State Highway Research Articles

Electrical Resistivity Testing of Concrete Cylinders: Bias, Precision, and Use in Process Control

Electrical resistivity is increasingly used as a test method to assess the transport properties of concrete. This paper describes an interlaboratory study that was conducted to determine precision and bias for resistivity measurements made in surface and bulk configurations of concrete cylinders. Tests were performed following AASHTO T 358-22 and AASHTO T 402-23. A verification device is introduced with a known resistivity (and impedance) to aid in determining the bias associated with resistivity measurements. However, this device can also be used as a training tool and as a tool to evaluate the qualifications of those new to performing the test. Concrete cylinders were prepared, cured, and conditioned using three methods: immersed in simulated pore solution, sealed, and immersed in lime solution. The samples were tested to determine the precision in the resistivity measurements of the samples for the different curing conditions. The paper discusses how resistivity testing can be used for quality control testing as well as quality acceptance. The results were used to develop precision and bias statements for resistivity measurements, which have been adopted in the latest American Association of State Highway and Transportation Officials (AASTHO) standards.

Using Statewide Transportation Planning Model to Forecast Demand for Electric Vehicle Charging at Stations Along Intercity Highways

The availability of Charging Stations (CSs) with adequate capacity is critical for the growth in ownership and usage of Electric Vehicles (EVs). In the United States, the state Departments of Transportation (DOTs) are responsible for planning CSs along the Interstate, national, and state highways. While the state DOTs have their Statewide Transportation Planning Models (STPMs), most of these models do not represent EVs internally. The state DOTs can only rely on the existing STPMs to forecast the demand for EV charging at specific CS locations in a state’s highway network. This research proposes a methodology that utilizes an existing STPM, EV and non-EV vehicle registration data, and hourly traffic volumes at strategic counting stations to predict the hourly demand for EV charging (charging port occupancy) at proposed CSs. This approach first estimates the volume of all passenger cars that will pass the vicinity of a CS along intercity highways, and identifies the Traffic Analysis Zones (TAZs) of their trip origins. Based on the EV adoption rates of the TAZs, EV range, and EV owner’s charging behavior, the methodology forecasts the volume of EVs that pass the vicinity of a CS and the number of EVs that will stop at the CS to charge every hour of the day. An example problem demonstrated the application of the methodology in the State of Texas. It not only forecasted the hourly occupancy at CSs along three major corridors, but also demonstrated how to determine the capacities of the CSs. The challenges of using the existing STPM and their solutions are discussed. This proposed methodology enables the state DOTs to forecast the demand for EV charging and the capacities at the proposed CSs along intercity highways, thus allowing the DOTs to apply for federal funds to accelerate the deployment of the CSs. (298 words)

Preliminary Study on Multi-Scale Modeling of Asphalt Materials: Evaluation of Material Behavior through an RVE-Based Approach

This study employs a microstructure-based finite element modeling approach to understand the mechanical behavior of asphalt mixtures across different length scales. Specifically, this work aims to develop a multi-scale modeling approach employing representative volume elements (RVEs) of optimal size; this is a key issue in asphalt modeling for high-fidelity fracture modeling of heterogeneous asphalt mixtures. To determine the optimal RVE size, a convergence analysis of homogenized elastic properties is conducted using two types of RVEs, one made with polydisperse spherical inclusions, and another made with polydisperse truncated cylindrical inclusions, each aligned with the American Association of State Highway and Transportation Official’s maximum density gradation curve for a 12.5 mm Nominal Maximum Aggregate Size (NMAS). The minimum RVE lengths for this NMAS were found to be in the range of 32–34 mm. After the optimal RVE size for each inclusion shape is obtained, computational models of heterogeneous Indirect Tensile Asphalt Cracking Test samples are then generated. These models include the components of viscoelastic mastic, linear elastic aggregates, and cohesive zone modeling to simulate the rate-dependent failure evolution from micro- to macro-cracking. Examination of load-displacement responses at multiple loading rates shows that both heterogeneous models replicate experimentally measured data satisfactorily. Through micro- and macro-level analyses, this study enhances our understanding of the composition-performance relationships in asphalt pavement materials. The procedure proposed in this study allows us to identify the optimal RVE sizes that preserve computational efficiency without significantly compromising their ability to capture the asphalt material behavior under specific operational conditions.

Epidemiological analysis of Road Accident Data Management System (RADMS) data in Tamil Nadu, India from 2011 to 2016: Future directions for an integrated national database

ABSTRACT Introduction: Globally, road traffic injuries (RTIs) are the eighth leading cause of death, with an estimated 1.35 million deaths yearly. In India, road traffic accidents (RTAs) are one of the major causes of mortality among the younger generation. We analyzed Tamil Nadu’s comprehensive Road Accident Data Management System (RADMS) data and described the epidemiological indicators of RTI in this setting. Methods: We obtained the data from the RADMS database for 2011–2016 and used 2011 population census data to project and standardize for different age groups and genders to calculate incidence. We calculated average annual percentage changes (AAPC) with a 95% confidence interval for the whole period. We computed Joinpoint regression analysis for trends and calculated the age-adjusted incidence rate with standard error (SE) using R statistical computing software. Results: We included 3,67,094 RTAs and 5,50,447 RTIs. We observed that the incidence of RTAs and RTIs declined between 2011 and 2016. Most injured were males (82%) and aged 20–39 years (49%). The highest number of accidents occurred on the state highways (65.2%) and on Sundays (17%). Age-adjusted incidence (per 1,00,000) declined from 121.87 (SE 0.4) in 2011 to 92.73 (SE 0.34) in 2016 (AAPC = -4.5% (95% CI = -7.8 to -1)). The age groups 30–39 and 20–29 were 9.82 (z = 8.98; P < 0.05) and 9.02 (z = 8.65; P < 0.05) times at a higher risk compared to 0–9 years old. The motorcyclists (14–27 times; P < 0.05) and pedestrians (12–23 times; P < 0.05) had the maximum risk of RTIs. Conclusion: Young adults, drivers, motorcyclists, and pedestrians remain vulnerable populations for RTIs. More accidents occurred in the state highways and on Sundays. The analysis provides insights on RTIs and RTAs, which will be used to reduce the burden of RTIs and save millions of lives.

Cat out of the bag: Coastal and Gangetic plains outside protected areas require focus for fishing cat conservation in southern West Bengal, India

State of West Bengal is the last stronghold for fishing cats in the country. Although Fishing cats has been mentioned as a vulnerable wetland species, few works have been conducted on their distribution pattern, habitat or ecology. Our study uses camera traps in various urban and rural wetland areas of South Bengal spanning more than 60,000 km2 to identify their presence. Out of 38 potential habitats, 24 regions came up with evidence of these cats spanning through the eight districts of southern West Bengal. We used presence absence data to fit an ensemble model to delineate suitable habitat for the species in the state. Results indicated areas less than 30 m of elevation and enough annual precipitation that functions healthy hydrological cycle in the areas of lower Gangetic plains to be most suitable for Fishing cats. High mortality of the species due to retaliation and roadkill is a known fact for the species in the state. Hence, we also demarcated conservation priority zones for the species in the state which suggested agricultural lands (51.02 %), wetlands (21.22 %), vegetation cover (18.6 %) with populistic tourism spots in urban patches of southern Bengal need to have focus from the concerned authority to save the remaining habitats. Accordingly, we further identified potential roadkill zones over state and national highways within the suitable habitat of the state.

Evaluation of Minimum Web Reinforcement Requirements for Slender and Non-Slender Beams

Prescriptive shear requirements in the U.S. from the American Concrete Institute (ACI) 318 (2019), the American Association of State Highway and Transportation Officials Load and Resistance Factor Design (AASHTO LRFD) Bridge Design Specifications (2020), and the fédération international du béton Model Code ( fib MC) (2010) include a minimum web reinforcement requirement. In general, slender beams require a minimum area of web reinforcement equal to 0.08% of the cross-section, while non-slender beams require up to 0.30%, or roughly three times more than the slender beam requirement. This investigation aims to evaluate the discrepancy between these requirements in relation to the strength and serviceability behavior of experimental test data. This is carried out through an analysis of existing and peer-reviewed databases. The results show that the minimum web reinforcement needed to ensure shear strength is consistent with code requirements for slender beams, but not non-slender beams. The minimum web reinforcement needed to restrain crack widths is consistent with code requirements for non-slender beams, but not slender beams. Thus, the prescriptive web reinforcement requirements for slender and non-slender beams do not appear to be derived from the same criteria. The requirement for slender beams is derived based on these members achieving their predicted strength, while the requirement for non-slender beams is derived based on the width of in-service cracks.

A systematic risk assessment approach for urban roadside infrastructure assets

Revealing potential risks and the influence of these risks on urban roadside vulnerable/risky zones has been a great deal for the last decades owing to increasing vehicular mobility. This study aimed to develop a risk assessment methodology for urban roadside infrastructure assets. In this context, seven risk parameters that are likely to affect hazardous aboveground assets installed on urban roadsides were determined, and weights of each parameter (order of importance) were presented based on expert surveys and literature information using the Analytic Hierarchy Process (AHP) method. Mathematical models were set up for each risk parameter using real field data, The American Association of State Highway and Transportation Officials (AASHTO), literature, related standards, and expert surveys by linear, nonlinear, and binary logistic regression analyses. Risk groups were created, and precautions were offered. The efficiency of the models was verified based on the 28 accident records and field observations in 172 assets. When considering the assets that undergo traffic accidents, 71% of the total assets are ranked in the critical and high-risk group. This ratio is consistent with the risk group definitions assigned in this study; thus, the model proposed is accurate and can be applied reliably. The verification process of the total risk model was sufficiently successful to be used in practice and can be generalized by considering the road and traffic characteristics, infrastructure facilities, and future requirements of the regions or countries that reflect similar historical and cultural concerns. Practitioners, governmental institutes, and researchers can apply this methodology to provide their own data with high transparency and reliability.

Design resistance strengths of composite steel box girder bridge using different codes

Bridges design based on prescriptive normative rules regarding loads and their combinations, safety factors, material properties, analysis methods, required verifications, and other issues that are included in design codes. In addition, Composite Steel Box Girder (CSBG) bridges present a prominent structural solution for straight and curved bridges with moderate spans, because of their large bending resistance and high torsional stiffness as well as rapid erection. This paper aims to perform a detailed theoretical comparative study between fundamental calculations of the design resistance strengths of shear, Vn or VRd, and flexure, Mn or MRd, in positive (sagging) and negative (hogging) moment regions, of CSBG highway bridges. The comparison is involved with design specification methodologies proposed by Egyptian Code of Practice (ECP-207-part 6), Bridge Design Specifications (BDS) presented by Association of State Highway and Transportation Officials (AASHTO), and European Standard (EC-4). On its turn, the study aims to standing on differences and similarities between considered standards in the design of such bridges.

Moisture Sensitivity Performance of Hot Mix Asphalt Mixture Incorporating Fly Ash Geopolymer (FAG) Asphalt Binder

In Malaysia, Hot Mix Asphalt (HMA) is widely used in asphalt production. HMA is a mixture of asphalt and aggregates that give durability to the road surface for pavement. Due to vehicles excessive traffic loadings that cause road surface damage, this pavement technology frequently undergoes maintenance and rehabilitation work. This study used recycled material as a modified binder and showned the best result in increasing stiffness and better rutting performance with high percentages of additives. This research focuses on the effect of FAG additive on asphalt mixture performance evaluation according to SuperpaveTM mixes design method. The procedures were specified according to the American Association of State Highway and Transportation Officials (AASHTO), American Society for Testing and Materials (ASTM), British Standard (BS) and Malaysian Standard (MS). The granite aggregate type was produced by a local quarry with conventional asphalt binder grade 80/100 and 60/70. Incorporation FAG in modified asphalt binder as levels of 0, 3, 5, 7, 9, and 11% by mass of asphalt binder. The performance of moisture sensitivity showed low moisture damage susceptibility for the mixture based on consistent values of TSR, in which all the specimens met the minimum TSR threshold of 80%. The optimization findings indicated that 9% of fly ash geopolymer might be the ideal content for modifying the asphalt binder. Overall, research findings suggest that using geopolymers may have improved some of the characteristics of asphalt binder and the performance of asphalt binders in pavement applications. Thus, the outcomes of this research were significantly used for further performance test and analysis on the asphalt mixture.

Environmental impacts from traffic on highway construction work zones: Framework and simulations

Emissions from internal combustion engine vehicles on highways are the major contributors to global warming in the United States. Transportation sector pavement-related emissions come from gasolines and diesel use in vehicles from pavement-vehicle interaction, which is affected by pavement conditions, and by the trucking of new pavement materials and demolition. The objective of this study was to develop a framework for determining the fuel use resulting in environmental impacts caused by construction work zones (CWZs) on a range of vehicles and to produce initial calculations of these impacts by modeling traffic closure conditions for highway maintenance and rehabilitation activities. The study included two common highway categories—freeways/multi-lane highways and two-lane highways. The framework was demonstrated using three CWZ operations under different traffic congestion levels. In the simulation results for a freeway with a CWZ and heavy congestion, fuel consumption increased by 85% and the carbon-dioxide equivalent emissions increased by 86%. Changing CWZ traffic congestion from heavy (average speed 5 mph) to medium (average speed 25 mph for a freeway section) reduced fuel consumption by 40% on a freeway. This study also included use of a pilot car in a CWZ on a two-lane road typical of lower traffic volume state highways and county roads to compare with the drive cycles in MOVES used for the scenarios. The pilot-car operation scenario results indicate that a one-lane closure with pilot-car operation on a two-lane road might consume 13% excess fuel because of idling time and the slow movement of vehicles following the pilot car.

Peer Exchange for Improving Accuracy of the Engineer’s Estimate for Highway Improvement Projects

The Wisconsin Department of Transportation hosted a peer exchange in 2021 to discuss topics related to improving procedures for developing the engineer’s estimate. The goal was to improve accuracy of engineers’ estimates by providing a forum for the exchange of ideas, lessons learned, and opportunities for the development of state-to-state relationships for continued improvements. Before the peer exchange, invited State Highway Agencies (SHAs) were asked to fill out an online survey to obtain preliminary information about their estimating procedures and practices, organizational approach, measurements of estimating accuracy and bidding history. Representatives from 16 SHAs responded to the survey and representatives from 11 SHAs and the Federal Highway Agency participated in the peer exchange. This article presents the results of the survey and a summary of the discussions during the peer exchange so that other SHAs can learn from them. The peer exchange provided a summary of the state of practice of the SHAs in preparing the engineer’s estimate and identified the following list of most impactful factors for differences between the engineer’s estimate and bidding results: low bid competition, geographic location, outdated data used in historical bid-based estimating, shortage of skilled workers and time, and market volatility. Discussions during the peer exchange uncovered how individual SHAs are approaching and dealing with these factors and those results are presented in the article. Other SHAs will benefit from the summaries of other SHAs’ current practices and the action items Wisconsin Department of Transportation identified resulting from the peer exchange.

Road mitigation structures designed for Texas ocelots: Influence of structural characteristics and environmental factors on non-target wildlife usage.

Roads negatively impact wildlife through habitat fragmentation, loss of habitat connectivity, and wildlife-vehicle collisions, thus road mitigation structures, such as wildlife crossing structures (WCS), wildlife guards (WG), and fencing are commonly used to address this issue all over the world, including in the United States. In South Texas, such structures were built or modified along a State Highway in an effort to address road mortality for the endangered ocelot (Leopardus pardalis) and non-target wildlife species. The goal of this study was to examine temporal changes in wildlife interactions with WCS and WG during and after their construction and modification along a South Texas highway and to determine whether environmental factors influenced use of WCS. Using camera traps deployed to monitor the road mitigation structures, we compared crossing rates, repel rates, and species richness of all species that interacted with the structures, and we examined whether differential wildlife use of WCS and WG was affected by one or more structural dimensions, distance to nearby vegetation, and water presence. Crossings through WCS by wildlife decreased following the completion of construction of mitigation structures; however, repel interactions at WG increased. Overall, crossings decreased at WCS that had higher openness ratios and during periods of precipitation and higher daily temperatures, but distance to vegetation had minimal influence. These factors were shown to influence crossings of each of the five most frequently observed species differently. Lastly, the presence of pooled water at one WCS caused a decrease in crossings when the water level was highest but was not a barrier at lower water levels. By examining influences on wildlife interaction with road mitigation structures, we conclude that a variety of structures, including different WCS configurations, can be beneficial in facilitating movement and restricting entry into the right-of-way for a diversity of wildlife species beyond the target species.

Enhancing local road pavement condition prediction using Bayesian-optimized ensemble machine learning and adaptive synthetic sampling technique

ABSTRACT Pavement condition prediction helps road agencies to schedule maintenance, rehabilitation, and reconstruction, and to allocate limited funds and resources to such activities. Compared to state highways, pavement performance prediction for local roads has received relatively little attention in the literature due to perceptions of low importance, low levels of investment in data collection, poor data quality, and high variation within the data elements. Additionally, local road pavement condition data may suffer from dataset imbalance, often leading to unreliable condition predictions. Hence, this paper introduces a methodology to predict local pavement condition using various single estimator and ensemble machine learning (ML) models along with the adaptive synthetic sampling method. The study develops nine (9) Bayesian-optimised ML models: category boosting (CatBoost), adaptive boosting, decision tree, extra trees, gradient boosting, light gradient-boosting machine, k-nearest neighbour, random forest, and artificial neural network. The ensemble ML and CatBoost were found to exhibit the best model performance, with an average testing accuracy of 0.82, specificity of 0.81, sensitivity of 0.63, and F-measure of 0.61. These results underscore the efficacy of ensemble ML models in pavement condition prediction. The proposed approach can be beneficial to local road agencies in their long-term planning, scheduling, and budgeting.

Shaping landscapes: transforming ethnic lands into state highways in Nagaland

ABSTRACT Land for the Nagas in Northeastern India reflects the local, culturally shaped concepts of physical space, ethnic relations, and social identity. It embodies the political security and the symbolic universe that determine the interpersonal relations and distribution system between various regional groups. Based on an ethnographic exploration, the paper traces how land once imbued in traditions such as sacred lands, monolithic spaces, and ancestral properties are expropriated into state highways. It argues how these new roads become a kind of contact space where the interface between cultural differences, historical memories, and notions of modernity and traditions are conflated and negotiated. The paper seeks to document the issues pertaining to the (re)shaping and (re)configuration of ethnic landscapes through the intrusion of the roadscape.

Assessing the setting behavior of ultra-high performance concrete

The setting behavior of ultra-high performance concrete (UHPC) is demonstrably different from that of conventional concrete; thus, tools and guidance extending beyond common test methods such as Vicat and penetration are needed. While UHPC is known for its enhanced mechanical and durability properties, due to the low water and high cementitious contents, UHPC-class materials are prone to early-age autogenous shrinkage. Recognizing that UHPCs are commonly supplied to construction sites as prebagged, proprietary mixes with unknown constituents, and that accurate determination of setting time is crucial in determining the early-age autogenous shrinkage of UHPC-class materials as well as for scheduling construction operations and quality control actions, this study explores alternate test methods such as isothermal calorimetry (ASTM C1679), semi-adiabatic calorimetry (ASTM C1753), autogenous shrinkage (ASTM C1698), chemical shrinkage (ASTM C1608), and dual ring test (American Association of State Highway and Transportation Officials (AASHTO T 363) to evaluate the setting behavior of UHPCs. Setting times obtained using the alternate test methods aligned well with each other and were found to be different than the setting times indicated through standard test methods. Discussion and guidance on the applicability and the use of alternate test methods to determine the setting time of UHPCs for various laboratory and field applications are provided.

Ensemble Learning with Pre-Trained Transformers for Crash Severity Classification: A Deep NLP Approach

Transfer learning has gained significant traction in natural language processing due to the emergence of state-of-the-art pre-trained language models (PLMs). Unlike traditional word embedding methods such as TF-IDF and Word2Vec, PLMs are context-dependent and outperform conventional techniques when fine-tuned for specific tasks. This paper proposes an innovative hard voting classifier to enhance crash severity classification by combining machine learning and deep learning models with various word embedding techniques, including BERT, RoBERTa, Word2Vec, and TF-IDF. Our study involves two comprehensive experiments using motorists’ crash data from the Missouri State Highway Patrol. The first experiment evaluates the performance of three machine learning models—XGBoost (XGB), random forest (RF), and naive Bayes (NB)—paired with TF-IDF, Word2Vec, and BERT feature extraction techniques. Additionally, BERT and RoBERTa are fine-tuned with a Bidirectional Long Short-Term Memory (Bi-LSTM) classification model. All models are initially evaluated on the original dataset. The second experiment repeats the evaluation using an augmented dataset to address the severe data imbalance. The results from the original dataset show strong performance for all models in the “Fatal” and “Personal Injury” classes but a poor classification of the minority “Property Damage” class. In the augmented dataset, while the models continued to excel with the majority classes, only XGB/TFIDF and BERT-LSTM showed improved performance for the minority class. The ensemble model outperformed individual models in both datasets, achieving an F1 score of 99% for “Fatal” and “Personal Injury” and 62% for “Property Damage” on the augmented dataset. These findings suggest that ensemble models, combined with data augmentation, are highly effective for crash severity classification and potentially other textual classification tasks.

Advanced analysis of intact, fire-damaged, and CFRP retrofitted bridge pier columns under vehicle collisions: Empirical equivalent static force equation and framework

A series of numerical simulations were completed to investigate the behavior of intact, fire-damaged, and Carbon Fiber-Reinforced Polymers (CFRP) retrofitted reinforced concrete (RC) bridge columns of varying sizes subjected to vehicle collisions. Three-dimensional finite element models of isolated RC columns and their foundation systems surrounded by soil volumes were developed using LS-DYNA. A comprehensive parametric study was carried out to investigate the effects of nine demand and design parameters on the performance of bridge columns. Studied parameters included: column diameter, column height, unconfined compressive strength, steel reinforcement ratio, fire duration, CFRP wrap thickness, wrapping configuration, vehicle’s mass, and vehicle’s speed. For each studied scenario, Peak Twenty-five Milli-second Moving Average (PTMSA) was employed to estimate the Equivalent Static Force (ESF) corresponding to each vehicle collision scenario. Resulting ESFs were then utilized to assess effectiveness of the current ESF approach available in the American Association of State Highway and Transportation Officials Load and Resistance Factor Design (AASHTO-LRFD) Bridge Design Specification for analyzing and helping design bridge columns under vehicle collision. Multivariate nonlinear regression analyses were used to derive an empirically based, simplified equation to predict the ESF that corresponds to a vehicle collision. Rather than constant design force, this equation established a correlation between ESF and kinetic energy, column axial capacity, and column height. Results indicated that the proposed equation is reliable and can accurately predict ESFs over a diverse range of collision scenarios that included intact, fire damaged, and CFRP retrofitted columns. To facilitate realistic implementation of the derived equation, an ESF assessment framework was also devised.

Pollution assessment and index properties of Okpulor soils, Rivers State, Nigeria: geochemical characterization, geotechnical and geoenvironmental implications

This study assessed soil pollution and index properties in Okpulor through geochemical, geotechnical, and geoenvironmental analyses. Twenty samples, comprising 14 surface and 6 shallow subsurface ones, underwent geochemical analysis for heavy metals (Fe, Cr, Cu, Zn, Ni, and Pb). Five geochemical indices, including the Geoaccumulation Index (Igeo), Enrichment Factor (EF), Contamination Factor (CF), Metal Pollution Index (MPI), and Potential Ecological Risk Index (PERI), were utilized. Simultaneously, six subsurface samples underwent geotechnical analysis for Natural Moisture, Grain Size, Specific Gravity, Bulk Density, and Atterberg Limits, following Unified Soil Classification System (USCS) and American Association of State Highway and Transportation Officials (AASHTO) guidelines. The Igeo highlighted significant heavy metal contamination in Okpulor soils, particularly Cd. EF values exceeding 1.5 underscored a strong anthropogenic influence, with CF indicating Cd's substantial contribution to overall contamination. PERI underscored the ecological risks associated with Cd contamination. Natural moisture content, ranging from 18.21% to 21.45%, indicated a notable presence of water in the soil during the dry season, potentially leading to increased leaching and migration of water-soluble contaminants. Bulk density values suggested moderate to lightly packed soils, impacting porosity and permeability, and influencing contaminant movement. Atterberg limits indicated low soil plasticity, impacting moisture retention and contaminant behaviour. Grain size analysis revealed poorly graded soils with a close sand-to-clay ratio, affecting water drainage. These geotechnical properties and heavy metal contamination reveal the intricate interplay between soil characteristics and contamination risks in the Okpulor area, emphasizing the need for targeted interventions to safeguard the environment.

Pozzolanic Reactivity of High-Alkali Supplementary Cementitious Materials and Its Impact on Mitigation of Alkali-Silica Reaction

The growing scarcity of conventional supplementary cementitious materials (SCMs) such as Class F, Class C fly ashes, and slag has necessitated exploring alternative SCMs previously considered suboptimal. In particular, high-alkali SCMs are often avoided because of the potential concern that their alkali content could release into the concrete pore solution, thus exacerbating the potential for alkali-silica reaction (ASR). However, preliminary research indicates that not all high-alkali SCMs are deleterious, and some can effectively suppress the ASR expansive reaction when used in sufficient dosage levels. This study evaluates the feasibility of using high-alkali SCMs, such as high-alkali natural pozzolans and reclaimed fly ashes, focusing on their pozzolanic reactivity and the correlation between the reactivity and their ASR mitigation performance. The pozzolanic reactivity of the SCMs was evaluated by the R3 test per ASTM C1897 and strength activity index test per ASTM C311. Thermogravimetric analysis was used to determine the calcium hydroxide consumption by the SCMs. ASR mitigation performance of SCMs was evaluated in accordance with American Association of State Highway and Transportation Officials (AASHTO) T380 miniature concrete prism test. Additionally, pore solution expression and analysis of paste specimens were conducted to determine the correlation between the total alkali and the released alkali levels into the pore solution. Based on the results of this study, all SCMs indicated high pozzolanic reactivity; however, individual performance varied by test method. Ultimately, the high-alkali SCMs, particularly natural pozzolans, did not appear to release any significant levels of alkalis into the pore solution readily and, therefore, show potential for ASR mitigation when used in sufficient dosage levels.

A Contribution to the Flora of Sariska Tiger Reserve, Alwar District, Rajasthan

Sariska Tiger Reserve, one of the 15 Tiger reserves of India, is located in the undulating plateau lands and wide valleys of the hill ranges of Aravalli system, near the civil district of Alwar in Rajasthan. Established in the year 1978-79, it is about 140 km from Jaipur on Jaipur-Delhi State Highway and spreads over a total area of 800 sq. km with a core area of 498 sq. km. The reserve consisting of 37 forest blocks is a classic example of a rare amalgamation of natural history and archaeology. The 9th and 10th century ruins of the Siva temple of Grah Rajer, the Mediaeval fort of Kankwari and the Tomb of Lord Bhartrihari add to the grandeur of this reserve which abounds in wild life. The paper deals with a short history, Topography, Fauna & Vegetation of the area.