Ultrasonic Pulse Research Articles

Enhancement mechanism of microbial mineralization modified coal gangue aggregate properties

Preparing concrete with coal gangue as the aggregate has significant environmental and economic advantages. Nevertheless, the fundamental characteristics of the manufactured concrete are significantly impacted by the high water absorption and low strength of coal gangue aggregate. The present study employs the microbial-induced carbonate precipitation (MICP) technique to efficiently enhance the characteristics of coal gangue aggregate (CGA). Starting from the circumstances of microbial mineralization, the effects of pH, temperature, and time on the capacity of bacteria for mineralization were taken into consideration. Following solution immersion treatment with varying concentrations of urea, calcium ions, and bacterial solution, the patterns of water absorption, crushing index, apparent density, and ultrasonic pulse resistance of CGA were examined. The precipitates produced by microbial mineralization, the micro-morphology, and the pore structure of the aggregate surface were all characterized, and the mechanism of the modification of CGA by MICP was revealed through the use of scanning electron microscopy (SEM), X-ray diffractometer (XRD), and nuclear magnetic resonance (NMR) techniques. Investigations were also conducted on the mechanical characteristics of modified coal gangue aggregate concrete. The results showed that the water absorption and crushing index of the CGA with optimal modification effect (M-CGA) decreased by 18.5 % and 24.1 %, respectively, which was attributed to the fact that the calcium carbonate formed in the cracks and pores of the CGA filled the aggregates and prevented the penetration of water. The 28-day compressive strength, split tensile strength, and flexural strength of modified coal gangue aggregate concrete prepared from M-CGA were increased by 8.13 %, 13.88 %, and 8.53 %, respectively. MICP is an effective method to improve the properties of CGA, which is conducive to the waste recycling of coal gangue.

Correlation between destructive and non-destructive evaluation to study of plastic waste aggregate mortar: a case study of mechanical proprieties

Non-destructive evaluation using ultrasonic pulse velocity (UPV) testing has extensive applications in the cement materials industry. Ultrasonic pulse velocity (UPV) test is accepted as alternative to destructive testing to determine the compressive strength, dynamic modulus of elasticity, and Poisson’s ratio, which are needed for structural design. In modern construction technology, the use of Plastic waste (PW) as a partial replacement to natural aggregates in a mortar mix is growing in popularity primarily because it reduces the initial capital cost of raw materials and the associated conservation in environment. In this regard, this study explains the correlations between mechanical proprieties, and UPV tests for mortar contains 25%, 50%, and 75% of waste aggregate of plastic. Mortar based on Plastic Waste (MPW) specimens were tested by direct, semi-direct, and indirect UPV. UPV measurements can be effectively used to determine the dynamic modulus of elasticity and Poisson’s ratio of Mortar based on Plastic Waste MPW. The dynamic elastic modulus and the Poisson’s ratio decreases for the same mortar composite when at increasing PW content. Thus, the incorporation of PW particles into the cement matrix confirms the capacity of composites to reduce the sound intensity and damp vibrations inside the composites. The results of this study will be significant for non-destructive evaluations of MPW, while additional recommendations for future studies are presented at the end of the paper.

Utilization of marble waste as fine aggregate in the composition of high performance concrete containing mineral additions

This study investigates the effect of adding marble waste as fine aggregate on the properties of high-performance concrete. To achieve this objective, 10%, 20%, 30%, and 40% of marble waste fine aggregate were substituted for ordinary fine aggregate in the composition of high-performance concrete mixtures containing silica fume and ground blast furnace slag. The fresh properties were studied using slump, fresh density and air content tests, while the hardened properties were assessed using compressive and flexural strengths, ultrasonic pulse velocity, water absorption, and chemical acid attack tests. The results obtained revealed that the addition of marble waste fine aggregate significantly improved the properties of high-performance concrete and increased its resistance to chemical acid attacks. The composition-based ground blast furnace slag containing 40% marble waste fine aggregate outperformed all other compositions, increasing compressive strength by 30.98%.

Evaluation of Destructive and Non-Destructive Testing of Existing Hotel Structures for Shopping Centre Conversion

Changes in the function of a building will affect the structural loading, which, based on government regulations in building permits, must be reviewed for the feasibility of building functions through structural assessment. This research aims to analyze the condition of the concrete quality of building beams, columns, and slabs that are more than 50 years old. The methods used include non-destructive testing (NDT) and destructive testing (DT) on the structures. From the results of the non-destructive UPV (Ultrasonic Pulse Velocity) Test on 20 elements (100 tests) using the PUNDIT tool, the average concrete quality based on BS 1881 and ASTM C597-16 standards was found to be 28.15 MPa for columns, 25.11 MPa for beams, and 25.60 MPa for slabs. The Hammer Test showed an average concrete quality of 27.95 MPa for columns, 31.41 MPa for beams, and 31.20 MPa for slabs. The destructive method using core drilling on 8 structural elements revealed an average concrete quality of 25.58 MPa for columns, 34.61 MPa for beams, and 35.89 MPa for slabs. The hardness test for reinforcing steel indicated an average yield strength of 361 MPa. The compressive strength results of the column structure concrete meet the minimum requirements of 21 MPa for special structure concrete quality based on SNI-2847-2019. It is recommended to recalculate the structure with concrete quality fc' 25 MPa and steel quality fy 360 MPa to identify elements that need structural strengthening.

Effect of Elevated Temperatures on Compressive Strength, Ultrasonic Pulse Velocity, and Transfer Properties of Metakaolin-Based Geopolymer Mortars

Effect of Elevated Temperatures on Compressive Strength, Ultrasonic Pulse Velocity, and Transfer Properties of Metakaolin-Based Geopolymer Mortars

Synergetic impact of volcanic ash and calcium carbide residue on the properties and microstructure of cementitious composites

The synergetic impact of using volcanic ash (VA) and calcium carbide residue (CCR) on the engineering properties of cementitious mortar was assessed. Cement was replaced with VA at 0–40 % by mass and/or CCR at 0–20 % by mass. Blended mortars were tested for flow, setting time, compressive strength, and ultrasonic pulse velocity (UPV). The flow increased when using VA but decreased with the inclusion of CCR. Compared to the cement-based control mix, ternary mixes had a lesser flow. The impact of VA replacement on the initial and final setting times was marginal until a substitution rate of 40 %, after which the setting times were prolonged. Similarly, the setting time was extended with CCR replacement. The compressive strength and UPV improved with the use of 10–20 % VA and/or 5 % CCR for binary and ternary mortar mixes, with the highest strength of 55.4 MPa and UPV of 4490 m/s being recorded for the mix comprising 20 % VA and 5 % CCR. Mixes were further analyzed through isothermal calorimetry, X-ray diffraction, and scanning electron microscopy. The cumulative heat generation was reduced for binary and ternary mixes except for those containing 20 % VA only. The microstructure analysis highlighted the formation of C-S-H and C-A-S-H as reaction products and the consumption of Ca(OH)2. This study provides novel insights into optimal combinations of VA and CCR for superior mortar performance, offering practical approaches to reducing cement content and lowering carbon emissions without compromising performance.

Development and evaluation of MgO-grit iron aggregate heavy density concrete for high temperature radiation shielding: Experimental and machine learning approach

This research focuses on the development and evaluation of heavy density concrete (HDC) for radiation shielding, utilizing both experimental and machine learning techniques. Various HDC specimens with different proportions (25 %, 50 %, 75 %, and 100 %) of grit iron aggregate replacing normal weight aggregate, in addition to control specimens with no grit iron scale aggregate, were cast. These samples were subjected to testing at temperatures ranging from room temperature to 1200°C to assess properties such as compressive strength, rebound number, ultrasonic pulse velocity, density loss, mass loss, linear attenuation coefficient (LAC), mass attenuation coefficient (MAC), half-value layer (HVL), tenth-value layer (TVL), and mean free path (MFP). Ensemble learning algorithms were employed using experimental data to predict compressive strength and new empirical expressions were formulated for mechanical and radiation shielding properties, including LAC, HVL, and TVL. The addition of grit iron aggregate, combined with MgO, demonstrated a significant improvement in the mechanical and radiation shielding properties of HDC. This research holds promise for applications in nuclear reactors operating at high temperatures.

Quantitative characterization on the restrained expansion of core concrete in SSCFST based on ultrasonic pulse velocity – A novel approach

The expansive agent (EA) is generally added in the concrete-filled steel tube (CFST) to produce the micro-expansion for core concrete to ensure the synergistic load bearing between the steel tube and core concrete, which guarantees its high strength. The quantitative analysis of the expansion induced by the expansive agent in practical engineering becomes difficult, due to the small magnitude of the micro-expansion. To address this issue, this study proposed a new method for characterizing the time-varying expansion of the self-stressed concrete-filled steel tube (SSCFST) based on the ultrasonic pulse velocity (UPV). The surface strain of the steel tube, the UPV of core concrete, and the porosity of core concrete under conditions of uniform casting and the simulated segregation were investigated. The results showed that the prismatic specimen expanded continuously in its free state, accompanied by a rapid increase in the associated UPV during the initial stage, followed by a subsequent plateau phase. However, in SSCFST, the expansion of core concrete initially increased but subsequently dropped, due to the restriction of the steel tube. As a result, the associated UPV increased. Further, the relationship between the difference in UPV and the expansion consumption was established through an intermediate variable, i.e. the pore-filling increment. And, a computational model for evaluating the circumferential expansion of SSCFST based on UPV was then proposed. The comparison between predicted results and actual measurements confirmed the applicability of the proposed model. This study is believed to offer a new technical solution for non-destructive testing and the quantitative characterization of the time-variant expansion of SSCFST.

Estimation of concrete compressive strength from non-destructive tests using a customized neural network and genetic algorithm

This paper introduces a novel approach for deriving an equation aimed at predicting concrete compressive strength, leveraging two non-destructive test results: ultrasonic pulse velocity and rebound hammer value. Traditional regression methods often fail to capture the complex non-linear relationships crucial for accurate concrete CS estimation, leading to limited effectiveness. In contrast, while machine learning models excel at mapping these non-linear relationships from non-destructive test results, their intricate internal mechanisms can be opaque, posing challenges for practical application and comprehension by engineers. This study aims to bridge these gaps by developing an estimation equation derived from the decoded weights of a neural network specifically designed to capture the intricate nonlinear mapping relationship. Initially, the equation is intricate and lengthy, comprising multiple terms. To streamline and refine it, a genetic algorithm is employed, focusing solely on the most pivotal terms. Consequently, the refined prediction equation demonstrates superior estimation performance with an RMSE of 3.40 MPa, an MAE of 2.70 MPa, an R2 of 0.92, and an R of 0.97 compared to several existing formulations. Furthermore, a comparative analysis is undertaken to assess the impact of the degree of equation simplification on its predictive accuracy. The findings offer insights into the pivotal roles of exponential function terms in enhancing prediction performance, as well as elucidating trigonometric function terms contribute the model’s complex non-linear mapping capability.

Technical issues on forensic assessment of post-earthquake building damage—Case study of the Hajj Dormitory Building, Mamuju, Indonesia

In the wake of frequent, strong earthquakes in Indonesia, detailed and comprehensive forensic assessments of post-earthquake building damage are necessary. On January 14, 2021, a destructive Mw 6.2 earthquake occurred in Mamuju–Majene, West Sulawesi, Indonesia. Over a hundred houses and facilities were heavily damaged, and there were even fatalities and injured people. Therefore, forensic work is required to assess the conditions and performances of existing buildings to ensure their safety. However, determining a building’s seismic capacity and safety after an earthquake is a challenge. It is substantially challenging to accomplish it solely through visual inspections, which must be done rapidly and during an emergency. This paper reports a complete assessment of the Hajj Dormitory building. An extensive forensic method including visual and detailed inspections was planned and performed. Detailed inspections comprised verticality, ultrasonic pulse velocity test, rebound hammer test, crack measurement, rebar scan/cover meter test, core drill, and geoelectric and cone penetration tests. Results showed that the Hajj Dormitory building superstructure was still safe and reliable; however, mandatory retrofitting was required in several parts of the column and beam. Further, technical issues associated with post-earthquake forensic methods of observed damage and their utility on the safety and reliability of an inspected building are presented, and recommendations are made based on extensive in situ work. Moreover, correlations and recommendations for each forensic method are presented, along with detailed rules of damage assessment.

Ultrasonic wave characteristics in multiscale cementitious materials at different stages of hydration

Monitoring the microstructural change in cementitious materials during hydration is an essential but challenging task. Therefore, a non-invasive and sophisticated technique is warranted to understand the microscopic behaviour of the multiphase cementitious materials (where the length scale of the constituents varies from centimeters to micrometers) in different stages of hydration. Due to exothermic hydration reactions, different hydration products start to evolve with individual mechanical properties. In concrete, an interface transition zone (ITZ) appears between the aggregate surface and paste matrix, which influences the overall properties of concrete material. In the present research, 1) several wave characteristics, such as wave velocity, energy distribution, and signal phase are found out using Ultrasonic Pulse Velocity (UPV), Wavelet Packet Energy (WPE) and Hilbert Transform (HT) methods, to monitor the hydration mechanism (1d-28d) in cement-based materials with two levels of heterogeneities (cement paste and concrete, representing microscale and mesoscale, respectively). Also, the unique nonlinear behaviour is studied in the frequency domain using the promising Sideband Energy Ratio (SER) and Sideband Peak Count Index (SPC-I) methods. 2) Numerical simulations are carried out to understand the wave interaction in the developing microstructure. A discretized microstructure of cement shows microscopic details of each phase at any instant of hydration (e.g., formation stage and after complete maturity level). The experimental and numerical investigations on the characteristics of the nonlinear ultrasonic wave propagation show the impact of microstructural development of multi-scale cementitious materials during hydration.

Evaluation of in-place strength and stiffness development in concrete structures using non-destructive test methods

ABSTRACT This study investigates the effectiveness of two widely used non-destructive assessment techniques – rebound hardness and ultrasonic pulse velocity – in evaluating the in-place compressive strength and modulus of elasticity of reinforced concrete structures. Large-scale reinforced concrete structures, composed of slab and wall elements, were prepared in the field for these measurements to estimate the mechanical properties during the curing process. The study found that environmental conditions significantly affected the ultrasonic pulse velocity results more than rebound hardness measurements. Standardized cylindrical specimens and cored samples from the concrete wall were prepared for comparison, revealing that cored samples exhibited slightly lower mechanical properties than standardized specimens. Notably, the modulus of elasticity demonstrated a strong correlation with rebound hardness. The experimental results indicate that non-destructive methods are more efficient for estimating the modulus of elasticity than compressive strength, and they have a potential as a quality inspection method for early-age concrete structures during the curing process.

Characterization of rigid open-cell foams using direct ultrasonic simulation.

An ultrasonic simulation technique based on the direct fluid model is proposed as an alternative to the analogous experimental technique to determine the tortuosity and characteristic lengths for high pore-density foams. It is beneficial as it reduces cost and almost eliminates the signal-to-noise issues encountered in the experiment. The proposed method is demonstrated for periodic microlattices with three different unit-cell configurations, 75%-90% porosity, and a pore size of about 200 microns. The technique is also applicable to high-resolution computed tomography (CT) scans of open-cell foams with a priori unknown microporous structure. An acoustic simulation software, ACTRAN® (Hexagon AB, Stockholm, Sweden), is used to model and perform analysis of the ultrasonic pulse propagation through the foam. Based on through-transmission by foam saturated with two different mediums, the tortuosity, and characteristic lengths are estimated from the high-frequency asymptotic behavior of the square of the propagation index (Nr2) versus the inverse square root of frequency (1/f). The predicted parameters are validated by comparing them with those determined by solving the electric conduction boundary value problem for the same configuration. Further, detailed parametric sensitivity analysis reveals the sensitivity of the Johnson-Champoux-Allard parameters to errors in Nr2 and so the effect of these errors on the acoustic absorption behavior of the rigid porous sample.

Crack Assessment on a Residential Building Due to Peat Soil Settlement at Ayer Hitam, Muar

Frequent problems in structure that build on the peat soil is cracking. This is due to the settlement that occurred by the peat soil as it has low in bearing capacity. The crack occurred on the residential building have become the main concern as crack happened on building showed the earliest sign of degradation. The increasing number of visible cracks at residential building with varies in length and width has a doubtful taught either the residential building is safe or not to be used. Apart from cracking, the concrete strength of the residential building is a concerned as the crack occurred may reduce the concrete strength. A single-storey residential building at Kompleks Penghulu Mukim Ayer Hitam, Muar is used to perform field measurement with respect to the cracking and concrete strength. 25 number of visible cracks with different length and width has been detected while monitoring the building. The crack length and size were measured using ruler and measuring tape. For measuring the concrete strength, a non-destructive testing (NDT) was used using Schmidt Rebound Hammer and Ultrasonic Pulse Velocity (UPV). The total 15 point was tested on column and wall inside the residential house by using two modes of transmission for UPV testing which was semi-direct and indirect transmission. The result of both rebound number and UPV has been analyze using statistical evaluation. The result is then being compared with the previous researcher that using the same regression mode of linear and non-linear mode when doing the analysis. From the result, it is found that the regression model for rebound hammer is more reliable to be used as the regression coefficient value got is nearly to one. For overall cracking and concrete strength quality, it is also found that the residential building needs proper maintenance as the settlement still happened and it is affected the residential building’s safety.

Evaluation of Residual Mechanical Properties of Non-sintered Hwangto Concrete Exposed to High Temperatures Using Ultrasonic Pulse Velocity Method

Evaluation of Residual Mechanical Properties of Non-sintered Hwangto Concrete Exposed to High Temperatures Using Ultrasonic Pulse Velocity Method

Investigation of the Engineering Properties of Glass Fiber Reinforced Concrete (GRC) Cured with Internal Resistance

In this study, it was aimed to produce glass fiber reinforced concrete (GRC) samples cured with internal resistance by placing resistance wires at different distances within the concrete molds and applying electric current at various voltages, while the mold surfaces were covered with stretch film. The engineering properties of these samples were then investigated. Previous studies have shown that the mechanical properties of conventional concrete, which were subjected to different curing methods, improved compared to samples that did not undergo any curing process. This study aimed to enhance both the engineering properties of the concrete samples and to accelerate the curing process. Glass fiber reinforced concrete (GRC) with dimensions of 50×50×4 cm was produced, and 25, 35, and 45V resistances were applied to three different molds with wire spacing of 5cm, 6cm, and 7cm. With this application, the GRC samples were subjected to internal resistance curing for the first 24 hours. By applying three different voltages to molds with three different wire spacings, 9 concrete samples were produced, along with 1 reference sample that did not contain any resistance wires and was not subjected to any curing process, making a total of 10 different concrete samples. After curing, the concrete samples were cut into 16cm×4cm×4cm GRC mechanical test specimens. The obtained specimens were tested for 7, 14, and 28 day compressive strength, flexural strength, unit weight, and ultrasonic pulse velocity. To examine the microstructure of the GRC samples, Scanning Electron Microscopy (SEM), Thermogravimetric Analysis (TGA), and Fourier Transform Infrared Spectroscopy (FT-IR) analyses were conducted. These analyses investigated the physical and chemical development processes of the samples, mass losses, products formed after hydration, and structural behaviors. As a result, it was observed that the early-age strength properties of GRC samples cured with internal resistance showed a partial increase compared to the reference sample that was not internally cured, especially in the 7-day samples. In the 14 and 28-day strength comparisons, it was observed that the cured samples showed improvement in flexural strength. According to the data obtained, the samples subjected to 35 volts of electric current yielded better results, especially in the early ages, compared to the reference sample.

Designing prepacked aggregate concrete for improved mechanical properties and its field application in constructing steel tube concrete

Prepacked aggregate concrete (PAC) is made by placing coarse aggregates of various sizes into a formwork and then filling the voids between coarse aggregate and grout. The mechanical performance of PAC is dominated by the compactness due to grout filling, but few study considered the pouring methods and grout performance synchronously. The coupled effect of pouring methods and grout performance on the compactness of PAC is investigated in this study. The results show that the gravity pouring method is only suitable for grouts with good flowability. The pump pouring method is more widely used. It can be adapted to grout with poorer fluidity and coarse aggregate with greater apparent density. The ultrasonic pulse velocity test method provides a relatively accurate evaluation of the compactness of PAC. Furthermore, due to the enhanced mechanical properties of PAC, the filed application potential in the preparation of steel tube concrete columns has also been confirmed, where the results exhibited that PAC based steel tube concrete contributed to an enhanced ductility and autogenous shrinkage.

Influence of Basalt Fiber on the Rheological and Mechanical Properties and Durability Behavior of Self-Compacting Concrete (SCC)

This experimental study presents the influence of basalt fiber on the rheological and mechanical properties and the durability behavior of self-compacting concrete (SCC). In this study, a total of five self-compacting concrete mixtures were prepared: one as a control mix and the other mixes with 0.05%, 0.1%, 0.15%, and 0.2% basalt fibers. Slump flow and V-funnel flow tests were employed to assess the influence of basalt fibers on the rheological properties of fresh self-compacting concrete (SCC). Additionally, mechanical properties, including compressive strength, splitting tensile strength, and flexural strength, were analyzed. Furthermore, the mechanical properties were assessed following exposure to elevated temperatures (400 °C and 600 °C) as well as 100 and 200 freeze-thaw (F/T) cycles. Additionally, water absorption and ultrasonic pulse velocity tests were conducted on the SCC mixes after 28 days of curing. The results revealed that the addition of fiber has a significant effect on the rheological properties of fresh SCC mixtures. As the volume of fibers increases, the reduction in rheological properties increases. Basalt fiber had no effect on the compressive strength, while the splitting and flexural strength were significantly enhanced by 33% using basalt fiber. As temperatures and freezing-thawing cycles escalated, the mechanical properties of SCC exhibited a decline. Experimental findings indicated that elevating the temperature to 600 °C resulted in a decrease of over 20% in both the tensile and compressive strengths of SCC. Moreover, the results demonstrated that the incorporation of basalt fibers substantially enhanced the mechanical properties of SCC when subjected to high temperatures and freezing-thawing cycles. In addition, water absorption increased slightly by the incorporation of basalt fiber.

Radiation shielding properties of shotcrete containing different aggregates

In this study, the physical and mechanical properties of wet mix shotcrete produced using crushed stone aggregate (CS), ferrochrome slag aggregate (FS), and barite (B) aggregate have been investigated. Furthermore, the radiation shielding properties have been determined experimentally, theoretically, and through simulation. A control sample was produced using 50 % CS and 50 % FS. Subsequently, shotcrete groups were produced by substituting B aggregate at replacement rates of 25 %, 50 %, 75 %, and 100 % instead of FS. The mechanical properties such as density, ultrasonic pulse velocity (UPV), compressive strength, flexural strength, and splitting tensile strength of the produced spray concrete groups were investigated. Additionally, experimental radiation shielding measurements were conducted using a high-purity germanium (HPGe) detector system with emissions from four different radioactive sources (133Ba, 137Cs, 60Co, and 22Na) spanning nine different gamma energies ranging from 276.5 to 1332.5 keV. As a result of the experimental measurements, the linear attenuation coefficients (μ) of the shotcrete samples were obtained. A proportional increase in μ was determined with increasing barite content. Using the experimental mass attenuation coefficient (μ/ρ) results, half-value layer (HVL) and tenth-value layer (TVL) thicknesses, as well as mean free path (MFP) values, were calculated. An increasing B aggregate ratio did not have a significant effect on the μ/ρ value, while an increase was observed in the HVL, TVL, and MFP values. Moreover, the WinXCOM interface was employed for theoretical calculations, and the FLUKA Monte Carlo code was utilized for simulation calculations. The obtained data were compared with experimental results, revealing a good agreement between them. Based on the obtained data, it was concluded that increasing the B aggregate ratio resulted in improvement in mechanical properties compared to the control sample, and additionally, it was determined that B aggregate-added shotcrete is an effective gamma radiation shielding material.

Training strategy and intelligent model for in-situ rapid measurement of subgrade compactness

Current methods for inspecting subgrade compaction quality are time-consuming and destructive. This paper presents an in-situ measurement methodology for rapid detection of subgrade compaction quality using Ultrasonic Pulse Velocity (UPV) and Intelligent Compaction (IC). Field compaction tests, field UPV test, and laboratory tests are performed to construct the heterogeneous datasets. A set of intelligent models are established to estimate the subgrade compactness in terms of the in-time measured UPV. The training strategy is proposed by expanding dataset quantity and dataset dimension to enhance the model performance. The model demonstrates high accuracy in compactness estimation and strong generalization in verification. This contribution can be utilized in engineering applications to effectively detect the compaction quality during the construction.