Peng

International Conference on Durability of Concrete Structures

The properties of chloride penetration of hybrid fiber reinforced self-compacting concrete (SCC) were investigated in this study. The results show that, the chloride penetration resistance of concrete can be improved by single incorporation either carbon or cellulose fibers. The concrete chloride diffusion coefficient D_RCM of 12-cm length carbon SCC with fiber content of 1.7 kg/m³, 2.72 kg/m³, and 3.4 kg/m³ decreases by 10.3%, 25.5%, and 18.2% compared to reference concrete without any fibers, respectively. Moreover, the concrete chloride diffusion coefficient D_RCM of cellulose SCC with fiber content of 1.2 kg/m³, 1.6 …

Moisture And Temperature Effects On Interface Mechanical Properties For External Bonding, Tamon Ueda, Justin Shrestha, Khuram Rashid, Dawei Zhang

International Conference on Durability of Concrete Structures

In order to develop rational guidelines for strengthening by external bonding, it is necessary to clarify longterm performance of interfacial bonding property. In this paper, moisture effects on bonding properties at FRP–concrete interface and temperature/moisture effects on bonding properties at PCM–concrete interface are presented. Shear bond strength of FRP–concrete interface is affected by moisture because resin–concrete adhesion strength is affected by moisture. Among tested CFRP external bonding systems, wet-layup CFRP systems all show the strength reduction, while prefabricated CFRP systems all show the strength increase after immersion. The bond stress–slip relationship and interfacial fracture energy also change, which can explain …

Mat-701: Predicting The Compressive Strength Of Ultra-Lightweight Concrete By An Artificial Neural Network, Jordan Ouellet, Jean-Luc Martel, Claudiane Ouellet-Plamondon, Alan Carter

Canadian Society for Civil Engineering

Ultra-lightweight concrete (ULWC) has potential applications for floating structures and architectural elements because of its dry density coming in at under 1000 kg/m3. The objective was to develop an artificial neural network (ANN) to aid the ULWC designer according to his needs. Boundary conditions were set for each material and 13 constraints based on the water binder ratio, density, air content, binder and aggregate content. The ANN predicted the compressive strength with a comfortable margin of error, with the gap encountered being attributed to variability in workability. Precise constraints and boundary conditions are needed to ensure a lower variability in …

Mat-702: Mechanical Behaviour Of Ultra-High Performance Concrete Obtained With Different Concrete Constituents And Mix Designs, Mahmoud Sayed-Ahmed, Khaled Sennah, Moulay Youssef Monsif

Canadian Society for Civil Engineering

This research investigates the mechanical behaviour for the Ultra-High Performance Concrete (UHPC) and UltraHigh Performance Fiber Reinforced Concrete (UHPFRC). UHPC and UHPFRC are designed to be self-consolidated concrete that level itself without mechanical vibration due to its highly flowability and moderate viscosity. UHPFRC is used as joint-fill cementitious materials for the connections of prefabricated bride elements and systems used for the Accelerated Bridge Construction and rapid bridge replacement. The main concrete constituents of such materials consist from: binders (cement), powders (fillers), liquids (additives), water, and fibers. Hence, the mixture proportion design should follow a densified mixture design algorithm to densify …

Mat-704: Resistance Of Concrete Incorporating Portland Limestone Cement To Sulfuric Acid, Mahmud Amin, Mohamed T. Bassuoni

Canadian Society for Civil Engineering

Concrete has long been the most popular choice for constructing key infrastructural elements such as sewer pipes, water treatment facilities, industrial floors and foundations. However, many field cases from all around the world have shown that concrete elements in these environments are severely damaged due to biogenic and/or chemical sulfuric acid attack. Since high alkalinity is required for the stability of the cementitious matrix, concrete is highly prone to acid attacks, which decalcify and disintegrate the hydrated cement paste to various levels based on exposure conditions and type of concrete. Numerous studies have been conducted to enhance the durability of …

Mat-705: Improving The Efficiency Of Zinc Sacrificial Anodes In Repaired Concrete, Ahmed G. Bediwy, Mohamed T. Bassuoni, Martin Beaudette

Canadian Society for Civil Engineering

Zinc sacrificial anodes are considered an effective and economical method to prevent the electrochemical corrosion of steel bars by providing cathodic current to bars, which can provide corrosion protection at low galvanic current densities in the range of 0.2 to 2 mA/m2. Sacrificial anodes are commonly used in RC structures particularly in bridge decks to mitigate a critical phenomenon that occurs in the original concrete beside the repaired patches, which is known as the ‘halo effect’. One of the key factors affecting the efficacy of zinc anodes is the resistivity of concrete or cementitious repair material in which these anodes …

Mat-707: Development Of Enhanced Test Methods To Evaluate Alkali-Silica Reaction In Concrete, Noura Sinno, Medhat Shehata

Canadian Society for Civil Engineering

The research presented in this paper studies the effect of sample geometry and temperature on expansion due to alkali-silica reaction (ASR) in concrete. Expansions of cubes and cylinders are compared to those of the standard prisms. Control samples, samples with fly ash (FA) and others with slag are investigated at two temperatures, 38°C and 60°C. At 38°C, results showed that smaller samples have higher expansion at early ages. However, larger samples such as cubes and cylinders seem to reach higher expansion compared to prisms after 32 weeks for both control and samples with fly ash. In addition, the results showed …

Mat-708: Monitoring The Corrosion Process Of Reinforced Concrete Flat Slab-Column Connection, Mahmoud E. Said, Amgad Hussein, Assem A. A. Hassan

Canadian Society for Civil Engineering

The corrosion of the steel reinforcement embedded in a two-way reinforced concrete flat slab around the column stub area was investigated in this study, which aimed to studying the effect of corrosion on the shear punching behavior. Two square flat slab-column connections were cast, the flat slab dimension was 1900 mm × 1900 mm × 150 mm, and the column dimensions was 250 mm × 250 mm. A specific delaminated area was corroded around the column stub to emphasize the effect of corrosion around punching area. The corrosion reached two levels of mass loss uniformly over that specified area: 0% …

Mat-711: Utilization Of Recycled Crumb Rubber In Structural Self-Consolidating Concrete, Mohamed K. Ismail, Assem A. A. Hassan, Madolyn A. Lundrigan

Canadian Society for Civil Engineering

The present work evaluates the impact of using recycled crumb rubber (CR) as a partial replacement of fine aggregate on the fresh and mechanical properties of concrete composite, especially when self-consolidating concrete is used. In this study, seven mixtures containing various amounts of fine CR (0-30% by volume of sand) were tested. The fresh properties tests included flowability, passing ability, and segregation resistance. On the other hand, the mechanical properties tests included compressive strength, modulus of elasticity, splitting tensile strength, and flexural strength. The results indicated that although increasing the CR replacement decreased the fresh and mechanical properties of concrete, …

Mat-712: Microstructural Investigations On The Self-Healing Ability Of Engineered Cementitious Composites Incorporating Different Mineral Admixtures, Ahmed Alyousif, Khandaker M. Anwar Hossain, Mohamed Lachemi, Mustafa Sahmaran

Canadian Society for Civil Engineering

The present study investigates the impacts that self-healing has on the microstructure characteristics of microcracked Engineered Cementitious Composites (ECC). These have two contrasting maturity levels and, furthermore, they involve three varying mineral admixtures that have very different chemical constituents. The impact of self-healing on the transport characteristics was examined by employing rapid chloride permeability tests (RCPT). The findings indicated that, if the appropriate mineral admixture type and conditioning were chosen, it would be possible to enhance the majority of the chloride ion penetrability levels following a 30-day period of water curing. As a result, the majority of the findings were …

Mat-713: Evaluation Of Ndt Techniques For Concrete Bridge Decks Using Fuzzy Analytical Hierarchy Process, Tarek Omar, Moncef L. Nehdi

Canadian Society for Civil Engineering

Considering the colossal backlog of deteriorating bridges, transportation agencies need to systematically evaluate bridge deck conditions in order to optimize the timing, scope, and approach of preventive maintenance, repair, and replacement. Over the last few years, there have been growing interest among bridge infrastructure stakeholders in using non-destructive methodologies for bridge inspection, evaluation, and maintenance. Nondestructive testing (NDT) techniques can provide needed information about the “under-the-surface” deteriorated condition of bridge decks. This paper examines the most common NDT technologies for assessing bridge decks. Each technology was rated based on five performance measures: capability to detect subsurface defects, speed of data …

Mat-714: Condition Assessment And Deterioration Prediction Tools For Concrete Bridges: A New Look, Tarek Omar, Moncef L. Nehdi

Canadian Society for Civil Engineering

Structural problems created by corrosion, ageing, aggressive environments, material defects and unforeseen mechanical or seismic loads can compromise the serviceability and safety of bridges. The importance of an effective bridge-management system (BMS) cannot be overstated, especially in light of the recent collapse of bridges in North America and elsewhere. Several technologies are available for assessing the condition of concrete bridges and a number of deterioration models are used to predict future bridge conditions and estimate associated funding requirements. This paper critically reviews the different available condition assessment and deterioration prediction approaches for concrete bridges. The potential applications of condition assessment …

Mat-716: Green Sidewalks Using Sustainable Two-Stage Concrete, Manal F. Najjar, Ahmed M. Soliman, Tareq M. Azabi, Moncef L. Nehdi

Canadian Society for Civil Engineering

Two-stage concrete (TSC) is a special type of concrete, which has a high potential for use in sidewalk construction owing to its high volume stability. TSC is characterized by its high coarse aggregate content. Hence, using recycled solid waste materials as a coarse aggregate will increase TSC sustainability, while providing a cost-effective alternative to natural aggregates. Aggregates are pre-placed in TSC. Hence, water absorption by recycled concrete aggregates and the associated rheology problems do not exist in TSC. This study explores the performance of green TSC sidewalks incorporating recycled concrete aggregates (RCA) and crumb rubber from scrap tires. Mechanical properties …

Mat-719: Investigation Of Grouted Precast Concrete Wall Connections At Subfreezing Conditions, Douglas James Provost-Smith, Mohamed Elsayed, Moncef L. Nehdi

Canadian Society for Civil Engineering

The effect of exposing grouted precast wall connections to subfreezing curing temperatures at early-age was explored in this study. In cold weather construction, heating of the surrounding environment of grouted precast wall connections is usually conducted for short periods of time. Hence, subfreezing conditions can affect the strength of the grout and the bond strength of the connection, which can ultimately compromise the integrity of the structure. In this study, grout specimens typical of that used in precast wall construction were cured at ambient conditions for one day, and then placed in an environmental chamber at subfreezing temperatures (-10°C and …

Mat-720: Effect Of Pore Structure On Concrete Deterioration By Physical Sulphate Attack, Ahmed R. Suleiman, Moncef L. Nehdi

Canadian Society for Civil Engineering

Repeated crystallisation of salt minerals has been considered as the driving force for surface scaling of concrete exposed to physical sulphate attack. This damage is initiated when stresses induced by the internal pressure created via repeated salt crystallisation exceed the tensile strength of the concrete. The degree of such damage will depend mainly on the structure and connectivity of pores, which control the penetration of sulphates into the concrete. Several factors affect the pore structure including the concrete constituents, mixture proportions and the curing process. Therefore, in this paper, the effect of the pore structure on concrete deterioration by physical …

Mat-721: Alkali-Silica Reactivity In Southwestern Ontario Aggregates, Ahmed R. Suleiman, Aaron Jobst, Moncef L. Nehdi

Canadian Society for Civil Engineering

Alkali-silica reaction (ASR) occurs between alkalis in concrete and reactive silica in aggregates. This reaction results in the formation of alkali-silica gel, which fills the pore space in the cementitious matrix, leading to expansion and damage. Reactive aggregates that can cause this type of damage were identified in different locations in Southwestern Ontario. X-Ray diffraction and petrographic analysis were used to investigate the type of reactive minerals in such aggregates. In addition, the effect of using different types of cement replacement-materials, including crushed limestone powder, fly ash, silica fume, and nano-silica on ASR were investigated in cement mortars incorporating the …

Mat-722: Effect Of Fiber Orientation On The Behavior Of Cfrp Confined Concrete Cylinders, Ahmed Sulaiman, Husham Almansour, Hassan Aoude

Canadian Society for Civil Engineering

This paper presents the results of an ongoing experimental investigation examining the effect of fiber orientation and stacking sequence on the behavior of FRP-confined concrete. As part of the experimental study, 100 mm x 200 mm concrete cylinders were jacketed with carbon fiber reinforced polymer (CFRP) sheets and tested under pure axial compressive loading. The specimens were confined using various CFRP stacking sequences, with fibers oriented at 0⁰, 90⁰, and ±45⁰. Furthermore, within each stacking sequence, the numbers of layers was varied from 4 to 8 to examine the effect of number of plies on the behavior of the FRP-confined …

Mat-723: Bond Behaviour Of Grouted Connections Under Monotonic Tensile Loads, Mohamed Elsayed, Douglas James Provost-Smith, Moncef L. Nehdi, Osama Eissa

Canadian Society for Civil Engineering

Grouted bar-in-conduit connections are versatile connections widely used in the precast concrete construction. In precast load bearing wall structures, two vertical wall panels are connected by a reinforcing bar, which is projected from one panel and grouted into a sleeve placed in the other. The main function of the ties is to resist tension induced by in-plane and out-of-plane straining actions and to provide ductility to the wall assembly through the yielding of the reinforcement. Limited information is currently available on the behaviour of such connections. This paper presents the findings of an investigation conducted to investigate the behaviour of …

Mat-725: Self Leveling Mortar: Why And How?, Ahmed Hassanein, Eman Shalaby, Omar Amer, Reem Ahmed, Sherif Orban, Amr Fathi, Yousef Abu Gharieb, Mohamed N. Abouzeid, Ezzat H. Fahmy

Canadian Society for Civil Engineering

Concrete floors can develop faults over time which can cause damage thus hindering smooth transportation, industrial aspects and some residential drawbacks. In addition, flaws and cracks are known to progress into more serious damage with time and use. Self leveling mortar has been used on a relatively limited scale worldwide to allow for more even, higher performance and easy-to-apply flooring. However, there has been little information available with respect to their use and best practices.

The primary focus of this work is to prepare mortar that possesses self-levelling flow characteristics. Hence, several mixtures have been designed using various constituents with …

Mat-731: Mechanical & Durability Properties Of Engineered Cementitious Composites With Different Aggregates, Mohamed A. A. Sherir, Khandaker M. Anwar Hossain, Mohamed Lachemi

Canadian Society for Civil Engineering

This paper presents the outcome of a study conducted to exhibit the effect of micro-silica sand and mortar sand on fresh, mechanical and durability properties of Engineered Cementitious Composites (ECCs). ECC is a ductile concrete characterized by strain hardening and multiple-cracking behavior under tension and shear. This study used locally available aggregates instead of standard micro-silica sand to produce cost-effective, sustainable and green ECC mixtures to be used for construction applications. ECCs prepared by both types of sands exhibited almost similar behaviour in terms of fresh, mechanical and durability properties which indicated the viability of producing ECC mixtures with mortar …