Journal of Materials in Civil Engineering

This paper provides results of a comprehensive investigation into the use of waste carpet fibers for reinforcement of clay soil slopes. The interaction between laboratory scale model slopes made of fiber-reinforced clay soil and surface strip footing load was examined. Results for the influence of two variables, namely fiber content and distance between the footing edge and the crest of the slope, are presented and discussed. The particle image velocimetry (PIV) technique was used to study the deformation of the slope under the surface loading. The front side of the tank was made of a thick Perspex glass to facilitate taking accurate images during the loading stage. To study the stress induced in the slope under footing pressure, excess pore-water pressure and total stress increase were measured at predetermined locations within the slope. The results showed that fiber reinforcement increased the bearing resistance of the model slope significantly. For instance, inclusion of 5% waste carpet fiber increased the bearing pressure by 145% at a 10% settlement ratio.

This paper aims to investigate the fractal characteristics of concrete fragments produced by impact fragmentation. The dynamic compressive tests for concretes with different static strengths were conducted by split Hopkinson pressure bar apparatus under various strain rates. The results indicate that the fragments size distribution of concrete after impact fragmentation can be statistically regarded as a fractal. The corresponding fractal dimension, as calculated by mass-size relationship, is an ideal indicator to describe the fragmentation degree. Under impact loading, the fractal dimension of impact fragmentation increases with strain rate. For a given loading rate, concrete with a higher static strength is less fragmented and has a smaller fractal dimension. In a word, the more serious the fragmentation is, the larger the fractal dimension obtained. The variation of fractal dimension essentially depends on the development of cracks inside and the compactness of concrete. Moreover, the dynamic compressive strength and impact toughness of concrete demonstrate an increasing trend with fractal dimension of impact fragmentation. Under a given fractal dimension, concrete with a higher static strength exhibits larger dynamic compressive strength and impact toughness. A modified renormalization group model can be used to describe the fractal behavior of impact fragmentation of concrete by taking the strain rate effect into account. To get closer to the real fragmentation process, this model can be further modified by assuming that the subelements produced each time have different sizes. In addition, based on mercury intrusion porosimetry tests, it is found that the pore structure of concrete also possesses obvious fractal characteristics. Concrete with lower porosity and finer pore structure exhibits a larger pore fractal dimension.

This paper presents experimentally investigated results of iron slime addition as additives in making bottom ash bricks. Bottom ash from coal burning thermal power stations of two different fineness (i.e., 1–0.2 mm and 0.075–0 mm) are mixed with varying contents of iron slime. Green bricks were dried and subsequently fired for 2 h at 1,000, 1,100, and 1,200°C. The strength and density of fired bricks increased with increasing firing temperature, fineness of bottom ash, and iron slime content, but decrease in porosity. With increasing firing temperature, the formation of iron silicate followed by iron aluminum silicate occurs, which is mainly responsible for imparting the strength of the bricks. The amount of lower melting phases increases with increasing iron slime content even at lower firing temperature, which is also responsible for increasing the strength and bulk density but reducing the porosity after subsequent cooling. The results suggest iron slime can be used as a binding material for making bottom ash bricks, even when fired at a lower temperature.

Porous asphalt concrete (PAC) is a particular type of asphalt mixture that has a high content of air voids that is generated because of an open-graded design. The objective of the study is to investigate the effect of the engineering properties of PAC on field performance. Three binders were selected for evaluation: conventional asphalt, polymer-modified asphalt, and highly modified asphalt. Comprehensive laboratory tests, including permeability, resistance to draindown, resistance to disintegration, resistance to rutting, and resistance to indirect traction, were conducted to evaluate the engineering properties of PAC mixtures. Stiff binders were shown to resist against particle loss and to enhance durability of PAC mixes through thick asphalt binder films. According to the laboratory results, a test road was constructed to monitor the performance of PAC pavements with aggregates having a nominal maximum size of 19 mm. Surveys for pavement performance were conducted at scheduled intervals. Test results indicated that the use of polymer-modified binders in surface courses was technically superior to that of traditional asphalt. There were indications of drainage improvement by replacement of conventional asphalt with polymer-modified binders according to measurements in the field. Porous asphalt–wearing layers were shown to maintain drainability for more than 8 years in this study. The engineering properties of PAC mixes obtained from the laboratory corresponded well with pavement performance evaluated in the field.

Compliance-derived equivalent cracks are often used in high-cycle fatigue cracking predictions for computational expediency. Its dependence on the cohesive stress zone, however, may limit general applicability under high-cycle variable amplitude fatigue loading and limit the objectivity of the Paris constants and fatigue fracture toughness. In this paper, notched three-point bend concrete specimens of different sizes are subjected to (1) different loading modes: quasi-static and high-cycle fatigue; and (2) different fatigue loading sequences: constant, variable, and random. The results indicate that the fracture toughness does not depend significantly on loading sequence or loading mode. The Paris constants are not size dependent when a crack resistance curve is inserted into a modified Paris law within the range of experimental conditions considered here. The observations and statistical comparisons were consistent for both beam sizes, although they exhibited some significantly different cohesive and fracture properties. More research is required, however, to further generalize these results by expanding the current experimental conditions to include different specimen sizes, geometries, and concrete mix designs.

Plastic represents an environmental issue, as only 7% of it is recycled. The plastic remaining is either burned, disposed of in an uncontrolled manner, or landfilled. Thus, to reduce the quantity of plastic that is disposed of, there is a need to increase the amount of the material that enters various product streams. This includes its use in the construction industry, and more particularly in concrete, which uses large quantities of aggregate. A novel aggregate (RPA) comprising recycled plastic was developed. The aggregate produced was lightweight, with a density ranging from 510 to $750\mathrm{k}\mathrm{kg}/{\mathrm{m}}^3$ and absorption of from 2.7 to 9.81%. Other properties were comparable to aggregates of similar densities. Various composition RPA was used in concrete, and the resulting properties of both fresh and cured concrete were measured. For a given water to cement (w/c) ratio, it was possible to achieve slump of between 40 and 220 mm and fresh density of between 1,827 and $\mathrm{2,055}\mathrm{kg}/{\mathrm{m}}^3$. Further, 28-day strengths of between 14 and 18 MPa were achieved. Flexural strength was also measured. SEM analysis was undertaken to view the structure of the aggregate and the interface between the RPA and the cement matrix.

Bituminous surface treatments (BSTs), or chip seals, can be placed soon after (e.g., within 1 year) the underlying asphalt layer is paved, toward the end of the life of the existing asphalt layer, or sometime in between. The placement of a BST, especially soon after the underlying asphalt layer has been placed, mitigates the oxidation of the asphalt in the underlying layer as well as the infiltration of surface water into the pavement structure, which helps to reduce the raveling, frost heaving, and cracking of the underlying asphalt layer and to preserve the pavement’s integrity. However, few studies, if any, have evaluated the effects of BSTs quantitatively. This study quantifies the effects of BSTs on the material properties of the underlying asphalt layer based on laboratory testing of field samples. Asphalt layer field cores were extracted from pavements without a BST and with a BST as a control in the same project, for two field projects in Washington State. The mixture tests included dynamic modulus, creep compliance, and indirect tensile fracture tests on field cores of underlying asphalt layer. The asphalt binder was extracted from the asphalt layers at different depths to evaluate the aging gradient throughout the pavement depth; this evaluation included performance grading, multiple stress creep and recovery, and monotonic tests. Testing results suggest that placement of a BST soon after hot mix asphalt (HMA) paving reduces the oxidation of the HMA. When the BST is placed on the HMA, no aging gradient exists in the top two layers of the HMA. When the HMA pavement is subjected to long-term aging, no aging gradient in the HMA layer is evident, regardless of whether a BST is present or not. Therefore, this study explained/confirmed that the placement of a BST immediately after the HMA layer is placed could be beneficial for reducing cracking in HMA.

Moisture damage in asphalt is one of the prime concerns for flexible pavements degradation worldwide. Many of the pavement distresses are the direct and indirect outcomes of the moisture intrusion in asphalt pavement. This study focuses on developing a neural network (NN) to determine the effect of types and percentages of chemical antistripping agents (ASAs) on the adhesion forces of polymer-modified dry and wet asphalt binder samples. Atomic force microscopy (AFM) test is conducted to determine the adhesion and cohesion forces of asphalt samples with varying contents of polymer and ASAs using four different functionalized and industrial tips. A NN adhesion force prediction model is developed on the basis of AFM laboratory data with varying percentages of ASAs. Except for adhesion loss measured by the ${\mathrm{NH}}_3$ tip, all results show improvement in adhesion loss attributed to the addition of ASAs. Among all the chemical ASAs, Morlife shows the best performance in the presence of 3% styrene-butadiene and 5% styrene-butadiene-styrene in reducing moisture effect (average 18% reduction for all sample types) on adhesion and cohesion forces. In all cases, an increase in percentage of additives of greater than 1% does not aid in resistance to the damage caused by moisture in polymer-modified asphalt.

To investigate the cracking of concrete in reinforced concrete circular pipe culverts, which are mostly manufactured by a process of centrifugal roller suspension, buried more than 5,000 mm under soil, a series of tests were designed to determine the strength of the pipe wall concrete. The experimental results demonstrate that a process of two-step centrifugal molding contributes to greater average concrete strength, better crack resistance, and improved impermeability. Both the tensile and compressive strength of the outer walls are greater using the two-step centrifugal molding than walls constructed using the vertical vibration casting method. The inner wall concrete strength manufactured by one-step centrifugal molding is lower than the strength for concrete using the other two methods. Based on tests and analysis, calculation factors of concrete strengths of the inner and outer pipe walls are proposed. Three-edge-bearing experiments were also carried out to validate the effectiveness of the proposed factors.

In this study, sugar beet molasses and molasses-based boron oxide compound (MBOC) were used to modify the base bitumen. Sugar beet molasses is an organic waste material obtained from raw sugar during the refining process at sugar refineries. Molasses-based boron oxide is a synthetic material derived chemically in laboratory conditions by using proper amounts of sugar beet molasses and boron oxide. Each additive material was added separately at a level between 1 and 10% by weight of the $50/70$ penetration grade-base bitumen. The effects of the modifications on the bitumen and bituminous mixture properties were examined by means of a laboratory test group including rotational viscosity, penetration, softening point, ductility, dynamic shear rheometer (DSR), and Marshall Stability and Nicholson stripping tests. According to the Marshall Stability and Nicholson stripping test results, the bituminous mixture performance was found to be improved by MBOC, however, it stayed at the same level with sugar beet molasses.

With raised national security awareness because of terroristic threats, more focus recently has been placed on barrier and safety systems that can prevent the loss of life and structural damage as a result of vehicular impact and blast loading. One potential method for dissipating some of a vehicle’s high kinetic energy is to use crushable concrete in the barrier design. In this study, multiple crushable concrete mixtures containing partial and full replacement of aggregate by expanded polystyrene spheres were tested in unconfined and confined compression tests to evaluate their capacity of energy dissipation. Unconfined testing showed high ductility of polystyrene concrete, but the samples ultimately failed in shear. More efficient use of the crushable concrete was encapsulating the specimens. Confined compression tests showed much larger energy absorption capacity of all mixtures studied. Changes in the water-to-cement ratio ($\mathrm{w}/\mathrm{c}$) and loading rate had minimal effect on energy absorption and strength. However, increasing the amount of polystyrene replaced caused an increase in deformability and decreased the strength capacity. Additionally, dynamic compression tests were conducted on confined samples. Image analysis of the test samples showed that with an increase in strain values, the compression of the polystyrene increased. As a result, the relative volume of concrete increased with a decrease in the relative volume of voids.

Engineered cementitious composite (ECC) is a cement-based material, commonly mixed with polyvinyl alcohol (PVA) fiber or polyethylene (PE) fiber as reinforcing materials. This paper reports the test results of ECC materials under high strain-rate compression, using a 100-mm diameter split Hopkinson pressure bar (SHPB) device. The stress-strain relationships under different strain rates are obtained and discussed. It is found that both the ultimate strength and the corresponding strain of ECC increase with the augmentation of strain rate, indicating that the compressive behavior of ECC is sensitive to the strain rate. The dynamic increase factors (DIFs) for strength and strain at strength are discussed.

Cement-stabilized base (CSB), a cement-stabilized material for road pavement construction activities, generally has better essential properties than an unbound granular material, a commonly used material for the pavement base structure. However, CSB requires further investigation to improve understanding of its performance and maximize its effective use. This study aims to characterize CSB with respect to its strength performance and damage evolution under static and dynamic loading conditions. Furthermore, a new mix-design concept for CSB, based on more rational mix-design parameters and processes, was developed. The standard crushed rock from a local pit in Western Australia was used as the parent material of CSB test specimens with varying cement contents in the study. The CSB characteristics under monotonic and dynamic compressive loading conditions were also examined. The tests were established to investigate the influences of loading rates to material responses and damage evolutions. The findings show that the strength of CSB depends on the moisture content at compaction, dry density, and compaction degree. According to the study results, a cement content ranging between 3 and 7% was suggested to obtain an effective CSB. The strength of CSB could also be estimated from a range of water-cement ratios and curing durations. However, this is valid only for CSB prepared from the moisture content at optimum moisture content (OMC) and greater. Under compression tests of dynamic loading and static loading, test results reveal that the responses of CSB test specimens under different rates of loading are explicitly different. The damage evolution through the damage parameter can be successfully used to capture behavior differences of CSB under various loading regimes of static and dynamic. Finally, concern about using design parameters derived from the static loading tests could arise due to the difference in the intrinsic behavior of CSB under static and dynamic loading conditions, based on the test results in this study.

The purpose of this paper is to develop mesoscale models for predicting the diffusivity of cement mortar by numerical and analytical methods. The interfacial transition zone (ITZ) volume fraction was calculated by a three-dimensional geometric model with randomly distributed aggregates. The decrease in the water–cement ratio of the bulk cement paste due to the presence of ITZ was also considered. The results showed that the bulk paste porosity decreased significantly at a larger aggregate fraction. The mortar diffusivity was predicted by analytical and numerical methods. The predicted mortar diffusivity was in conformance with the measured diffusivity. It also indicated that the decreasing rate of the diffusivity as the increasing fraction of aggregate was dependent on the ITZ contents. The predicted results for the cement mortar with oblate or prolate aggregates showed that the diffusivity was larger as the shapes of the aggregates were more spherical than oblate or prolate.

The corrosion-induced bond degradation between corroded steel strands and concrete is investigated in the present study. Ten pull-out specimens with different corrosion levels were tested to study corrosion’s effects on concrete splitting, strand twisting, failure mode, and global force-displacement behavior. The local bond characteristics are discussed and derived based on the test results. Experimental results show that the bond behavior depends on the corrosion loss level and does not have a monotonic trend. Strand corrosion had beneficial effects on the bond strength when the corrosion loss is less than 6.24% in the current study. The corrosion loss significantly decreased the bond strength when the corrosion loss is greater than 9.26% or the corrosion-induced crack is wider than 0.67 mm. The strand will be pulled out instead of fracturing when the corrosion loss exceeds 8%. Corrosion affects the bond strength more significantly than the tension strength for severe corrosion conditions. A simplified model is proposed to predict the residual bond strength between corroded strands and concrete. The proposed model’s predictions are validated with experimental data. Several conclusions and suggestions for future work are drawn based on the conducted study.

Adhesive materials play a key role in any strengthening system for concrete structures. Traditional organic adhesives have a major limitation of poor fire resistance; hence, developing an alternative inorganic material is needed. This paper aims to present an innovative cement-based adhesive, which has been fabricated and verified using a number of tests. A nanomaterial represented by graphene oxide and a series of cementitious materials was used in this work. Fresh properties such as setting time and flowability were tested to ensure suitability for practical applications. Mechanical properties were tested in terms of compressive, tensile, and pull-off strengths. The experimental results proved the adequate performance of the innovative cement-based adhesive in terms of fresh properties and mechanical strength. The results show that the adhesive mixture has a pot life up to 120 min with a flow of 7.5%, and remarkably high 13.8 MPa tensile, 101 MPa compressive, and 1.2 MPa pull-off strengths.

The present study proposed a new method for characterizing linear viscoelastic (LVE) properties of asphalt concrete (AC) under triaxial loading conditions. The presented method adopted the relaxation spectrum model derived from the Havriliak-Negami (HN) complex modulus model and an existing confining pressure–dependent equilibrium modulus model to simulate the triaxial complex modulus and relaxation modulus master curves. The confinement dependency of the triaxial master curves was considered in the relaxation spectrum and equilibrium modulus instead of the time-temperature shift factor. A confinement shift factor model was developed to incorporate the confinement dependency into the HN relaxation spectrum. The feasibility and effectiveness of the method were demonstrated by using the triaxial complex modulus test data sets of three different asphalt mixtures, and its advantages over existing methods were also discussed. The results showed that the method was able to accurately and completely characterize the triaxial LVE behavior of the mixtures in both frequency and time domains. Both the storage and loss moduli test data were simultaneously used during the determination of the model parameters. Thus, the LVE information in the experimental results was fully extracted and all the predicted triaxial master curves achieved relatively smaller deviations from the test data.

Stray current from direct-current light rail systems can corrode underground metal pipes, potentially causing significant damage to utility lines. To address this problem, Seattle Public Utilities has adopted two preventative measures: use of a dielectric rubber boot and a high-resistivity concrete rail bed. In this work, a constructible, high-resistivity concrete mix was developed using supplementary cementitious materials. The concrete is highly workable, can be placed year-round, and has a high early strength to minimize road closures. In addition, the resistivity is 100 times greater than standard concrete. Based on these data, concrete mixes using Type III portland cement with ternary combinations of silica fume, slag, and Class F fly ash were evaluated. Fresh-state properties, including slump, air content, and density, were determined. Samples were subjected to curing conditions similar to the Seattle area. The compressive strength and resistivity of the mixes were monitored over time. In addition, the effect of temperature on the setting behavior was evaluated. The results indicate that a constructible, highly resistive concrete mix design can be achieved.

Climate change in the form of global warming has been a popular topic for decades. However, similar issues have never been associated with the performance of pavement and paving materials. As a viscoelastic material, asphalt concrete is sensitive to temperature, which affects its mechanical performance. Asphalt pavements built under different climatic regions may perform differently with the same structure and material. A typical Virginia pavement structure with a drainage layer has been used as an example in the present work to perform finite-element method (FEM) simulations. Strain responses were obtained under moving wheel loading. The dynamic moduli of the surface layer and drainage layer obtained from laboratory tests were employed in the simulations for better accuracy. To understand the temperature effect, several groups of subsurface temperature distributions measured from asphalt pavements in North Carolina and Canada were used in the simulations. The rutting depths of asphalt layers in a typical Virginia pavement have been predicted using a mechanistic-empirical pavement design guide (MEPDG) rut-depth transfer function from the strain responses obtained in the FEM simulations.

Capillary rise is a serious phenomenon that may have potentially devastating consequences within buildings (biological corrosion, worsening of indoor comfort parameters, worsening of thermal resistance, etc.). Therefore, measuring moisture in building structures is still a current research issue and time domain reflectometry (TDR) is considered one of the most-effective nondestructive methods for moisture estimation in porous media. This paper reports a research examining the effects of different kinds of mortar on the capillary rise in yellow volcanic tuff walls. To this aim, three model walls were built with tuff and three different kinds of mortar (a traditional cement lime mortar and two premixed mortars, one of which was specifically designed to prevent capillary rise), and then instrumented with TDR probes, to carry out continuous monitoring of volumetric water content without the need of sampling or material destruction. Preliminarily, the calibration relationship linking relative dielectric permittivity, provided by TDR measurement, with volumetric water content, measured gravimetrically, has been experimentally determined in laboratory with yellow tuff specimens. The obtained results suggest that TDR can be suitable to reliable in situ monitoring of moisture dynamics in tuff walls in a nondestructive way. The velocity and height of capillary rise resulted strongly affected by the adopted type of mortar. In particular, the wall made with simple premixed mortar was characterized by the highest water absorptivity, whereas the one made with the specific antirise mortar showed the lowest moisture increase. The obtained results also allowed a physical interpretation of the behavior of water uptake related to the different types of mortars.

This work analyzes the effect of soil type on the process of enzymatic calcium carbonate (${\mathrm{CaCO}}_3$) precipitation. This methodology is tested for the stabilization of five soil types (poorly graded sand, two silty sands, a silty soil, and an organic soil) in order to examine the impact on strength and stiffness, based on the results of unconfined compression strength (UCS) and scanning electron microscopy (SEM) tests. The results of the UCS tests show that, in the case of the sandy and silty soils, the process of enzymatic calcium carbonate (CaCO₃) precipitation potentiates the strengthening of the soils while, in the organic soil, a detrimental biostabilization impact is obtained. The SEM tests show the existence of vestiges of calcium in all the soils, which is a sign that the precipitation of ${\mathrm{CaCO}}_3$ does in fact occur but with a different impact on the strengthening for each soil type. The results suggest that the low pH value of the organic soil, combined with its organic coating of the soil particles, are the key factors that explain the inefficiency of the biostabilization process concerning this type of soil.

Under appropriate atmospheric environments, weathering steels can be applied to steel structures without painting and can thereby reduce the lifecycle cost of those structures. In this study, environmental factors were measured and exposure tests were conducted in Vietnam in order to clarify the influence of environmental factors on the corrosion behavior and applicability of weathering steels in tropical and temperate regions in Southeast Asia. First-year corrosion loss (the $A$ value) showed a correlation with the amount of airborne salt and time of wetness. Corrosion loss ($y$) after $x$ years exposure is expressed by $y=A{x}^B$ approximately, where Parameters $A$ and $B$ depend on the corrosion environment. The $B$ values in southern and central Vietnam were approximately 0.4 to 0.9, which were less than or equal to that in Japan. Based on these results, it is considered that the environments in southern and central Vietnam are suitable for use of weathering steel when the amount of airborne salt is $0.05\mathrm{mg}·\mathrm{NaCl}/{\mathrm{dm}}^2/\mathrm{day}$ or less.

This research aimed to investigate the compressive strength and chloride resistance of concrete made with 30% of calcium carbide residue (CCR) and 70% fly ash (FA) as a binder without portland cement. There were three activation methods to promote strength development of a new cementing material: (1) adding 1% of NaOH by weight of binder; (2) curing concrete at elevated temperature of 60°C; and (3) increasing the fineness of binder by grinding. All concretes were tested to determine the compressive strengths at 1, 3, 7, 28, and 90 days. The chloride resistance of the concrete was also investigated at 28 and 90 days. The results revealed that three activation methods used in this study could improve the compressive strength of concrete made from CCR and FA mixture, with more significant effects occurring at the early age than at the later age. Increasing the fineness of a new cementing material was found be the most effective method compared with the other methods. The compressive strength of concrete activated by increasing the fineness of a new cementing material could be as high as 55.0 MPa at 28 days and increased to 65.1 MPa at 90 days. Moreover, the chloride resistance of concrete in terms of the chloride ion penetration and corrosion resistance of reinforcing steel in concrete could be considerably improved by three activation methods used in this study.

As tunnels are now longer and built more frequently, fire safety in tunnels has become a major issue throughout the world. The objective of this study is to investigate the flame resistance of warm-mix asphalt mixtures with flame retardants through a comprehensive testing program. In this study, a compound flame retardant (FR) was added to the asphalt and warm-mix asphalt. The comprehensive testing program included the flash point test and oxygen index test of the asphalt binder, the combustion test of loose and compacted mixtures, and a bench scale apparatus for combustion testing of asphalt mixtures in order to understand the flame resistance of the asphalt and mixtures. The results of the asphalt binder tests indicate that FR has no significant effect on the flash point but has an obvious effect on the fire point, and FR asphalt requires more oxygen because the FR prevents it from burning. During various combustion tests, the FR reduced the flame, lessened the smoke, and lowered the temperature but noticeably increased the burning time. It was noticed that the structural integrity of the burned FR mixture samples is preferable to the mixture without FR. The bench scale apparatus for combustion testing shows that the ignition time is extended, both the heat release and smoke for the FR mixtures are noticeably decreased, and both the carbon monoxide (CO) and carbon dioxide (${\mathrm{CO}}_2$) emissions are reduced. This means FR mixtures have better flame resistance and will have less potential for environmental pollution. Moreover, the results also show that a warm-mix asphalt additive has little effect on the flash point, fire point, or oxygen index of the asphalt. It also has little effect on the burning time and the flame height of loose mixtures. Because the warm-mix asphalt additive aids combustion, it decreases the maximum temperature and mass loss of the compacted mixtures during the firing process. It also shortens the ignition time and decreases the released heat, the total smoke, and the release of CO and ${\mathrm{CO}}_2$. Thus, the flame resistance of warm-mix asphalt with FR is the best due to the combined effect of the FR and the warm-mix asphalt additive, which means that the combination of modified asphalt is preferable for asphalt pavement in tunnels.

Roller-compacted concrete (RCC) and paver-compacted concrete (PCC) are widely used in mass concrete and pavement. Alternative supplementary cementitious materials (ASCM) can be used in RCC production for rheological, mechanical, and environmental improvement. This paper presents optimization of biomass fly ash (BFA) as ASCM and biomass bottom ash (BBA) as an alternative sand for RCC production. This optimization was carried out on RCC with a water-to-binder ratio ($w/b$) from 0.32 to 0.37. The BFA was used to replace up to 30% of cement and the BBA was employed to totally replace sand. The optimal replacement rates when combining the BFA and BBA was also carried out. The fresh (Vebe time and unit weight), mechanical (compressive and flexural strengths), and transport (water absorption, air voids, and electrical resistivity) properties up to 91 days were determined for all concrete mixtures. The results of concrete mixtures made with 10 and 20% BFA with 50% BBA showed 23 and 29% higher flexural strength than the limits required for practical use of RCC, respectively. These mixtures also exhibited very low permeability, which can be considered an indication for durable in situ behavior.

Current standards introduce different test methods to be used for the determination of the dynamic properties of polymers. Some of these have been applied in the last years for the evaluation of the thermoviscoelastic properties of interlayer in laminated glass. Even the latest draft standards, which provide test methods for the determination of mechanical properties of laminated glass interlayers, hesitate in providing a definite test procedure and thus allow the use of three different test methods depending on the kind of interlayer. Here, a short review of the test methods collected from the literature is proposed and some considerations are made regarding their strengths and weaknesses. The scope of studies surveyed does not claim to be exhaustive, but simply to be representative of the variety of procedures employed in research. The necessity is stressed to converge to as limited a number of test methods as possible that are also adequately simple and can therefore be applied in most research laboratories.

Output of municipal solid waste incineration (MSWI) can be classified as several different types of residues, of which bottom ash is a primary by-product. Utilization possibilities other than landfilling the incineration residues have been a tough task; most initiatives in this sense tend to use these residues as aggregate substitute materials in asphalt pavement. From previous research work, the use of MSWI bottom ash aggregates in asphalt pavement is feasible from the point of view of both environmental safety and structural stability. However, the MSWI bottom ash aggregates are highly multicomponent materials that consist of glass, brick, ceramics, metal, and slag. The compositional variability of bottom ash may affect the damage behavior of asphalt mixture considering that the strength and thickness of the interfacial zone are quite different for each aggregate-asphalt pair. Therefore, based on the finite-element method, numerical simulation has been conducted to investigate the effect of interfacial zone on the tensile damage behavior of asphalt mixture contained bottom ash under indirect tensile force. The stress distribution characteristics have been studied, and the effect of interfacial zone on the asphalt mixtures’ damage behavior has been discussed. The conclusions can provide a theoretical guide for the forecast and control of the tensile damage caused by the variability of components.

The combustion ash of a common nonwood biomass (wheat straw) was evaluated for value-added use in production of geopolymer concrete where alkali aluminosilicate hydrates are the primary binder constituents. The wheat straw ash was supplemented with other raw materials in order to achieve a desired chemical balance. The binder composition that performed well in experimental work comprised wheat straw ash:coal fly ash:metakaolin:gypsum at 0.50:0.25:0.25:0.05 weight ratios. The wheat straw ash–based concrete as well as a control portland cement concrete were subjected to a comprehensive experimental investigation. The workability, set time, compressive strength, residual compressive strength after immersion in boiling water, flexural strength, density, moisture absorption, voids content, capillary sorptivity, and acid and fire resistance of concrete materials were evaluated. The experimental results indicated that the nonwood biomass ash–based geopolymer concrete materials with proper binder formulation can provide desired mechanical attributes, moisture barrier qualities, durability, and fire resistance when compared with normal portland cement concrete.

The growing population in the modern world has resulted in an increase in waste generation and stockpiles. There have been increasing concerns on how to sustainably reuse wastes in civil and geotechnical engineering applications. Two major municipal waste streams are plastic wastes and recycled concrete aggregate (RCA) generated by demolition activities. A potential application for growing stockpiles of plastic and RCA waste is in the construction of roads because pavement base and subbases typically demand significant quantities of construction materials. In this research, RCA was blended with low-density polyethylene (LDPE) and high-density polyethylene (HDPE) plastics. A range of geotechnical tests such as California bearing ratio (CBR), unconfined compressive strength (UCS), and repeated load triaxial (RLT) tests were conducted on RCA–HDPE and RCA–LDPE blends. Comparison of CBR, UCS, and RLT results with those of typical quarry materials indicated that RCA–HDPE and RCA–LDPE can be used sustainably in the construction of pavement base and subbase layers. RLT testing results were further evaluated using resilient moduli models to characterize RCA–HDPE and RCA–LDPE performances under simulated traffic loads.

Incorporation of high quantities of reclaimed asphalt pavement (RAP) in new asphalt pavement construction is a contemporary approach for promoting sustainable roadway systems. Many highway agencies, however, have reported premature cracking and raveling of hot-mix asphalt (HMA) pavements constructed with high RAP content. In this study, cracking resistance of HMA Superpave mixtures with 20–40% RAP from various sources was evaluated by conducting semicircular bending (SCB), Texas overlay (OT), dynamic modulus (DM), and simplified viscoelastic continuum damage (S-VECD) tests. Test outputs were analyzed using a full-factorial two-way analysis of variance (ANOVA) and Tukey’s multiple comparison methods to quantify the effect of RAP quality and quantity on performance characteristics of Superpave mixtures. Although the SCB, OT, and S-VECD tests satisfactorily assessed cracking characteristics of HMA mixtures, results showed that the S-VECD test precisely captured the individual and combined effects of RAP source and RAP content. The DM test was unable to assess HMA mixture stiffness influenced by increased RAP contents or altered using various RAP sources due to the high error associated with the ANOVA model.