Materials Science and Engineering Commons^™

Key Construction Techniques For Emended Cap Unsealed Bottom Of Deep‑Water Hard Rock, Zeng Jian, Guan Xiaohui, Guo Zhiwei

Journal of China & Foreign Highway

In the construction of a deep-water embedded cap foundation，it was required to excavate the mud surface to the depth below sealing concrete and clean the bottom carefully，ensuring the height and quality of bottoming concrete.For hard rock under good geological conditions，there exist such problems as difficulty in excavation，long excavation time consumption，and high construction cost.Based on the construction of the main pier caps of the Chongqing Jiahua Metro Bridge，this paper adopted the method of combining theoretical analysis，numerical calculation，and engineering implementation verification，which developed an emended cap unsealed bottom key construction techniques for deep-water hard rock.This construction technology used the method of excavating the …

Influence Of Blasting Point Position And Foundation Pit Height On Blasting Vibration During Foundation Pit Blasting Excavation, Liu Kuan, Xu Zhihao, Tang Yuan, Shen Jun, Bao Xiaohua, Shen Pinghuan, Ou Yang

Journal of China & Foreign Highway

In view of inaccurate vibration prediction of foundation pit blasting，the influence of blasting point position and foundation pit height on vibration during foundation pit blasting excavation was studied by using finite element simulation software.First，based on the foundation pit blasting excavation of the Mawan Cross-Sea Passage，a numerical simulation was carried out to verify the applicability of the model.Then，under unchanged blasting center distance，the distance from the blasting point to the edge of the foundation pit and the foundation pit height were changed respectively，and the influence of these two factors on surface vibration was studied.The results show that a greater distance from the …

Excavation Method For Ⅴⅴ‑Grade Surrounding Rock Of Double‑Hole Eight‑Lane Super‑Long‑Span Tunnel, Shi Youzhi, Liu Xudong, Yong Jinzhu

Journal of China & Foreign Highway

In order to reduce the adverse effect of back heading blasting on the completed supporting structure at the entrance of a double-hole eight-lane super-long-span tunnel with Ⅴ-grade surrounding rock，the Niuzhaishan tunnel project in Pingtan was taken as an example.The original design of the double-side heading method is easy to cause the collapse of the temporary steel support that has been completed when blasting happens near the back heading.In view of this，this paper put forward scheme 1 of canceling the temporary transverse support and the up-and-down step method with vertical support （scheme 2）.It then used the finite element method to calculate …

Design And Evaluation Of Land‑Saving And Beautiful Median Barriers, Li Jingjun, Wa Ng Xin, Qi Jie, Wang Zijian, Liu Siyuan

Journal of China & Foreign Highway

During the construction and expansion of expressways and national and provincial highways，more diversified requirements have been put forward for the median barrier，including reliable protective performance，small footprints，beautiful traffic environments，and economic costs.However，the existing median barrier achievements still have some shortcomings.In order to better meet the design and use needs of median barriers for highways，theoretical analysis，computer simulation，and full-scale impact tests with real vehicles were adopted，and the force characteristics of different types of median barriers were analyzed.A new design concept of beam-column integration was put forward.Through systematic research on the barrier height，width，beam，column，foundation，and other structures，a land-saving and beautiful median barrier was developed.The median barrier had …

Multi-Region Plane Fitting Algorithm For Texture Depth Of Asphalt Pavements, Zhu Feng, Feng Xingle, Wu Chuan, Lin Xiaoyong

Journal of China & Foreign Highway

The existing calculation methods for texture depth of asphalt pavements are easily affected by external and human factors.Therefore，a multi-region plane fitting algorithm for the texture depth based on three-dimensional （3D） linear laser data was proposed.The algorithm preprocessed the collected 3D height data matrix of the pavement and derived a slope-based adaptive filtering algorithm for point cloud data.Then, the 3D height matrix was divided into multiple regions，and the local extremum of the center point was determined.Finally，with the three-point and one-surface plane fitting algorithm as the core，the texture depth of asphalt pavements was calculated.The experimental results show that the correlation between this …

Key Technology And Numerical Simulation Of Cast‑In‑Place Construction Of Main Arch Ring Of Reinforced Concrete Arch Bridge Based On Suspension Steel Arch Method, Su Xueping, Xia Zhengzhi, Lyu Songgang, Duan Pengjie, Lyu Yigang

Journal of China & Foreign Highway

Steel arch frame replaced such construction methods as floor bracket or segment cantilever assembly and it was applied to arch circle cast-in-place across deep water canyons in mountainous areas，which had certain advantages and was worth promoting and applying.By introducing the key construction technologies of Sanchahe Bridge，including steel arch frame cantilever fastener method assembly，arch water tank method precompression，and main arch ring layered pouring，the common problems in the construction process of crossing the deep water canyon were solved effectively.Based on Midas Civil overall modeling of finite elements，the key construction technologies adopted by the bridge were numerically simulated and analyzed，and the successful construction …

Guardrail Improvement For Old Bridges In Expressways, Liu Xinping, Zhang Shihui, Shang Zhongping, Han Yue, Zhang Qiang

Journal of China & Foreign Highway

In view of the insufficient protection grade of the guardrail in old bridges，a combined guardrail suitable for the low concrete wall guardrail in the old bridge was designed and developed by using finite element analysis while not damaging the main structure of the bridge.The protection grade was verified to reach SA grade through a full-scale vehicle collision test.The guardrail was designed with new high-strength alloy steel，with light weight and beautiful appearance.There was no need to dismantle the original concrete foundation in the old bridge，which is convenient for construction and requires low cost.Therefore，it is worth being popularized and applied in the …

Improvement Of Gravelly Laterite And Cement Stable Disposal In West Africa, Jin Haibing, Yi Zicheng, Zhuo Rong

Journal of China & Foreign Highway

Owing to poor gradation and high liquid limit and plasticity index，the application of gravel laterite on road paving is limited in West Africa.To overcome this issue，laterite granule combined with sand at different content was explored.The performance including the particle composition，limit water content and CBR value was investigated.The results indicate that sand treatment can improve the gradation，enhance the compactness，and reduce the plasticity index.The improved gravel laterite can meet the requirements of subbase，cushion，and base courses.Cement treatment can improve the mechanical properties of laterite grains.Cement and sand content affect the unconfined compressive strength significantly，with an optimal sand content range identified.Specifically，laterite granules mixed with …

Investigating The Impact Of Secondary Activation Time On The Adsorption Properties Of Activated Biochar For Arsenic Removal From Wastewater, Achyuth Bharadwaj Rayarao

Graduate Theses and Dissertations (2019 - present)

Biochar, a naturally occurring and renewable carbon material, becomes porous through activation. Activated biochar is an ideal candidate for use as an adsorbent. The objective of this study is to investigate whether activated biochar derived from Colorado soft pine serves as a better adsorbent and demonstrates enhanced adsorption capabilities after undergoing secondary physical activation at various activation times. The effect of secondary action time on physical adsorption properties drawn from the analysis of isotherm plots, surface areas and pore size patterns were examined by using a physisorption analyzer. Chemical structures were identified using both ultimate and proximate analyses, while porosity …

Micro-Mechanical Characterization Of Uhpc Stiffness Mechanisms: Towards A Better Understanding Of Concrete Elastic Modulus, Charissa N. Puttbach

Graduate Theses and Dissertations

Current design code equations for estimating the elastic modulus of specialty concretes like ultra-high performance concrete are not all suitable. Developing empirical curves from exhaustive experimental testing is challenging for concretes that may have high levels of cement replacement with mineral admixtures and fibers at varying volume contents. As such, an alternative approach is taken that seeks to understand the constituent microscale stiffness mechanisms and relate the results to the macroscale. Micropillars are fabricated on several cement paste phases using a focused ion beam. A modified pico-indenter is used to determine the linear and non-linear behavior under micro-compression loading. Micropillar …

Smart Manufacturing Of Cement: From Lab-Scale Simulation And Testing To Industry-Scale Deployment., Juan David Tabares Tamayo

Electronic Theses and Dissertations

Cement kilns are controlled by experienced process operators who follow experience-based industry guidelines using data collected and fundamental knowledge. The manufacturing process, which is equipped with sensors and equipment, transfers data/information to the operators to aid standardized decision-making operations. In contrast, companies have used such data to develop and implement digital solutions for predictive control systems; in effect, FLSmidth and Rockwell Automation. However, despite the availability of automated control systems and investigation in automation for process monitoring and optimization, opportunities to radically optimize cement manufacturing are still abundant and in need of implementation. Therefore, this research developed simulation models and …

Dynamic Impact Testing And Numerical Analysis Of Non-Proprietary Astm F2656-20 M50 Anti-Ram Barrier Components, Weston Kelley

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

In a post-9/11 world, hostile actors are using vehicles as weapons to inflict civilian casualties. Pedestrians, vulnerable road users, military personnel, and police may be targeted using a vehicle as a weapon. The United States Department of Defense (DoD) also utilizes Entry Control Facilities (ECFs) which are carefully designed transportation corridors to manage how threat vehicles are able to access military facilities. In 2004, DoD started to upgrade all ECFs using both passive and active barriers. Many anti-ram vehicle barriers were evaluated according to the criteria established in ASTM F2656, but to date few options are available which are (1) …

Seeding Effects Of Submicron Caal-No3 Ldh Particles On The Hydration And Properties Of Portland Cement And Sulfoaluminate Cement Pastes, Sukanta K. Mondal, Monday Uchenna Okoronkwo

Chemical and Biochemical Engineering Faculty Research & Creative Works

Layered double hydroxide (LDH) is reported to improve the durability of concretes, primarily due to its ability to exchange anionic species, including chloride, which is implicated in corrosion-driven durability issues. However, there is no comprehensive study investigating the effect of LDH on the properties of different cement systems at both early and mature ages. in this study, the early age and mature age properties of Portland cement (OPC) and calcium sulfoaluminate (CSA) cement pastes seeded with submicron-sized calcium aluminum-NO3 LDH (CaAl-NO3 LDH) were investigated. the effects of the 1–5%mass dosage of LDH on the hydration of both cement systems were …

Testing Of Recycled Polypropylene As A Viable Structural Material (Quarter 2), Isabella Jimenez-Melendrez, Katherine Timbes, Jocelyn Embleton, Tauni Dela Cruz, Zyra Kingston, Emily Byrd, Jacob Stinger

Architectural Engineering

5.25 trillion plastic particles have been found in the oceans each year, 3 million water bottles are consumed each hour, and one million plastic bags are used each minute in the United States of America (Williams). The vast majority of conventional plastics such as polyethylene, polypropylene, polystyrene, and more, are non-biodegradable (Tokiwa). To make matters worse, 70% of this non-biodegradable plastic is discarded into landfills and inevitably makes its way into the environment (Williams,). Plastic products have become vital to the United States economy due to their many uses in the construction, packaging, transportation, and health care industries. However, this …

Safety Evaluation Of Hawaii Dot Modified Type A-1 Flared Buried In Backslope Guardrail End Terminal, Sina Changizian

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

The Hawaii Department of Transportation (HDOT) desired to evaluate the crashworthiness of a guardrail end terminal design in which the upstream guardrail anchorage was connected to a block partially buried in a cut slope, known as a “Buried in Backslope” or BIB design. The HDOT BIB system used an upper W-beam with 8-in. deep blockouts attached to W6x9 steel posts and a lower W-beam rubrail located 3 in. below the upper rail. The system used two horizontal flares: 7.4:1 near the upstream anchor block and a 13:1 flare through the ditch.

Critical impact points (CIPs) were identified and recommended for …

Quasi-Static And Impact Load Response Of Bfrp-Reinforced Concrete Beams And Post-Terrorist-Attack Sub-Assemblages, José Luis Carrasquillo

Civil & Environmental Engineering Theses & Dissertations

This dissertation presents the outcome of a theoretical and experimental study of Basalt Fiber Reinforced Polymer (BFRP) reinforced concrete beams and post-terrorist-attack subassemblages subjected to either quasi-static or impact load. Both BFRP reinforcement as well as BFRP fabric are used in this investigation. The sub-assemblage consists of an otherwise two-span beam converted to a fixed-end single-span one owing to the loss of a middle column blasted off during the terrorist attack. The simply supported beams are subjected to a midspan quasistatic or an impact load. However, each sub-assemblage is subjected to a quasi-static load up to collapse to simulate the …

Thermo-Elasto-Plastic Stability Of Biaxially Loaded Hollow Rectangular Section Steel Beam-Columns With Applied Torsion, George Adomako Kumi

Civil & Environmental Engineering Theses & Dissertations

Presented herein is an experimental and theoretical study of biaxially loaded hollow rectangular section steel beam-columns with applied torsion at elevated temperatures. The theoretical analysis is based on a system of simultaneous materially nonlinear differential equations of equilibrium for which an iterative semi-analytic solution approach is formulated. Although the primary goal of this research is to study the influence of elevated temperatures on the steel member with the complex loading, rigorous analysis is also conducted of the member at ambient temperature for comparison. The experimental part of the study involves conducting tests on the members at both ambient and high …

Key Construction Techniques For Incremental Launching And High Falling Beam Of Long‑Span Simply Supported Steel Box Girder, Wu Yanbin, Lyu Maofeng, Yin Qijia, Yu Guanqiu

Journal of China & Foreign Highway

Based on the overpass project over Beijing-Hong Kong-Macao Expressway on Changsha Pan-Pan Road，this paper proposed a construction method of large-slope walking-type incremental launching and high falling beam of steel box girder given the difficulties in busy traffic under the bridge，large pushing slope，and great total height of falling beam.After the steel box girder assembly was completed，some bridge deck ancillary facilities were constructed in advance in the preassembly yard and the weight was allocated.The steel box girder was pushed synchronously，thereby reducing the aerial work on the bridge in the later stage.During the incremental launching construction of the steel box girder above the …

Different Forms Of Nano‑Sio2 In Emulsified Asphalt And Their Effects On Emulsion Storage Stability, Ji Chao, Cao Yuanhao, Li Zhigang

Journal of China & Foreign Highway

The insufficient storage performance of emulsified asphalt has always been a problem affecting its application，and there have been studies in China on nano-SiO2 particles as additives to improve the stability of emulsified asphalt，but the effect is not obvious.Based on the principle of Pickering emulsion，nano-SiO2 with surface modification was used as an emulsifier to directly emulsify matrix asphalt，and whether its stability improvement effect on emulsified asphalt is better than nano-SiO2 as a modified additive was explored.Firstly，three emulsified asphalt were prepared，namely ordinary modified emulsified asphalt A，emulsified asphalt B with nano-SiO2 as a modified additive，and emulsified asphalt C based on the new nano-SiO2 …

Study On Test Methods Of Wheel Sticking‑Free Emulsified Asphalt, Wang Peng, Qin Yongchun, Wang Jie, Xiong Weiming, Chang Rong, Fu Chongfeng, Feng Guoli

Journal of China & Foreign Highway

The wheel sticking-free emulsified asphalt is a key material to solve the wheel sticking problem in the process of asphalt pavement construction，with the wheel sticking-free effect as the core index.The accurate evaluation of the wheel sticking-free effect is important for the popularization and application of wheel sticking-free emulsified asphalt.Based on the research results in China and abroad，two test methods for wheel sticking-free effects （counterweight method and indenter method ） were innovatively proposed，and the wheel sticking-free effects of various emulsified asphalt were evaluated.The test results show that the two test methods can accurately evaluate the wheel sticking-free performance of emulsified asphalt，and …

Study On Mobilization Rate Of Rap Aged Asphalt Based On Ftir, Zou Xiaoyong, Li Ning, Wu Wenxiu, Wang Xin, Xu Xiaohe

Journal of China & Foreign Highway

During the preparation of the recycled asphalt mixture，part of the aged asphalt is first transferred from the surface of the recycled material to the new aggregate and then diffused and fused with the new asphalt，in which the percentage of transferred aged asphalt plays a key role in the final regeneration effect.In order to study the degree of transfer of aged asphalt in reclaimed asphalt pavement （RAP ），the mobilization rate （RMR） was calculated and analyzed based on the Fourier transform infrared spectroscopy （FTIR ）.The AC-13 graded recycled asphalt mixture was mixed and sieved to separate the new aggregate and RAP.The recycled …

Deflection Variation Rule Of Main Girder For A Concrete Cable‑Stayed Bridge Based On Combined Static And Dynamic Modification, Li Qi, Qi D Ongchun, Yang Hu, Zhao Zhiguo

Journal of China & Foreign Highway

In order to solve the problem of continuous downward deflection of the main girder for a concrete cable-stayed bridge during its service life，the deflection variation of the main girder for a long-span concrete cable-stayed bridge during its service was analyzed based on the modified model.A dual-objective optimization problem was constructed by using the combined static and dynamic finite element model modification method and was solved by the non-dominated sorting genetic algorithm （NSGA- Ⅱ）.The Pareto optimal solution set was obtained，and the coordinated optimal solution was found in the Pareto optimal solution set，so as to modify the finite element model.The calculated values …

Construction Technology Of Reactive Powder Concrete Prestressed Box Girder, Wang Xiaojie

Journal of China & Foreign Highway

At present，high-strength and high-performance concrete has some disadvantages，such as low flexural strength，large brittleness，and poor volume stability.Reactive powder concrete （RPC ） is a new type of material，which has good mechanical properties and high impermeability.It can reduce the amount of concrete to a greater extent and reduce the weight of the structure，achieving the purpose of safety，reliability，and cost saving.This paper applied RPC to highway prestressed box girder.Through the innovation and optimization of mix ratio，the change in traditional transportation technology，and curing technology research of steam curing shed，it effectively shortens the pouring time of RPC，ensuring the pouring quality and strength.

Fragilit Y Analysis Of Continuous Rigid Frame Bridge With High Piers And Long Span Subjected To Near‑Field Earthquakes, Sun Yongjiang

Journal of China & Foreign Highway

Near-field earthquakes are more destructive to the continuous rigid frame bridge with high piers and long span.Based on a new-built continuous rigid frame bridge with high piers and long span，considering the seismic demand probability of bridges under near-field earthquakes，this paper utilized OpenSees to analyze the time history of the bridge.The structure response of the bridge under near-field earthquakes was obtained by the nephogram method，and the vulnerability of the bridge under earthquake was analyzed based on the curvature demand probability model of the structure.The results show that the probability response of curvature demand of a continuous rigid frame bridge with high …

Lightweight Replacement Technology For Existing Soft Subgrade Based On Over‑Consolidated State, Huang Baotao, Zhang Mudan, Huang Xiangshuo, Fang Mingshan, Feng Jianxue, Huang Lizhen

Journal of China & Foreign Highway

In order to solve the differential settlement of soft subgrade in coastal areas，based on the elastic deformation theory of overconsolidation stress ratio，the calculation and analysis of artificial overconsolidation stress ratio and the new technology of lightweight replacement were carried out to reduce the additional stress of vehicle load and structure weigh.The results show that the replacement thickness of the lightweight material with suitable density can make the additional stress at the bottom of the subgrade less than the deadweight stress of the original soft soil，and the additional stress is less than the initial flow stress of the soft soil.The resulting …

Analysis Of Stress And Drainage Characteristics Of Water Film Between Tire And Road Surface And Influence Of Groove Parameters, Sun Zhenhao, Chen Jun

Journal of China & Foreign Highway

In order to study the stress characterist ics of water film on cement concrete road surface under the action of the tire and the influence of grooves，the finite element model of tire-water film-road surface was constructed using SolidWorks and Ansys Workbench.Based on computational fluid dynamics （CFD ） control equation and fluid-structure coupling theory，the flow law of water film on road surface under the action of the tire and the influence of water film thickness，driving speed，groove width，groove spacing，and groove direction on the hydrodynamic lift of tire were analyzed.The results show that the hydrodynamic lift of the tire increases with the increasing …

Influence Of Rap Content On Mechanical Properties And Pavement Performance Of Warm Recycled Asphalt Mixture, Ren Ruibo, Yin Liyang, Xu Qiang, Zhao Pinhui, Ma Shidong

Journal of China & Foreign Highway

Warm recycling technology is an effective new technology for recycling recycled asphalt pavement （RAP ）.In order to improve the pavement performance of warm recycled asphalt and effectively enhance the recycling rate of RAP，the influence of RAP content on the performance of warm recycled asphalt mixture was investigated through mechanical properties and pavement performance analysis，and the correlation between dynamic stability and mechanical parameters of creep tests under repeated loading was discussed.The results show that with the increase in RAP content，the high-temperature stability，shear resistance，and elastic deformation resistance of warm recycled asphalt mixture are improved，but the low-temperature crack resistance and water stability are …

Expressway Traffic Flow Prediction Based On Data From Multiple Related Toll Stations, Zhang Yang, Yao Fangyu, Yang Shumin

Journal of China & Foreign Highway

The strong inter-economic connection makes a spatial correlation between traffic data from multiple related toll stations between urban cluster regions，and an accurate description of this connection can improve the accuracy of expressway traffic flow prediction.However，due to many uncertainties，the correlation is difficult to be captured and quantified.To solve this problem，an ATGCN-ResGRU deep learning-based expressway traffic flow prediction method was proposed.By combining attention mechanisms，three graph convolutional networks （GCN ） topological networks with high，medium，and low attention levels were constructed，and spatial learning data was obtained according to the weighted attention level of each network.The connection of multiple related toll stations was quantified and graded.At …

Carbon Emission Calculation And Scheme Selection For Roadbed Drainage Ditches By Mechanized Construction, Xing Hao, Wu Jiarun, Li Han, Lin Yuliang, Guo Dongdong

Journal of China & Foreign Highway

Aligned with the peak carbon and neutrality goals，the mechanized construction of roadbed drainage ditches should consider not only construction efficiency and economic factors but also carbon emissions.This study，centered on the Meng-LYU highway，devised approaches to calculate roadbed drainage ditches' carbon emissions and investment costs across three stages：building material production，transportation，and construction.By introducing the concept of carbon trading to align carbon emissions and investment costs，a comprehensive comparison was conducted between the conventional supporting formwork method and the hydraulically powered sliding formwork method regarding equivalent carbon emissions.An orthogonal experiment was conducted involving the upper length of the roadbed drainage ditch，pouring thickness，haul distance，and construction length …

Study On Treatment Method Of Expansive Soil Embankment In Expressway Reconstruction And Extension, Wang Yuwei, Hu Yanli, Zhang Rui

Journal of China & Foreign Highway

In order to fully utilize expansive soil as filler in highway reconstruction and expansion projects，this paper draws on the successful experience of using expansive soil directly in road construction.It proposes an embankment treatment scheme that involves the use of geogrid-reinforced expansive soil with edge wrapping，based on the reconstruction and expansion project of the Hefei to Dagudian section of the G 40 Shanghai-Shaanxi Expressway.Through laboratory tests，the road performance and swelling characteristics of the expansive soil filler were investigated to determine the applicable scope and compaction control indices of the filler.Then，the feasibility of the embankment treatment scheme was demonstrated through the prediction …