Journal of Materials in Civil Engineering

Experimental investigations are carried out on plain concrete and fiber-reinforced concrete (FRC) with different volume fractions (0.5, 1, and 2%) of steel fibers to evaluate their fatigue behavior. Three load ranges, namely 20–65%, 20–75%, and 20–85% of ultimate load, are considered for studies under fatigue loading. Unified stress-number of cycles (S-N) expressions are proposed for estimation of flexural fatigue life of plain concrete as well as FRC based on the data obtained from the experimental investigations carried out in the present study and the S-N expressions reported in the literature. Influence of volume fraction of fibers is also incorporated in the S-N expression proposed for estimation of fatigue life of FRC. Hence, from a single expression based on the percentage of fiber volume fraction, fatigue life of FRC can be estimated. Numerical simulations are also carried out on plain concrete and FRC to estimate the fatigue life based on fatigue damage as well as a fracture-mechanics approach. Fatigue life estimated using numerical models adopted in this study correlates well with the experimental results.

This study focuses on the reuse of waste ferrochrome (FeCr) slag as a partial replacement for sand in the production of cement mortar with improved thermal and mechanical properties. Sand was replaced by FeCr slag in different percentages ranging from 0 up to 20% (by weight). The flowability test was performed to evaluate the mortar’s behavior in a fresh state. Tests for the compressive strength, flexural strength, drying shrinkage, thermal conductivity, and specific heat of the blended mortars have been conducted according to ASTM standards at 3, 7, and 28 days of curing. X-ray diffraction (XRD) was utilized to examine the phase composition. The scanning electron microscope (SEM) was used for inspecting the microstructure changes of the hardened samples. The results revealed considerable improvements in the compressive and flexural strengths; improvement ratios of about 33 and 39% were attained respectively at 20% FeCr slag replacement after 28 days of curing. The drying shrinkage generally decreased with increasing replacement of sand by FeCr slag. FeCr slag acts to increase both the thermal conductivity and specific heat effectively. FeCr slag caused remarkable modifications in the microstructure of the blended mortars.

From the rheological behavior of bitumen, one can understand the physical properties of water-foamed bitumen used in warm mix asphalt. Previously, rheological behaviors of water-foamed bitumen such as apparent viscosity, agitation torque, and shear rate have not been well documented. The objectives of this study are as follows: (1) evaluating the accuracy of the cup-and-bob test with a dynamic shear rheometer to investigate the rheological behavior of water-foamed bitumen, (2) analyzing the rheological behavior of water-foamed bitumen at various temperatures, and (3) proposing an optimum water content that decreases the apparent viscosity and required agitation torque of water-foamed bitumen. Bitumen with various water contents (ranging from 0.0 to 3.0% bitumen content by mass) were prepared for rheological testing. The optimum water content at each of these foaming temperatures was determined based on the testing results. This study concludes that the current cup-and-bob test methods accurately describe the rheological behavior of water-foamed bitumen. Within the accepted water content range, the apparent viscosity and required agitation torque of water-foamed bitumen decrease more dramatically as water content increases.

Pond ash (PA) and cement kiln dust (CKD) are major dust products from thermal power stations and cement manufacturing industries and pose disposal difficulties. This research work focuses on the geotechnical properties of pond ash mixed with cement dust and polypropylene (PP) fiber. Various experimental tests, including standard Proctor test, California bearing ratio (CBR) test, direct shear test, and triaxial shear tests, were performed. Pond ash was mixed with 10, 15, 20, 25, and 30% of CKD and 0.5, 1, and 1.5% polypropylene fiber. Standard Proctor tests were carried out on various proposed proportions in order to obtain the effective mix. Original pond ash maximum dry density and optimum moisture contents are $1.45\mathrm{g}/{\mathrm{cm}}^3$ and 23%, respectively. The mix of 75% PA, 25% CKD, and 1% PP fiber produced the maximum dry density. The CBR values increased gradually up to 80% for up to 25% CKD and 1% PP fiber. The shear strength parameters were determined using direct shear testing. The shear strength parameters of cohesion ($c$) and angle of internal friction ($\varphi$) obtained for the mix of 75% PA, 25% CKD, and 1% PP fiber were $5\mathrm{kN}/{\mathrm{m}}^2$ and 39.45°. The same composition was tested in triaxial shear tests under consolidated drained conditions, and shear strength parameters varied slightly. The mix of pond ash, cement kiln dust, and PP fiber can be used for highway embankment construction to strengthen its layers, low land area reclamation, as a structural fill in reinforced earth walls, and backfill material for conventional retaining walls.

This paper presents expressions for the principal effective stresses generated around a cylindrical cavity expanded in plane strain and undrained conditions in modified Cam-clay (MCC). The assumption made in the present analysis is that Poisson’s ratio, $v^{\prime }$, remains constant throughout the shearing process. Theoretical expressions are first applied to the simulation of two cylindrical cavity expansion tests in $K_o$ normally consolidated remolded Boston blue clay modeled as MCC. Thereafter, the paper analyzes field test results obtained by means of pressuremeter tests in a sensitive clay of Quebec. Effective stress paths, derived from application of Palmer’s total stress approach and the measured pore water pressures, are compared with theoretical curves obtained by assuming that the sensitive clay obeys an overconsolidated MCC model. Shear stress–shear strain curves deduced from Palmer’s approach are compared with the theoretically derived MCC relationships.

Marine clay deposits in Busan are subjected to artesian pressure from an aquifer. To estimate the effects of artesian pressure on the consolidation behavior of drainage-installed deposits in Busan, a series of large one-dimensional (1D) column tests with soft marine clay subjected to artesian pressure was carried out. Undrained shear strength and water content of clays were measured after the experiments. A finite-element method was also used to analyze consolidation behavior of the column tests and field embankment. During the consolidation process, the undrained shear strength of the soft marine clay subjected to artesian pressure increased less due to a lower increase in effective stress, whereas the water content of the clay subjected to artesian pressure was higher than that of soft clay without artesian pressure. The experimental results also showed that settlement in soft marine clay with artesian pressure was larger than that in soft clay without artesian pressure because artesian pressure contributed to preventing shear strength development, which resulted in lower soil stiffness. Numerical results were in good agreement with the experimental test results and a case of field embankment subjected to artesian pressure. It was found that artesian pressure acting on soft marine clay deposits affected time-dependent consolidation behavior, development of shear strength, and changes in the water content of the clays.

A laboratory investigation evaluates the potential of using stabilized fly ash from municipal solid waste incinerators (MSWIs) as a filler in asphalt mixtures. Nine asphalt mixtures composed of the same aggregate gradation and three different asphalt binders and three different fillers (limestone and two stabilized fly ashes) are prepared and tested. A chemical and mineralogical investigation characterizes the fillers before and after mixing with asphalt binders. The behavior of the mastics at low temperatures is estimated by a bending beam rheometer (BBR) test. The mixtures’ cracking behaviors at intermediate temperature are evaluated using the HMA fracture mechanics model. Results show that stabilized fly ash obtained from MSWIs can be reused as a filler in asphalt mixtures if the fly ash is subjected to a water leaching procedure to remove soluble salts. Mechanical properties of mixtures containing washed fly ash as a filler are in very good agreement with results obtained from the same mixtures containing traditional filler.

The main aim of this research is to evaluate the applicability of ponded ash in the production of backfill material. Many experiments were conducted to analyze both fresh and hardened characteristics of backfill material developed from various ponded ash–sand ratio, cement, and air foam contents. Then, the behavior of the material in the actual field experiment was investigated through light falling weight deflectometer and excavation tests. All mixtures yielded excellent flowability performance, ranging from 200 to 250 mm. The compressive strength was found to increase as ponded ash and cement contents increased, but the strength decreased with an increase in air-foam content or number of freeze–thaw cycles. From the actual on-site experiment results, it is feasible to use up to 100% ponded ash in the backfill material as an economical alternative to the compacted granular fill.

The purpose of this work is to investigate the resistance of alkali-activated metakaolin (AAMK) paste specimens blended with different amounts of quartz powder (QP) against different environmental conditions. Metakaolin (MK) was partially substituted with QP at levels of 10, 20, 30, and 40%, by weight. After initial curing, specimens were exposed to different conditions including air, potable fresh water, and seawater up to 12 months. Compressive strength before exposure as well as strength deterioration ratio (SDR) after exposure were determined. The mineralogical compositions for selected mixtures before and after exposure to seawater attack were identified by X-ray diffraction (XRD) and thermogravimetric analysis (TGA) and compared with those cured in lab air. The microstructure and morphology were identified using scanning electron microscopy (SEM). The results showed that the incorporation of QP in MK-based geopolymers seemed as promising candidates for marine structure applications.

Antimicrobial concrete is an initial and effective measure to control microbially induced deterioration (MID) of concrete. In this study, five kinds of bactericides were added to concrete, and the changes in weight, strength, and surface pH, as well as the micro morphology, mineral composition, and pore structure of concrete in artificially intensified sewage were investigated. Furthermore, the sterilizing rate of bactericides in sewage, the retention rate of bactericides in concrete, and the distribution of dead and live microbes within the biofilms were also analyzed. The results show that copper phthalocyanine (CP) has the best effect on concrete’s resistance to MID. After 3 months of sewage corrosion, the mass loss and strength of concrete treated with CP is about 40 and 200% of that of plain concrete, respectively, and the surface pH is still as high as 10.6, whereas that of plain concrete is almost close to neutral. This is not only due to the high sterilizing effect and low dissolution rate for CPC in sewage; the increase of concrete strength after adding CP also makes some contribution to its high resistance to MID. MID behaviors of concrete with sodium tungstate and zinc oxide are inferior to that of concrete treated with CP. However, the cost of sodium tungstate is five to six times as high as that of the other bactericides, and its bactericidal effect on microbes in sewage is worse. The mass losses of concrete with sodium bromide and dodecyl dimethyl benzyl ammonium chloride reach as high as 8.03 and 9.73% after sewage immersion, and their strength shows no obvious improvement in comparison to plain concrete. Moreover, in the long run, sodium bromide is not suitable for concrete to fight against sewage-induced deterioration due to its high dissolution rate, and dodecyl dimethyl benzyl ammonium chloride is just one kind of liquid bactericide and is not suitable for use in preparing concrete. The results obtained are expected to provide some theoretical basis for the application of bactericides in concrete against MID.

The performance of waterproof and cohesive material significantly affects the service life of concrete bridge deck pavement. In this paper, six kinds of waterproof and cohesive materials including epoxy asphalt, AMP-100, styrene-butadiene-styrene (SBS)–modified asphalt, and asphalt rubber (dosages of rubber power are 17, 19, and 21% respectively) were measured via oblique shear test, pull-off test, and shear test after loading under different test conditions. The impermeability and the influence of aging on material performance were studied. The viscosity and strength characteristics of epoxy asphalt were also studied at different curing times and temperature conditions. Results show that the optimum dosages of epoxy asphalt, AMP-100, SBS-modified asphalt, and asphalt rubber with 17, 19, and 21% rubber powder are 0.9, 0.3, 0.5, 1.0, 0.5, and $0.5\mathrm{kg}/{\mathrm{m}}^2$, respectively. The shear strength value of epoxy asphalt is the largest at 25°C, followed by SBS-modified asphalt. The shear strength and pull-off strength of several materials decline at different levels under the condition of high temperatures or being soaked in water. The order of shear failure life of the selected waterproof and cohesive materials is epoxy asphalt > SBS-modified asphalt > asphalt rubber (19%) >AMP-100. In various waterproof and cohesive materials, the shear strength and pull-off strength of epoxy asphalt after the aging of a specimen are the largest. Epoxy asphalt shows a good waterproof property under traffic load after the asphalt mixture has been paved. The viscosity change characteristic of epoxy asphalt is closely related to the temperature and curing time. The pull-off strength reaches its peak value after curing for 30 min, which is earlier than shear strength. The epoxy asphalt has a significant performance advantage as a waterproof and cohesive material for a concrete bridge deck.

Electromagnetic noise due to undesirable interferences from electronic devices, infrastructures inherent to smart homes, buildings or cities, computer networks, or medical diagnostics has become a serious concern for the construction industry. A straightforward measuring system that allows one to determine the electromagnetic shielding of construction materials has been designed and implemented. Concrete or mortar panels containing reinforcing grids or diverse additives were fabricated and so characterized. The higher electromagnetic shielding values are obtained for panels containing over 15% metallic fibers and those reinforced with grids with a sieve area below $150{\mathrm{mm}}^2$. Depending on the type and percentage of additive or reinforcement included, frequency-dependent behaviors have been observed within the measured spectrum, which encompasses the frequency range used in modern communications systems. In addition, in order to demonstrate the capability of characterizing actual materials without any previous adaptation to the measuring technology requirements, commercial boards have been characterized as received.

In this study, two types of modified asphalts were prepared via two different approaches, using as modifiers waste rubber and plastic and other raw materials. One approach followed a two-step mechanism of melting-blending thermal plastic elastomers (TPE) with the raw materials, which included waste rubber powder, plastic, styrene-butadiene-styrene, and plasticizer. The second approach involved the direct mixing of asphalt with the mixture of raw materials in a single step. From a comparison of the microperformance and macroperformance indices of the modified asphalts, it was found that the high-temperature preparation for the TPE polymer alloy–modified asphalt resulted in the relatively high aging of the modifying material, leading to poor performance. The asphalt prepared via the compound-modified approach exhibited better performance indices and distribution of the modifier in the base asphalt. The modified asphalt samples were characterized by atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FT-IR) and fluorescence microscopy (FM) techniques, which helped in the interpretation of the experimental data, textural characterization, and preparation techniques (melt-blending and direct mixing). The present approach could be deemed helpful in improving and optimizing the existing methods of rubber–plastic alloy-modified asphalt preparation, the specific quantities of the modifiers, and the modification parameters used in the asphalt-modifying industries, in order to achieve the best performance that meets market demands.

The effect of limestone powder content on the ${\mathrm{CO}}_2$ curing degree (the carbonation rate after the ${\mathrm{CO}}_2$ curing process), compressive strength, reaction products, and microstructure of concrete cured in a ${\mathrm{CO}}_2$ environment were investigated in this study. Various proportions of limestone powder (0, 10, 20, 30, 40, and 50%) were blended in concrete as partial mass replacement for cement. Concrete specimens with dimensions of $\phi 50\mathrm{mm}\times 100\mathrm{mm}$ were manufactured and initially preconditioned at $20\pm 2°\mathrm{C}$ with a relative humidity (RH) of $65\pm 5\%$ and circulated air for durations up to 5 h. ${\mathrm{CO}}_2$ curing was then carried out for 1–3 h in a chamber at a pressure of 0.2 MPa. Results showed that concrete incorporating limestone powder demonstrated a higher ${\mathrm{CO}}_2$ curing degree as compared with those without limestone under the same conditions. The remaining water-to-binder ratio was also critical for the ${\mathrm{CO}}_2$ curing of concrete regardless of the incorporation of limestone powder. There may exist an optimal remaining water content or remaining water-to-binder ratio for which fast diffusion and dissolution of ${\mathrm{CO}}_2$ results in the highest curing degree of concrete. Concrete incorporating limestone powder demonstrated higher optimal remaining water-to-binder ratio as compared to those without limestone. Quadratic response surface analysis indicated that a combined effect of the limestone powder content and the remaining water-to-binder ratio, rather than the individual factors, play a critical role in improving the ${\mathrm{CO}}_2$ curing degree of the concrete specimens incorporating limestone powder. The microstructure and reaction products of the ${\mathrm{CO}}_2$-cured concrete were characterized by thermogravimetric analysis (TG), Fourier transform infrared (FT-IR), X-ray diffraction (XRD), and scanning electronic microscopy/energy-dispersive spectroscopy (SEM/EDS) examination. It was found that limestone powder with a maximum particle size of $20\mu \mathrm{m}$ could serve as a nucleus for precipitation of reaction products, especially calcium carbonates, and induce the consumption of calcium silicates (${\mathrm{C}}_3\mathrm{S}$ and ${\mathrm{C}}_2\mathrm{S}$). Incorporating limestone powder can also generate more carbonation products and make the microstructure less porous.

The main objective of the study was to characterize the fatigue and rutting behavior of polymer-modified asphalt binders, by determining the effect of temperature and stress/strain levels on the results of multiple stress creep and recovery (MSCR) and linear amplitude sweep (LAS) test. The modifiers included styrene butadiene styrene (SBS) and ethylene vinyl acetate (EVA). These effects were quantified by means of nonrecoverable creep compliance ($J_{\mathrm{nr}}$) and percent recovery ($R$) values in MSCR, and fatigue power law model Parameters $A$ and $\alpha$ in LAS test. The results were also compared with the conventional binders, VG 10 and VG 30. A new methodology has been proposed to rank the binders based on different sets of priority given to various test parameters. From the laboratory investigation it was found that EVA-modified binder showed good performance at high temperatures, with the lowest $J_{\mathrm{nr}}$ values, but was found to be highly strain susceptible at intermediate temperatures. Stress levels had significant effect on the $R$ values in the MSCR test. The fatigue life for all the binders in the LAS test was found to be sensitive to the values of $A$ and $\alpha$. Conventional binders were found to have higher fatigue life than EVA-modified binders at intermediate temperatures and higher strain levels. SBS-modified binder performed well in both rutting and fatigue. The proposed methodology for evaluation of ranking can be successfully used to choose the best performing binder from a set of different binders based on the priority given to different tests. The usefulness of the methodology has been demonstrated using a suitable example.

Several studies have investigated the use of nanomaterials to modify asphalt binders and achieve improved properties. It is possible that in some cases nanomaterials do not disperse and agglomerate within the asphalt binder. In such cases, the benefits from the addition of these nanoscale modifiers are limited and are likely driven by mechanisms that can potentially be achieved using larger filler-sized materials. This study investigates the dispersion characteristics of a selected set of nanomaterials in surrogate solvents that represent a physicochemical environment similar to that of asphalt binders. The study also investigates the influence of these nanomaterials on the performance characteristics of asphalt binders. Results show that among the nanomaterials evaluated, those that tend to disperse relatively better in the surrogate environment, i.e., retain their nanoscale identity better relative to others, also tend to show a relatively better performance in terms of rheological properties. This is especially true at low temperatures.

This study aimed to investigate the performance of asphalt mixtures after natural bentonite clay partial replacement of mineral filler portion of aggregates. Different bentonite contents were used to replace the mineral filler by total weight of its portion of total aggregates, namely, 5, 10, 15, and 20%; additional bentonite contents were conducted for the stability test, namely, 25 and 30%. Marshall stability, flow, bulk density, hydraulic conductivity, and indirect tensile strength (ITS) tests were performed. Results showed that replacing mineral filler by natural bentonite clay in asphalt mixtures leads to the increase of density and stability, which increased to 11.57 kN for mixtures containing 15% bentonite (compared with 9.17 kN for the control specimen), with 23% loss when soaked with water for 24 h. Results indicate an increase in both flow and ITS values and reduction in hydraulic conductivity of the modified mixtures compared with control specimens.

Marsh cone and mini-slump flow tests are used widely to optimize the paste phase of self-compacting concrete (SCC). These tests are used to define the saturation point of a superplasticizer (SP) and to investigate their compatibility with cement and fine materials. However, neither tests provide a direct assessment regarding the segregation tendency of cement paste at high SP dosages. In this paper, a visual index was proposed to select the optimum dosage of polycarboxylate (PCE) superplasticizers for SCC paste and concrete mixtures. The method is based on the observation that the cementitious matrix undergoes an internal disruption once the optimum SP dosage is surpassed. This disruption is manifested with time in the form of bleeding and segregation, with a gradual formation of a white layer at the top surface. This phenomenon was captured photographically for mixtures with increasing SP dosage and presented as a visual deposit surface index (VDSI) to highlight the segregation tendencies of the mixtures at increased SP dosage. VDSI can be used to identify the saturation dosage of SP with results comparable to those obtained from the mini-slump flow test. The method is shown to be valid for mixtures incorporating cement alone or blended with limestone dust (LSD) and natural pozzolan (NP). It was successively applied to both cement paste and concrete mixtures.

The rapid development of urban areas and the increase in construction activities have resulted in a scarcity of land with favorable soil conditions, necessitating the use of locally available weak soils for construction activities through stabilization techniques. This study introduces a new material, areca fiber, and its suitability as soil reinforcement. Although areca is available abundantly in many parts of the world, its application in geotechnical engineering has not been explored. In the present study, bottom ash (BA) is used as a stabilizing agent, and the suitability of natural areca fiber as reinforcement is demonstrated through detailed experimental investigations and reliability analysis. The test method includes compaction tests, unconfined compression strength (UCS) tests, California bearing ratio (CBR) tests, and split tensile strength tests. The BA content was varied from 0 to 40%, the fiber content was varied from 0 to 1.5%, and the corresponding performance assessment was done. A small amount of cement (3%) was also added to improve the pozzolanic reaction. The UCS and split tensile strength tests were conducted on samples at different curing periods with a maximum curing for 90 days, whereas CBR tests were conducted after 7 days of curing for both soaked and unsoaked conditions. There was considerable increase in UCS, CBR, and split tensile strength of the soil with addition of BA, and the strength values increased tremendously in the presence of areca fiber. Mineralogical and microstructural studies were conducted on the stabilized soil sample using X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis. These results confirmed the formation of cementitious compounds in the XRD patterns and showed development of dense matrix in the SEM images. The performance of the modified subgrade soil was validated using a reliability approach, which found that the soil subgrade with BA and areca fiber can certainly be used as pavement material for low-volume applications.

This study presents geotechnical characteristics of a low-plasticity clay improved by xanthan gum biopolymer, which is an innocuous microbially induced polymer with high tensile strength. The samples were prepared by mixing clay at various proportions by weight of xanthan gum biopolymer (0, 0.5, 1.0, 1.5, 2.0, and 3.0%), and then tested at the end of different curing times (0, 7, 28, and 56 days). To demonstrate the influence of xanthan gum biopolymer on the clay, an intensive series of unconfined compressive strength, laboratory vane shear, fall cone, oedometer, permeability, swelling, and shrinkage tests were carried out on the samples. According to the testing results, strength of the clay samples increased with both the content of biopolymer and the curing time. The test results also indicated that permeability of the samples with xanthan gum biopolymer is lower, while the compression index and swelling percentage values are higher than the samples without treatment. Evidently, xanthan gum biopolymer application was identified as an environmentally friendly and sustainable alternative material for improving a clay.

In this study, fly ash was added to residual soil to produce soil–fly ash geopolymer bricks. This study investigated the effects of fly ash/soil, alkali activator/ash, ${\mathrm{Na}}_2\mathrm{Si}{\mathrm{O}}_3/\mathrm{KOH}$ (or NaOH), additional water content, curing condition, and curing temperature on the compressive strength of soil–fly ash geopolymer. The results showed that the optimum compressive strength was obtained when the ratios of alkali activator/ash, ${\mathrm{Na}}_2\mathrm{Si}{\mathrm{O}}_3/\mathrm{KOH}$ (or NaOH) and additional water were 0.6, 0.5, and 10% respectively. A higher amount of alkali activators was required for strength development in soil–ly ash geopolymer than conventional fly ash-based geopolymers. The formation of the rigid structure at low ratios of alkali activator/ash and ${\mathrm{Na}}_2\mathrm{Si}{\mathrm{O}}_3/\mathrm{KOH}$ (or NaOH) was unlikely. Compressive strength decreased when additional water was increased. High curing temperature and long curing duration showed a negative effect on strength development. The compressive strength of the soil–fly ash geopolymer varied as different mixing sequences of raw materials were used, indicating the importance of the formation of geopolymer gel in the structure. Compressive strength results obtained in this study demonstrate that soil–fly ash geopolymer can be a potential alternative to traditional clay-fired brick.

Flexural behavior of textile-reinforced concrete (TRC) samples were investigated by using three-point bending test systems under quasi-static and low-velocity ($1.0–4.5\mathrm{m}/\mathrm{s}$) impact loadings. Two types of TRC samples, namely basalt textile-reinforced concrete (BTRC) and alkali-resistant glass textile-reinforced concrete (GTRC) were tested. The mechanical performance of TRC composites was evaluated in terms of flexural strength, modulus, flexural ultimate strain, and toughness. Samples were tested under quasi-static bending at an initial strain rate of $3.33\times {10}^{-5}{\mathrm{s}}^{-1}$ at room temperature and flexural impact at five different initial strain rates (4, 8, 12, 16, and $18{\mathrm{s}}^{-1}$) and temperatures ($-50$, 0, 25, 50, and 100°C). The experimental results show that at room temperature, flexural strength has a significant increase with increasing initial strain rate, while flexural modulus first increases and then reduces. Changes in flexural ultimate strain and toughness are in an inverse trend. At the initial strain rate of $12{\mathrm{s}}^{-1}$, toughness and flexural strength generally decrease with increasing temperatures, but flexural modulus and flexural ultimate strain do not vary significantly. When textiles with six layers were used in the composite samples, the reinforcing effect was more significant. Initial strain rate, temperature, and the number of textile layers can significantly affect the flexural performance of TRC samples.

Road safety builds on traffic and driver–infrastructure interaction: nighttime visibility represents a key-aspect of this complex interaction. Therefore, providing an adequate road lighting system and improving drivers’ visibility in nighttime conditions is vital. In this sense, photoluminescent paints for pavements can improve road safety in terms of visibility. This study models photoluminescent phenomenon by referring to dense-graded friction courses (DGFC) and open-graded friction courses (OGFC), and evaluates the effects due to season. Measurements, based on the photometry technique, were carried out in the laboratory on cores. The photoluminescent phenomenon was investigated in terms of charge and discharge time linked to decay phenomena and modeled as a function of pavement type and paint treatments. Results show that photoluminescent performance depends on the luminance time and volumetric characteristics of bituminous mixtures. Results can benefit both researchers and practitioners and can allow optimizing painting treatments for different bituminous mixtures.

The influence of wet-dry cycles on the enduring performance (loss of mass, strength, and stiffness) of compacted fine-grained soils–portland cement blends might be important information for designing earthworks that could be subjected to severe climate conditions. This study assesses possible variations of cement-treated fine-grained soils’ accumulated loss of mass (ALM), unconfined compressive strength ($q_u$) and maximum shear stiffness ($G_0$) when subjected to wetting-drying cycles (mimicking severe climate conditions). Brushing of specimens (to check loss of mass), ultrasonic pulse velocity tests, and unconfined compression tests are performed after wetting-drying cycles for this study. Results show that, for each specimen tested, ALM changes at a constant rate with the number of cycles (NC). In addition, $q_u$ increases from zero to three wetting-drying cycles and fluctuates around an average for further cycles, whereas $G_0$ decreases from zero to three wetting-drying cycles and then fluctuates around an average (distinct for each dry unit weight and amount of cement used) for further cycles. The possible cause of such contradictory results is the effect of oven drying for 42 h at $71\pm 2°\mathrm{C}$ (during the drying part of the wet-dry cycles), which might provoke the catalysis of the chemical reactions of the portland cement, as well as the retraction (and consequent fissuring) of the specimens of silt–portland cement blends in the initial cycles. Finally, the porosity/cement index is found to be a predictor of the ALM, ALM/NC, $q_u$, and $G_0$ fine-grained soil–cement blends studied after a series of wetting-drying cycles.

On the basis of the one-dimensional fractal model, a two-dimensional fractal model is developed to investigate the particle size distribution (PSD) of heterogeneous geomaterials. Based on the simulation results for PSD curves of geomaterials, it is proved that the two-dimensional fractal model is superior to the one-dimensional fractal model. The PSD analyses indicate that two major mechanisms may govern the formation of the geomaterials and these characteristics can be captured by the two-dimensional fractal model. In this respect, the two-dimensional fractal model is better than the three-dimensional model. The two-dimensional fractal model is further adopted to investigate the relationship between the mechanical properties and PSD of geomaterials.

The present study was conducted to define low, intermediate, and high temperature performance of date seed oil modified binders (DOMB) mixed with different amounts of reclaimed asphalt pavement (RAP) binder varying from 0 to 30%. The Fourier transform infrared (FTIR) test was applied to evaluate the chemical structure of date seed oil (DSO) as virgin and modified binders. Rheological properties of binders were measured applying Brookfield viscosity test. Fatigue and rutting behavior of blends were predicted utilizing linear amplitude sweep (LAS) and multiple stress creep recovery (MSCR) tests, respectively. Results showed that the inclusion of DSO affected chemical properties of the binders and resulted in reduced viscosities. The Superpave high performance grade (PG) of binders was increased by one grade due to the addition of RAP; whereas the addition of DSO balanced that. In addition, fatigue behavior of the binders was improved significantly with the addition of DSO to the RAP blended as virgin binder (up to 70%). However, rutting resistance of the blends was adversely affected due to the softening effect of DSO.

The integrated transdisciplinary concepts and technologies for greener and more sustainable innovations for recycling waste materials through geopolymer technique into construction materials were developed in this research. The objective of this research was to study the strength and microstructural development of slag (S)-based geopolymer-stabilized recycled asphalt pavement (RAP) as a pavement base material. An attempt was made to study the influence of a liquid alkaline activator ($\mathrm{L}=\mathrm{NaOH}/{\mathrm{Na}}_2\mathrm{Si}{\mathrm{O}}_3$ ratio) on the strength development of RAP-S geopolymers, which was evaluated by an unconfined compressive strength (UCS) test and examined by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses. The XRD and SEM analyses results indicated that the main geopolymerization reaction product of RAP-S geopolymers was calcium alumino-silicate hydrate (C-A-S-H). Without ${\mathrm{Na}}_2\mathrm{Si}{\mathrm{O}}_3$ ($\mathrm{L}=\mathrm{NaOH}/{\mathrm{Na}}_2\mathrm{Si}{\mathrm{O}}_3=100:0$), the S-geopolymer exhibited a slow geopolymerization reaction. The silica presented in ${\mathrm{Na}}_2\mathrm{Si}{\mathrm{O}}_3$ was highly soluble; hence, a suitable content of $\mathrm{NaOH}/{\mathrm{Na}}_2\mathrm{Si}{\mathrm{O}}_3=60:40$ can produce RAP+20%S geopolymers as a base material whose 7-day UCS value met the minimum strength requirements specified by the Department of Highways, Thailand. However, when excess ${\mathrm{Na}}_2\mathrm{Si}{\mathrm{O}}_3$ content ($\mathrm{NaOH}/{\mathrm{Na}}_2\mathrm{Si}{\mathrm{O}}_3=50:50$) was used, the presence of silica retarded the geopolymerization formation rate, leading to UCS reduction. The outcomes of this research were found to be useful for making progress in innovative technologies and applications of geopolymers, which strongly reflected the improvements made in the practical applications of the S-geopolymer as a cleaner production by using the recycled waste material in road work.

Self-compacting concrete (SCC) is a highly fluid form of concrete that can consolidate under its own weight, thereby reducing the need of any mechanical compaction processes. Lightweight concrete (LWC), which incorporates the use of lightweight aggregates, can reduce the density of the concrete and therefore the potential associated dead loads. In recent decades, there have been numerous studies in the production of lightweight self-compacting concrete (LWSCC) that aim to combine the benefits of both SCC and LWC. Due to the various lightweight aggregates and their different material characteristics, it is imperative to assess whether the properties of both concretes still apply when using different lightweight aggregates. This paper aims to develop information about the fresh and hardened properties of lightweight self-compacting concrete using perlite, scoria, and polystyrene lightweight aggregates at varying replacement percentages. The fresh properties were investigated using the slump flow, $T_{500}$, and J-ring tests. Hardened properties include 7- and 28-day compressive and tensile strengths, and compressive stress-strain behavior at 28 days.

The novel cement grout asphalt composite (CGAC) in this study is a new semiflexible composite consisting of open-graded hot mix asphalt (HMA) filled by injecting cement grout materials. The mechanical performance and engineering properties of the composite were evaluated through laboratory tests, including the Marshall stability test, rutting test, three-point bending test, split tensile test, and permeability test. Moreover, field test sections were constructed, and the laboratory test results and in situ results were compared. The results showed that, after grouting, the performance of composite materials was further enhanced, especially their high-temperature stability and moisture sensitivity. In fact, no permanent deformation (rutting) occurred, and the tensile strength ratio (TSR) was increased by 18.7%. In situ test applications revealed that compared with manual grouting, mechanized grouting technology had positive influences on field constructability and performance of CGAC regarding Marshall stability and splitting tensile strength. Findings of this study are beneficial to design, construction technology, and pavement maintenance.

This paper aims to design high-performance deicing asphalt mixture based on a combination of deicing agent and high-performance modifier. The deicing asphalt mixtures were produced by replacing mineral fillers with deicing agents in the asphalt mixture. The high-performance modifier increases cracking resistance and high-temperature rutting resistance of asphalt binder. The mechanical performance of asphalt mixtures, including high-temperature stability, low-temperature cracking resistance, and moisture stability were evaluated using wheel tracking test, low-temperature flexural test, immersion Marshall test, and freeze–thaw splitting test. The deicing effects of asphalt mixtures were evaluated using an ice-layer rupture test, pull-off test, and interface shear test. It was found that as the content of deicing agent increases the deicing effectiveness is stronger while the mechanical performance degraded. The addition of high-performance modifier can remarkably improve mechanical performance of deicing asphalt mixture while cause negligible effect on the deicing effectiveness. The combination of deicing agent and high-performance modifier provides a promising way to design high-performance deicing asphalt mixture.

Many of the recycled asphalt pavement (RAP) mix design methods assume 100% blending of the RAP binder with virgin binder to estimate the properties of the binder in the RAP mix. However, 100% blending is not practically achieved. Thus, it is essential to have procedures for determination of the degree of blending so that the properties of the blend can be estimated more accurately from the properties of RAP and virgin binders. To achieve this objective, a detailed study is conducted to evaluate the level of interaction between RAP and virgin binders. This study considers two proportions of RAP (20 and 35%) and two viscosity grades of virgin binders (VG10 and VG30). The difference in the qualities of the binders in the RAP and virgin aggregate portions is evaluated in terms of different binder properties such as ${\mathrm{G}}^{*}/\sin \delta$, penetration, and softening point. The results show that the grade of virgin binder and RAP content in the hot mix asphalt concrete governs the degree of blending achieved. Based on the results of the study, a simple approach is proposed for estimation of the properties of the combined (blended) binder in the recycled mix.

In this paper, a method of developing high-strength concrete from recycled aggregates is proposed based on particle packing optimization (PPO) methods and presoaking of recycled aggregates. A total of 300 samples of concrete manufactured using 100% recycled aggregates and natural aggregates were analyzed and tested at 7, 14, and 28 days. On comparing the soaked and unsoaked recycled concrete aggregates (RCAs), it was found that the water absorption in aggregates was time dependent, which affected the workability of the fresh concrete for low water–cement ratio (W/C). However, it was found that on soaking the aggregates the absorption of water was instant (not time dependent). It was also found that by soaking the recycled aggregates (RAs) prior to concrete manufacture results in concrete with higher compressive strengths and lower slump. The average compressive strengths achieved for the recycled aggregate concrete (RAC) was approximately 83.0 MPa. From the literature reviewed, this might be the highest ever recorded compressive strength from concrete manufactured using 100% recycled coarse aggregates.

The concrete industry is a remarkable point source of carbon dioxide emission due to the disintegration of raw materials and burning of fuel during the cement manufacturing process. One efficient way to minimize such detrimental environmental effects is utilizing waste and byproduct materials as cement replacements in concrete. An alternative to the production of environmentally friendly concrete is the development of geopolymers. In this study, the possibility of creating structural rice husk ash (RHA)–based geopolymer concrete using high amounts of agricultural solid waste as a byproduct material is investigated. All the samples were reinforced by polypropylene (PP) fiber. The test results indicated that replacement by RHA-based geopolymer improved the mechanical properties of concrete and 100% replacement by geopolymer can be taken into consideration, having the best results environmentally, structurally, and economically. Moreover, the addition of PP fibers increased the flexural and splitting tensile strength. In addition, substantial ${\mathrm{CO}}_2$ reduction, as high as 63%, was measured to be emitted in the creation of the studied sustainable RHA-based geopolymer composites. From the microstructural point of view, reduction of the interfacial transition zone (ITZ) width between the paste and the aggregate is another outcome that could efficiently decrease water permeability.

Waste utilization in the form of recycling is important for sustainability in the transportation construction industry. In this study, an attempt was made to explore the use of recycled concrete aggregate (RCA) and waste polyethylene from milk packaging (WPMP) in bituminous paving mixes. RCA was pretreated with bituminous emulsion to reduce its water absorption, and in this paper is referred as pretreated recycled concrete aggregate (PRCA). Dense bituminous macadam (DBM) paving mixes were prepared individually using PRCA, RCA, and natural aggregate (NA) representing the coarse aggregate fraction, each being modified with WPMP. The performance of the different bituminous mixes was investigated in terms of Marshall test parameters, indirect tensile strength, moisture susceptibility, dynamic modulus, flow number, resilient modulus, and rutting. It was observed that the PRCA and RCA mixes in general satisfy the requirements in terms of Marshall test parameters and moisture susceptibility. Also, from the other performance tests, it was observed that the mixes containing PRCA with WPMP produce better results compared with DBM mixes prepared with conventional aggregates.

Fiber-reinforced cemented soil has been specified for various purposes. However, limited studies are available on the effects of basalt fiber on dynamic mechanical properties of cement-soil using a split Hopkinson pressure bar (SHPB). To evaluate the effects of basalt fiber on dynamic mechanical properties of cement-soil, a series of exploratory tests were carried out. Moreover, the microstructure of basalt fiber-reinforced cemented soil has been investigated based on the scanning electron microscope (SEM) test. The results indicate that the inclusion of basalt fiber causes an increase in both the dynamic strength and the energy absorption capacity. The dynamic strength increases with the basalt fiber content from 0 to 1.5%, and then decreases with the further addition of basalt fiber. Also, a close relationship can be achieved linking the basalt fiber content and the absorbed energy of cement-soil. In addition, it is shown that by adding basalt fiber to the cement-soil, the specimen behavior can be changed to a significantly more plastic behavior. Finally, a brief analysis to the microstructural properties of basalt fiber inside of cement-soil has been made.

Highly modified styrene-butadiene-styrene–modified asphalt (SBSMA) with an SBS content of 6–9% is gaining popularity in China as an efficient binder for open graded friction course pavement. However, the short-term aging of highly modified SBSMA cannot be properly simulated in the lab because it is too stiff to flow inside the rolling thin-film oven test (RTFOT) aging bottle. To investigate the short-term aging of conventional as well as high SBS content SBSMA binders, an innovative thin-film aging was proposed. It was not affected by the high viscosity and can age all binders at the same film thickness, providing them with the same level of aging severity. Two SBSMA binders with SBS contents of 4.5 and 7.5% (coded as SBS45 and SBS75, respectively) were investigated. To compare them with the actual short-term aging, their corresponding loose mix was collected in actual field projects for binder recovery. The binder’s chemical and rheological evolutions during aging were monitored using infrared spectra and master curves. The test results indicated that the thin-film aging was much more severe than the RTFOT and provided the SBS45 and SBS75 with a similar aging severity. For the SBS45, this aging severity was more serious than the actual short-term aging. However, for the SBS75, it was similar to the actual short-term aging; this was ascribed to the higher mixing and paving temperature of the SBS75 mixtures. Moreover, a similar logarithmic correlation between the asphalt carbonyl growth and SBS polymer degradation rate were observed for both SBS45 and SBS75, suggesting that high SBS content SBSMA may be more vulnerable to aging.

Pavement preservation plays a significant role in maintaining aging pavement infrastructure under severe budget constraints. An important component in this is the application of sealants to surface asphalt pavements. A recent study investigated the field performance and mechanical properties of asphalt mixtures from pavement sections treated with four sealants, including two new products called biosealants. Field cores from both the control and the treated section were collected, from the tops of which thin beam specimens were cut to perform creep and strength tests at low temperature. The core bottoms were used to prepare laboratory-treated samples using an application process that mimics the spraying of sealant in actual field conditions. These samples were also tested at low temperature. Based on the creep stiffness and strength results, no significant effects were observed for the field-treated mixtures but a number of significant effects were observed for the laboratory-treated mixtures. The results of Fourier transform infrared spectroscopy (FTIR) analysis supported the laboratory findings. As part of field performance testing and monitoring, distress surveys of the shoulder test sections were performed after sealant application, and laboratory findings were also verified using cracking values of the treated and untreated field sections.

The American Concrete Institute (ACI) and most state highway agency (SHA) organizations limit the amount of chlorides in fresh concrete to lower the risk associated with corrosion of steel reinforcement. It is often required to measure the chloride concentration of concrete powder samples to ensure that the published chloride limits are not exceeded. However, the standard documents provide no information on number of samples required for chloride testing for different concrete mixtures. This study explores the influence of concrete material proportions and the admixed chloride levels on the mean and variability of the chloride test results. Results from this research indicate that the maximum size and proportion of the coarse aggregate and the admixed chloride level significantly influence the chloride test results. Based on the estimated variability of chloride measurements from this research, a method to determine the number of samples for chloride testing is presented for different concrete mixtures.

Air voids in asphalt mixes significantly influence the material behavior and durability. Depending on their sizes, shapes, connectivity and distribution, they allow the inflow of water and oxygen, leading to oxidation aging and moisture damage. Additionally, they provide space for permanent deformation. The failure mechanisms are not yet known in every detail. A major cause for this is the lack of a suitable analytical method for air void structures. Still, today, the usual practice is to determine only a single total air void content for every asphalt layer by weighing and measuring methods, which do not distinguish between different appearances of air void structures and exclude layer boundaries. Image analysis is a suitable tool to gain further structural information as it “opens” and “illustrates” the air void structure across all layer boundaries. In the area of research, different approaches have been tested within the last years. Most of them rely on image acquisition by computer tomography (CT). In addition to the high expenses for this technology, the resolutions of typical CT-systems are currently too low for detailed scans of entire asphalt specimens with common dimensions (e.g., drill cores, 150 mm diameter). Furthermore, the distinction between air voids, bitumen, and aggregates is often fuzzy. As a practicable alternative, plane sections of asphalt specimens can be prepared and scanned by conventional flatbed scanners. In this case, the contrast between binder and aggregates and air voids is achieved by impregnation with pigmented resins. First attempts are known from Switzerland and Denmark, but they were limited in specimen size and image resolution. This paper presents recent advancements in the preparation, scan, and analysis of large asphalt plane sections. By using contemporary preparation and computing tools, it is now comparatively simple to get a detailed insight into the air void structure of large asphalt specimens. Furthermore, some examples are given to illustrate the potential of this enhanced examination method. Damage assessment, mixture design, and research can profit from the additional structure information.

Promoting the use of naturally available materials as a partial substitute to portland cement can be a viable solution for producing low carbon footprint and durable cements. This work assessed the chemomechanical behavior of hardened cement pastes with partial replacement of ordinary portland cement (OPC) with volcanic ash up to 50%. Volcanic ash was ground to two different mean sizes (17 and 6 μm) and then used to prepare cement–volcanic ash blends of various proportions. Mixtures were cured for 28 days; then the hardened cement paste specimens were studied for the effects of partial substitution with volcanic ash on mechanical properties, pore structure, and microstructure. The volcanic ash was engineered by decreasing the particle size, thus allowing for a greater extent of OPC replacement with volcanic ash. Strength increase was observed for specimens with up to 40% substitution of OPC with volcanic ash of a mean size of 6 μm, and this increase was attributed to the denser pore structure observed via mercury intrusion porosimetry (MIP) studies. Densification of specimens was attributed to the generation of secondary calcium silicate hydrate (C-S-H) gels when smaller-sized volcanic ash was used. This study provides a multiscale insight into engineering portland cement blends with partial replacement of portland cement with finer volcanic ash.

Previous research has proved that paraffin has a negative effect on the mechanical properties of asphalt binder; however, until now there are very few studies on the fundamental mechanisms on a microscale. To study the effect of paraffin on the microproperties of asphalt binder, three molecular asphalt binder models with different paraffin contents and two molecular models of SBS-modified asphalt binders are created in this paper. The glass transition temperature is then simulated by means of a molecular dynamics (MD) simulation, indicating a significant reduction of low-temperature stability due to paraffin. Simulations of density, Young’s moduli, Poisson’s ratio, bulk moduli, and shear moduli are also conducted. The results show that paraffin can influence the mechanical properties substantially, and reduces the high-temperature stability of asphalt binders. Simulation results on the self-healing behavior of asphalt binder with varying paraffin contents demonstrate that paraffin significantly slows the self-healing behavior rate. Based on the molecular simulation results, it is suggested that the paraffin content in asphalt binder should be maintained at a controlled minimum amount.

Ceramic tile coating systems are widely used on building façades. Such façades generally consist of a few layers of materials such as rough cast, base-rendering mortar, adhesive layer for tiles, ceramic tiles, and grout between the tiles. Building coatings, in general, are subject to a variety of hazardous weather conditions including temperature variations which, combined with different mechanical properties of the façade material layers, produce thermal expansions and stresses in façades. Currently, studies of façade fatigue produced by such stress variations are not reported in the technical literature but it is a very important issue for construction companies and property owners. The purpose of this research is to evaluate the fatigue of the base-rendering mortar layer and estimate the life cycle of ceramic tile façades traditionally used in South American cities. The paper also presents a practical methodology based on experimental and numerical evaluations to estimate the fatigue life of base-rendering mortar under temperature transients of typical building façades. The Wöhler diagram of the base-rendering mortar is experimentally obtained and the thermal stress assessment done with finite-element models. With the alternating stress and the Wöhler diagram, it was possible to evaluate the lifetime of the base-rendering mortar layer in some façades. A case study is presented, showing critical situations where fatigue life can be just a few years, as observed in practice.

This research presents a laboratory investigation into the effects of polyolefin and aramid fibers as a reinforcement material in hot-mix asphalt (HMA) mixtures, with different asphalt binders. Three commercially available asphalt binders were used: asphalt cement penetration grade AC60/70, natural rubber–modified asphalt (NRMA), and polymer-modified asphalt (PMA). The effect of fiber reinforcement in those asphalt mixtures was evaluated by a detailed laboratory experimental program, which included Marshall stability, indirect tensile strength (ITS), resilient modulus ($M_R$), indirect tensile stiffness modulus (ITSM), dynamic creep, diametrical indirect tensile fatigue, and rutting resistance tests. The performance evaluation was performed by comparing the results between asphalt mixtures with and without fiber reinforcement for the AC60/70, NRMA, and PMA. The laboratory results indicate that without fiber reinforcement, the PMA exhibited better performance than NRMA and AC60/70, respectively. The addition of fibers 0.05% by mass of the total mixture to asphalt concrete mixtures notably improved the rutting resistance, fatigue life, and resilient modulus, regardless of asphalt binder type. The average values of Marshall stability, $M_R$, ITS, and ITSM of all the fiber-reinforced mixtures was increased by approximately 17, 31, 11, and 33%, respectively, compared with the mixtures without fiber reinforcement. This research confirms that fiber-reinforced asphalt pavements exhibit superior performance to traditional asphalt concrete pavement, hence resulting in longer service life.

True-triaxial test data are fundamental in obtaining the constitutive laws of fiber-reinforced polymer (FRP)—confined concrete, especially concrete under nonuniform (passive) confinement. A new true-triaxial test system, which exerts passive confinement on concrete cubes, has been developed by the authors to fill the passive confinement gap in existing tests. To obtain true constitutive behavior from cube testing, it is essential to resolve the end-friction effect. In this study, the design of a friction reduction pad with polytetrafluoroethylene (PTFE) sheets was investigated, and a quantitative analysis was carried out to determine the pad’s friction reduction performance. Moreover, an equivalent confinement method was proposed to quantify pad performance under different pad configurations. The results demonstrate that a two-ply greased PTFE pad works efficiently for concrete under uniaxial compression. However, it does not prevent end friction from regenerating in the strain-hardening stage in passively confined concrete. The equivalent confinement method was further developed to quantify the regenerated end-friction effect and to obtain the inherent constitutive behavior of concrete under uniform passive confinement in a true-triaxial test system. This study is the first quantitative investigation of friction reduction performance specifically for concrete cubes with strain-hardening behavior.

This paper presented some geotechnical characteristics of low plasticity clay (LPC) treated with clinker in comparison with those of ordinary portland cement (OPC) treated LPC. The chosen percentages of both additives were 10, 12, and 14% for the stabilization of LPC. While the liquid limits of clinker and OPC treated LPC decreased, their plastic limits increased. The liquid limit (LL) and the plastic limit (PL) of clinker treated LPC were found to be lower than those of OPC treated LPC. The optimum moisture content (OMC) and maximum dry density (MDD) of LPC were increased by both clinker and OPC treatment. In addition, the OMC values of clinker treated LPC were higher than those of OPC treated LPC. However, the MDD values of clinker and OPC treated LPC were almost the same. The shear strength of LPC was also increased with the clinker and OPC treatments under both the wet-cured and air-dried conditions. The compressibility and swell characteristics of LPC were considerably reduced by both clinker and OPC treatments. Nevertheless, the swell and compressibility of clinker treated LPC were lower than those of OPC treated LPC. It was found that the clinker was more effective than that of OPC in the treatment of LPC.

The purpose of this study was to investigate and compare the abrasion resistance of self-consolidating concrete (SCC) with crumb rubber (CR) in conjunction with acoustic emission (AE) monitoring. The variables were the type of concrete (normal concrete and SCC), the coarse aggregate content, the use of supplementary cementing materials (SCM), and the CR content. The AE characteristics such as the signal amplitude, signal strength, and number of hits were obtained from the AE software used during the abrasion testing. The signal amplitude and strength data obtained were further analyzed to calculate the b-value, severity ($S_r$), and historic index [$H(t)$]. The results showed that the addition of CR negatively affected the abrasion resistance of the tested samples, whereas the addition of SCM greatly enhanced the abrasion. A good correlation was found between the abrasion damage and the AE parameters, including the number of hits, signal strength, b-value, $H(t)$, and $S_r$. The results also presented developed damage classification charts using the AE intensity parameters [$H(t)$ and $S_r$] to determine the ranges that indicate the extent of damage due to the abrasion of the tested mixtures.

A review of published literature on the corrosion of metal pipes reveals that current research on corrosion of full-size pipe sections in real soil conditions is highly limited, with almost no research reported on the corrosion effect on degradation of mechanical properties, and fracture toughness in particular, of cast iron pipes buried in real soil. This paper presents a new testing methodology for investigating the corrosion of cast iron pipes in real soil and evaluating its effect on the degradation of both fracture toughness and modulus of rupture in various environments represented by different pH values of soil. Microstructure analyses of pipe specimens before and after corrosion were also conducted to identify possible causes for degradation of mechanical properties, and specimens were compared with exhumed pipes. Both fracture toughness and rupture modulus of pipe specimens decreased with corrosion, and localized corrosion and formation of the graphitized zone in cast iron pipes were the primary causes for degradation of their mechanical properties. The results presented in the paper contribute to the body of knowledge of corrosion in realistic soil and its effect on the mechanical properties of buried pipes.

High reclaimed asphalt pavement (RAP) content mixes are likely to be susceptible to pavement distress such as fatigue cracking and raveling because of aged bitumen. In this study, the potential of recycling agents to restore hardened binders to desired properties was evaluated. Aged bitumen extracted from field cores was blended with different concentrations of a rejuvenating agent. The rheological properties of the asphalt samples were tested using a Brookfield viscometer and a dynamic shear rheometer (DSR). Furthermore, in order to better understand the recycling effect, the chemical properties of the binders were measured using Fourier transform infrared spectroscopy (FTIR) and gel permeation chromatography (GPC). A correlation was found between percentages of large molecules obtained from GPC and the viscoelastic properties of bitumen blends. The aging characteristics were determined by measuring functional group changes in carbonyl and sulfoxide peak areas by FTIR. Both rheological and chemical analyses are needed to characterize the effects of a recycling agent on bitumen blends.

Fine-grained soils have a low load-bearing capacity that hinders their use in pavement construction, slope protection, or foundation support. Therefore, the chemical stabilization of a soil with the addition of lime is a viable technique that could enable its use in civil construction. Unconfined compressive strength (UCS) and split tensile strength tests were performed to evaluate the improvement of a soil with lime and the existing correlation between these two tests. This study aims to determine the empirical relationships between the split tensile strength ($q_t$) and UCS ($q_u$) of a silty soil artificially cemented with hydrated lime ($L$). To calculate the $q_t/q_u$ ratio, soil–lime specimens are molded by controlling the dry unit weight, lime content, porosity, and water content, followed by curing for 15, 30, 60, 90, and 180 days. The voids/lime relationship determined by the porosity/volumetric lime content ratio ($\eta /L_v$) plays an essential role in this study, and it is the principal parameter used to assess the increases in $q_t$ and $q_u$ and determine their empirical relationship. The results demonstrate that $q_t/q_u=0.16$ for all curing times (15–180 days), so that it is an overall constant relationship ($q_t/q_u$). Moreover, with the addition of 9% lime, maximum resistances of $q_t$ (700 kPa) and $q_u$ (3,750 kPa) are obtained for the soil–lime mixtures after 180 days of curing. Moreover, two dosage equations that can be used as mix design relationships are obtained to determine the $q_t$ and $q_u$ of the lime-treated soils.

In recent years, roads in Singapore have had to be constructed on reclaimed land using marine clay as fill materials. Improving the engineering properties of the high water content, soft clayey soil in the reclaimed land in a cost-effective way before road construction becomes a challenge. It is expensive to treat high water content soil using cement because the amount of cement required would be excessive. In this paper, a study on the potential use of a waste-based binder as a substitute for portland cement for the improvement of high water content soil is presented. A series of laboratory tests were carried out to assess the undrained shear strength of binder-treated marine clay compared with the use of cement. The test results indicated that for soil with a high initial water content, the use of waste-based binder could shorten the curing period by about 20% while achieving the same unconfined compressive strength or increase the undrained shear strength at 14 or 28 days by 20 to 50% compared with the marine clay treated with cement of the same dosage. The aging effect of the waste-based binder was stronger. A microstructural study also shows that there are interlocking matrixes produced between soil particles in the binder-treated soil that contributes toward the increase in shear strength in the soil.