Journal of Materials in Civil Engineering

The generation of waste materials from industries like iron, steel, coal, and so on is so large that all countries are facing a shortage of dumping space for these waste materials and it is also causing serious environmental pollution. There is also a huge shortage of aggregate material. With a view to save the costly aggregates and preserve the environment, it is desirable that local natural materials and industrial wastes are used to the maximum extent. This will also lead to economy. Being bound, these materials produce lesser pollution as compared with the freely dumped state. For example, fly ash, if carried away in the air, is most harmful when inhaled. However, concrete mixes are confined enough to cause pollution. In the research reported in this paper, the equivalency factors for various materials used in subbase and base courses have been evaluated experimentally. Subbase courses made of coarse sand, stone dust, riverbed material, blast furnace slag, and Linz-Donawitz slag have been studied with respect to granular subbase course. For the base course study, various stabilized mixtures and different combinations of wet-mix macadam have been studied with respect to wet-mix macadam mixed with 5% soil. This has been done to find out whether the use of these materials can be significant in pavement construction and, if so, then to what extent. The research reported in this paper has been done with respect to various properties like modulus of elasticity, resilient strain, permanent strain, compressive strength, shear strength, failure load, and so on.

Scrap tire disposal has been a critical environmental problem in many urban cities due to the huge increase in the number of vehicles. Significant research efforts have been devoted in recent years to explore the use of scrap tires in civil engineering application, as reuse or recycling of scrap tires is the preferred option from a waste management perspective. This paper investigates shear and compressibility behavior of sand–tire crumb (S-TC) mixtures for their application in civil engineering projects. Unlike other studies where tire chips or tire shreds were used, shear strength of the S-TC mixtures has been found to decrease with the increase in the amount of tire crumbs in the mixtures. Significant increase in axial strain corresponding to peak deviator stress has been observed. This can be related to the ductility capacity of the mixtures, as confirmed by brittleness tests. It has also been observed that a larger proportion of plastic strain develops after the first cycle of unloading, and hence the settlement associated with the application of the mixtures can be significantly reduced by preloading.

Heterogeneous air void distribution is a common phenomenon in asphalt mixtures and is intimately related to the behavior of the asphalt mixture. Air void distribution within an asphalt mixture specimen is related to several factors, such as compaction effort, method of compaction (equipment), and aggregate gradation. In this study, virtual digital specimens generated by an open source discrete element method (DEM) program were utilized to investigate the effect of compaction factors on air void distribution. The compaction processes of a Superpave gyratory compactor (SGC) and a vibratory compactor were simulated by DEM. Effects of aggregate gradation, specimen height, mold size, mold shape, and compaction method on the inhomogeneous distributions of air voids were studied through statistical analyses. The results from DEM simulation were in good agreements with laboratory test results as well as those found in the literature. This research demonstrated that DEM simulation could be a potentially helpful tool for analyzing asphalt mix compaction and selecting appropriate aggregates for asphalt mix design.

Asphalt layers under different repeated loading and rest periods experience both fatigue and healing processes. The tests are costly and time consuming and the results are highly variable. Current methods of evaluating these phenomena using the overlay tester (OT) rely on counting the number of load repetitions until the crack breaks through the sample. This research provides a novel analysis method based on viscoelastic fracture mechanics and finite-element modeling to predict the actual crack growth rate in asphalt mixes, both in laboratory compacted and field samples, by using the OT. Furthermore, the new method uses the principles of viscoelastic fracture mechanics to find the fracture and healing properties of the asphalt mixes. The resulting test is fast, less costly, and more repeatable than previous methods using the OT. The precision of the test method was determined and improved by testing lab compacted specimens. The coefficients of variation of the undamaged properties of the laboratory compacted mixture are comparable with the test results.

This paper presents the development towards a constitutive relationship for permanent strain using repeated load triaxial testing (or RLTT) data under various stress regimes for three granular materials prepared to a single level of compaction and at different levels of moisture content. For each sample investigated, initial permanent strain models were developed. A predictive model (${\epsilon }_p$ model) with seven parameters was then suggested for each material following the general power law based on the permanent strain testing data. The model is capable of estimating the accumulated permanent strain at any number of cycles as a function of number of repetitions, considering the ratio of the mean normal stress to atmospheric pressure, $p_a$, the maximum shear stress ratio, moisture content and maximum dry density corresponded to the optimum, and weighted plasticity index. The ${\epsilon }_p$ model was applied on data from multistage permanent strain testing over many cycles to validate the model’s performance in predicting permanent strain. The permanent strain model was found to have a good to excellent statistical prediction accuracy for the three investigated materials.

The fracture behavior of thin films of bitumen in double cantilever beam (DCB) specimens was investigated over a wide range of temperature and loading rate conditions using finite-element analysis. The model includes a phenomenological model for the mechanical behavior of bitumen, implemented into a special-purpose finite-element user material subroutine, combined with a cohesive zone model (CZM) for simulating the fracture process. The finite-element model is validated against experimental results from laboratory tests of DCB specimens by comparing measured and predicted load–line deflection histories and fracture energy release rates. Computer simulation results agreed well with experimental data of DCB joints containing bitumen films in terms of peak stress, fracture toughness, and stress-strain history response. The predicted “normalized toughness,” $G/2h$, was found to increase in a power-law manner with effective temperature-compensated strain rate in the ductile region as previously observed experimentally. In the brittle regime, $G/2h$ is virtually constant. The model successfully captured the ductile and brittle failure behavior of bitumen films in opening mode (tension) for stable crack growth conditions.

Liquefied silty soil can experience repeated liquefaction as a result of aftershocks or other subsequent earthquake events, which can be considered to be previous cyclic loading. The effect of previous cyclic loading on the liquefaction resistance of low-plasticity silt is investigated in this paper. The experimental program included cyclic triaxial tests conducted on reconstituted Mississippi River Valley (MRV) silt specimens in the laboratory. Two major types of tests were conducted, in which: (1) specimens were loaded until full liquefaction; and (2) loading was stopped before liquefaction occurred. For the specimens loaded until full liquefaction, test results indicated that the rates of development of excess pore pressure and axial strain were greater in extension than in compression during the repeated liquefaction tests. Significant increases in liquefaction resistance were obtained, only as the relative density of specimens approached 100% after more than four liquefaction and reconsolidation tests. For the specimens not loaded until liquefaction occurred, maximum liquefaction resistance was attained when the cyclically induced axial strain was approximately 0.20%. Based on these findings, ground improvement techniques were proposed to improve liquefaction resistance.

The objective of this study was to quantify the levels and sources of variability in the measurements of volumetric and mechanical properties of dense-graded asphalt mixtures on the basis of existing test data from state agencies and contractors. To achieve this objective, data were collected from state DOTs and research agencies, and a statistical analysis was conducted on a per-state basis to provide an overall quantification of the levels of variability for the different volumetric and mechanical properties. A meta-analysis based on the collected data was conducted to identify sources of variability for volumetric and mechanical properties. According to the results of the analysis, levels of variability for a wide range of volumetric and mechanical properties were quantified. Levels of variability were comparable for various state DOTs located in different climatic regions. It was determined that results obtained by the state and contractor were statistically equivalent for the majority of the volumetric properties. Nominal maximum aggregate size (NMAS) of asphalt mixtures appeared to influence the magnitude of the variability observed for the various volumetric and mechanical properties. The results presented in this paper were part of the National Cooperative Highway Research Program (NCHRP) Project 9-48 entitled Field versus Laboratory Volumetrics and Mechanical Properties.

Increased environmental regulations and the rising costs of asphalt binder have encouraged researchers to investigate alternative binders that can be used for hot mix asphalt (HMA). This study focused on using bioasphalt as a possible alternative binder to petroleum-based asphalt. To evaluate bioasphalt as a HMA binder, both binder and mixture tests were performed. Bioasphalt was blended with traditional binders at different percentages (0, 10, 30, and 60%) by weight of the base binder. Binder test results, based on constant shear loading tests and multiple stress creep and recovery tests, showed that the addition of bioasphalt decreased the resistance to fatigue and rutting. The HMA mixture performance tests indicated that the addition of bioasphalt to the mix reduced the stiffness of the mix (dynamic modulus) and its resistance to rutting and fatigue cracking, but increased the resistance to thermal cracking. The moisture susceptibility test shows that bioasphalt mixes passed the minimum tensile strength ratio requirement.

The effects of fiber volume fraction and matrix properties on the mechanical performance of 15-mm thick short cut PVA (polyvinyl alcohol) fiber-reinforced cementitious composites were investigated experimentally. Fiber volume ratios of mixtures varied between 0.5 and 2.0% by volume. Two different water to cement ratios ($\mathrm{w}/\mathrm{c}$) have been used (0.25 and 0.35) for matrix production. Test results have shown that both fiber content and matrix strength have significant effects on flexural behavior and impact resistance of these composites. The combined effect of $\mathrm{w}/\mathrm{c}$ and fiber volume fraction on impact resistance was more drastic compared with specific fracture energies of composites determined under static loads. Especially under the effects of impact loads, higher values of $\mathrm{w}/\mathrm{c}$ and increased PVA fiber content significantly improved the energy absorption capacity of these composites.

This paper discusses the development and testing of long carbon fibers—fibers 75 mm long or longer—to improve the resistance of reinforced concrete to dynamic loading, such as blasts and impact. In the past, attempts to use long fibers in concrete have failed as a result of both balling (agglomeration) and poor dispersion of the fibers. In the present study, two types of long carbon fibers were developed and optimized for their use in reinforced concrete. The resulting long carbon fiber-reinforced concrete (LCFRC) was subsequently evaluated through impact and blast testing. Full-scale blast testing revealed that these fibers significantly increased the resistance of concrete spalling. In terms of the amount of material lost during the blast, LCFRC panels outperformed nonfiber concrete panels by nearly a factor of 10. This significant reduction in weight loss for the LCFRC panels translates into a substantial decrease in harmful, flying debris in a blast event, and a corresponding reduction in blast lethality.

As the concern for the environment and need for sustainable construction practices continues to grow, development of portland cement–free binders is gaining wide interest in the concrete research and engineering community responsible for design and construction of civil infrastructure. In this work, microstructural (as determined by quantitative X-ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy techniques) and material properties of alkali-activated fly ash concrete were evaluated to verify the material’s performance and structural viability. Results show that the heat-cured products of reaction of fly ash in an aqueous alkaline solution form a concrete binder with adequate design properties and promising durability aspects.

The durability of steel reinforced-concrete specimens made from three alkali-activated fly ash (FA) stockpiles and ordinary portland cement (OPC) in cyclic wet-dry chloride environment was evaluated over a period of 12 months. Testing methods included electrochemical methods, chloride diffusion and contents analysis, chemical and mechanical analyses, and visual examination. Geopolymer concrete (GPC) specimens made from Class F FA exhibited lower diffusion coefficients, chloride contents, and porosity compared with their GPC Class C FA and OPC counterparts. Overall, GPC specimens displayed limited signs of leaching and corrosion product formation, whereas OPC specimens exhibited the formation of multiple corrosion products along with significant leaching.

Oxidative hardening or aging of asphalt binder can lead to increase in viscosity, separation of components, loss of cohesion and adhesion, and eventually the degraded engineering performances. A common practice to minimize asphalt aging has been to use chemical additives or modifiers as antioxidants. The current state of knowledge in asphalt oxidation and antioxidant evaluation concentrates on monitoring the degradation in asphalt’s physical properties, mainly the viscosity and ductility. Such practices although satisfying direct engineering needs does not contribute to the fundamental understanding of the asphalt aging and antiaging mechanisms. As such, this study was initiated to study the antioxidation mechanisms of bio-based additives, using the beech-wood lignin as an example, by developing a quantum-chemistry based chemophysical environment in which the various chemical reactions among asphalt components, antioxidative ingredients and oxygen molecules, as well as the incurred physical changes can be studied. The techniques of X-ray photoelectron spectroscopy (XPS) were used to prove the validity of the modified and unmodified asphalt models.

Static and dynamic mechanical properties of cement-asphalt composites with various contents of asphalt incorporated were studied. Uniaxial compressive stress-strain curves of different cement-asphalt mortars (CAMs) with cement mass ratio (A/C) in the range of 0.2 to 1.0 were obtained by the Materials Testing System (MTS) under different testing temperatures ranging from $-40$ to 80°C. Two typical CAMs, one with A/C of 0.2 denoted by LAC and the other with A/C of 0.9 denoted by HAC, were chosen to be tested at varied deformation rates over a range of 0.3 to 30 mm/min at room temperature. The correlation between mechanical properties, e.g., peak stress or elastic modulus, and temperature or loading rate was, respectively, acquired. As a result, temperature sensitivity and loading rate dependence for mechanical behavior of different CAMs were analyzed. Dynamic mechanical analysis (DMA) on three cement-asphalt binders (CABs) with A/Cs from 0.2 to 1.0 was carried out, and temperature spectra and frequency spectra were obtained. The Burger model was used to simulate the viscoelastic mechanical behaviors of CABs. Results indicate that peak stress and elastic modulus of CAMs decline with the increasing A/C and temperature. The temperature sensitivity and the loading rate dependence for mechanical properties of CAMs with higher A/Cs are greater than those of CAMs with lower A/Cs. To quantify the dependence of mechanical properties on temperature and loading rate, temperature-sensitive factor and rate-influencing factor are defined separately. The two factors increase with the A/C, implying that CAMs with higher A/Cs have greater dependence on temperature and loading rate. Furthermore, the two factors for peak stress are bigger than those for elastic modulus for a given CAM. Dynamic modulus of CABs descends with the increase of A/C or temperature but ascends with the loading frequency. As the temperature rises or A/C increases, the viscoelasticity becomes more remarkable. The dependence of dynamic modulus of CABs with varied A/Cs on loading frequency is successfully simulated by using the Burger model.

Usage of special materials with unique properties in seismic resistant structures has increased to overcome their limited energy dissipation and ductility as a result of the 1994 Northridge earthquake. Among them, shape memory alloy (SMA) is a unique metallic alloy that has the ability to undergo large deformation while reverting back to its original undeformed shape; but because any new technology has its pros and cons together, using SMA in structures is not all benefit. In this paper, advantages and disadvantages of using shape memory alloys in structures are studied according to experimental results. Monotonic and cyclic static loading tests on Nitinol and steel bars are conducted to obtain their mechanical properties in tension and compression. Also, a comparative low-cycle fatigue test is conducted using steel and Nitinol samples. Considering the results, a simple and practical solution is developed to overcome some of the deficiencies of these two materials in seismic resisting structures.

The production of portland cement—the key ingredient in concrete-generates a significant amount of carbon dioxide. However, due to its incredible versatility, availability, and relatively low cost, concrete is the most consumed manufactured material on the planet. One method of reducing concrete’s contribution to greenhouse gas emissions is the use of fly ash to replace a significant amount of the cement. An experimental investigation was conducted to study the shear strength of full-scale beams constructed with both high-volume fly ash concrete (HVFAC)—concrete with at least 50% of the cement replaced with fly ash—and conventional concrete (CC). This experimental program consisted of 16 beams (12 without shear reinforcing and four with shear reinforcing in the form of stirrups). Additionally, three different longitudinal-reinforcement ratios were evaluated within the test matrix. The beams were tested under a simply supported four-point loading condition. The experimental shear strengths of the beams were compared with the shear provisions of both American Concerte Institute Committee 318 and AASHTO LRFD Furthermore, statistical data analyses (both parametric and nonparametric) were performed to evaluate whether or not there is any statistically significant difference between the shear strength of the HVFAC and the CC beams. Results of these statistical tests show that the normalized shear capacity of the HVFAC is higher than the CC for the beams tested in this investigation.

For investigations using finite-element methods, e.g., connection details under compression stresses, one needs to know not only the compression strength, but also the complete stress-strain behavior, including the hardening of the wood for all directions. Up to now, only a limited amount of information is available for corresponding values and data for New Zealand Radiata Pine. To gather this missing information, comprehensive compression tests were carried out at the University of Auckland, New Zealand. This includes different load-to-grain angles as well as different load-to-annual ring directions. The results are presented and provided in this paper. According to the different testing standards, including different test methods and different evaluation methods, the tests were done using different loading configurations. Both the stress-strain behavior, including softening or hardening parts, as well as the material properties, using different evaluation methods, are analyzed and described. The test results are also compared with the currently used material strength values of the New Zealand design standard. The presented results and information are a comprehensive basis for future research, especially numerical investigations, and can also serve authors of design codes.

The microstructural development of lime putty is widely recognized and commonly associated with an increase in quality. Many heritage institutions encourage the systematic application of lime putties in conservation; however, all the issues associated with age are not fully understood. Changes occur during storage underwater, which traditionally took place in pits to prevent carbonation. The properties of mortars, plasters, and decorative finishes formed from lime putties are intimately linked to manufacturing parameters such as storage time. The hydration of calcium oxide was investigated using an environmental scanning electron microscope with particular attention to the nucleation of calcium hydroxide crystals on the surface of calcium oxide. Crystal modifications were monitored. The results obtained confirm and quantify the influence of slaking time in the microstructure of lime putties that is also reflected in the current referred special characteristics of the mortars produced with them, such as greater plasticity, water retention, and reactivity of mortars. The results also emphasize that the most significant microstructural changes of the lime putties start to consolidate after 8 months of slaking and appear to continue to develop, even though at a slower rate, until at least 5 years.

The use of recycled asphalt pavement (RAP) materials for roadway construction is a sustainable approach and has received more attention in the recent years. However, permanent deformation, or rutting, is one of the concerns in the use of RAP as a base course due to traffic loading and creep deformation. To minimize the creep deformation, use of a novel polymeric alloy (NPA) geocell was proposed to confine the RAP. One tensile creep test was conducted at a room temperature of approximately 25°C to investigate the creep behavior of the geocell. Nineteen static plate-loading tests were conducted at a room temperature using a medium-sized loading system to evaluate the applied vertical stress-displacement response, the creep strain—time relationship, and the factors influencing the creep deformations of RAP bases. In order to verify the repeatability of the test method, two repeated creep tests were conducted. Well-graded aggregate cover was used in place of the RAP cover to investigate the cover effect on creep deformation behavior of geocell-reinforced RAP bases. The test results showed that the stiffness improvement factors for the geocell-confined RAP over the unreinforced RAP ranged from 1.2 to 1.6. Confinement significantly increased the strength of the RAP. The NPA geocell reduced the initial deformation of RAP samples or bases by 18–73% and their creep rates by 6–60% as compared with the unreinforced base. The creep deformations decreased with an increase in the degree of confinement and a decrease in the applied vertical stress. The well-graded aggregate cover reduced the initial deformation by 58% as compared with the RAP cover. The RAP had a higher creep rate than the geocell in the geocell-reinforced RAP bases.

A new approach for the characterization of linear viscoelastic (LVE) behavior of asphalt concrete is presented in this study. The proposed approach uses the associated function of the original Havriliak-Negami (HN) formulation to model the complex modulus of the material. The model coefficients are determined in two steps. First, the coefficients associated with the complex plane representation of complex modulus are solved in the Cole-Cole domain. Second, the coefficients related to the time-temperature shifting are determined. The results show that the approach can accurately characterize the LVE properties of asphalt concrete contained in the entire data set for the complex modulus. The approach overcomes several shortcomings in the conventional method of constructing a viscoelastic function master curve by fitting a sigmoidal function to test results. Each model coefficient in the proposed approach has a clear physical meaning in interpreting the LVE behavior of asphalt concrete; the same values of model coefficients can be used to construct the master curves of storage modulus, loss modulus, dynamic modulus, and phase angle. Also, the Kronig-Kramers relations are automatically satisfied because the mathematical forms of various viscoelastic functions are theoretically derived from the same complex modulus model, and thus, the results are in compliance with LVE theory. The proposed approach provides a unified and consistent way to characterize the LVE properties of asphalt concrete.

As steel structures become larger, taller, and longer, the demand for high-strength steel increases. High-strength steels exhibit different mechanical characteristics and hysteretic behavior for dynamic deformation than for quasi-static deformation. This is attributable to the strain rate and temperature dependence of steel materials when nonuniformly deformed in the plastic region. Therefore, to analyze and design structures using high-strength steels under dynamic cyclic loading, such as earthquake loading, it is necessary to consider the special dynamic hysteresis model of high-strength steels. In particular, when using finite-element (FE) analysis programs one should use the proper material characteristics for those steels. In this paper, dynamic hysteresis models for standard high-strength steels, with tensile strengths of 600 and 800 MPa, are formulated based on results of tensile tests and low-cycle fatigue tests over a range of strain rates from ${10}^{-4}-10{\mathrm{s}}^{-1}$. A three-dimensional elastic-plastic finite-element analysis program using a newly formulated dynamic hysteresis model is developed by the writers. Accuracy and validity of the developed finite-element analysis program is verified by correlation of the analytical and experimental results.

Epoxide resins are widely employed as adhesives and are being increasingly used in engineering industries. However, adhesively bonded components may suffer significant loss in strength when exposed to environmental attack. The most severe threat is water, and adhesive joint strength decay can be accelerated if externally applied stresses are present. In this work an attempt has been made to develop a model to predict the theoretical durability of butt mild steel joints made underwater. The model was based on experimentally obtained data using double-torsion underwater-made joints and ambient air-made double-torsion and butt joints. All joints were subjected to similar conditions, i.e., static stresses in the presence of water. The first step in developing a test method and model for predicting the environmental fracture data of butt joints made underwater has been proposed that was independent of the detailed butt joint geometry. The model appeared to be successful and accounted for the phenomenon of crack tip blunting that occurs in the adhesives. This is the first time such a model is reported in the literature that may be useful when all variables are included.

Some rocks are very attractive as ornamental stone, but not all of them accomplish the needed requirements to be used in construction. Serpentinite can be an appealing rock, very commonly used as dimension stone. However, not all serpentinites can be used in such a way. The most widely used commercial serpentinite comes from Pakistan and India (i.e., Rajasthan Green), but other countries also produce serpentinites, such as Italy (Verde Alpi, Verde Polcevera, Verde Prato), United States (Vermont Verde Antique), and Spain (Verde Macael, Verde Pirineos). The geomechanical properties of a serpentinite are strongly related to its mineralogy (serpentine-group minerals and carbonates, mostly), and not all serpentinites are created equal. We have compared the mineralogy and mechanical properties of serpentinites that comply with the Standard Specification for Serpentinite as Dimension Stone (i.e., Rajasthan Green, Verde Macael) with those that do not (Verde Pirineos). Verde Pirineos consists of lizardite, and the carbonates, mostly dolomite, are restricted to veins. Rajasthan Green consists of antigorite, and most of the serpentine has been replaced by carbonates, dominantly magnesian calcite. Taking into account their composition and textures, rocks with such differences will evolve in different ways in a weathering environment. In replacing damaged serpentinite from a building, it is important that the new piece have the same characteristics, otherwise the replaced tiles will not look appropriate in aesthetic terms. This is particularly important in restoring monuments. Petrographic studies and x-ray diffraction are essential in analyzing the commercial potential of these rocks, and results are directly related to the geomechanical behavior of the samples. Knowledge of these characteristics would help to choose the right replacement in case of restoration of monuments and other buildings.

Enhancement of local soils with fibers and cement for the construction of stabilized pavement bases, canal lining, and support layers for shallow foundations shows great economical and environmental advantages, avoiding the use of borrow materials from elsewhere, in addition to the need of a spoil area. In previous studies, a unique dosage methodology for cemented soils has been established based on rational criteria in which the porosity-to-cement ratio plays a fundamental role in the assessment of the target unconfined compressive strength ($q_u$). The present paper extends previous work by quantifying the influence of the amount of cement, the porosity, and the porosity-to-cement ratio in an assessment on tensile strength ($q_t$) and compressive strength of a fiber-reinforced artificially cemented sand, in addition to the evaluation of the $q_t/q_u$ relationship. A program of splitting tensile tests and unconfined compression tests considering four distinct dry densities and five cement contents, varying from 1–7%, was carried out in the research reported in this paper. The results show that a power function adapts $q_t$ and $q_u$ values well with increasing cement content and reducing porosity of the compacted mixture. The porosity-to-cement ratio is an appropriate parameter to assess both tensile strength and unconfined compressive strength of the fiber-reinforced sand/cement mixture studied. Finally, the $q_t/q_u$ relationship is unique for the fiber-reinforced sand/cement studied, being independent of the porosity-to-cement ratio.

Ultra-high performance concrete (UHPC) is a family of emerging materials for building and construction applications. Behavior of UHPCs at high temperature is very important to their reliability and safety. In the current study, two UHPC materials were studied using the thermomechanical analysis (TMA) technique between room temperature and 800°C. Both reversible and irreversible phase transformations were observed from the TMA results, which were likely attributable to the $\alpha \text{-}\beta$ quartz transformation and the dehydroxylation transitions, respectively. Thermal expansion coefficients exhibited significant variations in different temperature regimes. Postmortem scanning electron microscopy (SEM) examinations revealed extensive cracking in the heated samples. In addition, microporosities were observed in the calcium-silicate-hydrate (C-S-H) phase as a result of phase changes during heating.