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Schmidt rebound hammer test was employed in this study as a nondestructive test. This test method has been universally utilized due to its non-destructiveness for quick and easy assessment of material strength properties and quality of concrete of an existing structure. Industrial waste materials (air-dried alum sludge, treated alum sludge, limesto...
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A number of destructive and non-destructive tests were conducted on rock samples collected from various zones in northern Iraq. So far, for Iraqi rocks, few studies have correlated Schmidt hammer rebound (R) with both unconfined compressive strength (UCS) and Brazilian tensile strength (BTS). In this study, the objective is to develop a relationshi...
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... In recent years, other authors have also searched for the correct correlation relations between NDT methods and DT methods, because these correlations were not determined on non-standard concretes [22,23]. There are also studies using machine learning methods to predict the dynamic compressive response of composite materials [24]. ...
The research presented here demonstrates the practical aspects of the numerical correlation of the results of the compressive strength test. The destructive test (DT) in a hydraulic press and the non-destructive test (NDT) using a Schmidt hammer in several process variations were evaluated. The aim was to evaluate the real differences between the tool supplier’s curve and testing. Therefore, 150 concrete cube specimens with an edge length of 150 mm were produced using a mixture of three types of concrete classes: C30, C35, and C40. The test was carried out 7 and 28 days of age of the concrete. The Schmidt hammer test was carried out in horizontal (θ = 0) and vertical (θ = 90) directions and using a series of 10 measurements. Furthermore, the tests were performed in two sets: first, the sample was placed on the ground, and second, under a hydraulic jack with a load of 50% of the maximum bearing capacity of specific concrete. Then, regression analysis was performed on the data sets to establish linear mathematical relationships between compressive strength and number of bounces. The results showed that the correlation between the DT and NDT tests has a high value for each group, but the correlation equations are different and must be taken into account.
... The results of the compressive strength of concrete samples are shown in Table 3. along with the compressive strength of some tested materials obtained from industrial waste. 10.2 (0.7) Bet-10 8.7 (0.6) Concrete with fly ash [14] 4.5 -17.5 Concrete with alum sludge (treated in a furnace at 200 °C) [29] 24.0 -48.0 Concrete with Lime Stone [29] 33.0 -53.0 Concrete with quarry dust [29] 36.0 -65.0 Concrete with solidified wastewater treatment sludge [30] 3.9 -5.8 ...
... The results of the compressive strength of concrete samples are shown in Table 3. along with the compressive strength of some tested materials obtained from industrial waste. 10.2 (0.7) Bet-10 8.7 (0.6) Concrete with fly ash [14] 4.5 -17.5 Concrete with alum sludge (treated in a furnace at 200 °C) [29] 24.0 -48.0 Concrete with Lime Stone [29] 33.0 -53.0 Concrete with quarry dust [29] 36.0 -65.0 Concrete with solidified wastewater treatment sludge [30] 3.9 -5.8 ...
... The results of the compressive strength of concrete samples are shown in Table 3. along with the compressive strength of some tested materials obtained from industrial waste. 10.2 (0.7) Bet-10 8.7 (0.6) Concrete with fly ash [14] 4.5 -17.5 Concrete with alum sludge (treated in a furnace at 200 °C) [29] 24.0 -48.0 Concrete with Lime Stone [29] 33.0 -53.0 Concrete with quarry dust [29] 36.0 -65.0 Concrete with solidified wastewater treatment sludge [30] 3.9 -5.8 ...
Utilization possibilities of solidified fractions of industrial hazardous waste obtained by mixing with inert materials in construction were investigated. Waste mineral oils, water-hydrocarbon emulsions mixture, and waste filter cakes from the physico-chemical treatment of wastewater generated by washing of patterned rollers for a printing machine, were used as models of industrial hazardous waste in the solidification process. Investigation comprised preparation of concrete and asphalt mixtures for further testing. The solidified powder was analyzed regarding the granulometric composition, while the obtained concrete samples were further subjected to compressive strength determination, whereas the asphalt mixtures were tested in the context of potential waterproofing materials. According to the obtained leaching test results, all the samples met the required conditions for further application. Compressive strength test results were in the range of 8.7 - 22.6 MPa. Still, the measured compressive strength values were lower than expected, which is explained using solidified powder fractions of smaller grain size. According to the results, it can be concluded that the investigated mixtures cannot be used for structural building elements, but their usage is recommended for elements such as pavements, roadside, path cubes, concrete haberdashery, etc. Asphalt mixtures showed acceptable properties in terms of mechanical, durability, and waterproofing tests.
Over-extraction of aggregates from natural sources with rapid urbanization as well as massive waste generation in construction industry have imposed the need to utilize waste material as concrete constituent. Crushed Stone Dust (CSD) is such a supplementary material that can be utilized for the production of sustainable concrete. This study attempts to predict and optimize fresh and hardened properties of concrete utilizing CSD as a partial replacement of natural fine aggregate and Nylon Fiber (NF) as fiber reinforcement using Response Surface Methodology (RSM). A three-level factorial design of Box-Behnken was incorporated to investigate the effect of CSD, NF and W/C as three independent variables on compressive strength, splitting tensile strength, fresh density and workability of concrete as desired responses. All the developed probabilistic models were found to be significant in predicting the responses at 95% confidence level. Regression analysis in terms of correlation coefficient, coefficient of determination, coefficient of variation, adequate precision, chi-square, mean square error, root mean square error, and mean absolute error also indicated the accuracy and functionality of the developed models. The results reveal that both compressive and splitting tensile strength increase with increased NF content, but the rise in CSD percentages beyond a certain level has negative impact on strength of concrete. However, fresh density and workability of concrete show a declining trend with rise in both CSD and NF levels. From multi-objective optimization, 20% CSD, 0.75% NF and W/C of 0.49 have been found to be the optimum proportions for concrete mixture with a desirability of 0.915. Finally, an experimental validation was carried out with optimum mixture contents and relative error between the experimental and predicted optimized values was observed to be less than 5%.
