Journal of Materials in Civil Engineering

Quantitative analysis of the amorphous phase in binary blends of siliceous fly ash and hydrated cement is presented using the Partial Or No Known Crystal Structure (PONKCS) method. In binary blends, the total amorphous phase contains contributions from the glassy phase in fly ash and amorphous components of hydrated cement. A single pseudo-Voigt function is found to adequately fit the broad hump in the X-ray diffraction pattern resulting from diffuse scattering produced by the glassy phase in siliceous fly ash. The weight fractions of the amorphous component of hydrated cement and the glassy phase of siliceous fly ash in a binary blend are determined using the fitted profiles for the X-ray diffraction (XRD) patterns. For low lime content of less than 5%, the peak characteristics of the fitted function for the broad hump in the XRD pattern of fly ash are nominally identical for different oxide compositions of the glassy phase. The PONKCS method is shown to provide good accuracy in determining siliceous fly ash content in binary blends.

This project investigated the effect of weathering (UV light, oxidative, and water) on the performance of rubberized porous European mix (PEM) by laboratory tests and field pavement investigation. Three rubberized PEM mixes were produced by three processes: the dry process, the wet process, and the terminal blend in the laboratory. For comparison purposes, PEM mixture containing styrene-butadiene-styrene (SBS)-modified binder was also used. Weathering for 1,000 and 3,000 h on compacted PEM mixes were conducted. Dynamic modulus, rutting/moisture resistance, and Cantabro loss were measured for each mixture and aging condition. Additionally, the test sections of rubberized and SBS-modified PEM in Georgia were investigated through a visual inspection on the pavements and laboratory testing on core samples. The results indicated that (1) the weathering had increased the elastic properties and the rutting resistance, but had no significant effect on the moisture resistance and decreased the raveling resistance of PEM mixes; (2) the effect of weathering was more on the performance properties of rubberized PEM mixes in the dry process and the wet process than those of the SBS control PEM; (3) the first 1,000-h weathering had more effect on the dynamic modulus and the Cantabro loss of PEM mixes than the last 2,000-h weathering; and (4) all PEM field test sections of the dry process, the wet process, and the control showed excellent performance after 3 or 5 years of service.

A powerful texture feature extraction algorithm based on transform-based analysis of two-dimensional (2D) gray-scale images was employed in the aggregate image measurement system (AIMS) to quantitatively describe aggregate surface microtexture by way of a parameter called texture index (TI). TI has been used successfully to distinguish between unpolished and polished aggregates. The main goal of this research was to further evaluate this system using a broader range of aggregates in terms of mineral composition including highly uniform limestone sources and highly variable granitic sources. Results confirmed that TI successfully distinguished polished from unpolished aggregates for all mineral compositions. However, an excessively broad range of TI values was observed. Specifically, TI values of aggregates with highly variable mineral composition were far greater than any value previously reported in the literature. Interestingly, unusually high TI values were also observed for limestone aggregate particles obtained from field cores. It was hypothesized that non-roughness-related features such as surface color pattern resulting from mineral variation and absorbed asphalt resulted in artificially high TI. Independent experimental roughness evaluation using scanning electron microscopy (SEM) and surfaces prepared to the same roughness level confirmed this hypothesis. The results clearly indicated the need for a change in image acquisition and/or analysis algorithm to exclude the effect of surface color pattern in texture analysis of aggregate surface images.

In a flexible pavement, the base course is an essential component in that it supports the surface course and distributes traffic loads to the subbase and subgrade. Asphalt treatment is used on granular base course material to enhance the material’s properties and overcome its deficiencies. Due to its lower binder content and lower-quality granular material, asphalt treated base (ATB) exhibits a stress–strain relationship unlike either regular granular material or hot mix asphalt. Stress−strain relationship is the primary fundamental material property used for mechanistic-based pavement structural analysis and design. However, current guidance for choosing the parameter that characterizes the stress−strain relationship of ATB in pavement design is not clearly provided. This paper presents a study in which the stress−strain relationship of differing base materials, including three ATBs, a mixture of reclaimed asphalt pavement and granular material, and a typical granular base material, is compared and analyzed based on data measured from repeated triaxial compressive tests. The resilient modulus ($M_R$) was found to be capable of representing the stress−strain relationship of all materials selected. Further, the $M_R$ of selected ATBs was calculated at different stress states represented by bulk stress and octahedral shear stress to investigate and compare the stress-dependent property of the $M_R$ of selected materials. The stress-dependent property mechanism for each type of ATB was analyzed. The effects of stress-dependent $M_R$ on pavement performance were evaluated. It was found that pavement distress at the end of the design life could be either underestimated or overestimated if the representative value of $M_R$ is not properly selected.

This paper introduces the improved Fourier transform interferometry (FTI) system, which captures three-dimensional (3D) high-resolution images of aggregates. The improved FTI system uses the two-dimensional (2D) fast Fourier transform (FFT2) to rapidly measure aggregate morphologic characteristics from these images, including sphericity, flatness ratio, elongation ratio, angularity, and surface texture. Eight aggregate fractions, used in two different stone matrix asphalt (SMA) mixtures, were imaged and the calculated aggregate morphologic characteristics were found to be in good agreement with manual measurement results. The influence of aggregate morphologic characteristics on the mechanical performance of asphalt concrete is further examined on mixtures from Culpeper and Staunton in terms of dynamic modulus, flow number, and fatigue performance in laboratory experiments. Experimental results show that the mechanical performance of Staunton asphalt concrete samples was better than that of those from Culpeper, as was predicted from Staunton’s better aggregate morphologic properties, such as more cubical shapes and more angular and rougher surfaces.

Current Superpave performance grade (PG) grading specification utilizes a dynamic shear rheometer (DSR) at a gap height of 1-mm to determine the high-temperature performance grade of asphalt binders. It has been anticipated that rubber particulates greater than 25% of the gap height may interfere with the measurements, resulting in properties that may not represent the actual crumb rubber binder. Therefore, this study tries to adjust the 1-mm gap height for measuring high-temperature performance properties of crumb rubber binders to minimize the effects of interaction between the asphalt binder and rubber particle on PG grading results. Trial gap heights of 2 and 3 mm were used to test five different crumb rubber modified (CRM) binders. The CRM binders were evaluated using the standard Superpave high-temperature grading test and multiple stress creep and recovery (MSCR) test. Results were analyzed using statistical analysis, and through the comparison with single operator precision statements, where it was shown that higher variability is observed at the 2-mm gap height relative to the 3-mm gap height. Also, the repeatability between replicates was deemed acceptable, particularly for the 3-mm testing gap. Based on the results, a parallel plate gap height of 3 mm was recommended, and modified stress levels and testing temperatures for the MSCR test were proposed.

Single-blow impact testing of spruce and pine specimens were done to assess the effects of additional E-glass reinforcing on the tension face of a beam along with a rubber lamina adhered to the impact face. Comparisons between classic three-point static bending and dynamic pendulum tests proved the wood specimens did not absorb more energy in a dynamic loading; conversely, when reinforced with E-glass the spruce specimens absorbed about 2.5 times more energy, and the pine specimens absorbed 1.4 times more energy. The pine specimens treated with rubber and E-glass absorbed only about 1.5 times more energy, indicating a minimal positive effect by adding rubber. The most critical aspect of testing was the strain rate sensitivity of the E-glass.

Slip resistance is an essential parameter when dimension stones are used as inner and outer floorings. Declaration of performances of stones and their surface finishes (sawn, honed, polished, hammered, flamed, sandblasted, or brushed) in relation to conditions (wet or dry) in Conformité Européenne (CE) marking is essential for pedestrian safety. In this study, 130 samples taken from 81 stone types belonging to 13 types of petrographic families were tested according to the EN 14231 Standard, taking different finishes into consideration, during a ten-year period in the Marble Laboratory of Politecnico di Torino (Italy). A high number of pendulum friction tests (1,560) were conducted on 780 samples, and more than 7,000 readings were taken. On the basis of the obtained results, significant relations were found between the tested petrographic families and the types of finishes. A high correlation between open porosity, quartz content, and slipperiness of the stones with honed surface finishes was found. Moreover, the importance of the petrographic characterization of the stone, in relation to the declared surface finish, emerged as each petrographic family responded differently (according to its composition) to the action of the finishing abrasive.

The objective of this research project was to conduct a laboratory investigation of alternative polymerized asphalt mixtures in terms of moisture susceptibility, permanent deformation, dynamic modulus, and flow number of laboratory-prepared and field-prepared mixtures. The experimental design includes three alternative polymerized binders [ethene homo-polymer white powder polymer, an oxidized polyethylene wax-like powder polymer, and the combinations of styrene butadiene styrene (SBS) with ethane homo-polymer], a SBS binder, two reclaimed asphalt pavement (RAP) contents, three antistripping additives (ASAs) (hydrated lime and two liquids), and two aggregate sources. A total of 11 mix designs were performed in this study. Some of these materials were used to construct several field test sections. The results of field-prepared samples were compared with the laboratory-prepared samples. The laboratory-prepared sample test results indicated that similar asphalt binder content can be obtained in Superpave mix design, and that these designs satisfy the volumetric requirements of the South Carolina Department of Transportation (SCDOT). The indirect tensile strength (ITS) and tensile strength ratio (TSR) results showed that all polymers and liquid ASAs can be used to resist the moisture damage of asphalt pavement regardless of the aggregate source. In addition, the rut depths of mixtures generally were less than 3 mm for all polymer types, aggregate sources, and ASA types. The dynamic modulus ($|{\mathrm{E}}^{*}|$) and phase angle values of alternative polymerized mixtures generally were similar to those of SBS mixtures. The results imply that the properties of these hot mixtures prepared using the new polymers are comparable to SBS mixtures and pass all DOT specifications.

This paper proposes a new mechanistic-empirical rutting (MER) model to evaluate the permanent deformation (PD) behavior of unbound granular material (UGM). To characterize the stress dependence of rutting behavior in UGM, the MER model incorporated a softening stress term and a hardening stress term into the Tseng-Lytton model, which is based on the Drucker-Prager plastic yield criterion. Repeated load triaxial tests were performed on two types of UGMs in this study, employing seven stress states to calibrate the model coefficients, and two stress states to validate the accuracy of the model predictions. The correlations of the two incorporated stress terms with the accumulated permanent strains were established based on the triaxial test results. It was found that the correlations are fitted by power functions with 0.97–0.99 $R^2$ values. The proposed MER model was compared with the existing UGM rutting models, including the MEPDG model, Korkiala-Tanttu model, and UIUC model in terms of differences between the laboratory-measured and model-predicted PDs. Compared to the existing UGM rutting models, the MER model is better able to characterize the stress-dependent rutting behavior of UGM at various stress states. In addition, the prediction accuracy of the MER model is significantly higher than the existing models. A sensitivity analysis was also performed to evaluate the effects of cohesion and friction angle on the PD behavior. This demonstrates the potential of the MER model to characterize the moisture sensitivity of rutting behavior for the UGM. Finally, the MER model was implemented in a nonlinear finite element program to predict the rut depth of a flexible pavement. Compared to the MEPDG model, the MER model always predicts higher rut depths of the base layer and is more sensitive than the MEPDG model to the variations of load magnitude and base modulus.

Crushed bricks used in air lime mortars must show pozzolanic activity to obtain hydraulic products, and peak firing temperature is one of the main parameters for pozzolanicity of the fired clay bricks apart from clay type. In this study, solid clay mortars containing impurities as found in nature, which are used in the production of commercially sold bricks, were pulverized for a uniform firing process and then fired at nine different temperatures. The pozzolanic activity of the fired, pulverized clay was examined by commonly used direct and indirect test methods, and the results were discussed. Phase transformations of the clay and the reactions corresponding to temperature changes were also examined by X-ray diffraction (XRD) and thermogravimetric (TG) analyses. The common result of the methods reveals that clay treated at 850°C can be regarded as the best pozzolan, and the pozzolanicity of clay bricks significantly changes the mechanical properties of crushed brick-lime mortars.

Runway rubber removal is a maintenance function employed to ensure safe landing areas for aviation operations. Rubber deposits accumulate on runway areas where aircraft tires touchdown and braking occurs. This tire-rubber build-up occludes pavement microtexture and macrotexture, causing a significant loss in available skid resistance during wet conditions. Reduction of available pavement microtexture in a wet environment prevents the development of adhesional friction, which can result in viscous hydroplaning. Reduction of pavement macrotexture prevents the removal of bulk water from the tire–pavement contact area and also prevents the development of the hysteresis frictional component. To restore friction to safe levels for aircraft operations, rubber must be periodically removed. Several techniques for rubber removal are available. Water-blasting is a proven surface decontamination technique which employs the use of high-pressure or ultra-high-pressure water (UHPW) to blast rubber deposits from the runway surface. This effort provides a performance-based comparison between three commercially available UHPW water-blasting systems. The evaluation was conducted on an ungrooved portland cement concrete (PCC) runway with heavy rubber contamination along the touchdown and breaking zones. Several types of testing equipment such as a circular track meter (CTM) and dynamic friction tester (DFT) were used to characterize the surface properties of the runway before and after rubber removal. The measurements were used for statistical pairwise comparative analysis of International Friction Index (IFI), speed constant and mean profile depth (MPD). Treatment effect analysis of premeasured and postmeasured data revealed that UHPW systems improved the surface texture properties by at least 40% regardless of the decontamination equipment.

The effect of the outdoor exposure in the Uzungöl and Hıdırnebi plateaus for 15 months on oriental spruce (Picea orientalis L.) wood is examined in this paper. A number of oriental spruce wood samples with eight different protection processes applied to them are subjected to weathering conditions. Heat treatment and impregnation with micronized copper quaternary (MCQ) and ultraviolet (UV) absorbing acrylic resin (UVA-acrylic) as a wood finish are used. The obtained changes in the color and roughness values, chemical changes, and visual macroscopic changes to the wood samples with and without protection, subjected to natural outdoor tests, are compared. It is revealed that the application of acrylic resin containing UV absorber on oriental spruce after heat treatment increases the resistance of the wood samples to weathering conditions in visual, physical, and chemical terms. In addition, heat treatment is determined to protect oriental spruce without wood finishing.

This study investigated the effects of different casting procedures on compressive strength, water permeability, and interfacial transition zone (ITZ) porosity of rock-filled concrete (RFC). Mixes of concrete with the same proportions were cast using the self-compacting method (the casting procedure of RFC) and the vibration method (the casting procedure of normal concrete). A control group of concrete was prepared to reveal the effects of aggregate size. Compressive tests and water permeability tests were performed in accordance with the current codes. Scanning electron microscopy was used to calculate the porosity of the ITZ by processing the second electron and backscattered electron images of the ITZ. The findings indicate that the self-compacting method can improve compressive strength and particularly impermeability grade. Switching the vibration method to the self-compacting method also significantly reduces ITZ porosity, especially the ITZ porosity at the lateral surface of the aggregate.

The asymptotic homogenization method of differential equations with rapidly oscillating coefficients is used to evaluate the effective elastic stiffness of masonry structures. The equilibrium equations as well as the constitutive relationships at different scales are determined from the asymptotic expansion of the displacement field. The formulation is developed for a general three-dimensional problem. It is then particularized for a simple one-dimensional (1D) model that is applicable to available experimental results of a masonry prism. Key concepts of the method such as periodicity of the fields are highlighted in this 1D problem. A multiscale finite-element model was developed for a two-dimensional unit cell to solve the canonical cell equation that arises in homogenization, which provides numerical solution of the effective elastic moduli. In particular, the numerical study focuses on the in-plane action of the masonry panels that are used as the experimental specimens in laboratory tests. Comparing experimental and analytical (from classical computational homogenization) results, the multiscale homogenization model for linear elastic masonry structures is validated. The main advantage of this model is its straightforward extension for the study of the dynamic homogenization of masonry structures. Furthermore, the developed model is suitable for a comprehensive study of the stress localization in masonry structures for the determination of its strength-based limiting properties.

In this paper, the authors study the properties of cement-based bolt-grouting mortar that has been modified by adding mineral bauxite and gypsum. The results showed that when the bolt-grouting mortar consisted of approximately 12.5% bauxite and gypsum with a 1.0% addition of Portland Cement Association (PCA) type 4 (polycarboxylate superplasticizers), with a water-binder ratio equal to 0.3, it had the ideal properties, including a setting time between 0.5 and 1.5 h. The expansion rate on the 3rd day was larger than 0.09%, and the long-term expansion rate after 28 days stabilized at around 0.18%; the values of compressive strength at the 3rd and 28th days reached 34 MPa and 68 MPa, respectively. The maximum pullout load measured on a 1-m-long specimen on the 14th day was 71 and 87 kN. The hardened mortar was dense, as expected. The microanalysis using mercury intrusion porosimetry (MIP) and X-ray diffraction (XRD) showed that the total porosity of hardened mortar was less than 2.5%. There were plenty of ettringite crystals in the hardened paste, which was found to be able to endure steadily for a long period of time. The properties of cement-based, bolt-grouting mortar can be significantly improved by adding mineral bauxite and gypsum.

An experimental program was undertaken to develop and evaluate the performance of self-consolidating concrete (SCC) designed for connecting precast concrete deck panels to supporting bridge girders. The effect of curing conditions on early-age expansion and shrinkage of SCC made with expansive materials was evaluated. The effect of batching sequence, concrete temperature, and superplasticizer/water demand on SCC performance was investigated. Field mockup testing was conducted to evaluate the flowability and pumpability of the proposed SCC. Test results showed that the proposed SCC can maintain high filling and passing ability for 2 h and can exhibit adequate stability. The slump flow of the recommended SCC is $730\pm 50\mathrm{mm}$ ($29\pm 2\text{in.}$), the L-box blocking ratio is greater than 0.80, the difference between slump flow and J-ring is less than 50 mm (2 in.), and the V-funnel flow time is less than 6 s. The developed SCC mixture was implemented in the construction of the Kearney East Bypass Bridge Project in Kearney, Nebraska, in August 2015. A total of $92{\mathrm{m}}^3$ ($120{\mathrm{yd}}^3$) of the developed SCC was successfully placed through 100-mm (4-in.) diameter grouting/inspection holes located at 1.2-m (4-ft) spacing on the deck surface. The SCC was found to completely fill the shear pockets and haunches between the deck and the girders.

This paper studies the chloride diffusivity of concrete subjected to long-term exposure in a simulated marine environment with sustained compressive loading for up to 224 days. A series of concrete prisms were loaded under five different compressive stress levels (0, 0.2, 0.3, 0.5, and $0.7f_c$) and were subjected to different numbers (4, 8, 12, and 16) of wet/dry seawater exposure cycles. At the end of each exposure period, the concrete specimens were analyzed to determine their chloride penetration profile, the apparent chloride diffusion coefficient $D_a$ of the concrete, and the surface chloride content $C_s$. It was found that the $D_a$ and $C_s$ values are both time and stress dependent and that these two dependencies have complex interactions. The value of $D_a$ decreases with time due to the hydration of the cement matrix, whereas the value of $C_s$ increases over time. The effects of compressive stress on the values of $D_a$ and $C_s$ strongly depend upon the applied stress level, which has a threshold value at approximately 30% of the ultimate compressive strength. Below this threshold, the value $C_s$ remains constant; after this threshold, $C_s$ increases linearly as the applied stress increases. Below the threshold, the value of $D_a$ decreases marginally as the stress level increases. However, above the threshold, $D_a$ increases rapidly with the stress level as a result of microcracking. Through regression of the chloride penetration profiles, empirical models are proposed to quantify the dependence of $D_a$ and $C_s$ on the exposure time and stress level. The validity of these models is evaluated through comparisons with test results.

Though the mechanical properties of shape-memory alloys (SMAs) make them a promising material for reinforcement in concrete structures, their electrochemical behavior in concrete environments has not previously been studied. This study investigated the influence of galvanic coupling between a nickel-titanium (Ni-Ti)–based SMA and a low-carbon steel on their corrosion performance in simulated concrete pore solution. Three measurement cells were considered: SMA alone, low-carbon steel alone, and one with the coupled SMA and carbon steel. The specimens were immersed in the chloride-free pore solution for 20 days and then 3% by weight of NaCl was added to the solution. The specimens were then kept in the chloride-contaminated solution for 70 days. The corrosion resistances of the specimens were assessed by different electrochemical measurement techniques. The results of the electrochemical experiments showed a significant increase in corrosion activity of the coupled specimens compared with that for other measurement cells.

Testing steel in concrete pore solution has the advantage of avoiding the long time necessary for chlorides to penetrate the concrete cover. However, the time to corrosion of steel immersed in pore solution is different from that in actual concrete. The objective of this work was to study the impact of the presence of the steel and the distance between coarse aggregates and steel bars on the corrosion of the steel bars. Three distances between steel and the coarse aggregates were investigated in this study. Results clearly showed that the presence and the position of coarse aggregates with respect to the steel bars can significantly affect the access of steel to chloride ions and consequently, corrosion initiation on the surface of steel. It was determined that decreasing the distance between the coarse aggregates and steel had adverse impact on the corrosion initiation on the steel.

Shape-related properties of irregular particles are of interest in many fields. The volume and dimensions of rocks, such as coarse and larger fine concrete aggregates, can be physically measured rather easily. However, the surface area is difficult to measure physically, if at all possible. A combination of computed tomography and spherical harmonic analysis can be used to calculate the surface areas of micrometer-sized to centimeter-sized particles. This paper compares the success of several approaches that use easy-to-measure properties, specifically the orthogonal length, width, and thickness of a particle and its volume to estimate its surface area. A training set of 3,359 particles varying widely in size and shape is used to develop regression equations between various shape parameters. These equations are then used to estimate surface areas of cement and aggregate particles in three different validation sets. Improvements are offered to some existing surface area estimation methods. Finally, a novel method is proposed that estimates surface area with a mean absolute percentage error of 2.8 to 3.8% and with $\le 14\%$ individual particle error.

The objective of this study is to improve the thermal performance of masonry bricks produced by the factory Briqueteries du Nord. This industrial plant is located in the north of France. The use of additives in the raw material admixture presents a promising approach for improving the thermal performance of building materials, and consequently to respond of requirements of the thermal regulation. Therefore, three additives are selected as part of an approach supporting sustainable development and waste valorization: flax shives, maize starch, and polystyrene beads. This experimental study is focused on the effect of these additives on the physical, mechanical, and thermal properties of ceramic samples. Different characterization tests were conducted at the laboratory scale. The results indicated that mixtures containing 2.5% flax shives or 7.5% starch ensured an optimal thermal performance, taking into account the mechanical strength of these products.

This technical note develops a mathematical model to calculate the electrical resistivity of soil–rock mixtures based on macroscope structure of the soil and broken rocks, and further considers that the filling of pores between coarse grains by fine grains may result in a decrease in porosity and an increase in saturation degree. Thus, based on a standard model for the electrical resistivity of unsaturated soil, this study proposes a modified model for the electrical resistivity of unsaturated soil–rock mixtures and validated the accuracy of the model using experimental results. Then a simple and easy method for calculating the electrical resistivity of soil–rock mixtures is provided.

Electro-osmosis is a process coupling electrolyte flow and associated hydraulic flow under an external electrical field, resulting in the permeation of both electrolyte and pore fluid in porous media. One-dimensional column experiments were conducted to comprehend the effects of electro-osmosis treatment on the physical and chemical properties of a Na-bentonite by varying the electrode materials, including copper and iron as reactive electrodes and graphite and stainless steel as inert ones. Soil plasticity, free swelling ratio, zeta potential, and cation exchange capacity decrease after electro-osmosis, especially for the reactive electrodes. Moreover, soil microfabric is converted from the flocculated microplatelets to smectite aggregates of 10–30 μm in size. The original ${\mathrm{Na}}^{+}$ cations absorbed into smectite interlayer and adsorbed onto smectite external surfaces are exchanged with the released ${\mathrm{Cu}}^{2+}$ and ${\mathrm{Fe}}^{3+}$ for copper and iron electrodes, and the pre-existing multivalent cations such as ${\mathrm{Ca}}^{2+}$ for graphite and stainless steel electrodes. The resulting change in soil microfabric and chemical compositions decreases the water adsorption and holding capacity and also affects the physical and chemical properties of the Na-bentonite.