Journal of Materials in Civil Engineering

To highlight the influence of cement addition on laboratory characterization of lateritic gravel and the feasibility of cement–lateritic gravel for use in base construction, relatively comprehensive laboratory experiments were carried out on cement–lateritic gravels from République du Mali in Africa. It is shown, that although natural laterite gravels were gap-graded due to the lack of sand-sized and silt-sized particles, the aggregate breakdown and addition of cement would change the gradation and that the cement–lateritic gravel met the strength requirement for base-course construction in Africa. However, low contents of clay mineral properties of the fine grains in lateritic gravel resulted in the ineffectiveness of the cement reactions between lateritic gravel and cement, and then cement–lateritic gravels had poor water stability.

In this paper, the effects of NaCl concentration on saturation in concrete and ice-formation pressure and volume expansion of solutions are investigated; also, mechanisms of concrete salt-frost scaling are analyzed. Results show that the ice-formation pressure and volume expansion of solutions are significantly reduced with increased NaCl concentration, which positively affects the reduction of salt-frost scaling of concrete. On the other hand, the capillary-uptake degree of saturation and water-uptake rate in concrete obviously increase with increased NaCl concentration, which negatively affects the reduction of salt-frost scaling. According to the measured data, the ice-formation pressure in concrete is calculated, and the result quantitatively proves that the ice-formation pressure generated by 2–6% NaCl solution causes maximal concrete damage.

Fatigue cracking in an asphalt mixture is a process whereby microcracks in the asphalt–aggregate interface propagate into extensive interconnected cracks under repeated loads. The fatigue performance of asphalt is influenced by the load as well as the intrinsic nature of the asphalt–aggregate system. This study used the surface energy concept of asphalt and aggregate systems to characterize the fatigue behavior of asphalt mixtures. The surface energy of asphalt and aggregate at different temperatures were measured using Wilhelmy plate method and contact angle meter, respectively. By using dissipated pseudostrain energy of nonlinear viscoelastic material and micromechanics cracking model, the effect of surface energy on fatigue life of the asphalt mixtures was analyzed. Laboratory test indicated that the surface energy of the asphalt generally decreased with an increase of temperature. Compared with AH70 grade asphalt, the surface energy of styrene-butadiene-styrene block copolymer (SBS)-modified asphalt was less sensitive to temperature. Using SBS asphalt and basalt improved fatigue life of asphalt mixtures because of improved adhesion.

As hot mix asphalt (HMA) is the major paving material worldwide, how the quality of this material is assured is a critical issue. The current quality assurance (QA) practices include testing programs that yield inevitable variability as a result of, e.g., different operators, equipment, and methods. So far, very little research has focused on the variance and testing variability of HMA properties with respect to the material types and climatic conditions that are typical of Alaska. This study presents research to evaluate the variance in composition, volumetric, and mechanical properties between plant-produced and lab-designed mixtures of Alaska HMA, which was produced with various production/compaction scenarios and tested by different operating parties. The variability level of each tested property was quantified, compared with nationwide levels, and tested for influencing factors. This study further evaluated the method proposed in the National Cooperative Highway Research Program (NCHRP) 9-22 project, to predict the means and variability of mechanical properties with the measured composition and volumetric properties of Alaska HMA. According to the results, clear differences were observed between the plant-produced and lab-designed mixtures, and the magnitudes of the differences were higher for the volumetric and mechanical properties than for the composition properties. The variability of properties of Alaska HMA was within the nationwide range, with the lowest levels found on composition properties, followed by volumetric properties, and the highest on mechanical properties. The effects of the operating party and production/compaction scenario were also reported. The predicted results of the mechanical properties were found to deviate from the measured ones.

As the price of liquid asphalt continuously climbs, methods are being sought to decrease material costs without compromising material or pavement performance while having a positive influence on sustainability. One potential method is the use of recycled materials, such as recycled asphalt shingles (RAS) and reclaimed asphalt pavements (RAP). The objective of this study was to characterize the laboratory performance of conventional asphalt mixtures and mixtures containing RAP and/or RAS, with and without recycling agents (RAs). The RAS type utilized in this study was postconsumer waste shingles. Six 12.5-mm asphalt mixtures were designed to meet certain criteria with four of the six mixtures containing no RAs and two mixtures containing RAs [Hydrogreen and soft asphalt binder (Asphalt & Wax Innovations, Pass Christian, Mississippi)]. A suite of laboratory tests was used to ascertain the mechanistic behavior of the mixtures evaluated against major distresses. Laboratory testing evaluated the high-, intermediate-, and low-temperature properties of laboratory produced mixtures using the Hamburg loaded-wheel tester, the semicircular bending test, and the thermal stress restrained specimen test in addition to the dynamic modulus test. Results indicated that the use of RAs improved the blending between aged and virgin binders, which adversely affected the intermediate- and low-temperature performance of the mixture. With the increase in availability of aged binder in the mix, the inclusion of RAP and/or RAS with and without RAs showed an improvement in rutting performance.

Different modifiers composed of polyethylene glycol, paraformaldehyde, polystyrene, and polyphosphoric acid at different ratios (designated CD-0, CD-1, CD-2. CD-3, and CD-4) were added to coal tar pitch. The resulting modified pitches were prepared and designated control D-0 and D-1, D-2, D-3, and D-4, correspondingly. The objective of this study was to evaluate the properties of the control and modified coal tar pitches by the dynamic shear rheometer (DSR) test and microscopic imaging technology. The complex shear modulus $G^{*}$ and phase angle $\delta$ of the modified coal tar pitches decreased with increased temperature, which indicated a decline in the gradual capacity for resistance to permanent deformation at high temperatures. There was good correlation between the Christensen-Andersen-Marasteanu (CAM) model and the complex modulus master curve of the modified coal tar pitches. The test results showed that D-4 had a higher complex viscosity ${\eta }^{*}$ than that of the control D-0 and the other modified coal tar pitches (D-1, D-2, and D-3), along with a higher glassy complex modulus $G_g^{*}$, cross frequency $f_c$, rheological parameter $r$, and better resistance to rheological deformation. Control D-4 also had a strong capability to resist high-temperature permanent deformation. In addition, the homogeneity of D-4 was better than that of the control D-0 and the other modified pitches, as observed in microscopic images. Therefore, it could be concluded that D-4 had better properties compared with the others.

Traditional rejuvenators normally have a great deal of heavy fuel oils to supply the light oil component of asphalt binders, which decreases throughout a long-term aging process. However, heavy fuel oils can easily volatilize at a high recycling temperature (above 180°C), and this leads to a limited portion of reclaimed asphalt pavement (RAP) materials utilized in the recycled asphalt mixture (with a recycling rate less than 30%). Vegetable oils are rich in unsaturated fatty acids, which are similar to the light oil components, and have a better temperature resistance. Therefore, there is potential that vegetable oils can be utilized to recover the aged asphalt binder based on the asphalt rejuvenating mechanism. In this study, two rejuvenators with waste cooking vegetable oils (corn oil and soybean oil) to replace heavy oils and a commercial rejuvenator were used to recover the aged asphalt (extracted from RAP materials) with different ratios (by weight of asphalt) of 2, 4, 6, 8, and 10%. Dynamic shear rheometer (DSR) and rotational viscosity (RV) tests were used to evaluate the physical properties of the recovered asphalt binder. The low-temperature performance of the recovered asphalt binder was also evaluated by the bending beam rheometer (BBR) test. The laboratory tests and statistical analysis of variance (ANOVA) results show that the vegetable oil rejuvenators can effectively decrease the viscosity and stiffness of aged asphalt binder, which is beneficial for both fatigue and low-temperature cracking resistance. Furthermore, the rejuvenator can lower the viscosity and stiffness of the aged asphalt binder with a larger amount of vegetable oil. Overall, the vegetable oil content (6% to 8%) in the rejuvenator is proposed for recovering the aged asphalt binder in consideration of the rutting resistance under high temperatures.

Track performance is largely dependent on ballast performance. Unfavorable ballast conditions cause track geometry roughness and can contribute to increased rates of damage and deterioration to the rail, tie, and fastening components. Recent discrete element modeling (DEM) studies demonstrated a strong relationship between individual ballast particle movement and overall ballast performance. This paper presents a laboratory and numerical study on ballast particle movement under cyclic loading. In the laboratory test, a wireless device called SmartRock was embedded in a ballast box to monitor individual ballast particle movement beneath a crosstie under cyclic loading. In the numerical study, an image-aided DEM approach was utilized to generate DEM particles with a realistic shape of ballast particles and simulate the ballast box test. The laboratory test results recorded by the SmartRock and DEM simulations results were compared. Good agreement was observed between the simulated and recorded particle motion in terms of peak vertical, horizontal, and angular accelerations during ballast deformation. The results indicate that horizontal movement and rotation are important modes of motion for ballast particles under cyclic loading. The SmartRock is also shown to be capable of recording real-time particle movement including translation and rotation and, thus, can be used as a fundamental research and monitoring tool in railroads.

To address the large house-building demand in developing countries, soil can be used as an alternative building material because of its high availability as a source material, its ease of processing, and its low environmental impact. In this work, soil-cement blocks (SCBs) with three different contents of mineral wool waste and soil-cement blocks with three different contents of sisal fiber were fabricated, microstructurally characterized, and tested after curing for moisture absorption, abrasion resistance, compression, bending, and accelerated erosion. An increase of 29% in compression resistance was found when 1% of mineral wool was loaded into the SCBs, whereas an increase of 0.1% of sisal fiber lead to a 20-fold increase of the rupture modulus ($M_R$). From the results it is observed that both bending strength and compression resistance increased with the addition of mineral wool waste and sisal fiber.

Mostly disposed without treatment, fly and biomass ashes have been a challenge that threatens the environment. To use them as geoenvironmental materials for thermal insulating purposes, a fundamental studying of thermal property of the pure ashes is crucial. In this study, thermal conductivities of fly (class C and F) and biomass ashes (sugarcane bagasse and wood) are studied at dry, saturated, and partial saturated conditions under different effective stresses. Moreover, silica sand and kaolinite are used for comparison. The results show that thermal conductivity dramatically increases with effective stress in dry condition, but less increases in saturated condition. Providing partial-saturated conditions, a substantial increase of thermal conductivity is observed with the degree of saturation, which shows a good consistency with an empirical fitting model using thermal conductivities of minerals of dry and saturated materials. Fly ash class C is cemented by reacting with water that causes thermal conductivity to increase by reason of increased particle contact area. Finally, general thermal conductivities of fly and biomass ashes are much lower than both silica sand and kaolinite, which can be considered as insulating materials in geotechnical engineering.

Seven types of inorganic nanoparticles were selected to modify the base asphalt used in asphalt concrete pavement. The most suitable one, silicon dioxide (${\mathrm{SiO}}_2$), was screened out based on its excellence in improving asphalt pavement performance. ${\mathrm{SiO}}_2$ nanoparticles as a modifier, along with silane coupling agent, stearic acid, and polyethylenimine as the respective dispersants, were prepared at different levels to manufacture various nanoparticle-modified asphalt, from which the level of ${\mathrm{SiO}}_2$ nanoparticle–modified 5% ${\mathrm{SiO}}_2+2\%$ silane coupling agent was selected because of its outstanding performance. This nanoparticle-modified asphalt was then subjected to dynamic shear rheometer (DSR) tests and bending beam rheometer (BBR) tests to evaluate its performance when used in pavement, and scanning electron microscopy (SEM) tests, Fourier transform infrared (FTIR) spectroscopy tests, gel permeation chromatography (GPC) tests, and differential scanning calorimetry (DSC) tests to analyze the microscopic mechanism of ${\mathrm{SiO}}_2$ nanoparticles in asphalt modification. It was found that ${\mathrm{SiO}}_2$ nanoparticles can significantly improve asphalt performance at high temperatures. It was also evident from the frequency sweep test that the effect of ${\mathrm{SiO}}_2$ nanoparticles on the complex viscosity weakens gradually as the frequency increases, indicating that ${\mathrm{SiO}}_2$ nanoparticles improve asphalt performance more significantly at low-frequency conditions than at high-frequency conditions. Laboratory test results of pavement performance of asphalt concrete mixture show that ${\mathrm{SiO}}_2$ nanoparticles also considerably improve high-temperature stability and water stability of base-asphalt concrete mixture.

To study effect of plasticity on shear behavior of low-plasticity fine-grained soil, a Mississippi River Valley (MRV) silt with a plasticity index (PI) of 5.8 was treated with different dosages of sodium bentonite to modify its plasticity up to a PI of 13.5. The naturally occurring material originated from the MRV exhibited dilative behavior under normally consolidated conditions. The silt-bentonite mixtures tend to lose quasi-steady-state strength and dilative characteristics as the plasticity increased. At a PI of 13.5, the silt-bentonite mixture had plastic stress-strain clay-like behavior. Overconsolidation did not influence the friction angle of the natural silt, but for silt-bentonite mixtures with PIs of 6.2 and 9.4 the influence of prestress was evident. The normalized shear strength was significantly reduced with an increase in PI from 5.8 (natural MRV silt) to 6.0 (natural MRV silt with 2.5% bentonite added). Compared to the predictive relationships proposed by other researchers, the normalized shear strength of the natural silt was clearly higher. The critical PI was about 6 to differentiate clay-like soil and intermediate soil for the subject silt. The PI was found not to be an ideal parameter to identify the transformation of the shear behavior of the MRV silt, because the shear behavior had a big change with a slight change of PI.

The use of deicers in cold regions has raised many concerns regarding their negative impacts on the durability of concrete infrastructure. Numerous studies have been conducted in the laboratory settings with respect to the chemical and physical deterioration of concrete as a function of deicer type. However, little research has been done with concrete structures in the field, especially concrete bridge decks whose durability is also affected by temperature cycling and mechanical loadings. In this study, the effects of sodium chloride (NaCl) and potassium acetate (KAc) deicers were investigated using concrete samples obtained from the field bridge deck coring and those prepared in the laboratory. The relevant tests of both the field-cored and laboratory-fabricated concrete samples revealed that the two deicers (NaCl and KAc) imposed negative impact on the durability of the concrete materials. To compare the practical implications of these two deicers on concrete, their ice-melting capacity was tested. In addition, the mass loss, mechanical properties, including splitting tensile strength, compressive strength, and microhardness were tested to evaluate the deterioration of concrete samples after exposure to KAc and NaCl respectively. Relative to NaCl, field exposure to KAc caused more damage to concrete decks, partially due to the use of reactive aggregate. To further understand the deterioration effect of NaCl and KAc deicers on concrete materials, designed tests were carried out with laboratory-fabricated concrete samples. In both cases, the compressive and splitting tensile strengths of such samples decreased considerably after 3, 7, and 15 freezing/thawing (F/T) and wetting/drying (W/D) cycles. In addition to Ca leaching, needle-shaped and rod-shaped precipitates formed in concrete samples after F/T and W/D cycles in NaCl and KAc, respectively. The formation of these precipitates could be attributed to the chemical reactions between the cement paste and the deicers, and such crystallization process may lead to volume expansion of the pores in concrete.

Randomly distributed fiber and cement can be used for various purposes. However, no attention has been paid to the use of randomly distributed fiber and cement on seismic wave velocity of sandy soil and the relation between seismic wave velocity and unconfined compressive strength. In addition, there is no previous report on the use of nanosilica particles as a modifier for fiber-reinforced cemented sandy soil. In this study a series of unconfined compression tests and 144 ultrasonic pulse velocity tests have been conducted to explore the effects of polyvinyl alcohol (PVA) fiber and nanosilica particles on the mechanical characteristics of cemented sandy soil. Moreover, microstructural properties of cemented sand with nanoparticles have been investigated using scanning electron microscope, atomic force microscopy, and X-ray diffraction test. Finally, the ultrasonic pulse velocity test for the specimens has been performed in order to estimate the unconfined compression strength of fiber-reinforced cemented sand with nanosilica. The results of this study show that the inclusion of randomly distributed fiber increases the energy absorption capacity. Moreover, the secant modulus of elasticity of a specimen decreased with the increase of fiber content. Based on the results, a correlation between pulse ultrasonic velocity and the unconfined compressive strength at different ages was proposed.

This study is devoted to durability performance of a chemically-activated phosphorus slag-based composite cement (CAPSCC) against sodium sulfate attack. For this purpose, enough mortar specimens were prepared from phosphorus slag (80% by weight), Type II portland cement (14% by weight), and a compound chemical activator (6% by weight) at water-to-cement ratio of 0.37 and exposed to 5% sodium sulfate solution after being cured. Mortar specimens of both Types II and V portland cements (PC2 and PC5) were also prepared and used as control for comparison purposes. Based on experimental test results, after 12 months of exposure to 5% sodium sulfate solution, PC2, PC5, and CAPSCC exhibited 12.7, 7.5, and 2.1% loss in compressive strength, respectively. Measurements of expansion and weight changes were also done. Advanced studies by X-ray diffractometry and scanning electron microscopy were performed to characterize the products of the degradation process. All obtained results together confirmed the superior performance of CAPSCC against sodium sulfate solution that can be attributed to its very low potential for the formation of sulfate attack products, especially ettringite.

Research on the application of shape memory alloys (SMAs) in prestressing concrete structures has shown promising results over the last few years. Nickel-titanium-niobium (NiTiNb) has emerged as one of the SMAs that exhibit promise in prestressing applications. Despite the efforts to understand the mechanical behavior of NiTiNb, however, its corrosion resistance is yet to be understood. The main objective of this study was to investigate the influence that harsh corrosive conditions pertinent to civil structures might have on the mechanical behavior of prestressed NiTiNb SMAs. The study used an accelerated-aging test protocol to simulate actual field conditions by subjecting NiTiNb specimens to wet-dry cycles in NaCl solution. The behavior of as-manufactured SMA specimens was compared with that of specimens subjected to surface treatment. Carbon steel specimens were also tested for comparison. The state of corrosion and its impact on NiTiNb were evaluated using five different testing/evaluation methods: electrochemical testing, recovery stress testing, uniaxial tensile testing, scanning electron microscopic (SEM) imaging, and energy-dispersive X-ray spectroscopy (EDS). Test results indicate that NiTiNb SMA exhibits significantly better durability and corrosion resistance compared with carbon steel and can maintain its functionality under harsh chemical exposure.

This paper studies the use of recycled high-density polyethylene (${\mathrm{HDPE}}_R$) obtained from waste bottle crates as modifier in bitumen. Post-consumer HDPE was irradiated in order to casue a chemical interaction with bitumen. Accordingly, Fourier transform infrared (FTIR) spectroscopy was employed to determine the effects of the electron beam irradiation on the chemical structure of HDPE. Differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and fluorescent microscopy results signified that there might be a chemical interaction between electron beam irradiated HDPE (${\mathrm{HDPE}}_{\text{Re}}$) and bitumen. Physical and rheological tests were applied to the binders to investigate the effects of ${\mathrm{HDPE}}_{\text{Re}}$ polymer on the performance of the bitumen. Fundamental rheological tests performed using a dynamic shear rheometer (DSR) and bending beam rheometer (BBR) indicate that the ${\mathrm{HDPE}}_{\text{Re}}$ modifier provides a clear improvement in temperature susceptibility of bitumen. Thus, the ${\mathrm{HDPE}}_{\text{Re}}$ modification produces enhanced physical properties of bitumen, allowing the ${\mathrm{HDPE}}_{\text{Re}}$ modifier to be used as a modifier in bitumen especially to prevent permanent deformation.

The synergetic effects of the environmental and loading actions on mass transport process in concrete play an important role for the deterioration of mechanical properties and durability problems of reinforced concrete (RC) structures. Water is either the main agent responsible for the deterioration of concrete or the principal transport medium carrying aggressive species to ingress into concrete. This paper presents the results of an experimental investigation on the effect of short-term sustained uniaxial compressive or tensile loadings on water absorption by hollow cylindrical concrete specimens. An improved test apparatus aimed for the coupled effect of sustained loading on water absorption was designed to measure in real time the amount of water absorbed by the concrete specimen. The cumulative water content and axial/lateral strain of specimens under various stress levels (approximately 0–50%) were recorded. It was noted that under the short-term sustained tensile loading, the cumulative water content at a given exposed time generally increases with an increase of the stress level, while for the compressive case it initially decreases and then increases. The initial and secondary sorptivities, which are defined for characterizing the tendency of concrete to absorb water by the capillarity versus the compressive stress level, conformed to the polynomial function, except for the tensile loading case. which exhibited a linear relation. The ratio between initial and secondary sorptivity, as well as the quantitative correlations between the two sorptivities and stress level were proposed to account for the sustained loading effect on water absorption of concrete. Based on the unsaturated flow theory (UFT) model and experimental data, two forms of diffusivity, i.e., the exponential law and power functions, were both adopted to predict water distribution within a concrete sample under compressive/tensile stress states after 32-h absorption. The results indicated that the predicted water penetration depths by means of both exponential law and power functions in the UFT model increases with the increase of sustained compressive/tensile stress levels. The validation of the proposed model shows good correlation between the predicted water zpenetration depth and the test data.

The development of thermally efficient blocks as wall material to provide a reduction in the heating/cooling load of a building envelope has been investigated by a host of researchers. This paper focuses on the mix design of thermally efficient blocks by using a well-known optimization technique. The method is used to optimize the proportion of the raw materials, i.e., glass powder (GP), palm-oil fly ash (POFA), and oil-palm fibers (OPFs) to achieve minimal thermal conductivity values. Mix proportions were designed as per an orthogonal array with three factors and four levels. Experimental investigations, such as bulk density, water absorption, compressive strength, and thermal conductivity, were conducted. Effects on thermal conductivity caused by control factors were analyzed using signal-to-noise (S/N) ratios and analysis of variance (ANOVA) techniques. The analysis provides percentage contribution of individual control factors and the identification of significant parameters contributing to thermal performance. Furthermore, thermal conductivity values were estimated on the basis of the optimal performance levels of parameters. Last, for validation of the optimized results, experiments on thermal conductivity were conducted alongside the primary essential standard properties of density, water absorption, and compressive strength.

A national pooled-fund study supported by 19 states, the Federal Highway Administration, and the U.S. Army Corps of Engineers was conducted at the Cold Regions Research and Engineering Laboratory (CRREL) of the U.S. Army Corps of Engineers in Hanover, New Hampshire. The study, titled the Pavement Subgrade Performance Study (PSPS), aimed to develop failure criteria and prediction models for permanent deformation in the subgrade soil that incorporate the effects of soil type and moisture content. Full-scale pavement structures were built with the same crushed stone base and asphalt concrete surface layers on top of five subgrade soils. The soils were placed and compacted at three in situ moisture contents: the optimum and two other contents above the optimum. The pavements were subjected to full-scale accelerated pavement testing. An extensive volume of response and performance data was collected in the study. This paper presents the development of empirical models for permanent deformation of subgrade soils from the data obtained in the PSPS study. It describes the data collected by CRREL for the PSPS project and the statistical analysis used to derive the models for predicting permanent deformation in subgrade soils. For each soil type and moisture content, the analysis estimated constants for three models existing in the literature, including the model incorporated in the mechanistic-empirical pavement design guide pavement design model. A new model for predicting permanent deformation in subgrade soils is also proposed.

The high embodied energy of conventional geopolymer production, which resulted from the necessity of high alkaline activator content and heat curing, hinders the transition of geopolymer technology toward industrial applications. This paper introduces a novel geopolymer system based on hybridization between high calcium wood ash (HCWA) and pulverized fuel ash (PFA), which use a low percentage of alkaline activator (5% of binder weight), ambient temperature curing, and a pressurized forming method for the fabrication of load bearing masonry unit. The elimination of alkali hydroxide was made possible by the Arcanite mineral (approximately 12%), which is inherently present in HCWA. The HCWA-PFA geopolymer mortar blocks with various sodium silicate content (0–5%) and curing regime (water and moist curing) were assessed in terms of mechanical (compressive, flexural, and UPV) and durability performance (water absorption, total porosity, and intrinsic air permeability) over a curing period of up to 90 days. The addition of ${\mathrm{Na}}_2{\mathrm{SiO}}_3$ was found to enhance the early strength development of HCWA-PFA mortar blocks. Moreover, the mortar blocks exhibited continuous strength growth over a prolonged curing period. Moist-cured samples consistently outperformed their water-cured counterpart in every aspect. All of the fabricated HCWA-PFA geopolymer mortar blocks are classified as normal-weight, solid, load-bearing masonry unit.

In this research, a simplified approach based on size effect theory is used to extrapolate the strength values obtained on small asphalt mixtures specimens at low temperature with a modified bending beam rheometer (BBR). First, nine asphalt mixtures having different mix designs are prepared. Then, Weibull statistics and factorial design are used to evaluate the statistical distribution of the BBR measurements and the effect of conditioning time, loading rate, and testing temperature on material response, respectively. Finally, the BBR strength measured at three different temperatures is compared to the corresponding values obtained from two conventional test methods: direct tension (DT) and indirect tension (IDT) tests. It is observed that BBR strength values are statistically equivalent to those of IDT and DT when the size effect theory and the weakest link model are used to take into account the difference in volume, geometry, and stress field across the three testing methods.

This paper presents the concept of industrial symbiosis in which four industries available locally (steel plant, thermal power plant, aluminum plant, and stone quarry) are connected with the concrete industry. By-products generated by these industries (slag, fly ash, red mud, and quarry dust) were activated with a small amount of clinker to form four concrete mixes. The heat of hydration and the autogenous shrinkage were monitored on the fresh concrete mixes. The chloride migration and electrical resistivity of the concrete were measured at different concrete ages over 91 days. Drying shrinkage was monitored for 56 days, and compressive strength was tested after 28 and 91 days. The concrete prepared with a high volume of fly ash, slag, red mud, and quarry dust had very low chloride migration coefficients and less drying shrinkage compared to concrete prepared with ordinary cement. The synergetic beneficial effect of these by-products is explained by their complementary chemistry and particle-size distribution.

A significant amount of recycled asphalt pavement (RAP) material is produced from flexible pavement rehabilitation projects. RAP can be used as a base course material for sustainable pavement construction. Performance of a pavement largely depends on the strength of its foundation, which consists of the subgrade and base course layers. Geocell was used in this study to increase the strength of RAP bases. Nine large-scale laboratory cyclic plate loading tests were conducted on unreinforced and geocell-reinforced RAP bases with three different thicknesses (150, 230, and 300 mm) over weak and moderate subgrades to investigate the influence of geocell confinement, base course thickness, base course strength, and subgrade strength on permanent and resilient deformations of RAP bases. The subgrade was prepared by mixing Kansas River sand with kaolin and compacted at weak [target California bearing ratio $(\mathrm{CBR})=2\%$] and moderate (target $\mathrm{CBR}=5\%$) strengths. The test results showed that geocell confinement improved the performance of reinforced RAP bases by reducing permanent surface deformations and increasing resilient deformations and percentages of resilient deformation as compared with those of unreinforced bases. The RAP bases over the moderate subgrade performed better than those over the weak subgrade. Subgrade strength had a more pronounced effect than geocell confinement on the properties of RAP bases. Geocell confinement was more beneficial for the bases over the weak subgrade than those over the moderate subgrade. The relative improvement factors (RIFs) of the reinforced bases with respect to the unreinforced bases and the bases over the moderate subgrade with respect to the bases over the weak subgrade ranged from 1.1 to 11.4 and 1.2 to 17.2, respectively. The permanent deformation increased with the number of loading cycles and the RIFs increased with the permanent surface deformation of RAP base sections.

This paper presents a study carried out on concrete made with seven Tunisian cements with varying limestone filler content (binders) and manufactured on an industrial scale. The purpose of the study is to promote portland-limestone cement in countries where these cements are not usually used. The mechanical aspects of the concrete’s behavior were examined over a period of 3 days to 1 year. Permeability and accelerated and natural carbonation as a function of initial curing time were also studied over periods that were occasionally even longer. The results show that limestone filler does have a beneficial action on some properties, such as strength at early age, but is less beneficial for other properties, such as carbonation. However, the addition of limestone filler leads to concretes of entirely acceptable properties for current uses, certainly if filler content does not exceed 25%, and if optimized grinding of binders is conducted.

This research investigates the effect of carbonated fly ash inclusion in concrete as partial replacement of cement on the durability performance when exposed to salt, sulfate, and acid solution. The effect of chemical exposure periods (30, 60, 90, and 120 days) on compressive strength and weight of concrete with low volume (25%) replacement of cement was investigated for various water curing ages (28, 56, 90, and 180 days). A comparative assessment with low volume (25% cement replacement) fly ash concrete and control concrete was also conducted. It was observed from the results that low volume carbonated fly ash concrete demonstrated a significant increase in resistance to loss in compressive strength and weight against salt, sulfate, and acid attack. Gray relation-based analysis was performed to determine suitable parameters for simultaneous minimization of strength loss and weight loss under chemical exposure. It can be recommended that, due to its cost-effectiveness, easy processing, and environmental friendly nature, carbonated fly ash can be adopted in construction as a partial replacement of cement in concrete.