Concrete Technology Research Articles

Crack propagation and failure mechanism of 3D printing engineered cementitious composites (3DP-ECC) under bending loads

Engineered cementitious composites (ECC), as a self-reinforcing material featuring the characteristic of multiple cracking and strain hardening, provides a feasible solution to overcome the dependence on steel reinforcement in 3D concrete printing (3DCP). Nevertheless, interlayers in 3D printing ECC (3DP-ECC) create potential paths for crack propagation under bending load, which is expected to result in different failure mechanisms for bent 3DP-ECC. Different from the conventional multiple cracking behaviors of cast ECC, the test results reveal that 3DP-ECC exhibits two new crack propagation modes depending on the interface bond strength. In the first mode, bending cracks deflect into the interlayer, leading to the splitting of two adjacent filaments, while the filaments in the upper part of the interface crack countinue to exhibit multiple cracking behavior and bear loads. In the second mode, the localized shearing cracks became dominant when the interlayer bond strength was excessively low. This study comprehensively discusses the bending performance and failure mechanisms of 3DP-ECC exhibiting different crack propagation modes. The findings are valuable for enhancing the ductility design of 3DP-ECC beam components, ultimately contributing to the improvement of 3D concrete printing technology.

Shrinkage and thermo-mechanical properties of concretes incorporated with different substitutions of natural aggregates by cold bonded calcined attapulgite lightweight aggregates

Calcined attapulgite (CAT), a fibrous calcined clay represents a promising option for advancement as a relatively new cementitious material with strong pozzolanic activity. This study investigates the impact and potential use of CAT in producing cold-bonded lightweight aggregates and their utilization in microsilica (MS) and fly ash (FA) blended concretes by analyzing the shrinkage and thermo-mechanical behavior. Initially, attapulgite rocks were processed including crushing, grinding and calcination to produce pozzolanic material. Following this, a dry powder mix of 80% calcined attapulgite (CAT) and 20% Portland cement (PC) was pelletized into calcined attapulgite lightweight aggregates (CATLWAs) using cold bonding with moisture and cured for 28 days. Subsequently, twelve concrete mixtures were formulated considering different substitutions of normal aggregate with CATLWAs and various proportions of PC, MS and FA. Mechanical properties such as compressive, splitting, and flexural strengths as well as elastic moduli and impact resistance were evaluated. Drying shrinkage, weight loss and thermal conductivity were assessed for all mixtures. Likewise, scanning electron microscopy was employed to analyze microstructural changes. Experimental results indicated that the incorporation of fine and coarse CATLWAs reduced the concrete unit weight by approximately 22% compared to the control mixture. However, there was a declining trend in mechanical properties, especially for impact resistance with increasing CATLWA content. However, the use of binary and ternary blends of cementitious materials improved overall mechanical behavior. Regardless of CATLWA content, the utilization of CATLWA enhanced thermal conductivity up to 46.9%. These findings hold significance for using CATLWAs in sustainable lightweight concrete production, thus advancing lightweight concrete technology and offering valuable insights into their advantages and constraints.

Research on the Influencing Factors and Measurements of Freeze-thawing Resistance of Recycled Concrete

With the introduction of green building, solid waste utilization has become a key research focus in civil engineering. Recycled concrete technology plays a crucial role in the sustainable development of the concrete industry. However, its durability in cold regions remains a pressing challenge for engineers. This paper reviews domestic and international studies to summarize the performance and degradation mechanisms of recycled concrete under freeze-thaw cycles, focusing on four factors: recycled aggregate proportion, freeze-thaw cycle conditions, water-to-cement ratio, and admixtures. Evaluation systems for frost resistance of recycled concrete are also summarized. Finally, improvement measures for enhancing the frost resistance of recycled concrete are proposed, providing a theoretical basis for further research and engineering applications in this field.

Construction method for ecological protection of stone side slopes using composite vegetation concrete

Traditional ecological restoration technology has many challenges in dealing with the greening of steep rock slopes, especially in the case of serious soil erosion. In order to overcome these problems, this study aims to organically combine the traditional protection and reinforcement technology with the new vegetation restoration technology, and put forward a new ecological protection technology of composite vegetation concrete to realize the comprehensive protection and ecological restoration of rocky slopes. In this paper, by analyzing the mechanism and existing problems of ecological protection of rocky slopes, the design requirements of composite vegetation concrete are studied in detail, and the related construction technology is expounded. In the experiment, the vegetation coverage and incidence were systematically analyzed, and the results showed that some samples showed high vegetation coverage and low incidence. Comprehensive consideration shows that the average vegetation coverage rate is 93.7%, and the average incidence rate is only 5.21%, which all meet the corresponding standards. The composite vegetation concrete technology has a wide application prospect in stone slope protection, which significantly improves the slope vegetation coverage and compressive strength, and effectively promotes the slope greening and ecological sustainable development. Through this study, we aim to convey to readers that the comprehensive method of combining traditional and innovative technologies can achieve encouraging results in solving the problem of ecological restoration of steep rock slopes, and provide useful reference for engineering practice in similar environments.

Development of Interactive Learning Media Based on Video Tutorials using the Lectora Inspire and Macromedia Flash Applications in Stone and Concrete Engineering Courses

This research aims to create learning media in the Stone and Concrete Engineering course with the help of the Lectora Inspire and Macromedia Flash applications. The approach carried out in this study uses the R&D method using a 4D development model which includes the defining stage (define), design stage (design), development stage (develop) and trial stage (disseminate). The subjects of the study were civil engineering students enrolled in the Stone and Concrete Engineering course as many as 16 people. Assessment of the feasibility of learning media is carried out by providing validity and practicality questionnaires to media experts, material experts. Data from the questionnaire is then processed to determine the level of validity and practicality of the learning media. The effectiveness of learning media is measured from student learning outcomes using developed learning media. The assessment results from media and material experts for learning media made get an average score of 0.86 in the very valid category. The results of the assessment of the practicality of the learning media made get an average score of 86% in the very practical category. Based on the implementation of the pretest, the average score was 58.25 and the implementation of the posttest or final test obtained the average value was 80.12. There is an increase in student learning outcomes after being given video tutorial-based learning media so that it can be concluded that the level of effectiveness of using this media is very effective. Referring to the assessment of material experts, media experts, tests to students can be declared learning media that are developed suitable for use as learning media.

Analysis of test methods for frost resistance of concrete

Introduction. Frost resistance of concrete is one of the most challenging problems in concrete studies. Particularly important is the issue of methods of testing concrete for frost resistance. The existing standard methods require more detailed regulation of the test process in order to improve the reliability of the results.Aim. To analyze the regulatory procedures of testing concrete for frost resistance with a view to make suggestions for improving standards.Materials and methods. The analysis involved Russian and foreign standards and publications on methods of testing concrete for frost resistance.Results. The authors analyzed the methods of testing concrete for frost resistance, included in Russian and some foreign standards. The quality of determining the frost resistance of concrete can be improved by controlling the temperature while freezing and thawing, in particular, by assessing the temperature in the concrete of the test samples. Controlling the air temperature in the freezer should be recognized as insufficient. The criteria for the state of concrete samples during and after cyclic freezing and thawing should be further verified. It is necessary to continue full-scale testing of concrete under severe climatic conditions, taking into account the real conditions of freezing and thawing of concrete in structures, and comparing the results of laboratory and full-scale tests, including satellite samples.Conclusion. The analysis revealed the necessity to continue the research on clarifying the test methodology and criteria for assessing the state of concrete samples after freezing and thawing cycles. It is advisable to recreate devices for determining the dynamic modulus of elasticity of samples in freeze-thaw testing, to resume long-term full-scale tests of concrete under severe climatic conditions, and to develop a manual for creating frost-resistant concrete, taking into account the current level of concrete technology. Elimination of the existing drawbacks of the methodology will improve the reliability of test results.

The Axial Compression Behavior of Basalt Fiber-Reinforced Recycled Aggregate Concrete-Filled Circular Steel-Tubular Column

Recycled aggregate concrete (RAC) technology has received a lot of attention as a green environmental protection technology. However, the unsatisfactory mechanical behavior of RAC restricts its application in engineering practice. The structure of basalt fiber-recycled aggregate concrete-filled circular steel tubes (C-BFRACFST) can dually improve the mechanical behavior of RAC. To observe the axial compression behavior of the C-BFRACFST column, seven specimens were designed with recycled aggregate replacement ratio (0%, 50%, 100%), basalt fiber (BF) content (0 kg/m3, 2 kg/m3, 4 kg/m3) and length–diameter (L/D, 5, 8, 11) as variable parameters for axial compression tests. The failure mode, load–displacement/strain curve, axial compression deformation, ultimate bearing capacity, energy dissipation, and ductility of specimens have been analyzed. The derived constitutive relation of core basalt fiber-reinforced recycled aggregate concrete (BFRAC) constrained by the circular steel tube and the 3D finite element model of C-BFRACFST column have been established to simulate the whole process of compression. It is observed that instability or shear failure occurs in specimens under axial compression load. When the recycled aggregate replacement ratio was increased from 50% to 100%, the change in the energy-dissipation capacity of the specimens was not significant but the ultimate bearing capacity and displacement ductility coefficient decreased by 3.45% and 8.91%, respectively. When the BF content was increased from 2 kg/m3 to 4kg/m3, the change in the ultimate bearing capacity of specimens was not significant; the energy-dissipation capacity at the later stage of bearing increased, and the displacement ductility coefficient was noted to increase by 13.34%. When the L/D was increased from 8 to 11, the energy-dissipation capacity of specimens was decreased, and the ultimate bearing capacity and displacement ductility coefficient declined by 1.37% and 43.52%, respectively. The finite element simulation results are in agreement with the test results.

Predicting concrete strength through packing density using machine learning models

This study presents an innovative approach to predict concrete compressive strength using particle packing theories through machine learning techniques. The existing challenge in concrete engineering lies in the accurate estimation of concrete strength, a critical factor in construction. The adoption of particle packing theories, which hold great promise for enhancing concrete performance, has been limited due to the complexity and time-consuming nature of the required calculations. An approach encompassing particle packing models (JD Dewar Model, Compressible Packing Model, and Modified Toufar Model) with machine learning is the novelty of the work. These models optimize the packing density of aggregate proportions while minimizing the void ratio, essential for achieving desired compressive strength criteria. To train the model, a comprehensive dataset comprising 479 concrete mixtures, each associated with known compressive strength values relative to packing density, is utilized. A significant advancement in predicting concrete compressive strength is demonstrated by the results. The approach outperforms traditional empirical models, offering precise and reliable predictions based on packing density. Importantly, this innovation eliminates the need for time-consuming and costly trial-and-error procedures in concrete mix design. The strong performance of various models in predicting concrete strength using particle packing theories is underscored by the study, with R^2 values ranging from 0.664 to 0.999. By combining concepts of particle packing theories and machine learning, a more efficient and reliable method for predicting concrete compressive strength is achieved. This innovation has the potential to revolutionize concrete mix design, leading to more durable and cost-effective construction practices.

Potential improvement of clinker sand in the mechanical high temperature and transport properties with GGBS-based prepacked geopolymer composite

In this study, a new generation prepacked geopolymer composite (PGC) material that can meet different needs was obtained by combining geopolymer concrete (GPC) and prepacked aggregate concrete (PAC) technology. In the production of PGC, 5-8 mm quartz aggregates were placed in molds and, geopolymer mortar was injected between these aggregates. Aluminosilicate based blast furnace slag (GBFS) was used as binding in geopolymer mortars; sodium silicate (Na2SiO3) and sodium hydroxide (NaOH) was used as alkali activator. In addition, clinker aggregate in different proportions was used as fine aggregate (0–4 mm) in the production of mortar. Within the scope of the study, the physical, mechanical, permeability and high temperature resistance properties of PGC were investigated. The produced samples were cured at 30 and 60 °C for 6 and 8 hours. Hardened unit weights of PGC vary between 2342 and 2539 kg/m3, and sorptivity values vary between 0 and 0.04 kg/m2.min0.5. While the increase in curing temperature and curing time increases the hardened unit weight values, it decreased permeability values. While the increase of clinker aggregate in the mortar phase does not change the hardened unit weight, it significantly reduced permeability. When the PGC samples are cured at 30 °C, the compressive strengths are 20.38–39.03 MPa; when curing at 60 °C, the compressive strengths are 35.21–57.04 MPa. Flexural strengths, 2.35–6.96 MPa with 30 °C cure, achieved 4.27–9.93 MPa results with 60 °C curing. Increasing the curing time and curing temperature significantly increased the compressive and flexural strengths. The increase in the amount of clinker aggregate added to the mortar phase decreased the strength values. While the compressive strength values of PGC mixtures do not fall below 15 MPa after being exposed to 300 °C high temperature; after the application of 600 °C high temperature, it lost up to 70% of its strength. Increasing the curing time and curing temperature, increased the high temperature resistance. The increase in the amount of clinker aggregate in the mixtures, decreased the strength loss rate.

A mix design method for self-compacting recycled aggregate concrete targeting slump-flow and compressive strength

If waste concrete and excavated engineering soil can be recycled into self-compacting concrete, it could not only alleviate the shortage of natural resources but also realize the sustainable development of self-compacting concrete technology. Therefore, a novel method is proposed for designing self-compacting recycled aggregate concrete (SCRAC) mix. The method is developed by target slump-flow and target compressive strength, avoiding tedious adjustments and laboratory re-testing at the concrete level. The proposed method first determines the contents of natural and recycled coarse aggregate based on the target slump-flow and those of natural and recycled sand are then obtained. Then, the required effective water-cement ratio is calculated based on the target compressive strength. The required admixture content is determined based on the paste rheology. Eleven mixtures designed in this manner were cast and tested. The tested variables included the target slump-flow, target compressive strength, replacement ratio of recycled coarse aggregate (RCA) and recycled sand (RS) from the excavated engineering soil, and coarse aggregate size. The results showed that the proposed method was applicable to SCRAC with a 600–800 mm target slump-flow, 40–60 MPa target compressive strength, 0–100% RCA, 0 and 100% RS, and 5–10, 5–16, and 5–20 mm coarse aggregate sizes. Finally, SCRAC using the RCA and punching residues was successfully fabricated to further verify the feasibility of the proposed method. The proposed method provides design guidance for self-compacting concrete containing RCA and RS obtained from excavated engineering soil.

Feasibility Review of Aerated Materials Application in 3D Concrete Printing.

Recent years have witnessed a growing global interest in 3D concrete printing technology due to its economic and scientific advantages. The application of foamed concrete, renowned for its exceptional thermal and acoustic insulation properties, not only holds economic attractiveness but also aligns seamlessly with the principles of sustainable development. This study explores various solutions related to 3D printing technology in construction, discussing the design, production, and properties of foamed concrete mixtures. The integration of 3D printing and the potential for automating the entire process offers opportunities to boost productivity and reduce construction costs. Furthermore, the utilization of foamed concrete with its commendable insulation properties will enable a reduction in the usage of materials other than concrete (e.g., mineral wool, facade mesh, and polystyrene), significantly facilitating the recycling process during building demolition. This, in turn, will lead to the preservation of nonrenewable natural resources and a decrease in CO2 emissions. Despite the promising results, there have been limited studies focusing on 3D printing with foamed materials, whereas a survey of the existing body of literature indicates a notable absence of endeavors pertaining to the utilization of aerated concrete within the realm of 3D printing, especially geopolymer composites (GP) and hybrid geopolymer composites (HGP). The outcomes delineated in the ensuing discourse are demonstrative for conventionally used materials rather than the additive manufacturing variant. Hence, this work aims to systematically review existing practices and techniques related to producing foamed concrete with 3D printing technology. This analysis also contributes to the establishment of a foundational framework and furnishes a preliminary basis upon which future endeavors aimed at the 3D printing of aerated concrete can be embarked. The findings from the literature analysis justify the desirability of continuing research on this topic, particularly when considering the potential for large-scale industrial implementation. This article provides a comprehensive state of the knowledge on the development of 3D printing techniques for foamed concrete mixtures. By consolidating and analyzing findings from different studies, this article offers insights into the advancements, challenges, and potential applications of foamed concrete in additive manufacturing processes. This, in turn, contributes to the overall understanding and advancement of 3D printing technologies using foamed concrete as a versatile and sustainable construction material. The encouraging results obtained from the analysis further underscore the need for the continued exploration of 3D printing, especially with an eye towards its industrial-scale implementation.

Modeling of AAC composition without autoclaving proces

AbstractAutoclaved aerated concrete (AAC) technology is undergoing continuous development. This development has so far consisted mainly of expanding the palette of raw materials and preparing them accordingly. The breakthrough in AAC technology came as a result of the introduction of automatic control of production processes. The introduction of automation has made it much easier to maintain a proper autoclaving cycle. It allowed precise regulation of temperature rises in the initial phase of thermal processing. More favorable conditions made it possible to produce lightweight varieties of AAC while maintaining adequate strength of building components. For manufacturers, not only the performance characteristics are important, but also the cost of AAC production, especially the price of the binding material: cement and lime, and the energy‐intensive process of autoclaving. Reducing the cost of manufacturing autoclaved aerated concrete can be achieved by using pozzolanic mineral additives. The article presents research of the structure of AAC obtained using geopolymers. This allows both the modification of the raw material composition and the course of the autoclaving process.

Chemical prestressing of concrete structures; state of the art review

AbstractChemical prestressing was developed during the 1960s; however, and due to technical difficulties at that time, the technology was not considered as an alternative to conventional prestressing; instead, it was only used as a shrinkage compensating method. Still, recent development in concrete technology encouraged several researchers to revisit this technology, where significant achievements were made. This paper aims to present a state‐of‐the‐art review about the recent development in the chemical prestressing technology. This includes reviewing existing field applications, existing types of expansive additives, influence of different expansive additives, influence of curing methods, mix proportioning, mechanical properties, and structural behavior. Furthermore, a thorough discussion was performed and suggestions were made for future researchers to help further contribute to the development of this prestressing technology. It was concluded that although the chemical prestressing technology seems very promising, more research is required before using it in practical applications.

Thermal insulation performance of green concrete using bio and industrial wastes: An experimental approach

The research concentrates on improving the thermal conductivity of green concrete. Cement is a high thermal conductivity material, so the aim of the research is to reduce the amount of cement for the concrete production. The aluminum dust is having low thermal conductivity based on earlier studies as well as it was proved in this research. The Portland cement has been replaced by fine aluminum dust with 5 % interval and is to be determined the optimum mix proportion. Another problem is that structural strength is lost due to improper water curing, so Calotropis gigantea milk was added to concrete to improve the curing properties. Calatropis gigantea acts as bio self-curing agent of concrete which can treat on its own without external curing without compromising its strength and durability. The dosage of Calatropis gigantea milk is taken in different percentage of cement weights, like 0.1%, 0.2%, 0.3%, 0.4% and 0.5%. The tests found in the research are workability, compressive strength, and thermal conductivity for green concrete and conventional concrete then which are compared between them. The green self-curing concrete technology can be recommended for tall structures, remote constructions, and energy saving buildings.

Computational Complexity and Its Influence on Predictive Capabilities of Machine Learning Models for Concrete Mix Design.

The design of concrete mixtures is crucial in concrete technology, aiming to produce concrete that meets specific quality and performance criteria. Modern standards require not only strength but also eco-friendliness and production efficiency. Based on the Three Equation Method, conventional mix design methods involve analytical and laboratory procedures but are insufficient for contemporary concrete technology, leading to overengineering and difficulty predicting concrete properties. Machine learning-based methods offer a solution, as they have proven effective in predicting concrete compressive strength for concrete mix design. This paper scrutinises the association between the computational complexity of machine learning models and their proficiency in predicting the compressive strength of concrete. This study evaluates five deep neural network models of varying computational complexity in three series. Each model is trained and tested in three series with a vast database of concrete mix recipes and associated destructive tests. The findings suggest a positive correlation between increased computational complexity and the model's predictive ability. This correlation is evidenced by an increment in the coefficient of determination (R2) and a decrease in error metrics (mean squared error, Minkowski error, normalized squared error, root mean squared error, and sum squared error) as the complexity of the model increases. The research findings provide valuable insights for increasing the performance of concrete technical feature prediction models while acknowledging this study's limitations and suggesting potential future research directions. This research paves the way for further refinement of AI-driven methods in concrete mix design, enhancing the efficiency and precision of the concrete mix design process.

Various Methods of Strengthening Reinforced Concrete Beam-Column Joint Subjected Earthquake-Type Loading Using Fibre-Reinforced Polymers: A Critical Review

Fibre-reinforced polymer (FRP) composites are extensively employed in concrete technology due to their exceptional mechanical strength and durability. They serve a dual purpose, not only reinforcing damaged elements but also supporting heavier service loads and addressing long-term concerns in new infrastructure projects. Consequently, the objective of this review is to establish a comprehensive research database that focuses on evaluating the strengthening behaviour of reinforced concrete (RC) beam-column joints (BCJ) under earthquake loads through diverse types and application methods of FRP composites. The efficacy of these strengthening techniques is assessed by considering factors such as the loading capacity and dissipated energy of RC BCJ versus the joint confinement index provided by the fibre in the joint area. Through this state-of-the-art review, it becomes evident that FRP composites effectively enhanced the normalized load of specimens up to 27 kN/?MPa and enhanced the dissipated energy until 558.6 kN-mm for the case of specimens with a lower confinement index, less than 0.3. Additionally, the specimen strengthened with the deep embedment (DE) method resulted in a moderate normalized load and dissipated energy compared to those strengthened with the external bonded (EB) method. The test results indicated that the average normalized load and dissipated energy of the DE-strengthening method was 93% and 28.5% compared to that of the EB-strengthening method. These findings reveal that FRP composites offer distinct advantages in terms of load capacity and dissipated energy when used for strengthening earthquake-affected RC BCJ. Finally, based on the compilation of the previous works, this research proposes several techniques for utilizing FRP composites to enhance RC BCJ subjected to earthquake load.

Exploring Totalitarian Elements of Artificial Intelligence in Higher Education With Hannah Arendt

From the perspective of political philosophy, this article examines the extent to which artificial intelligence (AI) applications in higher education contain totalitarian elements. Drawing on the theoretical considerations of Hannah Arendt, the author first identifies the key characteristics of total domination and then relates these to two AI applications in the field of higher education: adaptive learning systems and AI-based text generators. On this basis, the article elaborates on the similarities between concrete AI technologies and totalitarian structures. Finally, the author formulates questions that can be used to examine if concrete AI applications exhibit totalitarian traits. The aim of this theoretical contribution is to provide a perspective that will help to identify new dangers of AI or to see already known dangers in a new light, leading to a deeper and broader discourse on the consequences of AI.

Fast-Setting Concrete for Repairing Cement Concrete Pavement.

The paper presents the results of laboratory tests and the complete results of the implementation of the Sprint fast-setting concrete technology used during the reinstallation of the concrete pavement of the DK50 road (the Młodzieszyn bypass). The problem of concrete pavement repair is related to economic and social costs and, above all, to long repair time. After an extensive analysis of various technologies, the authors created a dedicated solution, which, based on commonly existing materials, allows for a very quick repair of the existing pavement. The obtained properties of the fast-setting concrete allow the maintenance of rheological parameters for 2 h from its production and to install the mixture of the consistency of class S3/S4, while the obtained compressive strength exceeds 25 MPa within 6 h of installation. The concrete parameters obtained after 24 h show a strength exceeding 40 MPa, and after 28 days-exceeding 60 MPa. The tensile strength at shattering exceeds 5 MPa, while the tensile strength at flexural strength exceeds 7 MPa. In addition, all parameters of the fast-setting concrete meet the highest requirements currently set for newly built concrete pavement loaded by very heavy traffic. The most important parameter is the possibility to shorten the repair time of concrete pavement to one day, significantly reducing the social costs associated with closing a single lane or the entire road. An important element of the presented technology is the possibility of producing the mixture at a stationary concrete batching plant, and in the future-with the use of bags for patching potholes in road pavement.

Investigation of Uniaxial Compression Stress–Strain Relationship of Early Age Manufactured Sand Concrete and Its Application

To improve the construction efficiency of the manufactured sand concrete engineering at an early age, the uniaxial compressive stress–strain relationship of C50 manufactured sand concrete is investigated starting at 2 days to 28 days. With the characteristics of the stress–strain relationship, the uniaxial compression constitutive model is determined for the C50 manufactured sand concrete at early age. The influence of age, water-to-binder ratio, and fly ash admixture on the peak stress and peak strain of manufactured sand concrete is analyzed for the parameters of the constitutive model. Results show that the stress–strain curve of manufactured sand concrete is essentially similar to that of ordinary concrete. Via six typical constitutive models, the Sargin model produced the best fitting: its R2 mean is 0.9775, MAE mean is 0.1335, and MSE mean is 0.0175. Considering the influence of different factors, the early age uniaxial compressive constitutive models of manufactured sand concrete were proposed based on the Sargin model. Combined with the on-site construction process of the high pier formwork climb, the finite element analysis was carried out using the proposed early age uniaxial compressive constitutive model. Compared with the measured results of strain near the climbing cone, the error was less than 10% from the simulated value. The findings confirm that the proposed early age uniaxial compressive constitutive model presents great reasonableness for the manufactured sand concrete construction at an early age.

Optimized aggregate height measurement by laser with nonlinear fitting

The measurement of shape parameters of coarse aggregate is the premise to ensure the quality of concrete engineering. In the measurement of particle shape based on laser triangulation method, the selection of polynomial fitting parameters between different test scene displacement and image offset is often different. For coarse aggregate height measurement, an optimal laser triangulation method is proposed, and the best polynomial fitting times of aggregate measurement is obtained through data extraction and error analysis. Firstly, the laser streak information is collected from the aggregate surface based on the industrial camera, and the laser streak is processed by Gaussian filtering and color space transformation, and then the center line of the laser streak is obtained by the center method to obtain the corresponding aggregate height information. Finally, based on the comparison between the experimental measurements and the height values calculated by different polynomial fits, the laser triangulation solution method is optimized by different error factors analysis. The experimental results show that in the process of aggregate height measurement, the cubic term fitting solution is optimal with an average relative error of only 0.693%.