Concrete Research Articles

Učinak uzoraka utora na čvrstoću prionljivosti u betonu ojačanom bambusom

The use of bamboo as a reinforcement material in concrete has garnered attention in recent years due to its low cost, renewability, and high strength-to-weight ratio. However, the bond strength between bamboo and concrete is a crucial factor affecting the overall performance of bamboo-reinforced concrete structures. In this study, the bond between bamboo and concrete is investigated through pull-out tests. Three different groove patterns - rectangular, semi-circular, and V-notch - are examined for their bond strength. Various chemical treatments are also being explored to reduce the water absorption capacity of bamboo splints. The highest bond strengths achieved after using Bond Tite adhesive and bituminous paint are 1.94 MPa and 1.41 MPa, respectively. The findings of this study can be valuable in optimizing the design and construction of bamboo-reinforced concrete structures.

Recent Construction Technology Innovations and Practices for Large-Span Arch Bridges in China

Arch bridges provide significant technical and economic benefits under suitable conditions. In particular, concrete-filled steel tubular (CFST) arch bridges and steel-reinforced concrete (SRC) arch bridges are two types of arch bridges that have gained great economic competitiveness and span growth potential due to advancements in construction technology, engineering materials, and construction equipment over the past 30 years. Under the leadership of the author, two record-breaking arch bridges—that is, the Pingnan Third Bridge (a CFST arch bridge), with a span of 560 m, and the Tian’e Longtan Bridge (an SRC arch bridge), with a span of 600 m—have been built in the past five years, embodying great technological breakthroughs in the construction of these two types of arch bridges. This paper takes these two arch bridges as examples to systematically summarize the latest technological innovations and practices in the construction of CFST arch bridges and SRC arch bridges in China. The technological innovations of CFST arch bridges include cable-stayed fastening-hanging cantilevered assembly methods, new in-tube concrete materials, in-tube concrete pouring techniques, a novel thrust abutment foundation for non-rocky terrain, and measures to reduce the quantity of temporary facilities. The technological innovations of SRC arch bridges involve arch skeleton stiffness selection, the development of encasing concrete materials, encasing concrete pouring, arch rib stress mitigation, and longitudinal reinforcement optimization. To conclude, future research focuses and development directions for these two types of arch bridges are proposed.

An experimental batch study on separation of palm kernel and palm shell with salt solution

Abstract The effectiveness of the palm kernel separation process is of paramount significance, as it directly influences the quantity of palm kernels obtained. This efficiency forms the core of the decision-making process when considering how to best use palm kernel shells, which are a byproduct of the palm oil industry. These versatile shells have various applications, including their role as a fuel source, their use in producing activated carbon, and their utility as an alternative material in lightweight concrete. The primary aim of this investigation is to examine and enhance the efficiency of this innovative segregation technique, with a specific focus on identifying the optimal conditions for achieving effective segregation, particularly the ideal concentration of salt (NaCl) in a batch process. The research methodology comprises a wellstructured series of steps designed to systematically evaluate the segregation process. In the initial stages, samples of palm kernel and shell were collected from a local palm oil industry and meticulously prepared for experimentation. Subsequently, salt solutions with varying saturation percentage of salt solution beetwen 12 g/L and 380 g/L were prepared. As the samples were immersed in the solution, the denser palm kernel shells settled at the base, whereas the lighter palm kernels rised to the top, simplifying the separation of these two elements. The highest level of segregation efficiency was achieved at the 380 g/L of Consentration of salt solution. This suggested method offers advantages, including the capability to achieve a 100% separation of palm kernel and palm kernel shell.

Sideband Peak Count – a new nonlinear ultrasonic technique for monitoring damage progression in engineering materials

Linear ultrasonic (LU) techniques used by majority of the researchers working in material damage monitoring, are reliable for detecting relatively large defects. If the defect dimensions are in the range of the ultrasonic wavelength or larger, then those defects can be detected by analyzing the scattered ultrasonic fields. Material damage affects LU parameters such as ultrasonic wave speed and attenuation and their changes are detectable for relatively large defects. However, for small defects (when defect dimensions are significantly smaller than the wavelength of the propagating signal) the changes in the LU parameters are too small to detect or measure reliably. For detecting small defects engineers often use high frequency ultrasonic signals to make the defect dimensions greater than the wavelength. However, high frequency signals attenuate quickly and therefore, only very small regions near the ultrasonic probe can be inspected in this manner. Inspecting large structures by high frequency ultrasonic signals requires moving the probe mechanically from one point to the next and therefore, can be very time consuming. Nonlinear ultrasonic (NLU) technique on the other hand does not need to satisfy this restricting condition that the wavelength of the signal must be smaller than the defect size. NLU works well when the signal wavelength is much larger than the defect size. Therefore, relatively low frequency signals that can propagate a long distance and monitor a large area of a structure can be used for NLU measurements. Different NLU techniques can be used for detection and monitoring of small damages in a specimen. A relatively new NLU technique called the Sideband Peak Count-Index or SPC-I technique has been developed by the author and his collaborators. SPC-I technique for monitoring different types of materials – composites, metals, concrete, and other cement-based materials has been found to be effective. Along with those success stories of SPC-I the effect of topography and the advantage of topological sensing is also discussed in this presentation.

The use of coffee waste in bio-foamed concrete brick (B-FCB) to reduce the penetration of carbon dioxide (CO2) into concrete

Abstract The aim of this study was to examine the potential of coffee waste (CW) in reducing the carbonation of bio-foamed concrete brick (B-FCB). This study utilised coffee waste (CW) as an alternative material to replace cement, with different concentrations of 1%, 5%, and 10%. Furthermore, the utilisation of Bacillus tequilensis (B. tequilensis) was employed with the objective of achieving self-healing. A 2k factorial design was employed to perform a statistical analysis aiming to optimise the carbonation depth of B-FCB incorporating CW for a duration of 28 days. The experiment consisted of 11 runs. The performance of carbonation depth as response of this study was monitored with three main factors namely the density of concrete (D), coffee waste (CW), and B. tequilensis (B), respectively. The factors were bounded by upper and lower limits of 1300 kg/m3 and 1800 kg/m3, 1% and 10%, and 3x105 cell/ml and 3x107 cell/ml, respectively. The study established that the ideal carbonation depth was 8 mm, based on specific conditions as follow; 1300 kg/m3 of concrete D, 1% of CW and 3×105 cell/ml of B at 28 days. On the other hand, it was observed that the carbonation depth had a value of zero when the cement was replaced with 10% CW in runs 5, 6, 7, and 8. The empirical findings illustrate the effects of (CW) on reducing the level of carbonation in B-FCB, hence promoting its long-term sustainability.

Smart Bricks Curing System using IoT

The existing curing method for bricks lacks in precision and efficiency, resulting in inferior strength and durability in the finished product. Traditional procedures may result in over- or under-curing, causing cracks and decreased structural integrity. Furthermore, manual monitoring and intervention are labor-intensive and prone to human mistake. A smart bricks curing system designed specifically for concrete bricks is critical for obtaining optimal strength and durability. This technology seeks to reduce cracks that threaten the longevity of concrete by maintaining precise moisture levels during the hydration process. The research’s central feature is the implementation of sensors that continuously monitor moisture and temperature levels within the bricks.

Damage plasticity model for green concrete material

Damage plasticity model for green concrete material

Carbon sequestration in cementitious systems through CO2-rich hydration and chemically enforced CO2 mineralization

Cementitious materials as a medium of carbon capture, and utilization (CCU) have recently attracted considerable attentions. Atmospheric CO2 can be absorbed in hardened concrete, which can be also accelerated by early age CO2 curing. Compared to the CO2 curing of concrete materials, in-situ CO2 mixing technology can be widely applied because it can be used in a batch plant without an additional curing facility. In this study, the CO2 mixing time was set as the primary variable to elucidate the precipitation of the carbonate phases in the early stages and its effect on cement hydration. The dissociated CO2 is directly mineralized into calcium carbonate (CaCO3) in calcite phase. In addition, the longer the CO2 mixing time, the greater the precipitation of calcite (i.e., CCU capacity), thereby densifying the internal microstructure and improving early strength development. Interestingly, a certain amount of calcite converted to monocarboaluminate—an important factor for quantitatively assessing the degree of mineral carbonation in cementitious materials.

Performance analysis of supply chain for construction materials at high rise building project based on Supply Chain Operations Reference Method: A case study

Abstract Supply chain management is an approach to implementing lean construction efforts to minimize construction project problems, such as cost overruns, project delays, and disputes. Implementation of supply chain management is necessary, especially in the procurement of materials. However, there is a need to measure performance during the implementation. Results of measurement can show the extent to which the project operates and use it as a benchmark to determine the end impact of a project. This study’s purpose is to measure of supply chain performance with the supply chain operation reference (SCOR) method and use the analytical hierarchy process (AHP). Compile data using an observation with scoring form based on standards adoption, categories, and SCOR metrics through key performance indicators (KPI) and structured interviews with the contractor to validate. Limited to the study is the supply chain of ready-mix concrete materials. The AHP method give the weight of the output value of the KPI. The results of the KPI measurements from the contractor’s perspective are that one indicator is still at a low value, which is a cycle time for fulfilling orders. An overall result of 84.83 from the measurement KPI suggests a “good” performance category.

Analysis of failure mechanism of concrete pole based on finite element extended method

Concrete poles play an important role in distribution networks and are prone to degradation due to environmental influences. Fracture failures primarily result from structural deterioration, including both damage to the concrete structure under stress overload conditions and the deterioration of the concrete material itself. Due to the lower tensile strength compared to compressive strength, concrete structures often exhibit cracking and fractures. This study initially analyzes the structural deterioration process of concrete electric poles and subsequently develops a damaged model using the finite element method. The results reveal that the maximum tensile strength of concrete electric poles occurs at 2.4 m, while the compression is maximum within the 2–6 m range. Furthermore, an analysis of the main factors contributing to fracture failures and structural deteriorations of these poles is conducted using the finite element extension method. It is determined that shallower crack depths and higher concrete strength enhance fracture resistance and the bearing capacity of concrete poles. Notably, annular cracks at the 2.4 m height are more prone to spreading.

Use of Microwave Tomography Technology for Water Seepage Investigation in Buildings

In metropolitan cities like Hong Kong, it is densely populated and most people live in privately owned premises of reinforced concrete residential buildings. Owing to material deterioration under (a) environmental exposure, (b) poor construction workmanship, (c) lack of proper maintenance and (d) alteration of premises into sub-divided flats with bathrooms, water may seep through the floor slabs of the premises and infiltrate into the subject premises below, and this create nuisance to the subject premises. In this paper, the causes of deterioration of concrete material are elaborated.

The Characteristics of Polyester Concrete with Local Sand of East Borneo as Filter

Concrete is a mixture of coarse aggregate and fine aggregate mixed with water and cement as a binder and filler. The disadvantages of traditional concrete are that high water absorption causes low chemical resistance, low modulus of elasticity, low impact strength and a long hardening time to reach its maximum properties, namely 28 days. The solution to these shortcomings that is being developed for construction material applications is by using polymers as polymer concrete. In this research, polyester resin and sand aggregate were used as basic materials. Polyester resin is a type of thermosetting polymer that is widely used in various applications such as automotive parts, composites and construction because of its suitable processing characteristics and affordable price. Meanwhile, the sand used is local Kalimantan sand, where from the XRF and XRD test results, local Kalimantan sand is included in the silica sand type. This research varies the weight fraction of polyester resin used to determine its effect on polymer concrete characteristics such as porosity, water absorption, compressive strength, and macro observations. Variations in the polymer weight fraction used were 20%, 25% and 30%. Compressive strength testing was carried out at the age of 7 days of concrete. The results of the porosity test show that the average porosity of all variations is ± 0.5%. Meanwhile, the average value of water absorption for all fractions is 0.2%. And the highest average value of compressive strength in the 30% polyester resin weight fraction was 66.9 MPa. So it can be concluded that all variations meet SNI standards to become concrete materials.

Weak electric field strengthens the β-oxidation degradation of fatty acids by activated sludge to produce micro-nano CaCO3

Although a significant portion of calcium-rich concrete waste slurry water is unusable, converting this calcium into micro-nano CaCO3 enhances the performance of concrete materials. In this study, an electric field facilitated microbial β-oxidation, supplying sufficient carbonate for microbially induced carbonate precipitation (MICP) to produce valuable micro-nano CaCO3. Experimental results show that in the 0.5 V·cm−1, the accumulated concentration of carbonate changed most significantly, increasing by 10.24 times to 1400 mg·L−1. Correspondingly, the maximum increase in SCOD bio-degradation rate was 2.57 mg·L−1·h−1，consequently leading to a maximum 1.32 times increase in the yield of micro-nano CaCO3. Furthermore, the DC field had a positive effect on bacterial EPS secretion, with increased excretion of proteins and polysaccharides, which was beneficial for the adsorption and uptake of organics. Then the electric field increased the abundance of Proteobacteria in sludge by a maximum of 8.17 %, which also led to an improvement in the organic matter degradation ability of sludge. Finally, the NAD+, NADH, and FAD coenzymes involved in fatty acid degradation increased by 1.82, 1.87, and 1.25 times, respectively. And the number of FadL and FadD gene related to fatty acids metabolism were increased remarkably, which accelerated the uptake and acylation of fatty acids and relieved the inhibition of β-oxidation. In short, this work provides a novel strategy for MICP utilization in calcium-rich wastewater.

Long-term behaviour of stud connections in composite structures

Being critical components in composite structures, the short-term structural behaviour of stud shear connectors has been extensively investigated. Despite this, there has been somewhat limited attention devoted to their time-dependent behaviour. In this paper, the results of four long-term push-out tests are reported: the test parameters including the loading age and stud diameter. The test results are shown to be simulated accurately by a finite element model established using ABAQUS, in which the long-term behaviour of the concrete is considered by implementing a stepwise approach. The numerical procedure is applied to conduct a parametric analysis, with the effects of different parameters, viz., the loading age, concrete material, external environment, stud size and reinforcement ratio being considered. Based on the numerical results, an analytical formulation is derived for the creep coefficients of composite members with different loading ages. Comparisons with FE model data shows that the derived equation has sufficient accuracy and can be applied for designing composite structures considering their long-term response.

A Hydration-Based Integrated Model to Evaluate Properties Development and Sustainability of Oyster Shell Powder–Cement Binary Composites

Currently, oyster shell powder (OSP) is becoming more widely used in the production of cement-based materials. The purpose of this study is to propose a predictive model that can predict the properties of concrete materials incorporating oyster shell powder. The methods of this prediction model are given as follows. First, based on the measurement results of the heat of hydration in the first 7 days, the prediction parameters of the hydration model are obtained. Secondly, based on the hydration model, the measured results of the heat of hydration were extrapolated, and the heat of hydration from the start of stirring to day 28 was calculated. From the calculation results, the developments of compressive strength, ultrasonic velocity, and surface electrical resistivity were estimated. Finally, we evaluated the CO2 emissions of concrete incorporating oyster shell powder. The CO2 emissions corresponding to unit compressive strength and unit surface electrical resistivity were calculated. The important conclusions of the prediction model are given as follows. First, for different substitution amounts of oyster shell powder, the model result shows that the ultimate value of the heat of hydration corresponding to the unit cement mass is the same, i.e., 454.27 J/g. While the substitution amount of oyster shell powder increases from 0% to 30%, the model result shows that the cumulative 28-day hydration heat for 1 g cement increases the powder amount from 405.7 J/g to 419.3 J/g. Secondly, as the amount of substituted oyster shell powder increases from 0% to 30%, the model result shows that the cumulative 28-day heat of hydration per gram of cementitious material decreases this amount from 405.7 J/g to 293.4 J/g. Compressive strength, ultrasonic pulse velocity, and surface electrical resistivity can all be expressed as exponential functions of the heat of hydration. For compressive strength, ultrasonic pulse velocity, and surface electrical resistivity, the coefficients of determination for the simulation results and experimental results are 0.8396, 0.7195, and 0.9408, respectively. Finally, as the amount of substituted oyster shell powder increases from 0% to 30%, the model result shows that the CO2 emission per unit of compressive strength increases from 10.18 kg/MPa to 16.51 kg/MPa. As the amount increases from 0% to 30%, the model result shows that the CO2 emission corresponding to the unit surface electrical resistivity does not change significantly. In summary, the importance of this model is that it can predict various properties of concrete mixed with oyster shell powder, reduce the number of experiments, and promote the engineering application of oyster shell powder concrete.

Enhancing sustainability in self-compacting concrete by optimizing blended supplementary cementitious materials

Within concrete engineering, the uptake of self-compacting concrete (SCC) represents a notable trend, delivering improved workability and placement efficiency. However, challenges persist, notably in achieving optimal performance while mitigating environmental impacts, particularly in cement consumption. However, simply reducing the cement content in the mix design can directly compromise the structural-concrete requirements. Towards these challenges, global trends emphasize the utilization of appropriate waste materials in blended concrete. This study explored a promising strategy by integrating supplementary cementitious materials (SCMs) to contribute to the United Nations' Sustainable Development Goals (SDGs) in addition to the engineering contributions. It suggests an optimal combination of Metakaolin (MK) and Limestone Powder (LP) to partially substitute cement. The research methodology employs the response surface method (RSM) to systematically explore the ideal ingredient ratios. Through a comprehensive analysis of orthogonal array of 16 mixes, encompassing both mixture and process variables, this study aims to explain the effects of MK and LP addition on the rheological and mechanical properties of SCC with varying cement replacement levels. In terms of mixture constituents, the total composition of cement, MK, and LP was fixed at 100%, while coarse aggregate (CA), fine aggregate (FA), and the water-to-binder ratio were held as process variables. In order to assess the rheological properties of the mix-design, various tests including slump flow, L-box, and sieve segregation were conducted. Additionally, to evaluate mechanical strength, samples were tested for compressive strength at both 7 and 28 days. Findings from the experiments reveal higher concentrations of MK result in reduced workability and hardened properties. Through RSM-based designed experimentation covering both rheological and mechanical aspects, it is observed that the optimal cement replacement level lies between 40 and 55%. The findings of this study contribute to the advancement of sustainable and structurally robust concrete practices, offering insights into the optimal utilization of SCMs to meet both engineering requirements and environmental sustainability goals.

Effect of Construction Delays and the Preventive Role of Concrete Works Optimization: Systematic Literature Review

Delays in construction are a widespread global problem, leading to potential cost overruns and legal disputes. Additionally, delays can result in a decline in construction quality and loss of public trust. The aim of this study is to examine the effects of project delays in various regions and the preventive role of optimizing concrete works. Literature review and bibliometric analysis are carried out to determine global research trends. Findings show that optimizing concrete works can provide benefits such as cost savings, time savings, improved quality and safety, and environmental benefits. Optimization of concrete material composition is one of the most examined topics in this field. Based on the findings, construction firms have the potential to attain cost efficiencies while concurrently mitigating carbon emissions.

Development in the Study of Mechanical Prop-erties and Damage Constitutive Models of Rub-ber-Reclaimed Concrete

Advances in rubber-reinforced concrete technology and its applications in engineering are cru-cial for the thorough recycling and safe disposal of waste tire rubber and construction debris. Rubber-reinforced concrete (RAC) is a concrete material produced by substituting some fine and coarse aggregates with waste rubber particles and recycled aggregates. The incorporation of waste rubber particles endows RAC with distinctive mechanical properties and a distinct damage constitutive model. The mechanical properties of rubber recycled concrete mainly in-clude compressive strength, tensile strength, flexural strength, and elastic modulus. Compared to traditional concrete, RAC exhibits slightly lower compressive and flexural strengths but sig-nificantly enhanced tensile strength. This is due to the changes in mechanical properties caused by the softness and elastic properties of rubber particles. In addition, the addition of rubber particles can also improve the energy absorption capacity and impact resistance of concrete. On the other hand, in order to describe the damage behavior of rubber recycled con-crete, some constitutive models were studied. Common models include linear elastic model, plastic model, and damage model. The linear elastic model is suitable for describing the be-havior of rubber recycled concrete during the elastic stage; The plastic model is suitable for describing its deformation behavior during the plastic stage; The damage model can better describe the fracture and failure behavior of rubber recycled concrete, including shear damage, tensile damage, and compression damage. Tailored to the unique characteristics of RAC, these models consider the stiffness of rubber particles and the deformation characteristics of the binding materials, enabling accurate predictions of the stress-strain behavior of RAC. In conclusion, rubber-reinforced concrete possesses excellent mechanical and durability proper-ties, which can be accurately described and predicted using appropriate constitutive models. These findings are crucial for advancing the application and development of rubber-reinforced concrete.

Influence of Co-formers on the radiation shielding properties of zinc incorporated barium borate glasses for radioactive waste storage applications

The primary objective of the current investigation is to explore a novel series of Dy3+ions doped Zinc incorporated barium borate glasses synthesized through the classic melt quenching approach for the application of radiation defending. In this examination, the co-formers TeO2, Bi2O3, V2O5 and one of the glass formers P2O5comprised individually with the glass network. The non-crystalline phase of fabricated glasses symbolized by the empirical formula (64−x) B2O3+xA+15BaO+20ZnF2+1Dy2O3 (where x = 0, 20; A = P2O5, TeO2, Bi2O3, V2O5) and these pristine glasses were characterized by various techniques. Structural investigations were done by XRD, FTIR approach. FTIR analysis reveals the existence of functional group and their corresponding band assignments in the glass samples were recognized. The UV–Visible–NIR absorption spectra elucidates the optical properties including the energy transitions concerned with the trivalent Dysprosium ion, Urbach energy, direct and indirect bandgap energy using Tauc's plot method. The vanadium pentoxide (V2O5) co-former comprised glass network exhibits highly contrary behavior in optical scrutiny compared to other glasses. The Physical, structural attributes along with elastic properties are deliberated for the prepared glasses. The ionicity and covalency estimation validates the fact that the present glass samples exhibit maximum ionic nature. Radiation shielding parameters such as mass attenuation coefficients (MAC), half value layer (HVL) and effective atomic number (Zeff) for the titled glasses have been enumerated, discussed and reported. Among the prepared glasses, Bi2O3 co-former comprised glass exhibit better efficiency than the available concrete shielding materials.

STUDY OF THE EFFECT OF MINERAL ADMIXTURE ADDITION ON PAVING BLOCKS' PHYSICAL AND MECHANICAL PROPERTIES

Paving blocks, concrete bricks made from cement and sand, are a vital alternative to ground cover. Their extensive, precast nature, water absorption capabilities, affordability, and ease of use contribute to their popularity. However, the additional ingredients, particularly mineral admixtures, hold the potential to enhance these blocks' quality and performance significantly. The mineral admixtures used, such as limestone, quartz sand, and gypsum, are instrumental in improving the performance of paving blocks, offering a promising avenue for further research and application. This research, conducted with meticulous scientific rigor, investigated paving blocks' physical and mechanical properties. Paving block test objects were created using sand, cement, and crushed stone with mineral admixtures. The mineral admixtures used in this experiment, including gypsum, quartz sand, and limestone, were crushed before being used in a stone cruiser machine to make them powder and reactive. Compressive strength test, weat resistance test, volume weight test, water absorption test, and visual inspection were conducted experimentally. The research results, derived from a robust experimental setup, revealed that paving blocks with 10% gypsum additives, 6% quartz sand powder, and limestone powder produced a more excellent compressive strength value than standard paving blocks, values of 36,884 MPa, 37,573 MPa, and 38,950 MPa with a regular paving block compressive strength value of 36,119 MPa followed by a decrease in the percentage of absorption. This suggests that using mineral admixtures at a certain percentage as an additional material can improve the quality of paving blocks. However, it is essential to note that adding too many mineral admixtures can also decrease the strength of the paving block, emphasizing the need for careful application of these materials in construction. These findings provide valuable insights for civil engineers, construction professionals, and researchers in materials science and construction technology, enhancing their understanding of the role of mineral admixtures in paving block strength.