Concrete Barriers Research Articles

Sound barrier behavior of geopolymer composite manufactured from industrial waste

Noise pollution is an invisible hazard faced in industries, roads, and public places etc., and has become part of daily life. Noise affects the psychology and physiology of animals and humans and can lead to accidents and health issues. Noise can be reduced by using active or passive materials. Active mediums are in which enormous amount of external energy is used to balance the noise energy, whereas in passive medium sound is absorbed such as by using insulating materials. Conventionally, passive sound barrier panels made of concrete are used, which involve energy intensive manufacturing processes as they use Ordinary Portland Cement (OPC). The concrete sound barrier panels have a large carbon foot print as it releases carbon dioxide (CO2) during manufacture of OPC and during hydration of concrete. The global warming is caused due to emission of greenhouse gases mainly comprising of carbon di oxide. The cement industry emits 5 to 8 % of the world’s CO2 emissions and thus an alternate building material is required. The search for an ecofriendly green binding material to replace cement leads to discovery of geopolymer. Geopolymers are ceramic materials comprising of polymers made of inorganic aluminosilicate and fabricated by alkali activation of aluminosilicates. In this research work, the induction furnace (IF) slag and Class F fly ash are utilized along with manufactured sand (M Sand) an alternative material for the river sand, as fine aggregate. The environmental advantage of this material is that the ingredients are industrial waste and the geopolymer has negligible carbon foot print. The geopolymer composite specimens were subjected to sound absorption test using impedance tube studies and found to exhibit an increased sound absorption coefficient (α) between 0.2 and 0.35 in the frequency range of 1200 Hz to 6300 Hz. This study establishes that the geopolymer manufactured using industrial waste material can be effectively utilized as sound absorption material and can assist in mitigating noise pollution.

A model to predict the rear face damage caused by non‐deforming projectile impact on plain and steel fiber reinforced concrete barriers

AbstractThis paper presents a model for evaluation of the rear face damage in concrete barriers subjected to impact of non‐deforming projectiles. This is an improved and extended version of a previously published model, which now covers both plain and steel fiber reinforced concrete (SFRC) barriers. The rear face damaged area commonly measured in tests is characterized by an equivalent diameter, evaluated by the model. Calibration and then validation are based on published experimental data. Different sets of experiments, of plain concrete and SFRC, reported by different researchers, were used for the model's calibration and for its validation. The calibrated model's predictions show reasonable agreement with the reported experimental results, especially in view of their considerable scatter. The main findings from a parametric study of the model's predictions refer to the influence on the rear face damage (at barrier thickness lower than the scabbing limit thickness) of including steel fibers in the concrete mix, the barrier thickness, impact level, and the projectile diameter. The model's predictions demonstrate the lower extent of damage in SFRC barriers, compared to plain concrete. The use of the model enables quantitative assessment of this damage and of its reduction in SFRC barriers.

Strengthening Israel-Saudi Arabia Co-Existence towards Peaceful and Stable Middle East

One of the specific objectives of the United States President Joe Biden’s Middle East visit, in July 2022, was the intent of Saudi Arabia normalization of diplomatic relations with Israel. However, this was largely unachieved despite the fact that Israel and Saudi Arabia had long been in secret cooperation, without formal diplomatic relations between them, since Israel attained nationhood in 1948. This article sought to examine the concrete barriers to normalization of relations, extolling cooperation and disentangling the cyclic ambivalences of Saudi government towards Israel. Certain barriers could be removed, aimed at strengthening normal peaceful co-existence between the two countries. The neorealist and neoliberal theoretical perspectives are adopted as framework of analysis. Data were derived from both primary and secondary sources, made up of interview, government official documents and independent mediascape. Findings showed that the Israeli-Palestinian conflict remained the concrete barrier to normalized Saudi-Israeli relations. But areas of cooperation between the two countries, albeit covertly, include trade and common stance against security concerns. These and other areas of cooperation could be broadened to strengthen peaceful co-existence between the two neighbours. And more determined diplomatic efforts must continue, to resolve the generational and intractable Israeli-Palestinian conflict on ‘two-state’ solution basis. In conclusion, the ambivalences that have characterized relations between Israel and Saudi Arabia need be discarded. A Palestinian statehood is attainable, with rights of mutual co-existence between the parties and removing nuclear threat and need for balance of power, all necessary to make the Middle East relatively stable and peaceful.

Investigation of simultaneous effects of noise barriers on near-road noise and air pollutants

Noise barriers are one of the common solutions to control road traffic noise. Many studies have also shown that noise barriers cause reductions in near-road air pollutant concentrations. In this study, the simultaneous effects of a specific noise barrier application on near-road noise and air pollution at a specific location were investigated. In this context, air pollution, noise, and meteorological parameters were measured simultaneously at two points, road and receptor sides of a 50 m long, 4 m high glass fiber reinforced concrete noise barrier on a highway section. Results indicated that the noise barrier has an average 23 % reduction effect on the NOx concentration in addition to the noise level reduction at the receptor side. Besides, bi-weekly average passive sampler measurement results for BTEX pollutants indicate lower values at the receptor side of the barrier compared to the free field measurement results. In addition to real-time and passive sampler measurements, NOx and noise dispersions were modeled using RLINE and SoundPLAN 8.2 software, respectively. Comparisons of the measurement results with the model results indicated strong correlations. Model-calculated NOx and noise values under the free field conditions are highly compatible with a correlation coefficient (r) of 0.78. Although the noise barrier has a reduction effect on both parameters, it has been observed that their dispersion mechanisms are different. This study showed that noise barriers considerably affect the dispersion of road-sourced air pollutants at the receptor side. Further studies are needed to optimize noise barrier designs with different physical and material properties and application scenarios considering noise and air pollutants together.

Review of utilization of short concrete noise barriers as noise an abatement strategy

The initial construction cost of barriers has led to considerable interest by local Transportation agencies and the Federal Highway Administration (FHWA) to assess alternatives such as short noise barriers. Many agencies have found that the utilization of short concrete safety barriers as a noise mitigation strategy is highly beneficial. However, not much evaluation data is available to satisfy the FHWA noise requirements or to satisfy the Noise Reduction Design Goal (NRDG) (Noise Barrier Acceptance Criteria Analysis Publication No. FHWA-HEP-16-017). This paper presents an extensive review of the utilization of short concrete noise barriers as a noise abatement strategy. The study also reviews the relevant research, methodologies, tools, and technologies that have been used in evaluating the reasonableness and feasibility of this strategy. Various modeling techniques that can realistically model the insertion loss of short concrete noise barrier were also reviewed. A few proprietary short noise barrier systems were also evaluated for their reasonableness and feasibility. The study reveals a state of the practice survey of all DOTs with respect to the adoption and implementation of short noise barrier. The paper ultimately highlights the effectiveness, cost, use and implementation methodology of short solid barriers as an effective noise abatement strategy.

Replacing cement through data analytics and process control

Highway safety is a critical factor to one of the most vital parts of society's infrastructure. Slipform paving provides an economical means to quickly construct concrete barriers and drainage channels, which contribute to a highway's safety. This study follows a slipform paving company's journey in implementing an in-transit management system which can measure and adjust slump during the delivery of concrete. By allowing the system to manage the rheology, both productivity and material savings (through cement) were achieved. Furthermore, the system enables an immediately viable method to significantly reduce embodied carbon dioxide for the concrete industry.

Experimental and Numerical Investigation of Prefabricated Concrete Barrier Systems Using Ultra-High-Performance Concrete

The functionality and crashworthiness of concrete barriers in bridge systems can be affected by the deterioration of the connection between bridge decks and concrete barriers. A set of details for barrier-to-deck connections for accelerated bridge construction (ABC) applications are proposed. Component-level testing was carried out on a conventional cast-in-place (CIP) detail and two versions of connections using ultra-high-performance concrete (UHPC). The use of UHPC allows for shorter development length and lap splice length for dowel bars and the material characteristics provide strength and durability to the connection. Two connection details were proposed: (1) UHPC connection within the barrier segment (U-shape connection) and (2) UHPC connection in a recess inside the bridge deck (recessed connection). Besides simplified details, the construction sequence of the proposed recessed connection is suitable for ABC applications. It is observed that the proposed U-shape connection detail is emulative of the equivalent CIP concrete barrier system. However, the recessed connection system can undergo significantly larger deflections at ultimate load compared with the CIP barrier system and exhibits a preferred mode of failure while the deck does not undergo significant damage. The results of the component testing were used to calibrate non-linear finite element models. Using validated models, numerical analyses were performed to investigate the structural performance of conventional 15 ft long barrier modules connected to the deck overhang using the recessed connection. The model was subjected to the end-loading configuration and it was found that the proposed barrier system meets the strength requirement for the corresponding test level.

Influence of Reinforcement and Attack Angle on the Destruction of a Concrete Barrier Under a High-Speed Impact

Influence of Reinforcement and Attack Angle on the Destruction of a Concrete Barrier Under a High-Speed Impact

A dose calculation algorithm for radiosurgery treatment room shielding optimization.

Methods described in the literature for designing shielding for treatment rooms for radiotherapy systems often involve assumptions that lead to overestimations of the wall thicknesses required to meet dose rate constraints outside the room. The Leksell Gamma Knife (LGK) has built-in shielding that results in primarily scattered photons leaking into the room. The field of leakage radiation, therefore, has a wide spectrum of energies, up to the primary energies of cobalt-60, and is highly anisotropic, making standard site planning methods difficult to adapt to the LGK. Monte Carlo (MC) simulations are an alternative for dose calculations but are computationallyexpensive. The aim was to develop a dose calculation algorithm for fast estimations of dose rates outside the barriers of a treatment room. The algorithm could then be employed in iterative methods to optimize treatment room parameters such as wall thicknesses and position of the LKGunit. The algorithm uses pre-calculated MC simulation data in two steps. First, it uses phase spaces that describe single photons in the radiation field around the LGK. Using each photon's position and direction, they are raytraced to the outside of the room. Based on their energy, angle of incidence to the barrier, and the barrier's thickness, a depth-dose profile is sampled from a pre-calculated library of profiles. The contribution from each photon is added to the space outside the barriers, giving the total dose distribution. The barrier thicknesses are optimized by iteratively running the algorithm and finding the minimum thickness required to keep the resulting maximum dose rate outside below a given upperlimit. Comparisons between dose distributions from the dose algorithm and full MC simulations of two typical rooms show good agreement, with the maximum dose rate outside each barrier being estimated within what represents a 2 cm error in concrete barrier thickness. The algorithm is successfully used in optimizing the barrier thicknesses and the results show potential decreases in most barriers' thickness, compared to a conventionalmethod. The algorithm is a promising alternative to conventional barrier design methods, eliminating several shortcomings of the latter whilst being significantly faster than a full MC simulation. The flexibility of the algorithm would further enable solving more complex cases, such as optimizing the LGK position or barrier material to further reduce material use andcost.

Estimation of Vehicular Collision Force on Bridge Piers in the Presence of Sub-Standard Intervening Concrete Barriers

Critical infrastructures such as bridges should be resilient to extreme loading events. Among the potential hazardous events, vehicle collisions are becoming increasingly common. Modern American Association for State Highway Transportation Officials (AASHTO) bridge design specifications consider a limit state to account for vehicular Collision Force (VCF) and require addressing it when bridge piers are within the clear zone defined by AASHTO’s Roadside Design Guide. AASHTO specifies two methods to address this limit state: either by providing an intervening structure that is capable of absorbing the VCF and/or redirecting the colliding vehicle, or designing the piers to resist a lateral load equivalent to 2,670 kN (600 kips). Many old bridges that were designed before recognizing the VCF as a limit state fail to meet the modern specifications because either the piers were designed to resist a lower lateral load than the specified limit or the installed intervening concrete barrier is not a standard one that qualifies to solely protect the piers against VCF. This paper introduces a new approach to address the requirements of the modern standards. The approach is based on blended contribution between the available sub-standard barrier and the under-designed bridge pier. The proposed approach is based on a matrix of dynamic simulations using LS-DYNA and considering different crash scenarios. The results showed that in the presence of the sub-standard barrier, the estimated VCF can be at least reduced by about 25%, leaving 75% to be resisted by the existing pier.

Photon dose rate distribution inside and outside a brachytherapy room.

In a brachytherapy room irradiated with an Iridium-192 (192Ir) source, the spatial distributions of photon dose rates were measured and calculated for the dose distribution both inside and outside the room. The spatial distributions were measured using a thermoluminescent dosimeter (LiF-100) on the surfaces of the concrete walls and barriers of the irradiation room. The calculations were performed using the particle and heavy ion transport code system (PHITS) by considering the detailed model of the brachytherapy room and the radiation source used in the measurements. The measured and calculated doses exhibited a similar distribution pattern within and outside the brachytherapy room. To reduce the edge effect at the entrance door, the addition of a 3-mm thick lead layer on the surface of the concrete wall on the left doorstop is recommended. For the 60Co source, with the existing walls and lead door thickness, the dose at the control console and in front of the entrance maze increased by a factor of approximately 60.

The Borderlands

The Borderlands

Integrative conceptualization of products and business models for the circular economy: A systematic literature review

The increasing demand for sustainability is challenging manufacturing companies and endangers the viability of their current business models. Their historically linear value creation model needs to be restructured to remain viable and to be conform with the requirements of sustainability. As a result, the circular economy has emerged as a promising economic model. For implementing a circular economy, it is essential to adapt the existing product design and business model towards more circularity. However, the knowledge regarding interdependencies between the circular product design (CPD) and circular business models (CBM) remains vague in theory and practice, hence leading to untapped potentials in practice. The aim of this paper is a framework that allows for an integrative conceptualization of CPD and CBM for the circular economy. A systematic literature review was conducted to identify concrete challenges, barriers, drivers, and potentials for CPD and CBM. By consolidating the results, a framework is derived that characterizes the specific areas of influence for CPD and CBM. Through this, companies receive a deeper understanding about the functionality of a circular economy. Based on the outlined challenges, companies can effectively plan the implementation of the circular economy.

Подходы к геомиграционному моделированию при оценке безопасности пункта захоронения РАО в расчетном комплексе GeRa

The study focuses on the safety assessment of near-surface radioactive waste disposal facilities (NSDF) based on the numerical simulation of radionuclide transport in the near field via groundwater flow and mass transport processes using the GeRa software. It also evaluates the methods that may provide near and far field model coupling seeking to arrange a sound safety assessment process. The study specifically focuses on the degradation of the underlying concrete safety barrier indicated through a reduced radionuclide absorption capacity. The study provides calculations for those radionuclides that are typically found in the radioactive waste subject to disposal in deep disposal facilities. The findings evidence some fundamental difference in the activity-yield curves associated with the sorption properties, changes in the barrier properties and the half-lifes of the modelled radionuclides.

Numerical analysis of the possibility of noxious gases infiltration into a shelter located in a gas-bearing coal-rock mass

Shelters in coal mines are used to protect miners during accidents associated with gassing of roadways, fires, explosions of methane-air mixture. Supporting of the shelter must provide the necessary level of tightness to prevent the penetration of noxious gases from the mine atmosphere or gas-bearing rocks. The purpose of this work is to study the possibility of noxious gases penetration into a shelter in case of its sealing failure for the early detection of weak constructional elements and to ensure safe conditions for people in the shelter during accidents. To achieve the goal, methods of numerical simulation of time-dependent processes of elastic-plastic deformation and gas filtration were used. A coal-rock mass with a roadway and an adjacent shelter with typical supporting elements were considered at a depth of 400 m and 1000 m. The study of the stress state of the shelter support showed that under the considered conditions, in the case of a relatively small depth, hard steel and concrete constructional elements withstand the load without loss of their stability. With an increase in the depth of the shelter location, inelastic deformation of the concrete barrier between the shelter and the roadway occurs on a small area. The probable destruction of this zone will not lead to a violation of the entire barrier integrity, which makes it impossible to start mass exchange processes between clean air in the shelter and harmful combustion products in the roadway. The roof and walls of the shelter, covered with reinforced concrete and sealed, remain practically impermeable from the next day after their construction in both the first and second cases. But later, in the lower left corner of the shelter at a depth of 1000 m, methane from the coal seam begins infiltrating through the unsupported and unsealed floor. The developed numerical model can be used with other basic data on mining and geological conditions to identify constructional elements of a shelter, which lose stability during operation and threaten the shelter's tightness. Timely strengthening of such weak elements will prevent the danger of noxious gases infiltrating into the shelter. Keywords: time-dependent rock deformation, shelter, sealing failure, gas filtration, numerical simulation.

Rockfall protection wall that can withstand multiple strikes without needing to be repaired

In a hilly and congested urban environment, use of reinforced concrete barrier for hillslope protection is common. With some of these barriers, a layer of gabion is placed in front of the barrier to provide additional protection to avoid localised failure caused to the concrete surface as direct contact is made with a fallen boulder. In addition, the layer of gabion would also function as cushion which mitigates the transfer of momentum to the barrier wall behind it causing bending to occur. There has only been one study that targeted at modelling this cushioning mechanism, but it has only dealt with single boulder strike scenarios. Other studies on impact on gabions did not deal with momentum transfer, though they did investigate the effect of reducing the transmitted force and energy dissipation. This study presents a new design procedure which accounts for the cushioning mechanism of the gabion in multiple strike scenarios. Full-scale pendulum tests were conducted on a reinforced concrete barrier specimen which was fitted with a layer of gabions for validating the accuracy of the proposed predictive model. The design of a rockfall barrier wall taking into account multiple strike scenarios can significantly reduce the costs of maintaining reinforced concrete rockfall barriers during its service life.

Linac primary barrier transmission for concrete: Monte Carlo calculations.

Recent publications have called into question the accuracy of reference tenth-value layer (TVL) data cited in official reports for linac primary concrete barriers. Doubts have arisen based on both experimental and theoretical evidence. Most of the standard reference TVL values trace back to a publication that appeared in 1984 that used beam spectra that are not representative of modern linacs. This study reports a new set of TVL data for concrete based on modern linac beam spectra and a definition of the barrier transmission that is consistent with its use in shielding calculations. TVL values have been computed for concrete using Monte Carlo simulation for beam energies of 4, 6, 10, 15, and 18MV. The barrier transmission depends on the field size at the barrier and the distance from the distal surface of the barrier to the point of observation. The TVL values reported here lead to barrier transmission values that are up to a factor of 4 larger than those in official reports. The air kerma rate beyond the barrier does not obey an inverse square law as the barrier now acts like a new (non-point) source of radiation. For distance greater than 0.3m from the distal side of the barrier, inverse square predictions of the air kerma rate are low by up to a factor of 2. The average energy of the transmitted photons declines rapidly for all beam energies with increasing barrier thickness up to a thickness of about 50cm and then slowly increases with increasing thickness.

DNA Damage in Splenocytes of Mice Exposed to Secondary Radiation Created by 650 MeV Protons Bombarding a Concrete Shielding Barrier.

The proportion of splenocytes with a high level of DNA double-strand breaks was determined in mice exposed to primary and secondary radiation created by bombarding of a concrete barrier (thickness 20, 40, and 80 cm) by 650 MeV protons. The proportion of splenocytes with a high level of DNA double-strand breaks was assessed by flow cytometric analysis of γH2AX+ and TUNEL+ cells. It is shown that concrete barrier can significantly reduce primary proton radiation; the severity of negative biological effects in mice irradiated in the center of the proton beam decreased with increasing the thickness of this barrier. However, the spectrum of secondary radiation changes significantly with increasing the barrier thickness from 20 to 80 cm and the distance from central axis of the beam from 0 to 20 cm, and the proportion of the neutron component increases, which also causes negative biological effects manifesting in a significant (p<0.05) increase in the percentage of splenocytes with a high level of DNA damage in mice irradiated at a distance of 20 cm from the center of the proton beam and receiving relatively low doses (0.10-0.17 Gy).

Automating inspection of moveable lane barrier for Auckland Harbour Bridge traffic safety

A moveable lane barrier along the Auckland Harbour Bridge (AHB) enables two-way traffic flow optimisation and control. However, the AHB barrier transfer machines are not equipped with an automated solution for screening the pins that link the barrier segments. If the connecting metal pin pops out due to external force, the disjoined concrete barrier can be hazardous to motorist safety.After being restricted due to pandemic lockdowns, I reviewed previous research in anomaly detection to overcome the challenge of a small and unbalanced dataset. A technique was needed for a robust approach to data analysis and modelling on initially small and unbalanced datasets for similar circumstances where the expected dataset size may or may not become available within the expected timeframes. My research introduced a collectively synthetic minority-class data boosting, adaptive, incremental, and transfer learning method that utilises pre-trained neural networks. A novel technique for obtaining synthetic frames with different degrees of unsafe pin images cloned from the original video frames allowed a robust data analysis and modelling approach on small and unbalanced datasets. A universal system is produced for automated inspection that can ease the day-to-day work stress of the AHB safety inspectors. This system can be applied globally with minimum modifications to similar traffic management or anomaly detection and tracking scenarios.This presentation aims to introduce the proposed proof of concept (PoC) for supplementing movable lane barrier inspection. The produced PoC can be deployed on a vehicle or AHB barrier transfer machine to detect the unsafe pin and alert the user.

Handling The Identification of Burn Victims in A Traffic Accident: A DVI Case Report

The role of the forensic pathologist in a mass disaster is to identify the victims. The procedure refers to Interpol’s Disaster Victim Identification (DVI) guidelines. DVI consists of 4 stages namely Scene Examination, Post-Mortem Examination, Ante-Mortem Examination, and Reconciliation. Post-Mortem (PM) and Ante-Mortem (AM) data collected include fingerprints, dental records, DNA as Primary Identifiers, medical records, and property as Secondary Identifiers. At the reconciliation stage, at least there must be a match between one Primary Identifier or two Secondary Identifiers. Theoretically, 4-phase DVI should be performed according to the DVI standard in every disaster case. In fact, the implementation of DVI encountered many obstacles in the field. This article discusses the various obstacles and problems faced when conducting DVI in the case of a car accident with a truck on the Madiun-Ngawi toll road at KM 631 A to the Madiun – Nganjuk toll road. The chronology of this incident began when the elf’s vehicle hit a truck and a concrete barrier and then caught fire. Three victims were found in a burned condition leaving only the skeleton, thigh and psoas muscle. This of course does not allow fingerprints to be checked. The identification process is carried out only by comparing primary and secondary data as an identification guide given the condition of the bodies that are only slightly left. Then DNA examination was not carried out in this identification process. Tests for CO levels showed that the three victims indicated CO poisoning before they died.