Journal of Materials in Civil Engineering

In this study, the effects of two nanomaterials—nanoclay and nano hydrated lime—on the fatigue properties of bitumen were investigated. Nano hydrated lime was produced in a laboratory using a planetary ball mill. The milling process was conducted in the specified conditions of speed, time of rotation, and ball to powder ratio (BPR). The processing conditions were determined by a trial and error procedure. With the aim of evaluating the fatigue life of modified mixes, various filler-bitumen combinations were tested under linear amplitude sweep (LAS) testing, which was performed using a dynamic shear rheometer (DSR) instrument. The results indicated that nanoclay at 6% level (by weight of bitumen) increased fatigue life of the binder by approximately 40%. The specimen that contained 10% nano hydrated lime showed the fatigue life that was 49% greater than that containing 10% hydrated lime. Based on the results of this research, 6% nanoclay and 5% nano hydrated lime were the optimum amounts of these materials to be added to bitumen for nanomodification purposes.

An experimental study is presented examining the preparation and characterization of a smart gypsum composite board for thermal comfort building application. Composite boards were prepared by mixing 1–30% by weight nano-encapsulated $n$-octadecane phase change material (PCM) with gypsum to develop gypsum-based building materials with thermal energy storage (TES) capability. The nanocapsules were prepared by encapsulating $n$-octadecane in nano-sized styrene-methyl–methacrylate copolymer shells using one-step mini-emulsion in situ polymerization. A thermal performance testing device was designed to evaluate the heat storage effect of the resulting gypsum composite. The results indicated that composite boards containing $n$-octadecane nanocapsules effectively decreased the temperature peak of the experimental test room compared with gypsum board without $n$-octadecane nanocapsules. This suggested that the composite boards had good thermal energy storage properties. It was also demonstrated that the composite boards containing $n$-octadecane nanocapsules could be used as a smart heat storage medium for thermal comfort building application. From the thermal properties point of view, incorporating 10% by weight $n$-octadecane nanocapsules in gypsum was more beneficial than adding more than 10% by weight.

Extensive studies have focused on the beneficial use of coal fly ashes (CFAs) as a partial replacement for cement in concretes or mortars, in the effort of reducing the environmental footprint and embodied energy of concrete materials while removing CFAs from the waste stream. In this study, a pure fly ash paste (PFAP) was developed in place of ordinary portland cement paste (OPCP). This PFAP was prepared at room temperature and without direct alkali activation, unlike geopolymer or other fly-ash-based cementitious materials that need to be cured at a relatively high temperature or activated by alkalis. The samples were prepared using only the as-received class C coal fly ash, water, and a very small amount of borax (${\mathrm{Na}}_2{\mathrm{B}}_4{\mathrm{O}}_7$). On average, the PFAP featured 28-day compressive strength of about 36 MPa, and micro-nano hardness and elastic modulus 29% and 5% higher than the OPCP, respectively. The PFAP also featured 15% lower gas permeability, 27% higher ${\mathrm{Cl}}^{-}$ diffusivity, 20% lower dry density, and considerably higher surface resistivity and bulk resistivity. These mechanical, durability, and other properties of the PFAP make it a viable environmentally friendly (green) construction binder suitable for a host of structural and nonstructural applications. Advanced characterization of the raw material and PFAP pastes was employed to elucidate the hydration mechanisms of this green binder. While this work only showcases the properties of one specific CFA, the obtained knowledge sheds light on the role of class C CFAs in the hydration process and may benefit the expanded use of various CFAs in cementitious materials.

In this study, the large deposits of volcanic scoria rocks (SRs) of the Arabian Peninsula were investigated as cement replacement materials. The powdered SRs procured from three separate regions (SR1, SR2, and SR3) were incorporated in concrete mixtures at three replacement levels (10%, 20% ,and 30%, by cement weight). Additionally, two reference concrete mixtures with silica fume (SF) and ground quartz sand (GS) were fabricated for benchmarking. Fresh properties, compressive strength, chloride-ion penetration resistance, and pore-size distribution from mercury intrusion porosimetry (MIP) were obtained. Microstructural and elemental spot analyses using field emission scanning electron microscopy (FESEM) analyses of samples from concrete mixtures were performed. The results showed that powdered SR samples exhibit clear variations in morphology and mineralogical compositions depending on the volcanic lava field. The strength activity index (SAI) of SR3 was higher than SR1 and SR2 indicating higher pozzolanic reactivity. The compressive strength of concrete mixtures incorporating SRs is affected by both SR source and its replacement level. SR mixtures yielded improved chloride-ion penetration resistance compared with GS and control mixtures but much lower than SF. The microstructural analyses revealed that SR3 particles have higher pozzolanic reactivity than SR1 and SR2.

Hot mix asphalt (HMA) is a combination of siliceous, calcareous, or intermediate aggregate materials from selected sources, blended with formulated asphalt binders from various asphalt binder producers. These components are modified by additional additives to enhance the bonding of the binders and aggregates. Concern over moisture damage (stripping), defined as the loss of strength and durability in asphalt mixtures when the binder separates from the aggregate, has prompted years of research into a variety of failure mechanisms. Prominent in these failure mechanisms is the pH at the binder–aggregate interface. This technical paper addresses the pH variance of individual components and loose blended HMA mixes from 17 selected material sources and 2 asphalt binder sources to assess the pH of any chemical reactivity. The main objective of the paper is to determine whether pH variances of individual components or mixed HMA materials (asphalt binder, aggregate, and additives) point to suspect components or combinations that cause a chemical reaction and, thus, instability or moisture-induced stripping at the aggregate interface. This research may point to alkali-silica and alkali-carbonate reactivity of aggregates as potential contributing causes of moisture-induced damage in HMA mixes. Statistical analysis is used to interpret the interaction of the independent variables and indicate contributing components correlating with the pH variance and chemical reaction.

The 20 years since the introduction of self-compacting/self-consolidating concrete (SCC) have given plenty of opportunities for researchers, designers, and contractors to become familiar with SCC innovative properties and structural effects. The workability and durability of SCC have been investigated extensively, together with the tendency of SCC members to spall in fire, because of pore pressure, thermal self-stresses, and applied stresses. The interest for the constitutive behavior of SCC at high temperatures, however, is relatively recent, as most of the studies (not more than a dozen in total) have been published in the last 10 years. Though limited in number, these studies shed sufficient light on the behavior of SCC at high temperatures, in quasi-steady conditions, as demonstrated in this paper. This paper describes 11 experimental campaigns carried out in Belgium, China, Croatia, France, Germany, Greece, Italy, Sweden, and the United States, each with its own specimens, mix designs, test procedures, and methods for the treatment of test results. The experimental results considered in this paper concern both normal-strength and high-performance/high-strength concretes, generally devoid of fibers, unstressed during the heating process, and tested in uniaxial compression. The conclusion of this comparative study is that at high temperatures, SCC tends to behave similarly to ordinary vibrated concrete (VC), and that American Concrete Institute (ACI)-ASCE provisions for ordinary calcareous or siliceous concrete at high temperatures or past cooling are also applicable to SCC.

Low yield point (LYP) steel is a kind of excellent material used in seismic structures. To get its constitutive model under cyclic loading, 20 specimens made of LYP steel SLY100 were tested under different loading systems. Monotonic characteristics, hysteretic curves, and failure modes were analyzed. Skeleton curves under cyclic loads were fitted. Parameters of combined hardening model were calibrated and verified. Then the constitutive model was applied in the numerical simulation of BRBs. It was indicated that SLY100 steel exhibited significant cyclic hardening phenomena and possessed distinguished ductility even after being subjected to cyclic loading. The Ramberg-Osgood model fit the skeleton curves well under cyclic loading with strain increasing gradually; good consistency between the stress–strain curves calculated by ABAQUS and test curves demonstrated the accuracy of the hardening parameters proposed. The finite element (FE) model of the buckling-restrained braces (BRBs) with SLY100 steel in which calibrated results were applied could simulate BRBs’ performance well.

Rapid urbanization has been causing a change in the urban climate resulting in urban heat islands (UHIs). In the area of transportation pavement infrastructure and its effect on UHI, the impact of these changes can be reduced by using road materials that are low-temperature sensitive. Previous studies indicated that an increase in the impervious nature of urban grounds is one of the main causes of UHI, which is principally affected by pavement surface temperatures. Further, the associated predictive models focused on pavement temperature profiles along the depth of the system, discounting surface parameters such as solar flux and surrounding air temperature. This study established pavement-surface temperature models based on meteorological factors, which can be used to estimate heat energy flux from different pavement materials and systems. The models encompassed more than 670 data points, which were robust and represented low bias and very high precision (depicted by $R_{\mathrm{adj}}^2\ge 98\%$ and $S_e/S_y\le 0.13$), and were found to be rational through a validation process undertaken using the Long-Term Pavement Performance (LTPP) climate database. The models were also used to estimate the heat energy flux released by various pavement systems and helped in the recommendation of a pavement-surface type that would be a suitable UHI mitigation strategy.

This study investigates the impact of air content on the mechanical properties and resistance of natural pumice lightweight aggregate concrete to freezing. The distributional characteristics of bubbles in pumice lightweight aggregate concrete are analyzed, and a freezing-resistance forecasting model for air-entrained pumice lightweight aggregate concrete is established. Experimental results show that the distribution of bubbles in natural pumice lightweight aggregate concrete is different from that in ordinary concrete. More bubbles are found in pumice, and fewer bubbles are found in mortar. The air content of non-air-entrained pumice lightweight aggregate concrete is almost the optimal air content of ordinary concrete. However, aggregate concrete has poor resistance to freezing. The optimal air content of ordinary concrete does not apply to pumice lightweight aggregate concrete. Significantly improved freezing resistance is observed after air entrainment. However, the cube compressive strength of pumice lightweight aggregate concrete exhibited faster loss than that of ordinary concrete. The mean strength loss reaches 8.74% if air content is increased by l%. Cube compressive strength is an important mechanical index, together with freezing-resistance test results, when establishing a freezing-resistance forecasting model of natural pumice lightweight aggregate concrete.

Permeability is an important indicator of durability of cement-based materials. Surface treatment is a simple method to reduce the permeability of cement-based materials. This paper evaluates the air permeability of cement-based materials treated with fluosilicate and sodium silicate. An air permeability test was utilized to measure permeability. The results revealed that both fluosilicate and sodium silicate could effectively reduce the air permeability of concrete. The benefits of magnesium fluosilicate treatment occurred mainly during the first 28 days. Sodium fluosilicate pretreatment made the waterglass treatment more effective in reducing the air permeability of concrete. The thermal analysis of free Ca(OH)₂ in hardened cement paste found that the penetration depths of these inorganic surface-treatment agents were approximately 5 mm.

This paper presents the results of combined experimental and theoretical studies of the statistical distributions of the strength and fracture toughness of recycled polyethylene-reinforced laterite composites for potential applications in building materials. The composites are produced with different volume percentages (0–30% v/v) and particle sizes ($\sim 300\pm 0.02$, $\sim 600\pm 0.03$, $\sim 900\pm 0.03$, $\sim \mathrm{1,200}\pm 0.02$, $\sim \mathrm{1,500}\pm 0.04$, and $\mathrm{1,800}\pm 0.03\mathrm{\mu m}$) of powdered polyethylene (PE) in a laterite matrix. The composites with $\sim 900\pm 0.03\mathrm{\mu m}$ and 20-volume percentage of PE are shown to have the best combination of flexural-compressive strengths and fracture toughness. The statistical variations in the flexural-compressive strengths and fracture toughness are well characterized by the Weibull distributions.

This paper describes and discusses an experimental study on the effect of mineral filler on the fracture behavior and ductility of self-compacting concrete (SCC). Based on an experimental program, a series of three-point bending tests was carried out on 118 notched beams. SCC was prepared with various contents of mineral filler with water-to-cement (w/c) ratios of 0.47 and 0.6. For all mixes, the fracture parameters were analyzed using the work-of-fracture method (WFM) and the size-effect method (SEM) to obtain a suitable correlation between these methods that is used to calibrate fracture numerical models. Given an increase in mineral filler content and a decrease in the w/c ratio in SCC, the results yielded the following conclusions: (1) fracture energies, $G_F$ in WFM and $G_f$ in SEM, increase slightly; (2) the brittleness number increases; (3) the characteristic length ($L_{\mathrm{ch}}$) in WFM and the fracture process zone length ($C_f$) in SEM decrease, which may be due to an increase in the packing density and changes in the pore size distribution; and (4) the behavior of SCC specimens, based on the size-effect curve, approaches the linear elastic fracture mechanics criterion. In addition, the results showed that there is a significant correlation between $G_F$ and $G_f$ values ($G_F/G_f=3.0$).

A shift in the preconsolidation pressure or yield limit with suction, referred to as the loading-collapse (LC) yield curve, is an important feature of elastoplastic models of unsaturated soils. The LC curve is typically defined in the matric suction versus mean stress plane to account for the effects of matric suction. Conventional methods to determine the LC yield curve rely on a series of isotropic compression tests on specimens with identical stress history. This paper presents an alternative method to determine the LC yield curve from isotropic compression test results of specimens without identical stress history restrictions. A series of equations is proposed, derived from elastoplastic theory and incorporated into conventional compression test results, for drawing the specific LC yield curve. The advantage of the proposed methodology is that the compression tests results need not be taken from identical stress history specimens, which leads to a shorter time frame in the laboratory. Moreover, no additional parameters are required apart from those required in the conventional method. Test results from the literature are used to verify the proposed methodology, and a good agreement between the measured and calculated LC curves was found. The proposed methodology is a less time-consuming and more economical method to draw LC yield curve than the conventional method.

Compared to conventional hot-applied asphalt sealant, the new cold-applied crack seal bands have outstanding advantages such as high installation efficiency, fewer secondary failures, and more environmentally friendly. However, some new failure modes happen during field application. Based on field investigation and laboratory testing, the short-term and long-term failure modes of seal bands were identified in this study. The laboratory testing methods were then developed to evaluate the short-term or premature failures and explore the causes of the short-term failures of installation failure or bending, unevenness, and stripping. The strategies to prevent and reduce the short-term failures of crack sealing bands were recommended regarding material selection and construction control.

Stabilization via lime and/or cement is commonly used to improve poor subgrade soil. The key design parameters for lime stabilized soils and lime–cement stabilized soils (LSS/L-CSS) are strength and stiffness, the growth of which are dependent on both time and temperature. It is generally understood that increased curing temperature will result in increased LSS/L-CSS strength/stiffness; however, there is no quantitative framework for predicting this behavior. This paper proposes a modulus maturity function for LSS/L-CSS that estimates low-strain modulus as a function of the curing duration and the average curing temperature over that duration. To develop the maturity function, nondestructive seismic modulus tests were performed on cylinders cured at varying temperature regimes from three LSS/L-CSS construction sites. Variations in curing behavior were compared within and across sites and least-squares regression analysis was performed to assess the functional behavior of the data. Results indicate that seismic modulus growth in LSS/L-CSS is nonlinear in both time and temperature and should be characterized via a maturity function.

The use of composite materials on a structural engineering area is increasing every day because of the advantages of these materials over conventional materials. In countries like the United States, India, and China, structures made only from polymeric materials for electric energy transmission have been developed. However, there is no reported experience for substituting metallic members with composite elements on lattice power transmission towers. In this work, a methodology for evaluating the feasibility of replacing metallic members with composite members in lattice power transmission towers is presented. The methodology is on the basis of an analysis of the maximum compressive stress than can be developed along the metallic members constituting the inferior zone of a power transmission tower. The obtained results show that four polymeric material alternatives could be considered to manufacture composite members to replace metallic members, which are stolen or removed for some reason. It is possible to replace 0.5–3.0 m steel redundant members with engineering composite materials available in the market. From the experimental results, the connection of composite members cannot be screwed because perforation significantly reduces the mechanical properties of these composite materials around the holes.

The consumption of waste tire rubber in concrete has gained more attention from the point of view of enhanced engineering properties of the product, and also sustainability. Numerous attempts have been stated on the use of waste tire rubbers for the replacement of fine and coarse aggregates in concrete but there is vital need to comprehensively investigate the effect of them on the mechanical properties of rubberized concrete (RC). The aim of this paper is to explore the effect of rubber types and rubber content on mechanical properties of concrete. The compressive strength, tensile strength, flexural strength, modulus of elasticity, strain at maximum strength, and compressive stress–strain curves of RC are studied. Extensive databases used for evaluating the mechanical properties of RC include the measured compressive strength of 298 mixtures, measured tensile strength of 90 mixtures, measured flexural strength of 93 mixtures, measured modulus of elasticity of 156 mixtures, and compressive stress-strain curve of 15 mixtures. Three main rubber mixtures are replaced by fine and coarse aggregate in the collected experimental results that are crumb rubber (CR, with dimension of 0.5–5 mm), tire chips (TC, with dimension of 5–25 mm), and combination of crumb rubber and tire chips (CR+TC). The mechanical properties of these three types RC are evaluated and appropriate constitutive relationships are proposed.

Biorefineries are increasing in number and size and include products based on food, energy, and chemicals. Depending on size and targeted products, biorefineries produce distillation bottoms with surfactant characteristics in sufficient quantities that can be used as a warm-mix asphalt (WMA) technology. Isosorbide distillation bottoms (IDB), having amphiphilic properties much like a classical ionic surfactant, are derived as coproducts of bio-based chemical production and show potential for reducing mixing and compaction temperatures as well as having low-temperature performance grade (PG) benefits. The objective of this paper is to evaluate the performance and potential of IDB as an asphalt additive through asphalt binder testing and mixture testing. Binder gradations were conducted for multiple binders at several dosage rates to verify compatibility with various petroleum crude sources and determine the optimum dosage level. Testing indicates promising results and shows an optimal dosage rate at approximately 0.5% by weight of binder. Mixture testing was performed to evaluate the impact of IDB on mix compactability and moisture susceptibility. Laboratory mixture and binder testing show favorable results for further implementation of IDB as an asphalt additive.

Cement emulsified asphalt (CA) mortar is a key engineering material for ballastless slab tracks of high speed rail (HSR) and has a wide range of asphalt to cement (A/C) mass ratios. Depending on the A/C ratio, CA mortar may be composed of either cement-based or asphalt-based materials. In this paper, based on typical field service conditions of CA mortar of HSR and the characteristics of CA mortar, the testing conditions of dynamic mechanical thermoanalysis (DMTA) for CA mortar were determined, including by measuring the mode, specimen size, frequency, heating rate, and temperature range. Results show that DMTA characterized in this study indicates high repeatability and is an appropriate method for evaluating the thermodynamic mechanical properties of CA mortar. The vibration damping ability of CA mortar increases with an increase in asphalt content within a temperature range of ($-40$ to 60°C).

This paper develops a three-dimensional (3D) microscopic model to investigate the mechanical response of cement mortar with random defects at high strain rates. Ellipsoids with randomness in size, shape, and spatial distribution are used to simulate the defects in mortar matrix. First, we propose the steps to generate the ellipsoid. Second, a “take and place” algorithm is employed to generate a model of cement mortar composed of defects. The mapping algorithm is used to generate a finite-element grid. In finite-element modeling, the material model is used in an advanced general-purpose multiphysics simulation software package to simulate the nonlinear behavior of mortar matrix with strain rate effects. Numerical simulations of the specimen under static loadings agree well with test observations, which reveal that the proposed 3D microscopic model and finite-element analytical approach can give reliable predictions. Finally, numerical studies are conducted, focusing on the effect of the defects on the dynamic responses of cement mortar. It is demonstrated that the defects have effects both on the dynamic behavior and failure pattern under high strain rate loading.

Construction and Demolition Wastes (CDW) have been reused in many engineering works. This paper focuses their use in asphalt pavements by monitoring a real road with different types of field tests over eight years. The parameters obtained presented the same level of the natural granular materials traditionally used and showed the technical potential of the CDW aggregate mixtures for subbase and base layers.

This study aims to develop an improved understanding of the interfacial bond behavior of softwood glulam joints with bonded-in threaded steel rod. A total of 39 glulam joints with bonded-in single-threaded steel rods were tested to failure in the pull-pull configuration. The test results were presented in term of failure modes, load-relative movement response, pullout strength, and the corresponding slip. The distributions of bonded-in rod axial strain, interfacial bond stress, and relative movement were also analyzed to evaluate the local bond stress–relative movement response in the bond line. The results confirmed that the bond-relative movement response is dependent on the locations along the anchorage length, and the bond-relative movement responses located near both the loaded end and the anchorage end were observed to be stiffer than those at other locations. Finally, the predictions for the load capacity of the glulam joints with bonded-in threaded steel rod were carried out based on several existing empirical formulas.

Increasingly it is necessary to search for alternative materials to the construction industry to turn it more sustainable. In this regard, fly ash and carbide lime—residues from production processes—are targets of this study because of their applicability in the stabilization of slopes, base of pavements and manufacture of artifacts for building construction. Therefore, this work aims at the development of method (technique) that enables the prediction of the compressive strength for long curing time periods at standard laboratory curing temperature (23°C) through prediction equivalence with accelerated curing (using temperatures of 40 and 60°C). The porosity/carbide lime ($\eta /L_v$) ratio (corresponding to porosity divided by the volumetric carbide lime content) can be used to predict compressive strength ($q_u$). The results show that a power function adapts better the relation $q_u$ versus $\eta /L_v$, in which $L_v$ is adjusted by an exponent (in this case 0.11) for all coal fly ash—carbide lime mixtures studied. This correlation allowed the comparison of the unconfined compression strength between 1, 3, and 7 days in steam curing at 40 and 60°C with 7, 14, 28, 180, and 360 days at standard laboratory curing temperature (23°C) for different proportions of porosity and carbide lime content. The comparison of standard laboratory curing temperature and accelerated curing allowed generating equations which determines the time required for fast steam cure (40 and 60°C) to provide the same resistance for extended periods under standard laboratory curing temperature (23°C).