Journal of Materials in Civil Engineering

The influence of thermal and mechanical-induced cracking as well as the effect of construction defects including overvibration and insufficient vibration on concrete durability was studied in this research. Durability was evaluated using water absorption, electrical conductivity and electrical resistivity test methods. Results showed that although water and chloride ingress through concrete are not noticeably affected by short term tensile loading, the well distributed network of cracking induced by rapid heating significantly increases concrete permeability. Overvibration also affects the measured properties, but the presence of interconnected air voids induced by insufficient consolidation has a much more destructive effect on concrete durability.

Pavements steadily deteriorate attributable to many factors such as weather, traffic, water infiltration, and degradation of materials over time. Thus, pavement preservation and maintenance strategies have become an important field to understand and investigate for road agencies, owners, and managers of streets, highways, and parking lots. Environmental and mechanical weathering, which includes traffic loading, exposure to sun, water, freezing, and thawing, all lead to pavement deterioration and ultimate failure if maintenance and preservation are not performed on the roadway. The main objective of this paper is to verify the performance and effectiveness of using chip seal preservation techniques using either emulsified or hot mix asphalt. Two testing schemes are used; the first includes aggregate testing with an attempt to investigate how aggregate performance could relate to chip seal performance. The aggregate testing that would later reflect the pavement performance includes: gradation, flakiness, abrasion resistance, angularity, and embedment. The second testing scheme includes chip seal pavement evaluation using various laboratory and field testing. The chip seal evaluation emphasizes pavement micro- and macrotexture properties using measurements of mean texture depth and friction parameters. Moreover, pavement assessment includes evaluating the pavement performance based upon distress appearances. Distresses discussed are transverse, longitudinal, fatigue, pothole, patching, bleeding, loss of aggregate, rutting, and raveling. The case study presented includes eight sections in the State of Oregon whereby testing schemes are conducted. Pavement conditions were further analyzed prior to construction, right after construction and up to 2-year postconstruction. Findings show that aggregate properties have a significant contribution to the overall performance of chip seal pavements and the importance of the preseal pavement condition. Results further show that chip seals provide a significant performance improvement in pavement test sections by reducing the appearance of distresses after 2 years of service life. The study concludes that chip seals are an effective preservation tool when constructed with good quality aggregates and binders based on the documented improvement in cracking for all test sections observed.

The Cross model has been successfully used for modeling the shear thinning behavior of asphalt binders. Usually minimization of least squares/absolute error is used for obtaining model parameters. The curve fitted using these techniques shows more deviation at those parts of the domain where there are fewer observations. To improve the curve fit and eliminate this bias, an area minimization technique is proposed in this study. To the best of the authors’ knowledge, this technique is proposed for the first time in model parameter estimation. This paper discusses and compares least-squares and area minimization for fitting the complex viscosity master curves of four different asphalt binders at six different reference temperatures. The results clearly demonstrate that area minimization offers a solution that has less deviation throughout the domain of the observed data when compared with least-squares error.

This work focuses on the effect of nanozinc oxide (nano-ZnO) and organic expanded vermiculite (OEVMT) compound on physical and aging properties of styrene butadiene rubber (SBR) modified bitumen. The binders were aged according to thin film oven test (TFOT), pressure aging vessel (PAV) test and ultraviolet (UV) radiation. The results showed that the addition of antiaging additives could enhance the high-temperature stability of SBR modified bitumen by increasing in softening point and viscosity while declining in penetration. Antiaging additives have a positive effect on thermal and photo oxidation aging resistance of SBR modified bitumen. But the degree of improvement depends on the type and content of antiaging additive. Both the sulfoxide index (SI) increment and the butadiene index (BI) decrement of SBR modified bitumen $+1\%$ OEVMT $+3\%$ nano-ZnO (SOZ3) are smaller than that of a blank sample after all three aging modes, the result adding weight to the conclusion that the compound of nano-ZnO and OEVMT can efficiently enhance the performance of SBR modified bitumen to mitigate both thermal oxidative and photo oxidative aging.

This paper presents new models for computing the chloride-induced corrosion period based on combining Monte Carlo simulation and statistical analysis methods. The study is divided into two parts. The first part utilized Monte Carlo simulation to predict the probability of corrosion (1–200 years) for concrete containing metakaolin (MK) with different mixture proportions and concrete covers. Also, the effect of different mixture parameters (percentage of MK, binder content, and water-to-binder ratio) on the probability of corrosion was studied in this part. The second part adopted statistical analysis to develop models predicting the chloride-induced corrosion period (time to reach 10% probability of corrosion initiation) in various MK mixtures and identified the most significant factors affecting this period. Design charts were also developed using statistical analysis to facilitate and simplify the prediction of the chloride-induced corrosion period. The results showed that the probability of corrosion decreased as the percentage of MK increased. Also, using a lower W/B ratio or higher binder content in MK mixtures improved the effectiveness of MK to reduce the probability of corrosion. The results also showed that the most significant factor affecting the chloride-induced corrosion period was found to be MK replacement, W/B ratio, and binder content respectively, in order of significance. The developed models and design charts in this paper will help designers and engineers to better understand the influence and the importance of various mix design parameters of MK mixtures on the chloride-induced corrosion period estimation.

The mechanical strength of a fine-grained lateritic soil treated with CEMII/BM 32.5 N cement up to 9% by weight of dry soil and prepared at three different molding water contents was investigated by means of California bearing ratio (CBR), unconfined compressive strength (UCS), indirect tensile strength (TS), and triaxial shear tests. The effect of cement treatment on the microstructure of the lateritic soil was investigated by scanning electron microscopy (SEM) and Raman spectroscopy. The results indicated that cement improved the performance of lateritic soil, particularly at the optimum moisture content (OMC) and dry side of optimum (${\omega }_{\mathrm{DRY}}$), thus offering the possibility of using the tested lateritic soil in road pavement layers. Furthermore, soils with 6 and 9% cement addition satisfied the strength requirements so that lateritic soil can be used as a base course in rigid pavements. The results of triaxial shear tests revealed the existence of two types of behavior, namely, a ductile behavior for untreated soil and brittle behavior for cement-treated soil. These positive impacts are mainly related to the fact that cement addition gives way to the formation of ettringite, calcite, portlandite, and calcium silicate hydrates (afwillite and tobermorite), which derive principally from cement hydration.

In recent years, the environmental facet of industrial waste management has become imperative. The recycling of these residues in the civil construction sector is growing, since both industries have developed an increasing concern for the exhaustion of natural resources. In this scenario, one example is the ladle furnace slag (LFS), a by-product of the secondary refining of steel. It is mainly composed of calcium and calcium magnesium silicates. Thus, this research aims to develop a sustainable binder obtained from LFS as a substitution of hydraulic lime. In this sense, an extensive characterization of the LFS was carried out in its raw and processed forms. Subsequently, all the requirements for hydrated lime and hydraulic lime were verified according to Brazilian and Portuguese standards. Finally, mortars for coating and laying were produced with portland cement, lime, and the sustainable binder, and their main properties were evaluated in the fresh and hardened states. The chemical and mechanical properties of the sustainable binder were closer to those of the hydraulic limes. The obtained results indicate the technical feasibility of the use of LFS as binder for mortars in the replacement of lime.

In this study, the effect of specimen size on compressive strength of self-consolidating concrete (SCC) containing polypropylene (PP) fibers is experimentally examined. Six concrete mixtures with two strength levels (low and high strength) are proportioned. The specimens are geometrically similar, having circular cross sections of diameter 50, 100, 150, and 200 mm with a constant slenderness ratio of 2. Polypropylene fibers of two different lengths (6 and 12 mm) are added to SCC mixtures. As expected, an increase in specimen size leads to a reduction in strength for all specimens. However, the slope of reduction in strength decreases with the addition of PP fibers to concrete. Therefore the slope shows that the effect of increasing the specimen size diminishes after PP fibers are added to both low-strength and high-strength mixtures. In addition, three theoretical size effect models are assessed and new parameter values in the prediction models are proposed for SCC containing fibers.

Rehabilitating and preserving the current pavement networks have become top priorities for many highway agencies. The structural overlay is one type of rehabilitation solution widely used to improve the structural capacity of pavements. Selecting the proper overlay mixture with the desired performance plays a significant role in extending the service life of an existing pavement. This study focuses on evaluating the performance of overlay mixtures commonly used in rehabilitation projects in Oklahoma. The overlay performance was assessed by integrating laboratory tests with field distress surveys. Five mixtures varying in binder content, nominal maximum aggregate size, and reclaimed asphalt pavement content were identified. Laboratory performance of these mixtures was determined through conducting dynamic modulus tests, direct tension cyclic fatigue tests, Hamburg wheel tracking tests, and indirect tension creep and strength tests. The effect of mixture variables on stiffness and performance was investigated, and resistance of mixtures to fatigue cracking, thermal cracking, and rutting was evaluated. Also, the correlation between five different types of performance test results was investigated. It is recognized that Hamburg and direct tension cyclic fatigue test results are highly correlated, and the mixtures with less permanent deformation under cyclic loading are less susceptible to fatigue cracking. Also, a strong correlation between dynamic modulus and direct tension fatigue test results was found. The laboratory-estimated performance of the selected mixtures was then compared with observations from field distress over a period of time after placement of overlays. A few representative flexible pavement sections in the Oklahoma highway network rehabilitated with these overlay mixtures were identified, and their distress data were monitored. It was observed that field performance data are in a good agreement with laboratory evaluations, and the ranking of mixtures for cracking and rutting susceptibility captured in the laboratory correlates well with observations from the field. At the end of this study, a decision table is suggested for the use of laboratory tests in the selection of appropriate overlay mixtures. The decision tree is developed to prioritize the use of performance tests based on the condition of existing pavements and correlation between the performance test results.

The flexural fatigue behavior of an ultrahigh performance fiber-reinforced concrete (UHPFRC) is investigated. This UHPFRC is a self-compacting and industrially competitive version of an earlier material developed by the second author that is expensive because of the high cost of brass-coated steel fibers used in it. It is found that the distribution of fibers plays a crucial role in the fatigue resistance of this UHPFRC. Uniform distribution of fibers ensures that the material has a very high fatigue endurance limit (19 MPa)—more than 80% of its static flexural strength (24.36 MPa) at a mean stress of 44.5% (10.85 MPa)—but this decreases to approximately 64% (14 MPa) of the static strength (22.02 MPa) at a mean stress of 37% if the distribution is nonuniform with regions of few or no fibers.

This study aims to investigate the influence of aggregate homogeneity on the indirect tensile (IDT) strength of asphalt mixtures using imaging and discrete-element method. An aggregate homogeneity index, which was used to assess the aggregate homogeneity in asphalt mixtures, was briefly described, and the aggregate homogeneities of different asphalt specimens were assessed by the index. A micromechanical model for predicting the IDT strength was established by a discrete-element program called Particle Flow Code in Three Dimensions. On the basis of this model and by loading asphalt specimens along different directions, the influence of aggregate homogeneity on the IDT strength at low temperatures was simulated; the simulation results were verified by an actual IDT test. Results show that the IDT strength exhibits anisotropy. There is no obvious correlation between the aggregate homogeneity and the IDT strength. However, there is an obvious correlation between the aggregate homogeneity and the variation in the IDT strength.

Mechanical properties of strain-hardening cement-based composites (SHCC) subjected to impact and high-speed tensile loading were studied. The impact test setup was based on a free-fall drop weight on a three-point bending specimen. A servohydraulic high-speed tensile machine was used for tension tests. As the input impact energy increased from 6.7 to 67 J, absorbed energy increased from 0.7 to 3.6 J and remained constant at that level. Ultimate load and maximum deflection also increased with increasing input energy. Uniaxial tension tests on SHCC specimens were conducted at strain rates of 25, 50, and $100{\mathrm{s}}^{-1}$. Increases in tensile strength and strain capacity were observed with increasing strain rate. Digital image correlation (DIC) method was used to measure the full-field deformation in addition to the nature of the localized strain and shear lag region near transverse cracks. An analytical model was used to correlate the tensile and flexural impact responses and address the effect of localized failure on the overall sample response. The results indicate that the two test methods of impact and high-speed tension can be correlated by using a constitutive material model and that the correlation of the material properties under increasing strain rate with an increase in input impact energy can be addressed through cracking and size of the localization zone.

Dynamic modulus ($|E^{*}|$) is one of the primary required inputs for the mechanistic-empirical pavement design of asphalt concrete (AC) pavements. Prediction of $|E^{*}|$ using specific models and certain inputs has been proven to provide good accuracy and is valuable for states that do not have the equipment to conduct $|E^{*}|$ testing and/or do not have a $|E^{*}|$ database. However, when $|E^{*}|$ prediction is needed, it is still uncertain which model and material inputs provide good-enough or best accuracy, and what the significant influencing factors are for $|E^{*}|$ prediction. In this study, $|E^{*}|$ characterization of typical Alaskan asphalt mixtures was performed. In addition, the currently existing body of knowledge on $|E^{*}|$ studies conducted in the United States and other countries was reviewed and evaluated. Based on this evaluation, three commonly used models were selected for further evaluation of their $|E^{*}|$ prediction accuracy for 34 Alaskan mixtures. Various statistics were used for data analyses; however, results of the goodness-of-fit statistics such as $R^2$ with the reference to the line of equality were given the highest level of attention following the recommendations. It was found that using Level 3 inputs for two of the models could provide good-enough accuracy for $|E^{*}|$ prediction of Alaskan asphalt mixtures regardless of the influencing factors evaluated in this study. It is recommended that mixtures be grouped (e.g., hot mix asphalt, warm mix asphalt, with and without recycled asphalt pavement) if future modification of the predictive equations is needed.

Experimental methods for the characterization of shear strength and stiffness of both wood-based and glass-based or carbon-based composite materials are highly contested because shear properties are difficult to isolate experimentally. A comprehensive literature review on the subject is presented, considering methods for both structural composite lumber and traditional composite laminates. The researchers present a novel method for calculating shear strength, stiffness, and interaction parameters of laminated wood-veneer panels by coupling experimental data from tension and compression tests of multiaxial laminates with an optimization routine for two failure criteria theories from the literature. Optimal shear parameters are reported for both theories.

Cumulative fatigue damage caused by repeated loads is one of the important factors that leads to formation of asphalt pavement potholes after they have been repaired. Investigations show that a recurring pothole often starts along the bonding surface between the repairing material and the original asphalt pavement, and the bonding failure is closely related to the repetitive effect of the traffic load. This phenomenon indicates that fatigue damage exists along the bonding surface of pothole repairing structure. It involves fatigue resistance of the asphalt mix and the bonding material. The fatigue process of the asphalt mix can usually be divided into three stages of deceleration fatigue, constant-speed fatigue, and accelerated fatigue. Until now, the accelerated fatigue stage has not been precisely characterized. Based on the existing fatigue theory, the effects of material damage on pothole repairing structures were analyzed in this paper. The analysis was conducted on repairing composite beams by establishing a nonlinear viscoelastic-viscoplastic fatigue damage constitutive model. Three kinds of bonding materials were used in the composite beams to make a bonding property comparison. Results show that fatigue lives of repairing composite beams are typically affected by the bonding material and the stress ratio. The fatigue strain rate is correlated with the change of the stress ratio. Compared with previous models, the strain-fatigue life curve produced by the proposed model is better matched with test results. It is also proved that the proposed model can precisely describe the deceleration, constant-speed, and acceleration stages of fatigue damage, especially the third stage.

Compaction control for pavement foundations typically consists of determining the optimum water content and maximum dry unit weight from a Proctor test, and then specifies an acceptable water content and dry unit weight range in the field. Although this has become a widely accepted approach, it cannot provide the mechanistic parameters of the compacted structures. The purpose of this study is to examine the application for using gyratory compaction with an integrated pressure distribution analyzer (PDA) sensor kit for determining mechanistic compaction parameters that could be used to more directly support mechanistic-based earthwork compaction control. Correlations results are presented that link the moisture-density-undrained shear strength/resilient modulus of the gyratory-compacted specimens for loess (primarily silt) and glacial till (lean clay) embankment materials.

Pervious concrete is widely used in various fields because of its high permeability. Strength and permeability are two important design parameters for pervious concrete, but limited research has been conducted so far on their mutual relationship. A series of laboratory tests are carried out to demonstrate the effects of water–cement ratio, aggregate–cement ratio, and porosity on the properties of pervious concrete including strength and permeability in this study. In addition, a modified permeability testing method for pervious concrete is developed, as the existing permeability testing devices for pervious concrete have not considered the specimen–container interface leakage induced by the large number of open pores on the surface of specimen, thus affecting the testing precision of permeability.

In this study, the effects of pumice and metakaolin (MK) on the durability and microstructural properties of self-compacting concrete (SCC) are investigated. A total of 10 mixtures including different pumice and MK contents as cement replacement [0–15 and 0–10 by weight % (wt.), respectively] were designed. Fresh concrete tests, including slump flow, visual stability index, ${\mathrm{T}}_{50}$, V-funnel, and L-box, were carried out. Compression tests were performed to determine the mechanical properties. Water absorption, electrical resistivity, and rapid chloride permeability (RCP) tests were performed to assess durability properties. The microstructure of SCCs was studied via scanning electron microscope (SEM) images. The workability of SCC mixtures containing pumice and MK generally satisfied the fresh-state behavior requirements. With the inclusion of pumice, the compressive strength decreased at 28 days, whereas it increased significantly at 90 days. Most of the binary mixtures displayed strength enhancement over the control mix at ages of 28 and 90 days, and this improvement was more significant at 90 days. The SEM micrographs illustrated the packed pore structure of samples containing MK and pumice, which promoted the strength and durability properties of these mixes. The results suggest that, in general, the combined use of 10 wt.% pumice and 10 wt.% MK provides a suitable replacement ratio that enhances both the durability and mechanical properties of SCC.

A substantial amount of portland cement (PC) is required in grouting practice for soils and rocks. These grouting applications are relatively new areas in which PC could be substituted by high amounts of granulated blast furnace slag (GGBFS) and fly ash (FA) to produce grouts with low cost, environmental friendliness, good workability, and excellent long-term performance. In this study, rheological performance, i.e., flowability, minislump, setting time, bleeding capacity; mechanical properties, i.e., flexural strength, compressive strength, shear bonding strength, and shrinkage; and impermeability of cement-based grouts containing 60% GGBFS, 60% FA, or 20% $\mathrm{GGBF}+50\%$ FA were investigated. The fluidity, spreading ability, and stability of grouts were also studied in the presence of a superplasticizer (SP) by itself and in combination with an antiwashout agent (AWA). The range of the water-solid ratio was 0.4–1.2, and the curing durations were 28, 91, and, in a few cases, 182 days. The results show that fluidity, spreading ability, stability, and drying shrinkages of the cement-based grouts were improved by the incorporation of GGBFS (20%) + FA (50%). The SP and AWA should be used together to improve both fluidity and stability. The flexural strength, compressive strength, shear bonding strength, and impermeability of equivalent binary and ternary grouts were close to those of PC-only grouts at later ages. The use of Class C FA offers more benefits than the use of Class F FA. The applications of cement-based grouts containing GGBFS (20%) + FA (50%) are promising in geotechnical engineering.

Biaxial tension testing is an increasingly accepted tool to understand the mechanical behavior of architectural coated fabric membrane materials. However, different loading protocols in biaxial tests result in diverse results. This study investigates the different results between constant-force increment (CFI) and constant-rate (CR) loading protocols. Different loading procedures were proposed on a self-made biaxial tension tester to conduct systematic experiments. The mechanical behavior of a typical fabric was investigated by both CFI and CR loading. The stress-strain curves and their mechanical characteristics were compared. On the basis of test data, the authentic weft stress values in the CR loading protocol were observed to be 20% lower than the nominal load value. The elastic modulus determined by CR loading was significantly larger than that acquired by CFI loading. An obvious viscous effect is seen in the unloading stage under CFI loading. This did not arise under CR loading. Future work might focus on material to further strengthen the conclusion.

CSS-1H emulsions are the most commonly used slow-setting grades in Oregon. New engineered emulsions have recently been developed in Oregon to reduce tracking and increase interlayer shear strength (ISS). In this study, the performance of these emulsions, most effective application rates, and the effects of pavement surface texture and traffic/environment on ISS are evaluated. Results indicate that there are positive correlations between rheological tests and ISS from field cores, which generate a linear equation that can predict in situ ISS using the results of simple rheological experiments. Results show variances in application rates and uniformity by distributor trucks. Hence there is a need for unified guidelines on tack coat quality control and quality assurance (QC/QA) and construction practices.

Fly ash is the most generated coal combustion by-product (CCP) and causes the most substantial disposal issues. The current practice of landfilling these materials is costly and ultimately reduces available landfill space. The most desirable alternative to disposal is utilization. This alternative provides the economic benefit of the reduction or elimination of landfilling costs and supports sustainability through the reutilization of materials that would otherwise be considered wastes. Although the use of fly ash–soil mixtures as embankment fill is gaining more acceptance, traditionally there has not been wide use of these materials in other than small-scale applications. A primary reason for the limited use of fly ash–soil mixtures is that the geotechnical behavior of soil when mixed with fly ash is poorly understood. This paper presents the results of a study to develop generalized theory that can adequately predict the behavior of fly ash–soil mixtures. A mixture theory model was developed to predict engineering properties of mixtures based on the properties of the individual constituents. The developed mixture model implicitly considers the influences of physicochemical properties of the fly ash. Also, mixture theory–based consolidation and shear predictive models were developed to specifically predict geotechnical behavior of remolded fly ash–soil mixtures. Verification analyses indicate mixture theory is an effective approach to predicting consolidation and shear behavior of fly ash–soil mixtures.

Chloride-induced corrosion of reinforcing steel bars has a big impact on the performance of reinforced concrete (RC) structures subjected to saline environments, and it is essential to understand how chloride ions ingress in concrete. In this study, first, an experiment of chloride ingress in specimens under one-dimensional and two-dimensional diffusion was conducted in a climate chamber, and profiles of chloride concentration along the depth were obtained. Then, a mesoscopic model that considers environmental factors, i.e., temperature, relative humidity, and time of exposure, was developed to investigate chloride diffusivity in concrete. Concrete is treated as a three-phase composite: cement paste, aggregates, and interfacial transition zones (ITZs). It is assumed that chloride diffusivity can take place only in the cement paste and ITZ, whereas the aggregate is considered impermeable. Influence of ITZ thickness, i.e., 0, 50, and 80 μm, on chloride diffusivity in concrete is examined. Chloride concentrations, which are simulated with the mesoscopic model with consideration of environmental factors, are compared with previous test data. Finally, time to corrosion initiation of RC structures is predicted based on the developed mesoscopic model considering the distribution of aggregates, and the influence of environmental factors on the chloride concentration of the corrosion initiation point is investigated. It is found that ITZs have a significant effect on chloride diffusivity in concrete. However, different thicknesses of the ITZ, i.e., 50 and 80 μm, have a small impact on the chloride diffusivity in concrete; hence, an ITZ thickness 80 μm is recommended for efficiency. The simulation results with consideration of the environmental factors are in good agreement with the test data, and the corrosion initiation point on the surface of the steel embedded in concrete varies because of the distribution of aggregates. Corrosion initiation time decreases with increases in the water-to-cement (w/c) ratios but increases with increases in the thickness of cover, temperature, and humidity. An increase in either temperature or relative humidity can lead to a significant increase in the chloride concentration of the corrosion initiation point on the steel.

Piezoelectric energy harvesting in pavement is an advanced energy saving technology. It is carried out by laying the piezoelectric material in the pavement structure and converting the mechanical energy into electrical energy. The current energy harvester has difficulty meeting the complex requirements of pavements. In order to develop the pavement piezoelectric energy harvesting technology, in this paper, a stacked mode for a piezoelectric energy harvester is designed. The computer-controlled pressure testing machine (WHY-2000, Shanghai Hualong Test Instruments Corporation, Shanghai, China) was used to test the compressive property and the one–third-scaled accelerated instrument Model Mobile Load Simulator (MMLS-1/3) was used to test the fatigue properties of the piezoelectric transducer. Results showed that the designed piezoelectric transducer could bear loadings up to 150 kN, which can meet road traffic loading requirements. The piezoelectric properties of the transducer remain good after 100,000 cyclic loadings. The indoor laboratory test and the on-site test show that the piezoelectric transducer can work in real pavement in actual traffic conditions. The open circuit voltage can reach 280 V, which can provide enough electricity for sensing systems in the pavements. In all, the proposed new piezoelectric transducer provides a promising future for green energy use in the pavement industry.

Roller-compacted concrete (RCC) is widely used as an economical and durable pavement to withstand heavy loads on large areas or logging roads. The use of by-products from the cogeneration process of the paper industry, such as biomass-fly ash (BFA) as alternative supplementary cementitious materials and biomass-bottom ash (BBA) as an alternative sand, in RCC production is a promising approach in terms of economic and environmental aims. Laboratory investigations showed that two mixtures containing $10\%\mathrm{BFA}+50\%\mathrm{BBA}$ and $20\%\mathrm{BFA}+50\%\mathrm{BBA}$ with a water-to-binder ratio of 0.35–0.37 can meet the required consistency and 7-day flexural strength. However, most laboratory optimization works must be validated in situ using representative construction equipment, casting methods, and exposed conditions. Thus, these two RCC mixtures were selected for an in situ assessment through the construction of a storage slab with an area of $792{\mathrm{m}}^2$ and thickness of 0.3 m in Sherbrooke, QC, Canada. Fresh properties, isothermal deformation, internal temperature, and strength up to 308 days were measured. Core samples were cut from the slabs at ages of 28 and 308 days to follow up the concrete behavior with time. The compressive strength of the cores at an age of 308 days reached 32.9 and 30.4 MPa for the two tested mixtures, respectively. Finally, construction of the slab has allowed the recycling of 21 t of BFA and 88 t of BBA, which significantly contributes to the sustainability of the production of RCC and management of waste from the pulp and paper industry.

In this paper, the micromorphology of asphalt binders with wax warm additives is investigated by atomic force microscopy (AFM) and optical microscopy before and after aging. Performance grade (PG) 64-22 asphalt binder is used to produce warm mix asphalt binder containing two wax additives, LEADCAP and Sasobit, and then the warm binders are artificially short-term and long-term aged using the rolling thin film oven (RTFO) and pressure aging vessel (PAV) procedures. Microstructure and rheology properties of the binders are characterized using AFM tapping-mode imaging techniques and the Superpave asphalt binder test, respectively. The results of this study indicate that (1) the wax type and aging level have a significant effect on the micromorphology of the binders; (2) the binders with LEADCAP exhibit no “bee-like” structures; (3) the addition of Sasobit into the binder increases the dimension of the bee-like structures regardless of the aging level and binder types; (4) the dispersed domain has higher stiffness than does the para phase; (5) the aging of the binders increases the bee shape but reduces the number of the structures; (6) the expanded peri phase is observed after the aging; and (7) the binder roughness increases after aging and shows a good relationship with the stiffness results.

The recent depletion of high-quality and well-graded natural-aggregate sources is one of the factors compromising the production of good-quality shotcrete. For this reason, the use of various alternative aggregate sources has been receiving increasing attention as one of the promising solutions for this issue. In this study, the feasibility of using crushed aggregate obtained as a by-product of tunnel-excavation processes in wet-mix shotcrete (WMS) is evaluated based on laboratory tests. To fulfill this aim, efforts have been made to evaluate rheological properties of WMS mixtures incorporating crushed aggregates because shotcrete rheology is recognized as one of the most significant components affecting actual shotcrete behavior such as pumpability and shootability. Other tests performed include air content, slump, and flow. The acceptability of crushed-aggregate WMS mixtures with four standard gradations were evaluated first. Then, allowable gradation ranges for WMS mixtures made with crushed aggregate were suggested based on modified Dinger-Funk gradations and prescribed WMS performance criteria. Results indicate that the use of crushed aggregate may be a suitable measure effectively meeting both industrial demands and shotcrete performance requirements.

Capillary flow through discrete cracks is the main mechanism by which healing agents embedded in cementitious matrices travel to zones of damage to afford the host matrix a healing ability. However, the nature of the interaction between the healing agents in their fluid state and the host matrix is unknown and may limit the ability to predict the behavior and efficacy of self-healing systems. This study considered the capillary flow characteristics of a low-viscosity cyanoacrylate and ground granulated blast furnace slag in a water suspension using glass capillaries and channels formed from a range of concrete mixes. Both healing agents conformed closely to Poiseuille’s law and experienced increases in viscosity over the 40-min period that they were exposed to a cementitious environment. Numerical simulations of the capillary rise response of the healing agents in a discrete crack confirmed that the rate of damage and degree of saturation of the concrete element have a significant influence on the choice of healing agent in the design of self-healing systems.

Warm mix asphalt (WMA) is a green technology which has the potential to replace hot mix asphalt (HMA) because it reduces greenhouse gas emissions and energy consumption by lowering the temperature at which asphalt mixtures are produced and placed. During the design process, evaluation of the mix design and mechanical properties of WMA mixtures is necessary. Therefore, the ability to quantify compactability would be very useful. This paper presents details on the evaluation of asphalt mix design, workability, and mechanical properties of asphalt mixtures modified with nonfoaming WMA additives at lower working (mixing and compaction) temperatures. Further, it seeks to provide a wider gap between mixing and compaction temperatures to ensure that WMA mixtures are suitable for longer haul distances. Asphalt mix design properties were evaluated by the Superpave method for various design gyrations ($N_{\mathrm{des}}$), and workability properties were evaluated in terms of Superpave gyratory compactor (SGC) densification indices using the Bahia and locking point methods. Mechanical properties such as resistance to moisture-induced damage were evaluated by the tensile strength ratio (TSR) approach, rutting resistance was evaluated by a laboratory wheel tracking test using a wheel rut tester (WRT), and flexural fatigue characteristics were evaluated by four point bending using a repeated load testing (RLT) machine. The effects of nominal maximum aggregate size (NMAS), working temperature, and type of mixture on the properties of WMA mixtures were investigated. The experimental results were statistically analyzed to identify the major influencing factors and their significance.

Recently, a new soil improvement method to use a microbially induced calcium carbonate precipitation (MICP) process to generate biocementation in sand has been developed. In this method, the properties of biocemented soil are controlled by the calcium carbonate content produced through the MICP process. Various methods have been used in the literature to determine the calcium carbonate content in soil. However, the calcium carbonate content determination can be affected by the methods used and this effect has not been studied so far. In this paper, six different methods that can be adopted to measure the calcium carbonate content are examined experimentally: the titration, inductively coupled plasma (ICP), X-ray diffraction (XRD) TOPAS, thermogravimetric analysis (TGA), ASTM, and washing methods. The titration and ICP methods give the lowest value and the washing method the highest value. The other three methods, XRD TOPAS, TGA, and ASTM, produce values in between and the differences among the values measured by those three methods are small.

In this paper, shrinkage and fracture properties of 100-MPa ultrahigh-strength steel fiber-reinforced concrete internally cured with presoaked lightweight aggregate (PSLWA) are evaluated through shrinkage and bending tests. The results show that by using PSLWA to partially replace normal-weight aggregates, the shrinkage at 28 days after casting under sealed and dry conditions can be reduced from 600.7 to $274.2\mathrm{\mu m}/\mathrm{m}$ and from 706.6 to $373.4\mathrm{\mu m}/\mathrm{m}$, respectively. However, the introduction of lightweight aggregate (LWA) will lead to reduction of cracking, tensile, and flexural strength even with less negative impact on compressive strength. Adding steel fiber into the high-strength concrete can significantly improve fracture performance of the concrete even at 1% in volume content. These improvements present as increases in displacement at bending peak and in fracture energy determined from their stress-crack opening relationship.

The use of warm mix asphalt as an environmentally friendly alternative to hot mix asphalt is quickly building credibility and notoriety. Many technologies are being investigated that allow asphalt to be produced at a lower temperature. One warm mix technology currently being researched is the use of foamed asphalt binder. The foaming process expands the binder temporarily as injected water boils and expands. One limitation of this process is the minimum temperature at which asphalt can be foamed. The objective of this study was to conduct a preliminary study on the performance of methanol foamed asphalt binders and mixtures to reduce production temperature at a high level. According to this, the workability, rutting potential, aging performance, and moisture susceptibility were investigated. The results suggested that the methanol foamed asphalt had visibly better workability than control binder by lowering the mixing temperature by as high as 40°C. However, the rutting potential and moisture susceptibility may be compromised due to the lower aging and weak asphalt-aggregate interaction under low mixing and compaction temperatures. The mass loss results indicated that there was no methanol remaining in the binder after rolling thin film oven (RTFO) aging. Anti-stripping additives were recommended to be used for the methanol foamed asphalt mixtures to improve resistance to moisture damage.

This paper explores the beneficial use of low-reactivity coal fly ashes as cementitious binder in mortars without heat activation. A uniform design scheme was employed for the statistical design of experiments. Predictive models were developed to quantify the influence of mix design parameters on the compressive strength of fly ash mortars and enable the optimization of mortar designs. The slump flow and the 28-day surface resistivity of fly ash mortars were also studied. The first group of mortar specimens was fabricated using Class C and Class F coal fly ashes and admixtures intended to improve the strength and durability of hardened mortar. In the absence of chemical activation, these fly ash mortars exhibited a relatively low 28-day compressive strength in the range of 2.9–20.5 MPa. The second group of mortar specimens was fabricated using the same Class C fly ash along with the following chemical activators: sodium silicate, quicklime, calcium chloride, and sodium sulfate. Admixing chemical activators into fly ash mortars led to a noticeable improvement in their mechanical properties, with a 28-day compressive strength in the range of 16.8–33.6 MPa. Microscopic examination was conducted to shed light on the hydration behavior of fly ash particles using an electron probe microanalyzer. The results revealed the active role of chemical activators in promoting the dissolution of fly ash particles and the formation of hydration products.