Concrete Test Research Articles

Perbandingan Kapasitas Kolom Beton Bertulang Berdasarkan Variasi Bentuk Sengkang dengan Analisis Finite Element Method

Columns are one of the structural elements that greatly influence the behaviour of the structure. Columns are capable of holding axial compression loads and transmitting them to the structural elements below. Column capacity can be increased by the confinement of lateral reinforcement/stirrup. The stirrups function to maintain the compressive strength capacity of the concrete column before and after spalling. Advances in software technology have had a very significant impact on the development of structural element analysis methods, including software based on the Finite Element Method (FEM), Abaqus/CAE Student Edition. It can also simplify several laboratory research of Civil Engineering into a simulation. However, in simulation practice, parameters in the form of material data are needed as input. To get the same behaviour between the test object and the simulation, convergent parameters are needed. The parameters to be analyzed are CDP (Concrete Damage Plasticity) plastic parameters. While the simulation for loading, shape of the test object, and placement refers to the results of previous studies. The reinforced concrete column test model used consists of 5 (five) different variations of stirrups. The results of the simulation show that reinforced concrete columns with stirrups provide support in the form of shear force capacity that can maintain the value of the axial compressive strength capacity. From the five existing test models, it was obtained that the increase in the value of the axial compressive strength capacity of the column due to the variation of stirrups for column B, column C, column D, and column E to column A (without stirrups) were 115%, 120%, 121%, and 119% consecutively. The output values from the analysis include the diagrams of axial force and displacement, column interaction diagrams, and material stress-strain diagrams

Mechanical performances of thin-walled high-strength concrete-filled steel tube square columns with high-strength reinforced cages under biaxial eccentric compression

In the current research that both steel tube and concrete use high-strength materials, there are few studies on the small wall thickness of steel tube exceeding the standard. In order to make full use of the mechanical properties of high-strength steel and enhance its restraint ability on concrete, this paper designs a steel cage dominated by transverse steel bars. A total of 15 square high-strength steel tube high-strength concrete medium-long column test pieces are tested and studied. The main parameters of the specimens are slenderness ratio, loading eccentricity and the form of internal steel reinforcement cage. After the loading test, according to the test results, the failure mode of the specimen is obtained and the mechanical properties of middle-long concrete-filled steel tubular columns are analyzed. The research results show that the ultra-thin high-strength steel pipe can restrain concrete well, but with the increase of eccentricity, its restraint capacity is slightly insufficient; the built-in steel cage can slow down the bulging of the specimen and help the steel pipe to further strengthen the restraint on concrete, but the steel cage as an indirect constraint cannot avoid the final bulging damage. Due to the existing formula overestimating the effect of ultra-thin steel tubes, this paper proposes a calculation formula for the axial compression of thin-walled high-strength concrete-filled steel tubes with steel cage short columns. Based on this method, the bearing capacity of medium-long columns under biaxial eccentric compression is calculated with good accuracy.

Mechanical properties and energy evolution of drilling shaft lining concrete under hydro-mechanical coupling

As the drilling shafts in the western mines of China are going to cross the deep water-rich and weakly cemented rock layer, investigating the mechanical properties and energy evolution of shaft lining concrete within the context of hydro-mechanical coupling is crucial. In this study, concrete compression tests were conducted using the TAW-2000 rock testing machine. The concrete damage and rupture mechanisms were analyzed using a combination of mercury intrusion porosimetry and scanning electron microscopy. Moreover, a thorough investigation of the energy evolution throughout the concrete stress-strain process was conducted. The key results include the following: (1) The formulation of the normalized decay equation for the characteristic strength of concrete under hydraulic coupling was derived by computing the ratio of pore water pressure to confining pressure as the characteristic parameter. (2) The effective shear strength reduction factor characterizing the impact of water pressure on the effective shear stress with a correlation coefficient greater than 0.999. (3) The pore water pressure adversely affected the pore size distribution within the concrete, enhancing the connectivity between pores. (4) The total input energy, elastic energy, and dissipated energy were positively related to the confining pressure and negatively related to the pore water pressure. The energy consumption ratio served as a tentative criterion for assessing the strength failure of the shaft lining concrete, which is considered to be in a critically stable state when the energy consumption ratio is 1. These results provided valuable insights into the damage laws and energy-driven mechanisms of shaft-lining concrete under hydraulic coupling conditions.

Micromechanical modeling and experimental study of the flexural properties of impregnated woven textile-reinforced concrete

As a high-performance composite material in construction, textile-reinforced concrete has been of interest in recent years. This study significantly contributes to the characterization of textile-reinforced concrete through an extensive experimental and analytical investigation, focusing on impregnated textile-reinforced concrete under flexural loading. For this purpose, two sets of experiments were conducted. The first set involved model input parameters tests, including the tensile test of epoxy resin and E-glass yarn, as well as the compression and flexural tests of concrete. The second set is related to validation tests, specifically focused on the flexural behavior of textile-reinforced concrete. Micromechanical frameworks were employed to model the flexural behavior of textile-reinforced concrete and a multiscale micromechanical model based on the classical lamination theory was developed to predict the load-deflection diagram of textile-reinforced concrete in the three-point bending test setup. The modeling results demonstrated a remarkable agreement between predictions and experimental data. Key performance indicators, including the first crack force, ultimate force, flexural modulus, and maximum deflection, were accurately predicted with errors of 2.4%, 6.1%, 11.1%, and 6.3%, respectively. Furthermore, from a parametric study, it is perceived that the flexural modulus of elasticity in textile-reinforced concrete is predominantly influenced by concrete properties, while the ultimate strength of textile-reinforced concrete is significantly affected by the properties of the impregnated fabric.

Strain rate effect of concrete based on split Hopkinson pressure bar (SHPB) test

Concrete is a strain rate sensitive material, which is widely used in protective structures, and its strain rate effect needs to be considered. This study aims to obtain the real strain rate effect of concrete material. Firstly, the dynamic compression test of concrete was carried out by using split Hopkinson pressure bar (SHPB). The classical Holmquist-Johnson-Cook (HJC) model of concrete is modified based on the test results and the test data of the static performance of concrete. Then the finite element model is established. The numerical simulation results and theoretical analysis show that the inertia effect leads to the error between the test value and the simulation value. To eliminate the influence of inertia effect, this study embeds the inertia effect term into the constitutive model for secondary modification. According to the results of numerical analysis, the specific form of this term and its related parameters are determined. The modified constitutive model can better predict the test results and reproduce the damage morphology of concrete under impact load.

Investigation of the chloride ion transport mechanism in unsaturated concrete considering the nonlinear seepage effect

In this paper, the mechanism of chloride ion transport in unsaturated concrete considering the nonlinear seepage effect is investigated by indoor experiments and analytical modelling. The concrete sheet imbibition test is used to reveal the nonlinear characters of seepage including water convection and moisture capillary within the unsaturated concrete in case of various water-binder ratios. For modelling purpose, an exponential function is introduced to mathematically depict the nonlinear relation between the specific discharge and hydraulic gradient during both water convection and moisture capillary processes. Based on such nonlinear seepage models, new mathematical models are proposed for the problem of chloride invasion within the reinforced concrete structure. The solution for the mathematical model of chloride transport is resolved by Laplace transform and finite difference method, of which acceptability is verified by the comparison with the results from chloride ion invasion test. The result indicates that, compared with linear seepage law, the use of the proposed nonlinear seepage solution is preferred to depict the saturation-relative humidity curves from concrete sheet imbibition test. The consideration of nonlinear seepage can result in a slower chloride transport rate, which further makes a later flow start-up time and a smaller free chloride iron concentration within the concrete. Such effect can be enhanced with the increase of nonlinear flow degree. The paper provides an effective solution to evaluate the chloride invasion within the unsaturated concrete.

Splitting Tensile Test of ECC Functional Gradient Concrete with PVA Fiber Admixture

Engineered cementitious composite (ECC) functional gradient concrete has a promising application future, and its mechanical features are piquing the interest of researchers. The impacts of this strength class of concrete, interface reinforcement technique, ECC thickness (i.e., fiber dosage), and other factors on the splitting tensile strength qualities are explored using an experimental investigation of functional gradient concrete. The splitting tensile tests of 150 mm × 150 mm × 150 mm functional gradient concrete specimens were used to explore the link between concrete strength grade, interface reinforcing technique, and ECC thickness with polyvinyl alcohol (PVA) fiber additive and functional gradient concrete. The test results show that the splitting tensile strength of functional gradient concrete increases as the concrete strength grade increases; different interfacial treatments have a significant effect on the splitting tensile strength of functional gradient concrete; and the effect of ECC thickness change on the splitting tensile strength of functional gradient concrete shows different trends, which research can be used as an experimental reference for functional gradient concrete engineering applications.

High-temperature effect on the mechanical behavior of recycled fiber-reinforced concrete containing volcanic pumice powder: An experimental assessment combined with machine learning (ML)-based prediction

The increasing volume of waste generated by various activities has increased interest in using waste to create sustainable construction materials to achieve possible benefits. In addition, using recycled materials to produce fresh concrete is a desirable option because of its low cost, lower landfill space requirement, and the completed concrete quality. Therefore, an experimental inquiry is undertaken to ascertain the impacts of up to 20 wt% cement displaced by Volcanic Pumice Powder (VPP) with the incorporation of 1% and 2% Recycled Nylon Fiber (RNF) on the mechanical properties of concrete composites following room temperature to high-temperature (600 °C) exposure. Fresh concrete characteristics tests were performed, including slump, compacting factor, Kelly ball penetration, and density. The heat resistance of the concrete was then measured by calculating the percentage decrease in weight, the splitting tensile strength, and the compressive strength of the specimens. Heating mainly raised VPP's pozzolanic reactivity and lowered high vapor pressure through melting RNF. Therefore, VPP and RNF-treated concrete had superior mechanical performance than control concrete even when exposed to elevated temperatures. Further, the microstructural modifications brought on by RNF and VPP additions were also explored by deploying Scanning Electron Microscopy (SEM). The use of VPP in concrete led to an improvement in fresh properties, while RNF demonstrated deterioration in the same qualities. Despite this, supervised machine learning techniques are a central focus of this investigation because of their potential to predict concrete characteristics accurately. To predict the fresh and mechanical characteristics of concrete, both the Random Forest (RF) and the K-Nearest Neighbors (KNN) algorithm, along with their ensemble model counterparts, were explored. The outcomes revealed that RNF and VPP considerably improved the concrete's heat resilience and mechanical characteristics and halted the concrete composites' explosive spalling behavior at 600 °C temperatures. To prevent strength loss at high temperatures, it was discovered that adding 1% RNF content to concrete with 10% VPP was the best combination. In addition, the high coefficient correlation (R2) value of the RF and the ensemble model indicates great accuracy in outcome prediction, while the low R2 value of the KNN model indicates that the KNN model is less accurate.

A Test to Comprehensively Capture the Known Genetic Component of Familial Pulmonary Fibrosis.

The recent European Respiratory Society statement on familial pulmonary fibrosis supports the need for genetic testing in the care of patients and their relatives. However, no solution (i.e., a concrete test) was provided to implement genetic testing in daily practice. Herein, we tabulated and standardized the nomenclature of 128 genetic variants in 20 genes implicated in adult-onset pulmonary fibrosis. The objective was to develop a laboratory-developed test (LDT) on the basis of standard Sanger sequencing to capture all known familial pulmonary fibrosis-associated variants. Targeted DNA fragments were amplified using harmonized PCR conditions to perform the LDT in a single 96-well plate. The new genetic test was evaluated in 62 sporadic cases of idiopathic pulmonary fibrosis. As expected in this population, we observed a low yield of disease-causing mutations. More important, 100% of targeted variants by the LDT were successfully evaluated. Furthermore, four variants of uncertain significance with in silico-predicted deleterious scores were identified in three patients, suggesting novel pathogenic variants in genes known to cause idiopathic pulmonary fibrosis. Finally, the MUC5B promoter variant rs35705950 was strongly enriched in these patients with a minor allele frequency of 41.1% compared with 10.6% in a matched population-based cohort (n = 29,060), leading to an estimation that this variant may explain up to 35% of the population-attributable risk. This LDT provides a solution for rapid clinical translation. Technical laboratory details are provided so that specialized pulmonary centers can implement the LDT in house to expedite the clinical recommendations of expert panels.

Geopolymer using different size fractions of recycled brick-based mixed demolition waste

The hike in CO2 emission from the cement industry calls for an alternative binder to cement. On the other hand, constructionand demolition waste management is a global concern. This research aims to demonstrate the complete applicability of brick-based demolition wastes in geopolymer mortar and concrete. Ground Granulated Blast Furnace Slag (GGBS) was used with brick waste to improve performance. 3 M, 4 M and 6 M NaOH were used for mortar preparation, and 6 M NaOH was used for concrete tests. The performance of the geopolymer binder and mortar was compared with the control specimen. 5 % to 20 % incorporation of demolition waste powder (DWP) with GGBS was explored to find the optimum binder combination. A 10 % incorporation for 3 M and 15 % for 4 M and 6 M was found optimum. Then, 10 % to 100 % incorporation of brick sand was studied to examine the influence of brick-based demolition waste on the fresh and hardened properties of mortar. Sand: Binder: Alkaline activator was taken 3.375: 1: 0.45 for mortar. The workability of mortar varied with the increase of brick sand content. The flexural and compressive strengths were decreased with an increase in brick sand content for all molarities of NaOH; consequently, the water absorption increased with brick sand content. The maximum mortar compressive strength of 27 MPa was found for 10 % demolished sand with a 6 M alkali concentration. However, consistent results were obtained with a 4 M concentration. Geopolymer concrete from brick-based demolition waste was prepared using 6 M NaOH. The UPV result indicates the regular quality of the concrete cube, with acceptable capillary water absorption after 24 h. However, the compressive strength of geopolymer concrete could be useful for non-structural works, and therefore, further studies with higher strength of NaOH for geopolymer concrete are recommended.

CFD Analysis of Ultra-High-Performance Concrete Rheological Tests

This study connects and compares the results from two different rheological measurement techniques, namely, the slump test and rotational rheometry, on UHPC (Ultra-High-Performance Concrete) through the use of commercially available numerical simulation software ANSYS Fluent 2022 R2. The workability and resulting mechanical properties of the UHPC (a material used in construction) are highly dependent on its rheology and, hence, also on the composition and level of homogeneity of the assessed mixture. It is generally understood that the most suitable rheological model for concrete mixtures is the Hershel–Bulkley model. However, obtaining reliable rheological data is complicated as the wide-gap rotational rheometers developed for concrete show bias in their measurements even on precise laboratory equipment, while common industrial tests, such as the slump test, do not produce the usual shear rate–shear stress relation and, hence, do not allow for more complex analysis. Recently, a new methodology for the rheological measurement of non-Newtonian fluids that utilises a simple power input–rotation speed measurement was published. However, in this study, only model liquids were evaluated, and the method was not validated for more complex fluids such as pastes. Therefore, it was the goal of this study to show this method’s suitability for fine pastes through a comparison with the slump test, using numerical simulation.

Prediction of Wet Area of Underwater Tunnel Lining

The issue of water seepage poses a significant challenge in tunnel infrastructure. Wet areas are commonly used to evaluate the degree of water seepage in tunnel projects. To investigate the feasibility for numerical simulation to predict a wet area, we selected concrete test blocks with two types of defects—holes and cracks—as the research specimens. Numerical models for various seepage conditions were constructed using TOUGH2, and the results were validated through laboratory experiments. Additionally, the Shenjiamen Subsea Tunnel was simplified into a numerical model, employing TOUGH2 to forecast its future wet area performance within the scope of national standards. The outcomes of our research revealed that point seepage and line seepage exhibited circular and elliptical morphologies, respectively. Moreover, external water pressure and defect size exerted a significant influence on the expansion of the wet area. Notably, the impact of crack width surpassed that of hole diameter. Encouragingly, the numerical models generated using TOUGH2 for unsaturated concrete demonstrated excellent agreement with laboratory test results concerning the geometry, size, and pattern of the wet area. These findings signified the potential of TOUGH2 numerical simulation as a valuable tool in predicting the lifespan of tunnels.

Study on the freezing resistance and repair technology of prestressed high-strength concrete pipe piles

This article takes a prestressed high-strength concrete tube pile (PHC tube pile) in Tianjin Port as the research object, considers the influence of the type of admixture, forming process, and maintenance method in the process of concrete fabrication, and carries out a rapid freeze-thaw test of PHC tube pile concrete. The changes in the mass loss rate, relative compressive strength, and relative dynamic modulus of elasticity with the number of freeze-thaw cycles, as well as the influence characteristics and mechanism of the admixture type, forming process, and curing method, were obtained. Based on this study, the repair and reinforcement of the base concrete were carried out using ultrahigh toughness cementitious composites and cementitious permeable crystalline composites, and a rapid freeze-thaw test was conducted on the repaired concrete specimens to verify the repair and reinforcement effects of the two materials. The study showed that the mass loss rate, relative strength, and relative dynamic elastic modulus can better characterize the freezing resistance of PHC piles, and it is safer to use the relative dynamic elastic modulus as the evaluation index of the freezing resistance of PHC pile concrete than the mass loss rate. The concrete admixture, forming process, and maintenance method have significant effects on the freezing resistance of the PHC pipe pile mix. The splitting damage surface of both ultrahigh-toughness cementitious composites (UHTTC) and cementitious capillary crystalline waterproofing (CCCW) repaired concrete is a reinforced surface, and both repair materials can improve the freezing resistance of PHC pipe piles through the crack arresting effect and reduction in initial porosity.

Pengaruh Abu Serbuk Kayu Kulim dan Serbuk Tempurung Kelapa terhadap Kuat Tekan Beton

This research combines kulim wood dust and coconut shell powder as a substitute for concrete materials. Ash from kulim sawdust has silicca properties. Meanwhile, coconut shell powder can be mixed in concrete. This study aims to determine the effect of using kulim sawdust ash as a partial substitution of cement and coconut shell powder waste as a partial substitution of fine aggregate on compressive strength and to determine the ideal proportion of the percentage variation of added ingredients. Concrete planning uses an experimental method that refers to SNI 03-2834-2000, SNI 03-1974-1990 and the Unisla Concrete Practicum Guidebook. With a total sample of 12 test objects with the quality plan K-225. The results of the normal concrete compressive strength test with an N code of 19.55 MPa. The results of testing the compressive strength of concrete with added materials with code A1 are 19.29 MPa. The results of testing the compressive strength of concrete with added materials with code B1 are 18.84 Mpa. The results of testing the compressive strength of concrete with added materials with code C1 are 18.46 MPa. Based on the results of the study it was concluded that the added ingredients of kulim wood powder ash and coconut shell powder did not significantly affect the compressive strength of concrete and the higher the added material value the lower the concrete compressive strength value and the lower the added material value, the higher the concrete compressive strength value.

Quantum cohomology from mixed Higgs-Coulomb phases

We generalize Coulomb-branch-based gauged linear sigma model (GLSM)–computations of quantum cohomology rings of Fano spaces. Typically such computations have focused on GLSMs without superpotential, for which the low energy limit of the GLSM is a pure Coulomb branch, and quantum cohomology is determined by the critical locus of a twisted one-loop effective superpotential. We extend these results to cases for which the low energy limit of the GLSM includes both Coulomb and Higgs branches, where the latter is a Landau-Ginzburg orbifold. We describe the state spaces and products of corresponding operators in detail, comparing a geometric phase description, where the operator product ring is quantum cohomology, to the description in terms of Coulomb and Higgs branch states. As a concrete test of our methods, we compare to existing mathematics results for quantum cohomology rings of hypersurfaces in projective spaces.

Penggunaan Silika Fume Untuk Reduksi Semen Dengan Limbah Granit Sebagai Pengganti Agregat Kasar Terhadap Kuat Tekan Dan Kuat Tarik Beton

Concrete is a mixture of cement, sand, gravel, and water. In order to obtain good quality in the process, added ingredients, waste, or other materials with a certain ratio value are added. In this case, the use of granite waste as a substitute for coarse aggregate that is easy to find and the use of silica fume which aims to increase the compressive strength of concrete. The purpose of this study was to determine the effect of granite waste and silica fume, as well as the relationship between compressive strength and tensile strength of concrete with these variations. The percentage of granite waste and silica fume varied, ranging from 5%-10% granite waste and 0%, 7.5%, 15%, 22.5%, and 30% silica fume. Concrete testing was carried out after the concrete was 28 days old. The planned compressive strength is 25 Mpa. From the results obtained, the average normal concrete compressive strength was 27.69 Mpa and the average normal concrete tensile strength was 3.14 Mpa. The addition of 5% - 10% percentage granite waste and 0% silica fume obtained an average compressive strength of 27.74 Mpa and 27.65 Mpa, and an average tensile strength of 3.18 Mpa and 3.16 Mpa. The percentage of 10% granite waste and silica fume 7.5%, 15%, 22.5%, and 30% obtained average compressive strengths of 26.42 Mpa, 26.33 Mpa, 25.10 Mpa, and 25.01 Mpa respectively and average tensile strengths of 2.71 Mpa, 2.64 Mpa, 2.50 Mpa, and 2.41 Mpa respectively.

Using Autoclave Concrete Prism Testing to Evaluate ASR Reactivity in Concrete Using Laboratory Tests and Outdoor Exposure Blocks as Benchmark Data

Abstract The alkali–silica reaction (ASR) occurs in concrete that contains silica in a reactive aggregate, sufficient alkalis, and sufficient moisture. Although the most widely accepted tests for evaluating ASR potential are the concrete prism test (CPT) and the accelerated mortar bar test, each test has limitations. Because of the need to test concrete mixes within a short period of time, an accelerated autoclave test method (autoclaved CPT [ACPT]) was investigated using concrete prism samples boosted to 3.0 % total alkali content subjected to an exposure temperature of 271°F (133°C) with a corresponding pressure of 29 psi (0.2 MPa) for 24 hours. A suite of aggregates was evaluated by concrete prism specimens using both the ACPT and CPT methods. The ACPT was able to classify individual aggregate fractions for ASR reactivity with 97.2 % accuracy for the proposed limit of 0.09 % expansion for 36 tested mixtures and approximately 130 specimens. Data from this test suggest that a week-long test could be considered an effective screening tool for the alkali reactivity of coarse or fine aggregate fractions. In addition, miniature CPT (AASHTO T 380, Standard Method of Test for Potential Alkali Reactivity of Aggregates and Effectiveness of ASR Mitigation Measures (Miniature Concrete Prism Test, MCPT) and 12-year outdoor exposure block results are evaluated and compared with both CPT and ACPT results. Although the data suggest a general agreement between these methods, further testing is warranted along with multi-laboratory precision evaluation.

Mechanical Properties of Rigid Pavements Incorporating Different Percentage of Steel Fiber

Nowadays, rigid pavement construction has widely used in road construction industry. Although rigid pavement is widely used in road construction, it tends to fail within time due to many reasons. Fatigue is the important aspect in the rigid pavement design. Due to applications of the heavy loads fatigue occurs in the pavement in the form of micro cracks. Fatigue concepts which is an important parameter in cement concrete pavement and mainly failure occurs due to fatigue failure. As a result, it is crucial to optimize and improving concrete structures to suit diverse engineering requirements. This paper investigates the effect of steel fiber on the improvement of structural behavior such as compressive, tensile and also flexural stiffness performance of rigid pavements. In this respect, the concrete mix design accordance to Design of Normal Concrete Mix (DOE) method was employed in the preparation of the specimens. A series of concrete laboratory tests have been carried out to evaluate the mechanical properties of the concrete sample incorporating 1, 3 and 5% of steel fiber. As a result, the performance (compressive, tensile and flexural) of modified rigid pavements improved remarkably 15-60% with 5% additive of steel fibre at 7 and 18 days curing time. Based on these studies, the addition of steel fiber reinforcement into the rigid pavements has a significant effect on mechanical properties of reinforced concrete mixture.

Modern concrete composites for earthquake-resistant construction

Objective. The purpose of the research is to develop earthquake-resistant building composites Method. The study is based on experimental dynamic testing of fine-grained concrete. Existing approaches to ensuring seismic safety of buildings and structures are analytically summarized. Result. Domestic and foreign experience in designing fine-grained concrete compositions for earthquake-resistant construction is presented. Compositions of fine-grained concrete of various classes were obtained using raw materials of natural and man-made origin. Recipes were proposed and their construction, technical and dynamic properties were studied. Conclusion. The strength of fine-grained concrete increases with decreasing loading time, and at a loading time of approximately 0.01 sec or a loading rate of about 5000-7000 MPa sec, this excess is about 30% compared to the statistical strength of concrete. This allows us to recommend fine-grained concrete for structures experiencing dynamic impact.

A Subpixel Concrete Crack Measurement Method Based on the Partial Area Effect

To improve the accuracy of concrete crack measurement with a machine vision method in structural health monitoring and in technical status evaluation, a subpixel crack measurement method based on the partial area effect was proposed. (1) First, a pixelwise crack image segmentation method was established through a multi-step process of multi-threshold fusion and morphology operation, and a novel pixel degree crack width calculation method was developed with the extraction of the middle points, the center line and its normal, and the intersection of the center line normal and crack edges. (2) Then, a subpixel algorithm based on the partial area effect was introduced to locate vertical, horizontal, and oblique cracks in subpixel crack edges, and the subpixel crack width could be calculated along the crack center line pixelwise. (3) Finally, the proposed method was verified by indoor concrete beam crack measurement tests with a digital microscope, and the results show that the maximum relative errors of the subpixel width of the horizontal, vertical, and oblique straight cracks measured by the proposed method were 3.06%, 8.97%, and 5.16%, respectively. The absolute error of the crack length was less than 0.30 mm, and the measurement accuracy could reach 0.01 pixels. The subpixel crack measurement method provides a novel possible solution for structural health monitoring.