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Abstract The utilization of geopolymer as a grouting material has gained significant attention in research and construction applications. Geopolymer grout is a type of binding material that differs from traditional grouts, typically based on Portland cement. Researchers have explored its effectiveness and potential applications in grouting processes, considering its unique properties and characteristics. In this paper, various studies employing and utilizing geopolymer as a grouting material are reviewed. The emphasis is on mixture design of geopolymer grout, physical property, chemical composition of geopolymer grout, rheological behavior of geopolymer grout such as yield stress (in case of Bingham fluid) and viscosity, and engineering properties such as compressive strength, expansion, shrinkage, etc.

Abstract The southeast Texas (SETX) coastal area, owing to its unique geographical location and geological attributes, is facing a spectrum of geological challenges, such as ground subsidence, flooding, and coastal erosion. This study endeavors to evaluate the recent instances of ground subsidence and their associated rates, focusing on comprehending their implications for flooding within SETX. Employing the Persistence Scatterer Interferometric Synthetic Aperture Radar (PS-InSAR) technique, this study employs Sentinel-1 SAR satellite data with descending orbit observations spanning from January 2020 to March 2023. Our findings indicate that both the northwestern and eastern regions of Houston have been settled with rates up to 2 cm/year. This settlement trend is consistent with data derived from GPS and groundwater level measurements. This investigation explicitly shows the substantial temporal and spatial variations in subsidence rates, predominantly influenced by localized groundwater extraction due to urbanization (e.g., population growth, land development, etc.). By advocating for the integration of InSAR, GPS, and groundwater measurements, this research aspires to make valuable contributions toward the mitigation of subsidence and flood-related hazards in the SETX area.

This study examines the strategic incorporation of various recycled materials into asphalt concrete, specifically focusing on municipal solid waste incineration bottom ash (MSWI BA), recycled asphalt shingle (RAS), and recycled concrete aggregate (RCA). Due to the high porosity of MSWI BA and RCA, and the significant asphalt binder content (30–40%) found in RAS, there is a need to increase the amount of liquid asphalt used. RAS is posited as an efficient substitute for the asphalt binder, helping to counterbalance the high absorption characteristics of MSWI BA and RCA. The research objective is to quantitatively evaluate the effect of the combined use of RAS, MSWI BA, and RCA in Hot Mix Asphalt (HMA). This study encompasses several laboratory evaluations (i.e., rutting and tensile strength tests) and a cost–benefit analysis, which is a life cycle cost analysis. The results indicate that the combined use of these materials results in a higher tensile strength and rut resistance when compared with the control (with virgin aggregate). According to the cost–benefit analysis result, when the three recycled materials are used for an HMA overlay over an existing aged pavement, it could be 60–80% more cost-effective compared to a conventional HMA overlay, thereby offering significant economical savings each year in the field of road construction.

In the realm of geotechnical engineering, understanding the mechanical behavior of soil particles under external forces is paramount. The main topic of this study is how to use deep learning image analysis techniques, especially transfer learning models like VGG, ResNet, and DenseNet, to look at response images from models of reflective photoelastic soil particles. We applied a total of six transfer learning models to analyze photoelastic response images. We then compared the validation results with existing quantitative evaluation techniques. The researchers identified the most outstanding transfer learning model by comparing the validation results with existing quantitative evaluation techniques using performance metrics such as the coefficient of determination, mean average error, and root mean square error.

This study investigated the positive effect of the combined use of recycled asphalt shingles (RASs) and municipal solid waste incineration (MSWI) bottom ash (B.A.) in asphalt concrete, which contributes to enhanced sustainability in pavement engineering. In addition, unlike traditional approaches that employ individual recycling material in hot mix asphalt (HMA), the combined use of the two waste materials maximizes the mechanical performance of the asphalt mixture. The addition of RAS (with 30–40% aged binder) as an additive generally enhances the strength/stiffness of the asphalt mixture. The high porosity/absorption of MSWI BA results in an additional amount of liquid asphalt binder in the mixture. As an admixture, RAS could supply the additional asphalt binder in the mixture when MSWI BA is used as an aggregate replacement. This research was conducted in two phases: (1) to examine the effect of MSWI BA alone and its optimal asphalt content (OAC), and (2) to assess the combined effect of B.A. and RAS in HMA. Multiple laboratory testing methods were employed for the mechanical performance investigation, including the Marshall stability test, rutting test, and indirect tensile test. The testing results show that the 20% B.A. replacement exhibits the best performance and that it requires an additional asphalt binder of 1.1%. For the combined use of MSWI BA and RAS, 5% RAS shows the best mechanical performance. All mixtures that contain the B.A. and RAS show greater strength than the control specimen (regular HMA).

In this study, the effects of graphene oxide nanoflake (GONF), a low-cost carbon-based nanomaterial, on mechanical properties and flexural fatigue performance of different concrete mixtures (i.e., normal concrete (CTRL), GONF mixed concrete (GO-C), steel fiber reinforced concrete (SFRC), and GONF mixed SFRC (GO-SRC)) were investigated, and the feasibility of implementation of the mixtures in rigid pavement was examined. The results demonstrate that the fatigue performances of CTRL and SFRC are enhanced by GONF of 0.1% by weight of cement although the static mechanical strength and modulus of elasticity are barely affected. While the maximum tensile stresses and deflections of concrete slabs calculated by Westergaard's solution show almost similar values regardless of the mixture types and slab thicknesses, the maximum principal stresses induced in the slabs computed by finite element (FE) analysis were increased by SFs about 7–12% under the vehicle and environmental loading conditions in accordance with the slab thickness. In both cases, however, the GONF and SFs reduced the stress ratio, affecting the fatigue performance. The fatigue models of the mixtures for an application in rigid pavement are proposed based on Mechanistic-Empirical Pavement Design Guide, and scenario studies show that the GONF of 0.1% can significantly reduce the slab thickness by 12.6–14.6% regarding the pavement service life of 25–50 years.

The roller-compacted concrete pavement (RCCP) has the same ingredients as the pavement made of normal vibrated concrete (NVC). Microstructure images show that RCCP has higher pack density compared to NVC specimens. The 28-day compressive, splitting tensile, and flexural strengths of RCCP are by 9%, 4%, and 25% higher than those of NVC. The final water absorption and porosity values are by about 8% and 10.6% lower for RCCP in comparison with NVC.

Abstract This paper investigates the effect of clay content on the shear strength of clay–sand mixtures. Bentonite and Jumunjin sand were mixed to prepare clay–sand mixtures with varying clay contents of 5, 10, 15, 20, 25 and 30%. The shear strength of clay–sand mixture was measured using direct shear tests and angle of repose tests in dry condition. The angle of repose of the clay–sand mixture was measured to be greater than that of pure sand for the studied range of clay contents. Likewise, the internal friction angle of the clay–sand mixture was measured to be higher than that of pure sand, reaching a peak at the clay content of 10%. Theoretically, the behavior of the clay–sand mixtures was to be governed by large size particles at clay contents smaller than 23.5%, which agrees well with the visual inspection on the mixtures. At clay content of 25.1% or greater, where the contribution of large particle was theoretically assumed to be none, the results from the angle of repose tests were significantly scattered, indicating that the clay started playing a key role in the behavior of mixtures.

A procedure for determining the optimized composition of layer properties for a continuously reinforced concrete pavement (CRCP) system was constructed using field tests, finite element (FE) analysis, and regression analysis methods. The field support characteristics of a rigid pavement system were investigated using a falling weight deflectometer (FWD), dynamic cone penetrometer (DCP), and a static plate load test. The subgrade layer exhibited a more uniform condition than the aggregate base, and the modulus of the subgrade reaction of the aggregate base and subgrade combination (effective k-value) was improved by about 1.5 times by introducing a 2 inch (50.8 mm) asphalt stabilized base (ASB) layer. Thereafter, FE support models describing the actual field conditions were studied. The effects of the thickness of the stabilized base layer, the elastic modulus of the stabilized base material, and the effective k-value on the composite k-value of the support system were identified using a regression analysis method, and the results showed that the variables had a similar effect when determining the composite k-value. Afterward, a procedure for selecting the layer properties for producing a suitable composite k-value was constructed, and we identified that the maximum stress in the concrete slab was induced at different levels, even with identical composite k-values. Lastly, regression relationships were derived to estimate the maximum stress in the concrete slab by considering both the support layer properties and the concrete slab. Subsequently, an algorithm for selecting an optimized layer composition of the CRCP structure was construction considering the economical aspect.

With the continuous research efforts, sophisticated predictive molecular dynamics (MD) models for C-S-H have been developed, and the application of MD simulation has been expanded from fundamental understanding of C-S-H to nano-engineered cement composites. This paper comprehensively reviewed the current state of MD simulation on calcium-silicate-hydrate (C-S-H) and its diverse applications to nano-engineered cement composites, including carbon-based nanomaterials (i.e., carbon nanotube, graphene, graphene oxide), reinforced cement, cement–polymer nanocomposites (with an application on 3D printing concrete), and chemical additives for improving environmental resistance. In conclusion, the MD method could not only compute but also visualize the nanoscale behaviors of cement hydrates and other ingredients in the cement matrix; thus, fundamental properties of C-S-H structure and its interaction with nanoparticles can be well understood. As a result, the MD enabled us to identify and evaluate the performance of new advanced nano-engineered cement composites.

Over the past decades, extensive studies on municipal solid waste incineration (MSWI) ashes have been performed to develop more effective recycling and waste management programs. Despite the large amount of research activities and the resulting improvements to MSWI ashes, the recycling programs for MSWI ashes are limited. For instance, although the U.S. generates more MSWI ashes than any other country in the world, its reuse/recycle programs are limited; bottom ash and fly ash are combined and disposed of in landfills. Reuse of MSWI ashes in the construction sectors (i.e., geomaterials, asphalt paving, and concrete products) as replacements for raw materials is one of most promising options because of the large consumption and relatively lenient environmental criteria. The main objective of this study was to comprehensively review MSWI ashes with regard to specific engineering properties and their performance as construction materials. The focus was on (1) the current practices of MSWI ash management (in particular, a comparison between European countries and the U.S.), (2) the engineering properties and performance of ashes when they are used as substitutes of construction materials and for field applications, and (3) the environmental properties and criteria for the use of MSWI ashes. Overall, the asphalt and concrete applications are the most promising, from both the mechanical and leachate viewpoints. However, cons were also observed: high absorption of MSWI ash requires a high asphalt binder content in hot-mix asphalt, and metallic elements in the ash may generate H2 gas in the high-pH environment of the concrete. These side effects can be predicted via material characterization (i.e., chemical and physical), and accordingly, proper treatment and/or modified mix proportioning can be performed prior to use.

Depressions due to sinkhole formation cause significant structural damages to buildings and civil infrastructure. Traditionally, visual inspection has been used to detect sinkholes, which is a subjective way and time- and labor-consuming. Remote sensing techniques have been introduced for morphometric studies of karst landscapes. This study presents a methodology for the probabilistic detection of sinkholes using LiDAR-derived digital elevation model (DEM) data. The proposed study provides benefits associated with: (1) Detection of unreported sinkholes in rural and/or inaccessible areas, (2) automatic delineation of sinkhole boundaries, and (3) quantification of the geometric characteristics of those identified sinkholes. Among sixteen morphometric parameters, nine parameters were chosen for logistic regression, which was then employed to compute the probability of sinkhole detection; a cutoff value was back-calculated such that the sinkhole susceptibility map well predicted the reported sinkhole boundaries. According to the results of the LR model, the optimal cutoff value was calculated to be 0.13, and the area under the curve (AUC) of the receiver operating characteristic curve (ROC) was 0.90, indicating the model is reliable for the study area. For those identified sinkholes, the geometric characteristics (e.g., depth, length, area, and volume) were computed.

Continuous pavement deflection profiling in a nondestructive manner has received great attention because of its efficiency in pavement evaluation. The Rolling Dynamic Deflectometer (RDD) is a continuous pavement deflection profiling technology and has demonstrated its successful use at many pavement projects. However, RDD’s current test speed of 1.6 km/h (with the prototype rolling sensor) often limits its use in large-coverage projects and traffic congested areas. Increasing the test speed creates a higher-noise environment, lowered signal-to-noise ratio, and sensor decoupling with the ground surface. This study presents the enhancement to the RDD for increased test speed, associated with the new design of the lower-level rolling sensor and higher-performance digital filter and data processing. The new sensor along with the enhanced data processing could increase the spatial resolution of the deflection data, which allows the increase of the test speed of the RDD.

This paper aims to investigate the effects of edge-oxidized graphene oxide nanoflakes (EOGO) on the mechanical properties and sorptivity of cement composites. The EOGO used in this study was produced by a mechanochemical process that assists the production of EOGO in large quantities at significantly reduced costs, enabling its practical use for infrastructure construction. The scope of this work includes the use of EOGO as an additive in cement composites, including cement paste and mortar. This study explores two mixing methods: The dry-mix method and the wet-mix method. The dry-mix method uses EOGO as dry powder in cement composites whereas the wet-mix method uses a water-dispersed solution (using a sonication process). Varied percentages of EOGO, ranging from 0.01% to 1.0%, were used for both methods. To evaluate the concrete durability, the effect of EOGO addition on sorptivity of the cement composites was investigated by performing total porosity and water sorptivity tests. It was found that 0.05% of EOGO is the optimum proportion to exert the highest strength in compressive and flexural strength tests. In addition, the dry-mix method is comparable to the wet-mix method (with dispersion of EOGO), thus more practical for field engineering applications.

The object of this study is to investigate the feasibility of ball-milled graphene oxide nanoflakes (GONFs) produced by a mechanochemical process as an additive in Ordinary Portland Cement (OPC)-based paste and concrete. Different percentages of GONFs (0.01–1 wt. %) were added in OPC paste mix to find the optimum content of GONF in GONF-combined cement composites. To investigate the effect of the changes in the mix design on OPC paste, two mix design methods were employed: (1) Dry-mix, where GONFs and OPC powders are mixed prior to paste formation and (2) Wet-mix, where sonicated GONFs solution is used as the pour water with OPC paste mix. Data from mechanical tests (compressive and flexural tests) showed that OPC paste incorporating 0.05% GONF resulted in the highest strength for OPC paste. The results of strength tests indicated that Dry-mix is competitive as compared with Wet-mix. Scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) was used to identify GONFs inside products of cement hydration. To explore the practicality of using GONF in concrete, concrete specimens were made, cured and tested with different percentages of dry-mixed GONFs (0.01–0.1 wt. %). The result of strength test showed that GONF improves the compressive and flexural strengths of concrete around 15% with 0.01 wt. % GONF.

Aggregate type and mineralogy are critical factors that influence the engineering properties of concrete. Temperature variations result in internal volume changes could potentially cause a network of micro-cracks leading to a reduction in the concrete’s compressive strength. The study specifically studied the effect of the type and mineralogy of fine and coarse aggregates in the normal strength concrete properties. As performance measures, the coefficient of thermal expansion (CTE) and compressive strength were tested with concrete specimens containing different types of fine aggregates (manufactured and natural sands) and coarse aggregates (dolomite and granite). Petrographic examinations were then performed to determine the mineralogical characteristics of the aggregate and to examine the aggregate and concrete microstructure. The test results indicate the concrete CTE increases with the silicon (Si) volume content in the aggregate. For the concrete specimens with higher CTE, the micro-crack density in the interfacial transition zone (ITZ) tended to be higher. The width of ITZ in one of the concrete specimens with a high CTE displayed the widest core ITZ (approx. 11 µm) while the concrete specimens with a low CTE showed the narrowest core ITZ (approx. 3.5 µm). This was attributed to early-age thermal cracking. Specimens with higher CTE are more susceptible to thermal stress.