Reinforced Concrete Pipe Research Articles

Key Parameters for Assessing the Deterioration of Reinforced Concrete Pipes in Water Networks

Key Parameters for Assessing the Deterioration of Reinforced Concrete Pipes in Water Networks

Field Test Study on Large Diameter Reinforced Concrete Pipe Jacking in Moderately Weathered Siltstone Stratum

Field Test Study on Large Diameter Reinforced Concrete Pipe Jacking in Moderately Weathered Siltstone Stratum

Analysis of Reinforced Concrete Pipe Strain Due to Jacking Force Case Study: Sudetan Ciliwung River Project to the East Flood Canal

Pipe Jacking is an innovation in trenchless technology that has been utilized in various sectors including municipal wastewater systems, oil and gas transportation, and hydraulic engineering. One of the critical aspects to ensure the success and safety of the pipe jacking process is strain monitoring. This study discussed the strain characteristics of reinforced concrete pipe structures during pipe jacking. The analysis was conducted using a numerical approach, which compared to field monitoring. Field strain monitoring was performed by strategically placing strain gauges along the pipe during the jacking operation, resulting in real-time data on deformation and pressure values. When the strain was monitored, the numerical test was conducted simultaneously using finite element analysis of Rocscience 3D. Those activities were done to consider the interaction between the reinforced concrete pipe and the surrounding soil. The strain analysis results indicated that the pipe responded during the pipe jacking process. The values of strain were various, depending on jacking force, condition of excavated soil layers, and distance between twin tunnels. The maximum stress occurred at the beginning of jacking process, when the pipe infiltrated into the soil with stress value of 512 kPa.

Damage and deformation behavior of reinforced concrete pipes with varying joints under surface explosion

Reinforced concrete pipes (RCP) are the mainstay of urban water transmission networks. Urban development entails increased potential for blasting activities (such as subway tunneling, excavation, and demolition) as well as the risk of accidental explosions. This paper provides a detailed description of the damage evolution and deformation process of RCP under explosive loads using validated numerical simulation methods. A concise phenomenon-based method is introduced for RCP damage grading. Furthermore, a comparative analysis is conducted on the damage and deformation of RCP resulting from explosions at different locations and with varying weights. At last, this paper especially investigates and explains the impact of four commonly used joint types on the RCP’s response to explosions. The research results help to enhance the understanding of damage evolution and deformation behavior of RCP (or similar structures) induced by explosion, and are also references for protection, repairing and failure identification of segmented structures subjected to explosion.

Acoustic Emission Characterization and Cracking Characteristics of Reinforced Concrete Pipe

Acoustic emission (AE) and digital image correlation (DIC) technology were used in this study to monitor the behavior of reinforced concrete pipe (RCP) in the optimized three-edge bearing test (TEBT). At the same time, the AE source location of different pipe sections was simulated. The results show that the whole compressive loading process for RCP could be divided into 3 to 4 stages. Both the AE counts and AE energy could well characterize the cracking of concrete, and AE energy was more sensitive to the breaking of steel bar. The amplitude and duration of AE signal produced by the breaking of steel bar were larger than those produced by the cracking of concrete. The AE frequency for concrete cracking was relatively scattered. The AE frequency for steel bar breaking was small and concentrated, and this frequency distribution showed an exponential decreasing trend. The results of optimized AE source location showed that the generation and development of cracks occur in the initial loading stage. The results of multi-index analysis showed that the cracks in the top (loading position) and the bottom (bearing position) of the RCP show that the cracks extend from the inner wall to the outer wall, while the cracks on the left and right sides perpendicular to the loading direction show that the cracks extend from the outer wall to the inner wall.

Experimental Study on Mechanical Properties of Rectangular Reinforced Concrete Pipe with Corrosion Defects

Rectangular reinforced concrete pipes are widely used in various municipal projects. Because they are often located in weak strata in urban areas, they are prone to structural defects such as corrosion, which in turn leads to a decline in the bearing capacity of reinforced concrete pipes and, in severe cases, causes disasters such as pipe collapse. In this paper, the mechanical properties of rectangular reinforced concrete pipes with corrosion defects are studied through laboratory tests, and the influence of the pipe failure mechanism and corrosion depth on the ultimate bearing capacity of pipes is analyzed. A numerical simulation method is used to verify the test results, and the numerical simulation results are In good agreement with the indoor test results. The research shows that the failure mode of rectangular reinforced concrete pipe under TEB test conditions can be divided into an uncracked stage, a crack development stage and a failure stage. With the increase of corrosion depth, the ultimate bearing capacity of the pipe decreases. When the corrosion depth is equal to the thickness of the protective layer, the ultimate bearing capacity of the pipe is more than 30%, and the corrosion depth has a great influence on the mechanical properties of the pipe.

Decision-Making Guidance for the Optimal Selection of Culvert Renewal Methods

A variety of trenchless techniques are becoming popular for renewing culvert structures, but their suitability, cost, design life, construction, and environmental and societal footprint vary widely. The selection of the optimal culvert renewal method can be an overwhelming process for transportation agencies, thereby warranting a user-friendly guidance tool. This study describes the culvert renewal selection tool (CREST) that prescribes an optimal technique based on various host culvert characteristics and multiple selection criteria. The CREST tool comprises 12 renewal techniques that include open cut, pipe bursting, and a variety of grouting and pipe lining techniques. Performance synthesis of these techniques based on five criteria form the core of the CREST tool, which subsequently leverages the principles of the analytical hierarchy process for decision-making. The CREST model is demonstrated for application for reinforced concrete pipe (RCP) and corrugated metal pipe (CMP) culverts considering nonstructural, semistructural, and full-structural renewal categories. Monte Carlo simulation procedures are adopted for determining the user-defined criteria preferences for demonstration purposes. The CREST tool and the results of this study will provide primitive guidance to transportation agencies for choosing culvert renewal techniques.

Bending Strength of Connection Joints of Prestressed Reinforced Concrete Pipe Piles

The connection joint of prestressed concrete pipe piles is a typical steel–concrete structure, and its bending strength has evolved into a critical factor affecting the safety of supporting structures in underground engineering. Based on full-scale bending tests of five specimens of large-diameter prestressed reinforced concrete (PRC) pipe piles and connection joints, as well as the corresponding finite element numerical simulation, the bending bearing and deformation characteristics of connection joints of PRC pipe piles were analyzed, together with the effects of concrete strength, precompression stress, and connection mode of joints. The results showed that the crack resistance of the welded joint of PRC pipe piles was equivalent to that of the pipe pile shaft, but the ultimate bending moment of the joint was about 58–87% of that of the pile shaft. The bending failure mode of the pipe pile joint was mainly manifested in the end plate yielding into a drum shape, with the tension side of the pile hoop and the end plate clearly separated from the pipe pile, and crushed concrete at the upper edge of the pile hoop. The bending strength of the joint can be improved by increasing the bonding strength between the end plates of the joint or embedding Rachel reinforcement in concrete. In addition, synchronously increasing the strength grade and reinforcement ratio of concrete or strengthening the precompression stress of concrete are favorable measures.

The Effect of Microbiologically Induced Concrete Corrosion in Sewer on the Bearing Capacity of Reinforced Concrete Pipes: Full-Scale Experimental Investigation

The main part of sewer pipelines is commonly made up of precast reinforced concrete pipes (RCPs). However, they often suffer from microbiologically induced concrete corrosion (MICC), which has made them less durable than expected. In this study, three-edge bearing tests (TEBT) are performed on full-scale RCPs with preset wall losses to determine how MICC influences their bearing performance. For this purpose, several bearing indices such as D-load, peak load, ultimate load, ring deflection, ring stiffness, and failure energy are presented or specified to characterize the load-carrying capacity, stiffness, and toughness of these RCPs. It is found that crown concrete corrosion hardly changes the mechanical behavior of the first elastic zone of RCPs, so that D-load is not affected, but it shortens the crack propagation zone significantly, leading to a reduction in ultimate and peak loads. Furthermore, RCPs’ ring stiffness and toughness are negatively correlated to thickness of wall loss, while the transverse deformability of the ring cross-section is positively correlated with it. Additionally, it was found that crown corrosion affects the ultimate load of different sizes of RCP in different ways. The 2000 mm RCP is affected the most, with a 50 percent reduction in ultimate load. The 1000 mm RCP follows, with a 36 percent reduction, and the 1500 mm RCP has a reduction of less than 20 percent. This research contributes to comprehending the degradation of in-service sewage pipes, hence informing decision making on sewer maintenance and rehabilitation.

Quantitative model for residual bearing capacity of corroded reinforced concrete pipe based on failure mode

Reinforced concrete pipes (RCPs) are widely used as jacking pipes in various infrastructures, such as sewers, tunnels, and pipe galleries. However, owing to the presence of harmful chemicals and microorganisms in the surrounding environment, the pipe gradually corrodes, thereby thinning the pipe wall and lowering the residual bearing capacity (RBC) of the structure. For the daily maintenance of the RCP, the RBC should be evaluated precisely to ascertain the service status of the pipe, and if necessary, timely rehabilitation can be performed to yield the optimal repair outcome and cost efficiency. In this study, quantitative models for RBCs of both intact and corroded RCPs are proposed; these models are based on the plastic collapse failure mode of rigid pipe. Additionally, the impact of uncoordinated deflection between concrete and reinforcement has also been characterised. A series of numerical simulations were developed on the basis of the finite element method (FEM) to evaluate the RBC of corroded RCPs, and the FEM results are consistent with those of the quantitative model. Finally, three-edge bearing (TEB) tests were conducted by incorporating both intact and corroded RCPs. The results of the TEB tests also revealed the reliability of the quantitative model.

Retrofitting of damaged reinforced concrete pipe with CAC-GGBFS blended strain hardening cementitious composite (SHCC)

Reinforced Concrete Pipes (RCP) has been widely used for long-distance sewerage pipeline globally. However, concrete pipes are susceptible to microbially-induced acid corrosion (MIC) which leads to premature failure far before reaching their asset life. The aim of this study is to investigate the effectiveness and efficiency of using CAC (Calcium Aluminate Cement) – GGBFS (Ground Granulated Blast Furnace Slag) blended SHCC (Strain hardening cementitious composite) to retrofit damaged RCP. Prior to the retrofit, RCP was pre-loaded to 70%, 80%, 90% of its ultimate strength to create cracks. Retrofitted pipes were tested under three-edge bearing (TEB) load for assessment. Load–deflection relationship, load–strain behaviour along with pipe ductility and stiffness were analysed and discussed. Experimental results show that the ultimate load-carrying capacity of the retrofitted RCP increased up to 50.6% compared to original RCP. The retrofitted pipe acted monolithically with the lining material without debonding observed before failure. Moreover, a prediction formula was proposed to calculate the load-bearing capacity of retrofitted RCP in addition to experimental work. The theoretical model considers the impact of the pre-loading level on the original RCP and was verified with the experimental results. CAC-GGBFS blended SHCC is proven to be an effective repair solution to damaged concrete sewerage pipelines.

Enhancing corrosion resistance of RC pipes using geopolymer mixes when subjected to aggressive environment

The durability of reinforced concrete (RC) pipes depends upon the corrosion resistance of the reinforcing steel and the resistance of concrete mixes against an aggressive environment. This research paper aims to compare the performance of R.C. pipes made of ordinary Portland cement (OPC) concrete mixtures with others made of two different geopolymer concrete mixes based on different ratios of granulated blast furnace slag (GBFS), fly ash (FA), and pulverized red brick (RB) subjected to three different environments, ambient, tap water (TW), and an aggressive environment, and a solution of 10% magnesium sulfates + 5% chloride (MS-CL). An accelerated corrosion setup has been applied to accelerate the corrosion process in the tested samples. The evaluation of change of compressive strength of concrete and microstructure of different mixes was investigated too. Fourier transform infrared (FTIR) spectroscopy has been studied on all pipes. Geopolymer concrete mixes based on 90% GBFS and 10% RB show better results in all cases. Geopolymer concrete mixes based on 63% GBFS, 27% FA, and 10% RB increase the concrete compressive strength in the magnesium sulfate and chloride environment by 5% compared to tap water. It can be concluded that the geopolymer concrete mixes produced of 90% GBFS and 10% RB perform well under all environments, and its microstructure shows stable behavior in an aggressive environment.

Experimental study of the separated joint of an underground pipeline rehabilitated by cured-in-place pipe

Reinforced concrete pipes (RCPs) were commonly used in older underground pipelines in Taiwan, China. However, their joints are prone to damage, including fracture and separation, from problems such as overloading, poor backfilling, and liquefaction. For the rehabilitation of such aged pipelines, trenchless methods are preferred to minimize the impact on transportation. The cured-in-place-pipe (CIPP) rehabilitation could be one of the most popular trenchless methods suitable for the cases with angular alignment and changing cross-section. However, according to the existing standards, no details are available on the performance of the rehabilitated parts of the damaged pipeline, including the effect of separated joint. This study designed and conducted laboratory testing on the composite pipe joint (the CIPP rehabilitated RCPs with a separated joint) with different scenarios, including radial and longitudinal loading tests. The radial test results indicated that, for a small separation distance, CIPP rehabilitation can restore the original function of a pipeline and improve its hoop strength. The longitudinal test revealed that the damage due to bending was controlled by the tensile strength of the liner material. The ultimate flexural strength decreased as the separation distance increased. However, pipelines may be subjected to additional loads due to flotation or subsidence, for which the longitudinal loading capacity is often the limiting parameter. For such conditions, it is necessary to confirm, by more research, whether the wall thickness is sufficient.

Hydraulic and Structural Analysis of Complex Cross-Section Reinforced Concrete Pipes to Improve Sewage Flow in a Combined Sewer System

A complex cross-section reinforced concrete pipe that combines a sub-pipe for the flow of sewage in dry weather and a main pipe for the flow of rainwater was developed to reduce sedimentation of the combined sewer system in dry weather. The sub-pipe was designed, considering the flow velocity, constructability, and maintenance. By fitting the sewage data in the dry weather to the normal distribution, the ratio of the cross-sectional area of sewage flow to that of the pipe was determined to be approximately 0.418, which could cover 99.85% of the sewage volume of the target site. Based on this ratio, the diameter of the sub-pipe corresponding to the combined sewer system with a pipe diameter between 450 and 1300 mm was determined. The hydraulic performance analysis results showed that the flow velocity increased by 11 to 12% compared to the circular pipe based on the full sub-pipe and by more than 15% depending on the water level. The shear stress increased by more than 16.5%, and higher tractive force was observed. Structural safety was determined as the crack load and failure load far exceeded the minimum criteria, thereby verifying the feasibility and field applicability of the complex cross-section reinforced concrete pipe.

Structural performance of damaged rigid pipe rehabilitated by centrifugal spray on mortar liner

There has been growing interest in using trenchless technology, especially centrifugal spraying techniques, to renovate the sewer pipe network in China. In this study, a damaged reinforced concrete pipe (RCP) (i.e., 14.7% vertical deformation) with one-meter diameter is rehabilitated by centrifugally spraying on a 50 mm thickness mortar lining. The ultimate (Du) D-load only increased by 2% compared to host pipe’s residual strength; however, other pipe properties exhibited improvement. Based on the behavior of two experimental results, finite element models were established, and an innovative pipeline damage quantization model was proposed. Through parameter sensitivity analysis, the effects of interface strength and fracture energy on pipe bearing capacity were studied. It was discovered that interface bonding performance affected the service load of the rehabilitated pipe. From the analysis of pipeline initial state deformation influence on the repaired structure bearing capacity, it was discovered that selecting a reasonable repair time point can effectively improve the functionality of the pipe network and reduce repair costs. An analysis of RCPs structural repair with a vertical deformation larger than 14% revealed that it is difficult to repair damaged pipes only employing mortar spraying. A structural design method based on the service load and ultimate load is presented in this paper.

Basalt‐polypropylene fiber reinforced concrete for durable and sustainable pipe production. Part 2: Numerical and parametric analysis

AbstractA nonlinear 3D FEM was developed for reproducing the three‐edge bearing test (TEBT) of pipes. The model was validated by considering the experimental results on standard reinforced concrete pipes (RCPs) and fiber‐reinforced concrete pipes (FRCPs) with 1000 mm internal diameter presented in the Part 1. The relative error between numerical simulation and laboratory test results for both the service (D0.3) and the ultimate (Du) D‐load (DL) were lesser than 2.1% and 6.3%, respectively. Additionally, a new structural design process that takes into consideration the geometric and mechanical variables involved into the TEBT of pipes, including the type and reinforcement configuration, is proposed. Because of applying this approach, design‐oriented tables with minimum steel‐cage reinforcement ratios for RCPs and FRCPs valid for pipes with inner diameters ranging from 300 mm to 1800 mm are established for the pipe strength classes I to V and wall thickness A, B, and C defined in the ASTM C76. Based on the numerical results, it can be confirmed that the hybrid use of basalt‐polypropylene fibers permits to reduce the steel reinforcement ratio respect to the equivalent RCP and, for some diameters and strength classes, the total elimination. These results represent a step forward in the use of fiber reinforced concrete in the pipe industry, which can lead to more durable and sustainable piping products.

Culvert Renewal with Cementitious-Geopolymer Spray–Applied Pipe Lining: Field Data Collection and Assessment

A structurally spray-applied pipe lining (SAPL) is a trenchless method to inhibit further deterioration and structurally renew deteriorated pipes, culverts, and drainage structures. The primary SAPL materials generally fall into two broad categories of cementitious and polymeric materials. SAPLs can be a key strategy in extending service life and managing the future issues expected from the aging network of gravity pipes and culverts. However, currently no standard design methodology exists for SAPL. Most lining vendors utilize the cured-in-place pipe (CIPP) design methodology as specified in a current standard, and others use various analytical structural design approaches. This paper assessed the existing conditions of 24 culverts renewed with SAPL in the states of Delaware, Florida, Minnesota, New York, North Carolina, Ohio, and Pennsylvania by considering various physical and operational factors. The inspections were focused on large-diameter corrugated metal pipes (CMPs) and reinforced concrete pipes (RCPs) renewed with cementitious and geopolymer SAPLs. This study is part of a broader research project to develop a standard design methodology for this renewal method. Identifying potential problems after installation can be considered during planning and design of SAPL. Therefore, the first objective of this paper is to conduct field data collections and in situ inspections of recent SAPL projects to identify renewal defects and installation issues. The second objective of this paper is to make suggestions for development of proper performance construction specifications to prevent SAPL potential problems. The data collected through the field inspection are used to assess the structural conditions of these projects. The results present a strong need for SAPL performance construction specifications, a standard design methodology, a robust quality control protocol, postinspection requirements, and recommendations for SAPL installation improvements.

Basalt‐polypropylene fiber reinforced concrete for durable and sustainable pipe production. Part 1: Experimental program

AbstractAn experimental program consisting in producing and testing reinforced concrete pipes (RCPs) under the three‐edge bearing tests considering different types of reinforcement was carried out. Four types of RCPs were produced, these reinforced with: (1) polypropylene macrofibers; (2) basalt microfibers; (3) combination of both (hybrid reinforcement); and (4) plain concrete. The analysis of the crack patterns and both service and ultimate mechanical responses allowed concluding that the use of fibers do not lead to an effective increase of the first cracking load; however, both types of fibers allowed a better crack width control respect to the standard RCP. In this regard, basalt microfiber reinforced concrete led to a better response caused by concentrated loads (jacketing) whilst polypropylene macrofibers increased the concrete pipe performance in terms of bearing capacity and flexural crack control. The hybrid fiber reinforced concrete was found to be the most suitable alternative for increasing the load bearing capacity and the crack width control for service loads. These incipient experimental results permit to conclude that this type of hybrid basalt‐polypropylene fiber reinforced concretes are an interesting alternative to traditional steel‐cage RCPs.

Modeling structural behavior of reinforced-concrete pipe with single, double and triple cage reinforcement

Reinforced Concrete Pipe (RCP) is widely used in storm and wastewater management owing to its resiliency and reliability. This study proposes nonlinear 3D finite-element models (FEMs) to explore the effects of reinforcement configuration on RCP structural performance. RCP having 825-mm, 1200-mm, and 1800-mm in diameter with the three reinforcement configurations commonly used by industry, namely single-cage, double-cage, and triple-cage, were modelled for evaluating 65D, 100D, and 140D pipe design classes. FEM predicted load–deflection was validated using experimental results on full-scale RCP specimens. Average FEM prediction error of service and ultimate loads was 6.8% and 6.3%, respectively. FEM stress contours suggested agreement with experimental observations. The development of stress in the concrete and steel reinforcement during the there-edge bearing test (TEBT) was evaluated and discussed. A thorough parametric analysis was performed on developed single and double-cage FEMs and demonstrated that the influence of the reinforcement area, cover, positioning, and yield strength on RCP behavior could be rationally captured by the numerical models.

Gradient Boosting Coupled with Oversampling Model for Prediction of Concrete Pipe-Joint Infiltration Using Designwise Data Set

Infiltration of groundwater through reinforced concrete pipe (RCP) joints under hydrostatic pressure has been a major costly challenge in municipal sewer network systems. Analysis of an exclusive designwise infiltration test data of RCP joints showed that conventional regression analysis failed to produce reliable predictions. Accordingly, tree-based machine-learning techniques including random forest, extra trees, and gradient boosting classifiers have been deployed in this study to create reliable models. A large designwise data set identifying failure of RCP joints and the effect of key design parameters was collected using a novel experimental program. Due to the resulting unbalanced experimental data set, oversampling techniques including synthetic minority over-sampling technique (SMOTE) and density based synthetic minority over-sampling technique (DBSMOTE) were employed to enhance predictive performance. Gradient boosting coupled with DBSMOTE offered a robust machine-learning model for predicting RCP joint hydrostatic infiltration. The hybrid gradient boosting classification (GBC)-DBSMOTE model achieved superior predictive accuracy in terms of several classification indicators, with promising capability to create RCP joint hydrostatic infiltration performance charts that capture the effects of key design parameters, such as pressure duration and level, pipe size, and gasket sealing. The robust predictive model could produce design charts that aid municipalities in proactively averting sewage system infiltration problems at low cost, instead of the prevailing reactive approach to this problem.