Permanent Formwork Research Articles

Study on the compression performance of 3D printing concrete permanent formwork composite columns

Study on the compression performance of 3D printing concrete permanent formwork composite columns

Evaluation of the flexural stiffness of a lattice girder composite slab at the construction stage according to the lattice girder shape

Lattice girder composite slabs (LGCS) for use in construction stages are structures in which part of the lattice girder is embedded in precast concrete panels with a thickness of less than 100 mm. they serve as a permanent formwork supporting the casting loads of on-site concrete while constituting a portion of the RC slab. In this study, analytical research was conducted to evaluate the flexural stiffness of LGCS effectively and simply considering a range of variables. Based on the results, an Euler-Bernoulli beam-theory-based equivalent sectional analysis method is proposed. To achieve this, the study extracted the second moments of area (Iexp) from the experimental results of previous researchers and compared them with the second moments of area (Ibeam) calculated using the Euler-Bernoulli beam-theory-based sectional analysis, analyzing how the ratio (Ibeam/Iexp) varies according to the design parameters. Variable analyses over a wide range were conducted by expanding the types and ranges of variables, and the effects of different variables and ranges were analyzed by comparing the second moments of area based on an FE analysis of LGCS (IFEM) with those based on a beam analysis (Ibeam). Furthermore, to apply the equivalent sectional analysis method to LGCS, equivalent second-moment-of-area formulas were proposed through the equivalent neutral axis and equivalent arm length for each sectional element.

Study on shear performance of BMSCC prefabricated shell and square steel tube composite permanent formwork beam

A novel type of permanent formwork (PF) concrete beam has been proposed with the aim of reducing carbon footprint, conserving energy, and enhancing construction efficiency. Specifically, the U-shaped PF is constructed using basic magnesium sulfate cement mortar, and square steel pipes with holes are utilized in place of traditional vertical and horizontal reinforcements. During on-site construction, the composite beam can be easily completed by pouring ordinary concrete into the PF. Shear failure tests were conducted on two PF beams and a reinforced concrete (RC) contrast beam with varying strip spacing. It was observed that the remaining rectangular steel strips, resulting from opening holes on both sides of the square steel pipe, acted as shear stirrups. The results indicate that the PF beam demonstrates typical shear and compression failure, and the precast shell is securely bonded to the core concrete without any peeling phenomenon. When comparing to an equivalent RC beam with the same transverse steel yield strength and dosage, the cracking load of the inclined section is increased by 28.3 % and the ultimate load is increased by 21.4 %. Compared to RC beams, PF beams exhibit an increased number of cracks but reduced width. And The ductility of PF beams were improved. Decreasing the distance between steel strips on both sides of the PF beam results in an 10.3 % increase in cracking load and a 9.4 % increase in ultimate load. By introducing the concrete constraint coefficient and the steel tube web resistance coefficient, the formula for calculating the shear capacity of the PF beam was established.

TESTING OF MODELS OF BRIDGE DECKS WITH REINFORCED CONCRETE FIXED FORMWORK

In Ukraine, in the second half of the 20th century, the vast majority of highway bridges span structures were built from precast concrete. This was due to the requirement of construction industrialization in the USSR, which required the maximum use of prefab structures. Therefore, the bridge deck slabs had a significant number of longitudinal joints. The experience of maintenance of bridges prefabricated reinforced concrete span structures has shown that a significant number of defects occur in their slabs due to the presence of joints. Taking into account the above, the current state building regulations of Ukraine for bridge design indicate that in the case of using prefabricated reinforced concrete beams, their surface should be covered with a layer of cast-in-situ reinforced concrete with a thickness of at least 14 cm. Taking these requirements into account, reinforced concrete span structures of highway bridges are arranged mainly precast and cast-in-situ: installing of precast beams, concreting of the cast-in-situ slab above them. This design requires using of formwork for the slab installation. A promising direction in cast-in-situ bridge construction is using of various types of permanent formwork. However, their use has not been studied to date. Having studied the experience of using non-removable formwork, it is proposed to test series of samples to determine the suitability for further operation of one or another option, in addition to studying of the joint operation of non-removable formwork plates as part of the combined cross-section of the deck slab.

An investigation on enhancing the bonding properties of 3D printed concrete permanent formwork and post-casted concrete

Employing 3D-printed permanent formwork (3DPF) technology for rapidly manufacturing prefabricated components constructed with reinforced concrete represents a promising application of additive manufacturing technology in load-bearing constructions. Ensuring efficient bonding between 3DPF and post-casted concrete (PCC) is a prerequisite for the widespread adoption of this technology. This research aims to enhance the 3DPF-PCC interface through: physical (groove), chemical (cement paste) and composite methods. The interfacial bond strength was quantitatively analysed by splitting tensile strength and shear strength. X-ray computed tomography scanning was utilized for the quantitative characterization of pore structures. Digital image processing techniques were employed to monitor crack development during splitting tensile tests. The mechanism for strengthening the shear strength of the grooved interface was elucidated using a finite element model, and a modified formula for calculating the shear strength of the 3DPF-PCC grooved interface was proposed. The physical method improves shear strength by increasing interlocking structures significantly. The composite method weakens mechanical interlocking structures, increases interface porosity, and adversely affects interface bonding strength. It is recommended that future engineering applications adopt the physical process to improve mechanical interlocking structures and ensure interface bonding strength.

A Compressive Load Bearing Analysis of 3D-Printed Circular Elements

Large-scale construction 3D printing is a promising platform technology that can be leveraged to fabricate structural elements such as columns, piers, pipes, and culverts. In this study, the axial compression and split tensile performance of 3D-printed steel-fiber-reinforced circular elements fabricated with different configurations (hollow, hybrid, mold-cast, and fully 3D-printed) is evaluated. This study further investigates the performance of multi-material circular hybrid elements (3D-printed shells with different backfilled core materials) in an attempt to assess their suitability as a new construction paradigm. The experimental results revealed that the fully 3D-printed steel-fiber-reinforced circular elements exhibited a higher load capacity (up to 36%) and a distinct crack pattern compared to the other configurations. The void ratio of circular elements has varying effects on its axial load capacity depending on the printing material and significantly influences its splitting tensile load capacity. Furthermore, the compatibility between the 3D-printed shell and the cast-in-place core is identified as an influential factor in the structural performance of the hybrid elements. The results suggest a promising construction approach where low-cement material can be utilized as infill material for a cost-effective 3D-printed permanent formwork, offering a viable solution for specific infrastructure development applications.

Evaluation of the performance of reinforced concrete beams with 3D-printed permanent formwork

Evaluation of the performance of reinforced concrete beams with 3D-printed permanent formwork

Enhancing the flexural performance of concrete beams with 3D-printed UHP-SHCC permanent formwork via graded fiber volume fraction

Conventional concrete structures often rely on labor-intensive and wasteful formwork systems. In contrast, 3D concrete printing (3DCP) technology offers a more efficient alternative for fabricating complex-shaped permanent formwork. This study fabricates innovative composite beams using 3D-printed ultra-high-performance strain-hardening cementitious composites (UHP-SHCC) as permanent formwork, followed by casting infill materials. The spatially tailored fiber dosage distribution in the 3D-printed UHP-SHCC permanent formwork enables the performance optimization of the composite beam. The flexural behavior of three such formed composite beams is evaluated using four-point bending tests. A reference beam with homogeneous fiber distribution in the UHP-SHCC formwork is also tested for comparison. The failure mode, overall load–displacement response, and cracking performance of four beams are comprehensively characterized and compared. The results reveal that employing graded fiber dosages in UHP-SHCC formwork enhances fiber efficiency and structural performance while reducing fiber usage and material costs. The use of 3D-printed UHP-SHCC formwork with graded fiber distribution, despite using 25% less fibers and reducing the material cost by 12.8%, leads to a 65.6% increase in strength and over 50% increase in energy absorption, or a 77.4% increase in ultimate displacement with comparable peak load to the reference beam with homogeneous fiber distribution.

Flexural performance of hybrid deck structures constructed using glass textile-reinforced concrete permanent formworks and reinforced concrete

Flexural performance of hybrid deck structures constructed using glass textile-reinforced concrete permanent formworks and reinforced concrete

The strength of complex compressed reinforced concrete structures utilising hollow concrete blocks

Structures in which elements from different materials work together are successfully used in various combinations. Recently, new, effective construction materials and products have appeared. In complex or multi-component structures, elements made of materials with different physico-chemical or strain-strength characteristics should be sensibly combined for joint work. The more fully the properties of the components’ materials are utilised, the more efficient the design itself is. By analysing global practice, it can be seen that small concrete blocks have become widespread. The use of masonry made of hollow concrete blocks in modern construction differs from traditional ones in that the void area (up to 70%) makes it possible to create complex high-strength load-bearing structures by filling them with monolithic reinforced concrete. This also enables speeding up the construction process itself and reducing the cost of work on the construction site. The purpose of the study was to examine the strength of centrally compressed columns composed of hollow blocks and concrete filling with different transverse and longitudinal reinforcements, as well as to improve their calculation methodology. Experimental studies of centrally compressed columns, with different percentages of reinforcement using hollow concrete blocks as permanent formwork, have been carried out. The article presents the results of the research on strength, but the results of the strain studies were not included in this work. The proposed method of calculating complex constructions can be applied in design practice. A good correlation was observed between the experimental results and the results of the analytical model.

Testing the effect of UHPFRC jacket thickness and steel fiber volume fraction on NSC‐UHPFRC column compressive behavior

AbstractSeveral efficient applications of ultrahigh‐performance fiber‐reinforced concrete (UHPFRC). Among them are UHPFRC jackets utilized for strengthening or permanent formworks of the steel reinforcing normal strength concrete (NSC) columns since UHPFRC jackets could enhance the compressive strength and other properties of the NSC column. However, the efficiency of a UHPFRC jacket simultaneously depends on its thickness and the added steel fiber volume fraction. The paper aims to explore the interaction effect of UHPFRC jacket thickness and steel fiber volume fraction on the behavior of UHPFRC jackets confining the NSC core under compressive load. The circular ultrahigh performance concrete jacket filled inside with the normal strength concrete, named NSC‐UHPFRC column specimen, is tested under loading on the NSC core. UHPFRC jacket thickness of 18‐49 mm with three adding steel fiber volume fractions was conducted for the experimental study. The investigation and analysis of the effect of the UHPFRC jacket and the steel fiber volume fraction on compression behaviors of NSC‐UHPFRC columns proceeded after the compressive strength test results were validated using Richart's model. This comprised a review of various parameters such as specimen failure pattern, stress–strain relationship, and ductile indices. The Weibull distribution was employed to explain the interaction effect on the variation in the experimental results. Finally, an interaction model was proposed and used to discuss the interaction effect of UHPFRC jacket thickness and steel fiber volume fraction and the optimum condition of the compressive strength of the NSC‐UHPFRC columns.

A numerical study on a novel demountable cold-formed steel composite beam with profiled steel sheeting

Cold-formed steel composite beams are known for their unique advantages, like being lightweight and ease of installation. The use of profiled steel sheeting in cold-formed composite beams reduces construction time and costs by acting as a permanent formwork in the composite beams. The current study presents a 3D finite element model of cold-formed steel composite beam specimens comprising a cold-formed double-lipped channel section, profiled steel sheeting, concrete slab, and bolted shear connector. Employing bolted shear connectors, structural components can be deconstructed and replaced after their service life expires or if they are damaged. The characteristics of the materials obtained from an experimental program were assigned to the finite element model. Geometric characteristics, material nonlinearities, and loading procedures were attentively simulated, and a dynamic explicit procedure was employed for the numerical analyses. A comparison of the results obtained from the finite element models and the available experimental results validated the precision of the models. Then, numerical studies were conducted to investigate the effects of various parameters, including compressive strength of concrete, thickness of concrete slab, height and grade of cold-formed steel section, thickness of profiled steel sheeting, number and diameter of shear connectors, on the behavior of the composite beam. The results showed that the height and grade of the cold-formed steel section and compressive strength and thickness of the concrete slab have a significant effect on increasing the capacity of the composite beam.

Three-Dimensional-Printed Engineered, Strain-Hardening Geopolymer Composite as Permanent Formwork for Construction of Reinforced Concrete Beam

Three-Dimensional-Printed Engineered, Strain-Hardening Geopolymer Composite as Permanent Formwork for Construction of Reinforced Concrete Beam

Historical defects in buildings – No. 5: Wood-wool formwork

In this latest note, Hugh Docherty discusses the use of wood-wool slabs as permanent formwork to reinforced concrete slabs and the potential problems that can arise in this form of construction.

Enhancing interface shear performance and bending resistance of UHPC permanent formwork for composite short beams by different interface treatment

The study assessed interfacial shear properties of precast UHPC (ultra-high performance concrete)-cast-in-place NC (normal concrete) composite specimens using six interface treatments: smoothing, epoxy resin, grid chiseling, sand blasting, grooving, and steel stud connectors. Shear loads and slip were recorded for analysis. Optimal treatment guided fabrication of U-shaped UHPC permanent formwork with varying thicknesses, forming UHPC permanent formwork-NC/RC composite short beams for flexural tests. Results showed interface roughness treatment significantly enhanced interface shear performance. Notably, 1.8 cm SWM grid chiseling produced the highest shear strength, 4.7 times smoother interface. Increasing UHPC formwork thickness increased ultimate load capacity; 20 mm thickness was 81.4% higher than 10 mm. Treating U-shaped UHPC permanent formwork bolstered bending resistance; chiseling and grooving enhanced ultimate load capacity by 30.1% and 19.5%, respectively. UHPC permanent formwork outperformed RC short beams, modifying failure modes and enhancing bending capacity. The findings offer practical insights for UHPC formwork application in engineering.

Seismic performance of Fe-SMA prestressed segmental bridge columns with 3D printed permanent concrete formwork

The integration of digital fabrication technology with prestressed segmental column construction offers significant potential for accelerated bridge construction with material-efficient design. This study aims to explore this potential by developing a novel prestressed segmental column system that utilizes permanent 3D printed concrete (3DPC) formwork for column segment fabrication. Prestressing is achieved in the proposed system by using partially bonded iron-based shape memory alloy (Fe-SMA) reinforcement. Large-scale experiments were conducted on two columns under combined gravity and lateral loading to evaluate the seismic performance and feasibility of the proposed system. The ratio of steel to Fe-SMA reinforcement in the column design was the variable considered in this study. The experimental results showed that the columns could withstand lateral drifts of up to 5% without collapse and the permanent 3DPC formwork showed no premature failure or delamination. Furthermore, the columns exhibited self-centering characteristics, maintaining a residual drift of 1% up to a target drift of 4% when the reinforcement ratio of steel to Fe-SMA rebars was 0.3. The results highlight the potential of the proposed prefabrication concept in designing material-efficient and seismically resilient bridge columns with low damage characteristics.

Village road restoration in electrical steam power plant area in Banten, Indonesia through embankment reinforcement using geoframe technology

This paper presents a case study of the restoration of village road located between Zone 2A and Zone 2B after the excavation for box culvert underneath it. Geotechnical investigations showed that the area will be constructed upon volcanic rock material. The height of the Geoframe is approximately 19.7 meters. This system is a combination of polyester strip for reinforcing element and connected with clamp to the facing made of galvanized steel as a permanent formwork and non-woven geotextile material for filter element. The inclination of Geoframe structure can reach almost vertical with over 85⁰ inclined facing. The result of this work, Geoframe’s facing can be grown with vegetation (grass) to accentuate a natural and green structure. From design perspective, the embankment safety factor was above the criteria stated in Indonesian National Standard for Geotechnical Design Requirements which is above 1.50 and design with pseudo-static earthquake load which is above 1.10. The system has proven to be easy to implement in the field, fast and can be carried out with good quality control.

Seismic performance of precast frame with UHPC composite beams and HSC columns under cyclic loadings

This research investigates the seismic performance of precast frame with ultra-high performance concrete (UHPC) composite beams and high-strength concrete (HSC) columns. An experimental study was conducted on two frame specimens with 1/2-scale, three-story, and two-bay: a precast UHPC-HSC composite frame (UHPC-HSC frame) and a fully cast-in-place concrete frame (RC frame). The precast UHPC-HSC frame consists of composite beams with precast U-shaped UHPC permanent beam formworks and cast-in-place beam cores, precast HSC columns, and cast-in-place UHPC connections. The results indicate that both frames exhibit a mixed sidesway mechanism with beam hinges dominating. The UHPC-HSC frame demonstrates better structural integrity and experiences smaller structural damage, making it more suitable for rapid repair after earthquakes. The hysteresis curves of both frames are plump. The load-carrying capacity of the UHPC-HSC frame is 15.78% higher than that of the RC frame. The UHPC-HSC frame exhibits better ductility and deformation capacity compared to the RC frame. The whole and interstory ductility coefficients of both frames are greater than 3.49. The energy dissipation capacity of the UHPC-HSC frame is superior to that of the RC frame. At θ = 4.5%, the cumulative energy dissipation value of the UHPC-HSC frame is 18.66% higher than that of the RC frame. The research results can provide a reference for the engineering application of precast UHPC-HSC frame with UHPC composite beams and HSC columns.

Interfacial bonding performance of 3D-printed Ultra-High Performance Strain-Hardening Cementitious Composites (UHP-SHCC) and cast normal concrete

Using 3D-printed elements as permanent formwork for structural members is an efficient way to integrate 3D printing technology in the traditional construction field which could also enhance structural capacity and possibly address the reinforcement challenge during 3D concrete printing. The bonding performance between 3D-printed formwork and post-cast concrete is crucial for maintaining the overall mechanical performance of the structures. This study experimentally investigates the interfacial bonding properties between 3D-printed Ultra-High Performance Strain-Hardening Cementitious Composites (UHP-SHCC) permanent formwork and post-cast normal concrete (NC). Three groups of prismatic composite specimens with smooth, grooved, and 3D-printed interfaces are subjected to the splitting tensile test to evaluate the interfacial bonding. A fully cast normal concrete specimen is also tested as a reference for comparison. The failure modes, splitting tensile strength, and effective bonding area ratio of normal concrete are analyzed and discussed. Results reveal that the splitting tensile strength of interfaces with grooved and 3D-printed preparation is significantly higher than that of the smooth interface, with an increase of 92.2%–114.8 %.

Investigation of the Working Features of Concrete Structures Manufactured Using Technologies of Additive Building Manufacturing

The most common approach to the application of additive manufacturing technology today, which provides for printing the contour of buildings and structures with the creation of non-removable concrete formwork for the construction of load-bearing and enclosing structures. The features of the operation of a non-removable formwork under the action of lateral pressure of a concrete mixture are investigated. The results of the experimental research stage implemented on the basis of the SMITH Research Institute of the Moscow State University of Civil Engineering are presented, in which the strength characteristics of samples selected from single-layer concrete structures made using additive manufacturing technology, as well as the bearing capacity of fragments of non-removable formwork of rectangular and closed cylindrical shape under the influence of simulated pressure of a concrete mixture were studied. In the course of the work, the influence of parameters such as the width and height of the printed layer, as well as the presence of cold seams between individual layers of the printed structure on the strength and bearing capacity of the forming elements of the permanent formwork was studied. The work execution is aimed at accelerating the introduction of advanced technologies in construction in terms of creating scientific and technical groundwork for the development of additive construction production and the development of the domestic regulatory and technical base in the field of construction 3D printing.