Cracking Of Mass Concrete Research Articles

Temperature damage assessment of mass concrete based on the coupling mechanism of hydration-temperature-humidity-constraint factors

Temperature cracking of mass concrete is an important issue affecting the safety of concrete foundations in civil engineering. This problem extends from the construction process of concrete foundations to the operation stage. This study uses low-temperature-rising (LTR) polymers to regulate the hydration process of cementitious materials, and prepares LTR mass concrete. Taking the hydration degree of concrete-cement system as the basic state variable, the multi-factor effects of actual hydration process, temperature, humidity changes, and constraints on mass concrete are comprehensively considered. A concrete temperature-damage model based on the coupling mechanism of “hydration-temperature-humidity-constraints” is established, and the temperature, stress, and temperature damage evolution laws of LTR mass concrete and ordinary mass concrete are calculated. The reliability of the model is verified through field tests. The results show that the finite element method can effectively simulate the development of concrete temperature, stress, and damage degree based on actual working conditions under multi-factor coupling.

Early-age cracking in mass concrete: Modeling and case study of an extra-large exhibition pool

Early-age cracking is one of the most common and challenging problems in the construction of mass concrete structures. This paper addresses the effects of factors such as temperature, hydration, creep, and shrinkage on the time-varying properties of concrete during construction by establishing an energy-based constitutive model for early-age concrete within the framework of continuous damage mechanics. The model comprehensively describes the damage of concrete due to the aging effect related to the degree of hydration, where the mechanical damage is driven by the work conjugated to the elastoplastic damage energy release rates. The thermal evolution during hydration is fitted with a large amount of experimental data, enabling the partial decoupling of multi-factor effects and facilitating the establishment of a sequential thermal-mechanical coupling analysis method. After preliminary verification through restrained ring cracking tests, the proposed model and method are applied to simulate the construction of an actual large-scale Orcinus orca exhibition pool. By predicting and analyzing the worst-case scenarios, the cracking risk, potential cracking mode, and cracking location of the large pool are determined, providing an important basis for practical construction control and optimization. Examples of these strategies include segmented schemes, reinforcement optimization, and the addition of tensile fibers, as well as selecting the best wind speed, environmental temperature, and casting temperature during construction. These efforts provided crucial guidance for the actual construction of the exhibition pool, and as a result, no visible cracks were found in the completed structure.

Prevention And Control of Mass Concrete Cracks in Building Construction Engineering

As a kind of building material, mass concrete plays an important role in building construction. It is widely used in engineering projects and needs to be controlled in many aspects, otherwise cracks may appear and affect the safety and performance of the project. In this paper, the crack problems of mass concrete structures are studied and analyzed, such as cracks caused by mix ratio, temperature change, foundation deformation. Firstly, by understanding the internal and external causes of cracks in mass concrete, the key issues were suggested. Then, the method to prevent and control the crack of mass concrete is put forward from the selection of reasonable raw materials and mix ratio, pouring method, temperature control and other aspects. The research results can be used as reference to reduce the negative impact of cracks in building construction engineering. While improving the safety and service life of housing construction projects, it also improves the economic value and reduces the time cost of rework.

Effect of Working Temperature Conditions on the Autogenous Deformation of High-Performance Concrete Mixed with MgO Expansive Agent.

Currently, mass concrete is increasingly utilized in various engineering projects that demand high physical properties of concrete. The water-cement ratio of mass concrete is comparatively smaller than that of the concrete used in dam engineering. However, the occurrence of severe cracking in mass concrete has been reported in numerous engineering applications. To address this issue, the incorporation of MgO expansive agent (MEA) in concrete has been widely recognized as an effective method to prevent mass concrete from cracking. In this research, three distinct temperature conditions were established based on the temperature elevation of mass concrete in practical engineering scenarios. To replicate the temperature increase under operational conditions, a device was fabricated that employed a stainless-steel barrel as the container for concrete, which was enveloped with insulation cotton for thermal insulation purposes. Three different MEA dosages were used during the pouring of concrete, and sine strain gauges were placed within the concrete to gauge the resulting strain. The hydration level of MEA was studied using thermogravimetric analysis (TG) to calculate the degree of hydration. The findings demonstrate that temperature has a significant impact on the performance of MEA; a higher temperature results in more complete hydration of MEA. The design of the three temperature conditions revealed that when the peak temperature exceeded 60 °C in two cases, the addition of 6% MEA was sufficient to fully compensate for the early shrinkage of concrete. Moreover, in instances where the peak temperature exceeded 60 °C, the impact of temperature on accelerating MEA hydration was more noticeable.

Preparation of Butyl Acrylate Copolymer Emulsion and Its Regulation Effect on Cement Hydration

Due to its large volume and poor thermal conductivity, mass concrete is prone to temperature cracking caused by heat release during cement hydration after pouring. To address the issue of temperature cracking in mass concrete, this study utilized emulsion polymerization to prepare polybutyl acrylate (PBA) emulsions. At an optimal dosage of 1.5%, the addition of a PBA emulsion reduced the temperature rise of cement paste by 12.4%. The inhibitory mechanism of a PBA emulsion on cement hydration was analyzed by characterization techniques such as isothermal calorimetry, X-ray diffraction Rietveld full-profile fitting method (XRD), thermogravimetric-differential scanning calorimetry (TG-DSC), and mercury intrusion porosimetry (MIP). The results showed that the C3S content in the cement specimens with 1%, 1.5%, and 2% PBA increased by 13.83%, 23.52%, and 34.65% compared to the blank group, respectively, while the C3A content increased by 92.59%, 79.63%, and 96.30%, respectively. The addition of a PBA emulsion can slow down the hydration rate of C3S and C3A, thereby reducing the temperature rise and fall rate of cement hydration, reducing the peak heat release of the hydration reaction, and ultimately achieving the inhibition of the cement hydration reaction. In addition, the mechanical properties of PBA-modified cement-based materials were also tested. The results show that the addition of PBA can affect the early strength development of cement samples, but has no effect on the strength after 60 days. Therefore, PBA can be used as a hydration temperature rise control material to reduce the risk of temperature cracking in mass concrete.

Investigating thermal cracking in mass concrete of a bridge abutment: field measurements and numerical modelling

ABSTRACT Concrete is the most extensively used construction material in the world due to its widespread availability and ease of placement. However, the hydration process after concrete placement generates a significant amount of heat. For beams, columns, and slabs that have a large surface area-to-volume ratio, this heat dissipates easily through the surface. However, for dams, raft foundations, and bridge abutments, heat dissipation is slow due to the small surface area-to-volume ratio. Such units are identified as ‘Mass concrete’ and require special consideration for managing this heat generation and thermal behaviour to avoid thermal cracking. This article presents a case study where cracking was observed during the construction of a highway bridge abutment in Oman. The study discusses forensic measurements and uses numerical modelling to investigate and identify the cause of cracking. The numerical model used showed good agreement with the field measurements and revealed that the cracking occurred due to a thermal shock caused by the early exposure of the mass concrete surface to low ambient temperature. The study also proposes measures to control and minimise thermal cracking in arid regions like Oman.

Cracks Analysis and Control Measures of Mass Concrete

Based on the cracking causes of a raft foundation in a project, this paper expounds the common types of mass concrete cracks and their causes. The effects of raw materials, admixtures, etc. on temperature cracks of mass concrete are mainly discussed, and the mutual effects need to be considered when using composite admixtures.The prevention measures of mass concrete temperature cracks are expounded from the perspectives of raw material selection, construction organization design, etc.

Cracks Analysis and Control Measures of Mass Concrete

Based on the cracking causes of a raft foundation in a project, this paper expounds the common types of mass concrete cracks and their causes. The effects of raw materials, admixtures, etc. on temperature cracks of mass concrete are mainly discussed, and the mutual effects need to be considered when using composite admixtures.The prevention measures of mass concrete temperature cracks are expounded from the perspectives of raw material selection, construction organization design, etc.

Field test study on early strain development law of mass concrete in cold weather

The early cracking of mass concrete in low temperature environment has always been a hot issue in the industry. The exploration of the development law of temperature and strain of mass concrete in low temperature environment is conducive to prevent its early cracking. Strain gauges are embedded in the upper, middle, and lower layers of the four measuring points of mass concrete on site to obtain the development data of early temperature and strain. Then analyze these data and reveal their internal laws. The following conclusions are drawn: (1) During the 0–30 h of concrete curing monitoring, the temperature in the middle layer of concrete is the highest, followed by the temperature in the upper layer, while in the subsequent monitoring period, a cooling gradient is formed from the lower layer to the upper layer. (2) The maximum compressive strain of concrete mainly occurs in the middle layer, and the maximum temperature and maximum compressive strain of concrete are positively correlated with its thickness. The ratio value of temperature difference between inside and outside of concrete and its thickness is the key factor affecting its external tensile strain. The strain of concrete decreases with the decrease of temperature and the development of strength, and finally tends to be stable. (3) The thickness of concrete has a significant effect on the complexity of the early strain development curve, but it does not affect the time when the strain development tends to be stable. (4) The decisive factor affecting the spatial correlation of concrete strain development is not its thickness and temperature, but the specific factors need to be further discussed.

Multi-level modeling of thermal behavior of phase change material incorporated lightweight aggregate and concrete

An image-based multi-level modeling method is proposed to estimate the effective bulk thermal conductivity of lightweight aggregate (LWA) impregnated with phase change material (PCM). The pore structure heterogeneity of the LWA and the uneven distribution of the PCM are considered by the model. The microstructure of the LWA is represented at two length scales (micro-level and macro-level), which are analyzed individually using imaging techniques. The reconstruction process is conducted on two-dimensional images to obtain three-dimensional digital representative volume element of the LWA, upon which multi-level numerical modeling of heat conduction is performed to estimate the effective bulk thermal conductivity of the PCM-LWA. The computed thermal conductivity of 0.34 W/(m∙K) is closed to experimental result and compared with estimates based on five traditional analytical methods for the sake of superiority analysis. Finally, the simulated thermal conductivity is used in a concrete level simulation to show its feasibility for modeling the thermal behaviors of PCM-LWA-incorporated concrete mixtures, in which PCM are employed to mitigate the hydration heat and prevent thermal cracking in mass concrete. The scale-up simulation manifests that the PCM-LWA not only reduced the peak temperature in the concrete by 3.18 °C but also changed the temperature distribution and gradient pattern inside the concrete.

A Mathematical Model of the Expansion Evolution of Magnesium Oxide in Mass Concrete Based on Hydration Characteristics.

The low swelling property of magnesium oxide concrete is a significant feature that can be used to control the cracking of mass concrete. Based on the characteristics of the chemical reaction, this work proposes a coupled hydro-thermo-mechanical model that can be implemented with the finite element method for predicting the autogenous volumetric deformation of magnesium concrete. By introducing the degree of the hydration reaction of magnesia and the degree of the hydration reaction of cementitious materials as intermediate variables of the chemical reaction system, a prediction model of the concrete temperature and chemical fields is established, and using this model, the effect of the temperature on the reaction rate can be considered in real time. In addition, by combining the relationship between the degree of the hydration reaction of magnesium oxide and the comprehensive expansion of concrete, a mathematical model for calculating the expansion stress of magnesia concrete was established. The algorithms were derived by mathematical equations, and the simulation results were compared to the experimental temperature and autogenous volumetric strain curves, which showed that the hydration model provides a relatively high accuracy. The model was also applied to an arch dam, and the coupled thermo-chemical-mechanical responses of mass concrete during construction were investigated. Simulation results show that the increase in temperature (hydration of cementitious material) and expansion volumetric deformation (hydration of MgO) of the concrete on the upstream and downstream surfaces lags obviously behind that of the inner regions. Quantitative analysis for differences of internal and external expansion is worthy of further attention and study on a basis of further experimental data as well as monitored data.

Present status and issues of control technology for cracking of mass concrete in Japan

This paper presents the current state of the control technology for cracks caused by heat generation due to the hydration of cement during construction in Japan. For the prediction analysis for thermal cracking of mass concrete, this paper presents the CP method that was developed for the first time in the world, the thermal cracking probability, the simple evaluation method that can predict and estimate the thermal cracking without performing complicated analysis and the evaluation method for expansive materials using the mechanical energy conservation hypothesis. In addition, issues are introduced for the next revision of the guidelines.

Measures for Thermal Cracking in Mass Concrete in the Umekita (Osaka) Underground Station

JR東海道線支線地下化・新駅設置事業では，JR大阪駅北エリアの西端を走行するJR東海道線支線のうち約2.4 kmを大阪駅側に移設・地下化し，新駅を設置する。地下水位はG.L.－2.0mと高く，鉄道地下化区間において施工するRC構造物の大部分が地下水位よりも低いため，温度ひび割れの発生が漏水に直結する。温度ひび割れに対して有効な対策の一つに，低熱セメントの適用が挙げられるが，新駅区間付近の2層6径間のボックスカルバート構造をはじめとした全ての大断面のマスコンクリートに適用するのではなく，適切な低熱セメント量で十分なひび割れ対策効果を得る手法について検討することとした。本稿では，その検討の経緯と実施の結果について報告する。

Application of hydration heat inhibitor in crack control of mass concrete of tunnel side wall

The structural deformation caused by temperature change is the main reason for cracking of mass concrete. In order to avoid or reduce the crack of the side wall of cast-in-place mass concrete in tunnel, the effects of different dosage of hydration heat inhibitor on the internal temperature rise curve of concrete, strength and the properties of the mixture are analyzed through experimental research, and the optimal dosage of 1% of cementing material is finally determined. The engineering application results show that after adding hydration heat inhibitor to the tunnel side wall concrete, the maximum temperature rise in the tunnel side wall is obviously reduced, and the arrival time of the temperature peak is delayed. No cracks appear in the tunnel side wall, and the crack control effect is good.

Research on Anti-Crack Design of Super-Long Concrete Structure

There are many reasons for cracks at super-long concrete, which may be due to factors such as tensile stress and temperature shrinkage. Combined with the existing research and in-depth analysis from multiple angles, the causes of mass concrete cracks and the design method of temperature post-casting zone are described. Finally, related technical suggestions and supplementary measures were also put forward. At present, the anti-crack design of super-long concrete structures is mainly based on experience. Structural measures are used. The comprehensive effect lacks check and review. Even if the maximum crack width is checked, the load effect of concrete forming and cool shrinkage is basically not combined. For different requirements, an appropriate crack controlled standard is selected, and the maximum crack width limit of concrete specifications is generally used as the upper limit.

The problem of temperature cracking in concrete gravity dams

Introduction. The concreting of solid structures, such as concrete dams, bridge constructions, foundations of buildings and structures, is accompanied by exothermic heating, caused by cement hydration. Heat, emitted by mass concrete blocks, slowly leaves constructions. A substantial temperature difference frequently arises between the solid concrete centre and its surface. If this temperature difference reaches a critical value, thermal cracking occurs, which destroys structural continuity. Temperature problems and those associated with thermal stress state should be resolved to pre-assess and prevent potential cracking. This problem has enjoyed the attention of specialists, and it has been the subject of numerous research projects. Materials and methods. The overview is based on the information about implemented research projects focused on the thermal cracking of mass concrete dams and its prevention. Computer modeling techniques were applied to develop a mathematical model capable of projecting and assessing the potential cracking of mass concrete. Results. The co-authors have compiled an overview of advanced approaches to the assessment of potential thermal crack formation, contemporary problem-solving methods and selected research findings obtained using the finite element method. The co-authors offer a thermal behaviour/thermal stress state projection methodology for solid concrete, as well as a thermal crack formation assessment methodology. Conclusions. The thermal cracking problem has not been solved yet. The proposed methodology and a projection-oriented numerical model can be used as a reference by civil engineers in the process of designing and constructing concrete gravity dams. It may help to reduce cracking probability caused by heat evolution in cement.

Special Issue: Interdisciplinary approaches for cement-based materials and structural concrete

Preface This special issue of the Journal of Advanced Concrete Technology presents seven invited journal papers, which were selected on basis of outstanding conference contributions during the International RILEM/COST conference SynerCrete’18, held on 24-26 October 2018 in Funchal, Madeira Island, Portugal, which gathered 183 participants. The selection was made by the scientific committee and the chairpersons among 184 contributions. The conference itself dealt with interdisciplinary approaches for cement-based materials and structural concrete, intending to provide added value through collaborations across the entire field of structural concrete – ranging from concrete technology, over simulation and structural design, production and building, up to operation, monitoring and maintenance. Exciting fields of research such as performance-based design, 3D modelling for analysis/design, Building Information Modelling and even robotics (e.g. digital fabrication or robotics design) were included, while retaining focus on multi-scale approaches at time and spatial levels. Overall, the hereby promoted journal papers are representative for the successful balance act between a great versatility of the conference contributions and the targeted synergizing of expertise aiming on the ultimate goal of reliable and durable concrete structures. SynerCrete’18 also marked the end of COST Action TU1404 “Towards the next generation of standards for service life of cement-based materials and structures” (www.tu1404.eu), offering a final forum to the discussions raised during the funded period of the Action from 2014 to 2018. A sense of accomplishment was felt by all the members of the Action, in the view of the important achievements of networking tools that were brought about by the extended Round Robin Testing Programme (RRT+), the Numerical Benchmarking Activities and 24 Short Term Scientific Missions (STSMs). Some of the selected papers in this special issue are the result of fruitful collaborations initiated by COST Action TU1404. A further remark in regard to the wide international institutional support that this conference attained, is about the direct support of RILEM, fib, JCI and ACI. Specifically, with regard to the Japanese Concrete Institute, a mention is given to the special session dedicated to the most recent version of “JCI Guidelines for Control of Cracking of Mass Concrete”, as it was indeed one of the most inspiring documents that influenced the genesis of COST Action TU1404.

Finite element simulation of prevention thermal cracking in mass concrete

The mass concrete structures play a very important role in civil engineering. The cracking of concrete is regarded as one of the biggest engineering problems. Therefore, it is very necessary for the cracking of mass concrete to do the control analysis. Some factors should be considered in mass concrete crack control analysis, mainly including the heat releases model of concrete, the mechanical model to the concrete, the process of temperature control in the pipe model. Differential evolution algorithm and equivalent algorithm are adopted to solve the coefficient of adiabatic temperature and cool water effect. In the paper, stress field calculation, back analysis calculations, and cooling pipe processing create secondary development based on the ABAQUS software platform. The second development of the code is used to reasonably solve the problem with one actual aqueduct in hydraulic engineering.

Finite element simulation of prevention thermal cracking in mass concrete

Finite element simulation of prevention thermal cracking in mass concrete

JCI-RILEM International Workshop on “Control of Cracking of Mass Concrete and Related Issues concerning Early Age Cracking of Concrete Structures”─CONCRACK 5─実施報告

JCI-RILEM International Workshop on “Control of Cracking of Mass Concrete and Related Issues concerning Early Age Cracking of Concrete Structures”─CONCRACK 5─実施報告