Construction Formwork Research Articles

ბეტონში წყლის შემამცირებელი და შეკავშირების მარეგულირებელი ქიმიური დანამატების შესახებ

The article states that in order to prolong the safe service life of concrete under the influence of various artificial and natural factors, an appropriate chemical admixtures is used. Using water-reducing and bonding control chemical admixtures mainly reduces the frictional force between the cement particles. This simplifies the transportation of the concrete mixture, its placement in the construction formwork, and its reinforcement. It is possible to control the setting time of concrete according to climatic conditions. Laboratory and field tests are required to select this supplement. It is necessary to carry out proper scientific-research work on the establishment and application of the mechanism of influence of the water-reducing and bonding control chemical additive on the properties of concrete.

Prediction of the Lateral Pressure of Self-Consolidating Concrete on Construction Formwork Systems Using Machine-Learning Algorithms

Prediction of the Lateral Pressure of Self-Consolidating Concrete on Construction Formwork Systems Using Machine-Learning Algorithms

A multiple buffering high-fall protection structure and its impact response

High-fall accidents are the most serious safety accidents in the global construction of tall buildings, and existing techniques cannot effectively prevent large-energy impact accidents such as the overall fall of construction formwork, resulting in huge safety risks. Therefore, this paper proposed a flexible protection structure with multiple buffering mechanisms by using a high-strength steel wire net as the intercepting component, and energy dissipators and buffer supports as the buffering and energy dissipation devices. Based on the mechanical model of the critical components, established a simulation model for the overall falling dynamic impact protection of construction formwork, and carried out four cases of parameter analyses that used the material of the intercepting net, whether to use energy dissipators and buffer support as control variables. The analyses show that the multiple buffering and energy dissipation mechanisms composed of steel wire net, energy dissipators, and buffer supports can effectively reduce the response of each component. Nine sets of parametric analyses based on the finalized structure were conducted with the stiffness of the intercepting net and energy dissipator as parameters The results indicate that the smaller the stiffness of the intercepting net and energy dissipator, the better the structural performance. The novel structure proposed in this paper can effectively protect against large-energy falling object impacts and improve the safety of building construction.

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

Form-finding for free-curved reinforced concrete shell structure considering structural performance and construction formwork

A computational approach for free-curved reinforced concrete (RC) shells that simultaneously considers structural performance and associated construction strategy is proposed. First, for the rapid design and construction process, a unit–formwork construction system (UFS), which uses multiple construction methods dependent on curvature, is developed, and a mock-up test is conducted to validate its effectiveness of UFS. Although the construction time was reduced, the construction costs were confirmed to be approximately twice those of conventional methods. Furthermore, the error between the measured surface coordinates of the plywood form board (PFB) and corresponding three-dimensional (3D) data is computed, and the study confirmed that the error in construction was within half of the required level. Second, a multi-objective optimization problem is formulated to obtain a shell configuration and a suitable distribution of curvatures on the PFB by minimizing the squared normal curvatures of a PFB surface and the strain energy of the completed shell structure under distributed loads. To assess the manufacturability of PFB, the normal curvatures on the surface of the PFB, which are represented as quadrilateral meshes, are calculated. Finally, numerical examples demonstrate the efficiency of the proposed method for designing a free-curved RC shell from the perspectives of structural design and constructability.

Formwork Engineering for Sustainable Concrete Construction

This study provides a comprehensive review of the engineering challenges of formwork in concrete construction. The paper investigates different formwork systems, their design based on form pressure, and the difficulties of form stripping. Alternative binders are gaining more and more interest by opening new opportunities for sustainable concrete materials and their impact on form pressure and concrete setting is also investigated in this paper. The discussion involves several engineering challenges such as sustainability, safety, and economy, while it also explores previous case studies, and discusses future trends in formwork design. The findings pinpoint that choosing an appropriate formwork system depends significantly on project-specific constraints and that the development of innovative materials and technologies presents significant benefits but also new challenges, including the need for training and regulation. Current trends in formwork design and use show promising possibilities for the integration of digital technologies and the development of sustainable and ‘smart’ formwork systems. Continued research within the field has the possibility to explore new formwork materials and technologies, which will contribute to the implementation of more effective and sustainable practices in concrete construction.

Challenges for structural health monitoring of concrete curing using piezoelectric sensor and electromechanical impedance (EMI) technique: A critical review

Monitoring the strength of early-age concrete is crucial by assessing an accurate time of removing construction formwork and loads on the structural elements, as well as the high technology strength identifications. This high technology is based on electromechanical impedance (EMI). EMI technique might also be monitored for efficient and verifiable effects, such as the curing phenomenon in situ investigation level. The curing effect on concrete strength elements has been significantly detected using piezoelectric patches (PZT) as smart material devices in electromechanical impedance investigation. This EMI approach is also becoming a sustainable solution for diagnostic demands in order to determine the signature characteristics at earlier phases of the concrete strength growth. In 2005, the first investigation on the curing problem was published, then became increasingly well-known in many relevant studies. Consequently, this paper presents the most recent state-of the- art curing studies by EMI technology. The literature reviews categorized relevant information into vital concrete curing challenges to be highlighted in future research. State-of-art listed the critical outputs and findings as installation techniques, computing technology integration, modelling, analysis techniques, signal processing, and environmental factors. In conclusion, EMI technology might potentially be transformed into a self-contained monitoring device to detect early damage in concrete. Similarly, the appropriate research gaps might examine more experiments and simultaneously provides an explanation for more research problems in the field of structural health monitoring.

Design Method and Impact Response of Energy-Consuming High-Fall Flexible Protection System for Construction

High-fall accidents refer to accidents where construction personnel, building materials, and equipment fall from a height, usually resulting in serious casualties and significant economic losses. This paper proposes a high-fall flexible protection system and its design approach with a tensile yield energy-consuming mechanism to solve high-fall accidents. The design approach based on component characteristics that obtained through tests contains energy matching, component internal force balance, and a two-level energy consumption mechanism. Component tests were conducted with mesh bursting tests and energy dissipator static tensile tests to obtain the characteristics of the intercepting net under the flexible boundary condition, and the force-displacement model of the ring-type energy dissipater. Combined with an actual project, we designed a high-fall flexible protection system with a protection energy level of 800 kJ for the core tube of an ultra-high-rise building construction using this method. The impact of dynamic response under multiple cases including the overall fall of the construction formwork was analyzed by dynamical numerical calculation models. The result shows that the system can effectively intercept high-falling objects and exhibit good two-stage energy dissipation characteristics to consume the impact energy. Compared with the protection system without an energy consumption mechanism, the internal force response of the steel wire rope and the suspended frame reduce by about 60%, and the energy consumption capacity increase more than six times. The protection technique proposed in this paper can effectively solve the problem of high-level impact protection such as falling construction formwork equipment, and improve construction safety.

Research on Formwork Construction Technology of Railway Bridge

With the continuous development of railway bridge construction, the application of new technology, new technology and new materials is becoming more and more extensive, which puts forward higher requirements for the design and construction of formwork. This article takes railway bridge templates as the research object, and focuses on the technical difficulties in the design and construction of prefabricated and assembled bridge templates for segments. Combined with the currently under construction Zhengzhou to Xuchang railway elevated bridge project, the short line method is used for construction, and the types of railway bridge templates, design and construction techniques of templates are introduced. Combining engineering examples to illustrate the characteristics of template design and construction, this provides a reference for the design and construction of similar bridge templates in the future.

NPA Cells in the Marine Environment

Novel Polymeric Alloy (NPA) cells are a cellular confinement system with the engineering properties required by international standards for long-term confinement in demanding infrastructure projects. Three-dimensional NPA cells are used as a cover protection system against channel, stream and shoreline erosion caused by flowing water and tractive forces. NPA cells enhance the performance of conventional erosion control materials and dissipate energy from flood, current and wave action for hydraulic and marine structures and are a best available technique for canals, channels, drainage, shorelines, riverbanks, sea-walls, dams and port infrastructure. Soft or hard armor is used to optimize the erosion protection for natural or man-made channels, hydraulic structures and barriers. The surface treatment is dependent upon the geometry, hydraulic, site and environmental conditions along the water course, as well as optimization and cost-efficiencies. For example, sand infill is used for beachfront erosion control, vegetation for riverbank protection, gravel in sites subject to moderate flow velocities and concrete hard-armor in high velocity channels and walls subject to wave action. Reinforcement of load support structures in port applications can use sand, granular or recycled materials. Whereas the suitability of a cellular confinement system is directly dependent on the key attributes of the cell as well as its geometry, cells made of Novel Polymeric Alloy (NPA) have measurable higher tensile strength, resistance to deformation and environmental durability to hydraulic forces and thermal cycling over the project lifespan than conventional HDPE-based soft-cells. This includes high resistance to photochemical degradation – leaching of additives, oxidation and UV light – to preserve confinement for the lifespan of the project. Concrete solutions in non-erodible canals and walls are particularly advantageous with NPA cells. While the cellular mattress eliminates form work for fast construction, NPA cells add high tensile strength to the concrete. The creates a strong yet flexible mattress, which absorbs hydraulic forces and ground movement and resists cracking of the concrete for improved surface durability. Additionally, the high reinforcement factor of the NPA system also enables a reduction in concrete thickness to improve cost-effectiveness and sustainability. These properties also make NPA cells suitable to load support pavements used in marine ports, wharfs, terminals and container yards situated on soft, compressible and saturated soils, using sand for structural infill with no loss in structural stability.

Selection of formwork options when constructing high-rise buildings by AHP method (Case Study: Cao Lanh city, Vietnam)

Selecting the right construction formwork solution is vital to the success of a construction project. It can help speed up the construction schedule, boost quality, reduce construction costs, and ensure the safety of workers on the construction site. Construction contractors should carefully consider the project’s characteristics and their capacity when selecting the most suitable formwork solution. The Analytic Hierarchy Process (AHP) method is a decision-making tool that can be useful in selecting the best formwork solution for constructing high-rise buildings. The AHP method allows decision-makers to break down complex decisions into smaller, more manageable parts and to evaluate alternatives based on a set of criteria. The paper presents the process and propose the use of the method in selecting formwork options.

Influence of parameter uncertainty on the low‐carbon design optimization of reinforced concrete continuous beams

AbstractSustainable structural design can benefit the low‐carbon building industry. This study developed a hybrid optimization approach to analyze the influence of parameter uncertainty on the low‐carbon design optimization of reinforced concrete components. The proposed approach combined Monte Carlo simulations with a genetic algorithm for stochastic design optimization considering uncertainty in carbon emission factors. Based on a “cradle to site” system boundary that considers the production, transportation, and construction of reinforcement, concrete, and formwork, a case study of a continuous beam was conducted. The results revealed the significance of carbon emission factor choices on the optimal solutions. Further parametric analyses indicated the rational ranges of sectional dimensions and material strengths from a probabilistic perspective, and suggestions were accordingly proposed for low‐carbon design alternatives. Overall, the choices of emission factors can change the values of objective functions in the optimization, and therefore, affect the optimized design parameters of reinforced concrete beams.

Development and comparative of a new meta-ensemble machine learning model in predicting construction labor productivity

PurposeThe study is aimed to compare the prediction success of basic machine learning and ensemble machine learning models and accordingly create novel prediction models by combining machine learning models to increase the prediction success in construction labor productivity prediction models.Design/methodology/approachCategorical and numerical data used in prediction models in many studies in the literature for the prediction of construction labor productivity were made ready for analysis by preprocessing. The Python programming language was used to develop machine learning models. As a result of many variation trials, the models were combined and the proposed novel voting and stacking meta-ensemble machine learning models were constituted. Finally, the models were compared to Target and Taylor diagram.FindingsMeta-ensemble models have been developed for labor productivity prediction by combining machine learning models. Voting ensemble by combining et, gbm, xgboost, lightgbm, catboost and mlp models and stacking ensemble by combining et, gbm, xgboost, catboost and mlp models were created and finally the Et model as meta-learner was selected. Considering the prediction success, it has been determined that the voting and stacking meta-ensemble algorithms have higher prediction success than other machine learning algorithms. Model evaluation metrics, namely MAE, MSE, RMSE and R2, were selected to measure the prediction success. For the voting meta-ensemble algorithm, the values of the model evaluation metrics MAE, MSE, RMSE and R2 are 0.0499, 0.0045, 0.0671 and 0.7886, respectively. For the stacking meta-ensemble algorithm, the values of the model evaluation metrics MAE, MSE, RMSE and R2 are 0.0469, 0.0043, 0.0658 and 0.7967, respectively.Research limitations/implicationsThe study shows the comparison between machine learning algorithms and created novel meta-ensemble machine learning algorithms to predict the labor productivity of construction formwork activity. The practitioners and project planners can use this model as reliable and accurate tool for predicting the labor productivity of construction formwork activity prior to construction planning.Originality/valueThe study provides insight into the application of ensemble machine learning algorithms in predicting construction labor productivity. Additionally, novel meta-ensemble algorithms have been used and proposed. Therefore, it is hoped that predicting the labor productivity of construction formwork activity with high accuracy will make a great contribution to construction project management.

Deformation, Bearing Capacity, and Reliability of Building Formwork System Based on Real-Time Monitoring

The deformation performance of aluminum alloy formwork under stress is investigated in this research using static tests. The entire model of aluminum alloy formwork under load during construction is investigated using finite element simulation. And then, there’s the project’s actual value. The function is established during the construction period under the limit state of typical use of the wall in terms of reliability. The fluctuation characteristics of the dependability index of the out-of-plane deformation of the concrete wall are explored, and various results are produced, by taking into account the various reinforcement variables of the aluminum formwork. The study discovered that when the number of uses increases during the turnover usage process, the bearing capacity of the building formwork support gradually decreases, and the associated reliability index falls below 2. Adding horizontal and vertical rods above 3.6 m to the single support system, in combination with other elements, is recommended to strengthen its stability. The results reveal that joint semirigidity and wall thickness have a significant influence on the ultimate bearing capacity of construction formwork. The change characteristics of building formwork ultimate bearing capacity in the process of repeated turnover use are studied by increasing the initial defect method to simulate the increase of building formwork turnover times, with the conclusion that the more repeated use times, the lower the building formwork ultimate bearing capacity.

Modified Formwork System for Slab Element

Abstract: Formwork in construction is the use of support structures and moulds to create structures out of concrete which is poured into the moulds. Formwork can be made using moulds. Out of steel, wood, aluminium and , or prefabricated forms. 2. Formwork refers to either temporary or permanent moulds into which concrete or similar materials are poured. In the context of concrete construction, the falsework supports the shuttering moulds. 3. Formwork is an ancillary construction, used as a mould for a structure. Into this mould, fresh concrete is placed only to harden subsequently. The construction of formwork takes time and involves expenditure up to 20 to 25% of the cost of the structure or even more. The operation of removing the formwork is known as stripping. Stripped formwork can be reused. Reusable forms are known as panel forms and non-usable are called stationary forms. Keywords: Modified Formwork, Slab

Study on Permanent Thermal Insulation Formwork of Mass Concrete Prepared by Different Types of Nano-modified Lightweight Aggregate

Aiming at the problems of low strength, flammability, easy falling off, and aging of traditional organic thermal insulation materials, inorganic thermal insulation materials of different types of nano-modified lightweight aggregates were prepared in this paper. The feasibility of preparing permanent thermal insulation formwork of mass concrete with nano-modified lightweight aggregate was studied through experiments and calculation analysis of mechanical, durability, and thermal properties. The results show that the water absorption of shale ceramsite modified by nano-permeable hydrophobic agent is reduced to 1.21%, and the water absorption rate of inorganic precast hollow aggregate produced by nano-silica powder is lower, which is 0.79%. Inorganic precast hollow aggregate concrete, modified shale ceramsite concrete, and organic foamed aggregate concrete have the characteristics of high strength, fire resistance, aging resistance and low thermal conductivity. Inorganic precast hollow aggregate concrete and modified shale ceramsite concrete have excellent impermeability and frost resistance. Organic foamed aggregate concrete has the lowest thermal conductivity and good thermal insulation effect and its durability can be improved by surface protection technology. According to the principle of equivalent surface heat release coefficient, it is feasible to use lightweight aggregate precast formwork as permanent insulation formwork of mass concrete with thickness between 50 and 100 cm. The permanent thermal insulation formwork of nano-modified lightweight aggregate concrete can also be used as the formwork for concrete construction to realize the temperature control measures of tracking thermal insulation and slow cooling of mass concrete, reduce the risk of cracking, and improve the construction efficiency.

Construction Technology and Analysis of High and Large Formwork for Automobile Ramp

A square project in Hangzhou has the characteristics of high floors, deep foundation pits, large loads, and dense surrounding buildings and various municipal pipelines, which brought great difficulties to the construction, especially the formwork support part. This paper takes the construction of the tall formwork of the automobile ramp as an example to illustrate the design process and construction technology of the tall formwork of the project’s automobile ramp. The rationality of the design of tall formwork was checked by PKPM software. The quality and safety monitoring measures of the construction process are also given.

Understanding the fall-related safety issues in concrete formwork

The construction industry recorded high rates of fatalities and injuries due to falls at the workplace. Among other activities, concrete formwork tends to have more fatal falls. This study aims to understand the fall-related safety issues in the formwork lifecycle of construction projects. To achieve this, the process of formwork activities was mapped, and the safety risks associated with each activity were classified. Method development and risk identification focused on interviews with construction professionals involved in the construction of formwork and site observations of the formwork activities. The overall finding was that pouring, stripping, and erection activities have more issues related to falls. Future research is being carried out to assess the risks of falls from the construction experts’ views to prevent fall accidents in the future.

Analysis of the construction of a reinforced-concrete free-form roof formwork and the development of a unit-construction method

Since the advent of the modernist movement in architecture, organic shapes have attracted designers. Digital fabrication technology and three-dimensional computer-aided design have made the architectural design of free-form shapes much easier. However, the construction of these shapes still has many risks in terms of cost and time management. This study aims to develop a new unit construction method by integrating digital fabrication with the conventional wooden construction technique on a large architectural scale and compare its productivity throughout the construction process to the conventional method. This paper first illustrates the current situation of free-form shape production by surveying a reinforced-concrete roof-construction project using a conventional construction method in Japan. We then develop a new construction method in which curved surfaces are divided into portable units in order to reduce on-site labor and ensure a high degree of accuracy. Finally, we analyze its productivity by conducting some assembly experiments. The new method reduces on-site labor costs by 93% compared with the conventional method.

Concrete density estimation of linac bunker walls using impact-echo testing.

To estimate the concrete density of a newly constructed bunker using impact-echo testing prior to the installation of the linear accelerator. A newly constructed bunker showed visible honeycombing after the removal of the construction formwork. Impact-echo testing, which is based on the propagation and reflection of elastic waves in solids, was applied to confirm the bunker shielding integrity. A mechanical impact on the bunker wall generates a stress pulse, which propagates through the wall and is reflected or refracted by voids or changes in material characteristics such as density. Surface displacements caused by the reflected waves are recorded by a transducer, located near the impact point. The resulting displacement-time curves are analysed in the frequency domain for anomalies. The dominant frequencies are related to the depths from which stress waves are reflected within the structure. If the dynamic elastic modulus and Poisson ratio of the concrete are known, then the measured velocity of the so-called P-wave can be related to the concrete density. Validation measurements on a wall with known concrete density gave an estimate within 3% of the true density. Measured velocities on the honeycombed wall ranged from 3750m/s to 4300m/s, corresponding to densities of 2894kg/m3 and 2201kg/m3 respectively, with the majority of estimated densities ranging from 2307kg/m3 to 2544kg/m3. A radiation survey after the installation of the linear accelerator confirmed adequate shielding. Impact-echo testing presents a viable solution to confirm bunker shielding integrity before the installation of a linac.