Introduction

Recycling waste materials is considered one of the best ways to protect the environment and nature. In recent years, many investigations have been performed on the possibility of using waste glass as a partial replacement for construction materials1,2,3. In the literature, it was observed that the waste glass might provide an alternative to increase the sustainability aspects of concrete, as several investigators have shown through their work. Since concrete is one of the most utilized construction materials in different applications, it is important to improve its sustainability and performance. To achieve this goal, many different studies have been conducted. Omer and Saeed4experimentally observed the influence of WGP, and the test results showed that the concrete compressive strength (CS) reduced with the increase of waste glass powder (WGP). Taha and Nounu5 reported that no significant alteration was obtained in the CS of concrete with the presence of recycled glass sand as a sand substitute. It was reported that the CS of concrete decreased by 16% and 10.6% at 28 and 364 days correspondingly, when 20% of the Portland cement was swapped with pozzolanic glass dust. Bheel et al. (2020) also investigated WGP used as a partial cement substitute by using WGP of 0%, 10%, 20% and 30% of the weight of the cement. It was observed that WGP concrete workability was enhanced compared to that of controlled combination concrete. It was noted that the CS of concrete enhanced by 12% and the splitting tensile strength enhanced by 7.5% by using 10% of WGP in concrete. The other investigation was completed by Yassin et al.6. In this investigation, Yassin et al.6 studied WGP material recycling in concrete as a partial replacement for cement. Therefore the influence of WGP was observed related to reference examples without WGP. At the end of this investigation, it was observed that swapping cement partly by glass dust enhanced the strength of concrete by up to 20%. Hama et al.7examined the influence when WGP was chosen as a cement replacement with ratios of 0% (reference), 10%, and 15%. Correspondingly, the structural productivity of WGP inclusion in R-C-Bs was observed. For this purpose, nine R-C-Bs were utilized in this investigation. In addition to the influence of WGP on flexural productivity, the influence of reinforcing details was also examined. Mohammed and Hama8examined the structural advantage of the inclusion of WGP combined with plastic aggregate in R-C-Bs. At the end of this investigation, Mohammed and Hama8 concluded that beams with the inclusion of glass dust demonstrated greater load ability. Jain et al.9investigated the use of granite dust and waste soda-lime glass dust obtained from WG bottles. It was concluded that for the CS, the greatest increase was about 37% for a 15% glass dust combination. This rise might be by reason of the large surface area resulting from the glass dust. Al-Jubouri10 observed the importance of using WGP as a fractional cement replacement and concluded by examining some properties of hardened concrete, having crushed glass (0%, 10%, 15%) and relating them with the control combination without replacement. The implications of these examinations showed the increase of strength in all cases since glass dust has a high pozzolanic influence. The reinforced concrete T-beams with WGP had fractures more extensive than the control T-beams, where the final fractures enhanced by 3.5– 50% in relation to the corresponding control T-beams. Castillo et al.11 defined the progressive observing system for calculating the shear and flexure productivity of pre-stressed R-C-Bs’. For this aim, the observing system was based on collecting data from (a) several monitoring arrangements, (b) experimental component testing, and (c) information from code-based damaging test procedures on large-scale examples. It was observed that there is a high potential for understanding and analyzing the complex mechanical procedures of the shear productivity of R-C-Bs. Furthermore, a primary assessment of the digital image correlation verified exterior strains with the strains on the inserted reinforcement and provided a partially good agreement. Strauss et al.12examined a digital image correlation method and its capability to evaluate productivity signs, for instance, fracture forms, fracture openings and vertical and horizontal bending. The obtained values were then compared to the required aims so that structural productivity calculation approaches might be applied in an effective and maintainable manner. Another investigation was completed to investigate the theoretical model for the estimate of the shear-flexural strength of slender R-C-Bs with and without transverse reinforcement13. In this investigation, Marí et al.13 derived simple results for shear strength confirmation and for designing transverse reinforcement. Elsayed et al.14examined the flexural and shear productivity of R-C-Bs having reused coarse aggregate, waste aluminum fiber and WGP. For this aim, five R-C-Bs were planned to fail in flexure (inclusion 100% natural coarse aggregate, 20%. WGP and 0% waste aluminium fiber) and the last five R-C-Bs were considered to fail in shear (inclusion 100% recycled coarse aggregate, 20% WGP with 0%, 1%, 2%, and 3% waste aluminum fiber, correspondingly). At the end of this investigation, the load-carrying capability of tested recycled coarse aggregate concrete R-C-Bs was enhanced by adding waste aluminum fiber. Omer and Saeed15 investigated the effect of substituting up to 15% WGP, categorized by two distinct particle sizes, as a cement substitute on the 180-day shear performance of R-C-Bs with differing cement content and without stirrups.14 beams in all, each with the same size of 200 mm × 250 mm × 2000 mm, were employed for this purpose. To determine the influence that the aforementioned characteristics have on the shear performance of beams, as well as fracture patterns, modes of failure, load-deflection behavior, and strength capabilities at various loading stages, an investigation was conducted. According to the findings of the research, the incorporation of WGP into concrete beams did not have any adverse impacts on the cracking load ability, shear strength, or flexural cracking load ability of the beams. Indeed, it has the potential to enhance the latter. Next, Yassen et al.16 performed another investigation, the purpose of which was to conduct an experimental investigation into the impact that the incorporation of WGP has on the shear behavior of R-C-Bs when they are subjected to bending loads. Specifically, Yassen et al.16 investigated the load-vertical displacement relation, the load-strain relation, the cracks pattern/propagation, the load-cracks relation, and the mode of failure. The protocol for the experiment involves the testing of 9 beams that are simply supported and measure 150 mm x 150 mm x 900 mm. These beams are meant to fail under shear. The three factors that have been investigated are the WGP content, which may be either 0%, 10%, or 15% as a partial replacement of cement; the steel reinforcement ratio, which can be equivalent to either 2Φ16mm or 2Φ12mm; and the spacing between stirrups, which can range from 65 to 170 mm. The presence of WGP enhanced the beam strength, as seen by the increase in ultimate load at failure compared to the control beam. Compared to the control beam, 10% and 15% replacement increased the load at failure by 39% and 23%. The study conducted by Mustafa et al.17focused on the flexural behavior of R-C-Bs that used WGP as an alternative to cement and fine aggregates. Ten R-C-Bs were evaluated in the experimental program. These included control beams, beams with 10% and 20% WGP values replaced with cement, and beams with 10% and 15% WGP values replaced with fine aggregate. Regarding the structural level, beams that include 10% WGP exhibited an increase in the cracking and ultimate loads by 29.0% and 6.9%, respectively. On the other hand, beams that contain 20% WGP exhibited minor decreases in the cracking and ultimate loads.The flexural behavior of the glass-recycled concrete in the R-C-B was examined by Talukder18. In this investigation, it was shown that a 20% glass component increased CS by 12.5% over a glass-free one. However, when more glass is added to the mixture, the strength diminishes. Furthermore, since there was only a 1–8% variance for adding glass content up to 20% replacement, the flexural capacity of beams with WGP was extremely similar to that of the control beams.

As can be observed from the previous investigations, there are several researches on the inclusion of WGP in the literature. Investigators have established variations in the properties of concrete, and have discussed the importance of the flexural behavior of reinforcement concrete with WGP. This investigation is also supposed to complete the lacking part in the literature in terms of relating the experimental implications with the information gained by the digital image correlation method. Additionally, in this investigation, DIC is also used to evaluate the experimental test implications. In this regard, the present study aims to fill the existing gap in the literature. Details are given in the following sections.

Materials and methods

Within the scope of this investigation, CEM-I 32.5 Portland cement was used, along with certain quantities of cement that were related to WGP, so as to achieve structural strength. A ratio of 0.5 water to cement was intended to be used. Additionally, WGP was used in 10%, 20%, and 30% weight proportions to replace the cement. Glass that is 100–200 microns in thickness is considered fine glass. 1 to 4 millimeters is the size range of fine aggregates. A 5–12 mm coarse aggregate variety of sizes was employed. At the same time, tests for compression strengths, splitting strengths and flexural strengths were performed according to the relevant ASTM standards19,20,21. The production of cylindrical examples with dimensions of 100 mm x 200 mm and cubic examples with dimensions of 150 mm x 150 mm x 150 mm were utilized in this study. The results are given in Table 1. More details can be found in22.

Table 1 Average results of concrete test22.
Full size table

The samples were designed with dimensions of 100 × 150 × 1000 mm. The reinforcement preparation and test formation are symbolized in Fig. 1., which also demonstrates the reinforcement layout. This investigation is dedicated mainly to the weight% of WGP as its primary variable, with the SS as its secondary variable of attention. Three of these examples were chosen as references23 and did not contain any WGP, as the other examples had varying quantities of WGP based on their Wf percentages: 10%, 20%, and 30% respectively. Table 2 demonstrates the features of the examples that have been composed.

Table 2 Properties of specimens.
Full size table
Fig. 1
figure 1

Reinforcement layout for samples.

Full size image

Experimental results and discussion

Influence of changed SS on reinforcement on WGP

In this part of the investigation, to examine the influence of changed SS on reinforcement, R-C-Bs were tested with changed SS. Since R-C-Bs are designed as shear beams, they are symbolized by the letter S, while the letters GP represent Glass Powder, the next number is the beam number (270 mm in beams 1,4,7,10; 200 mm in beams 2,5,8,11 and 160 mm in beams 3,6,9,12) and the last % value symbolizes the percent change of cement with glass powder by weight. For example, in the sample S_GP5_10%, the symbol S indicates that the beam is a shear beam, GP glass powder additive is used, the number 5 indicates that the stirrups inside the beam are placed at a distance of 200 mm, and 10% indicates that 10% glass powder is used instead of cement.

There are five types of shear failures in R-C-Bs. These are Diagonal Tension Failure, Shear Compression Failure, Shear Tension Failure, Web Crushing Failure, and Arch Rib Failure. Damages vary according to different SS and WGP ratios in beams. Detailed information is presented in the following sections.

Situation 1: fracture and load-bending (L-D) behavior of R-C-B (S_GP1_0%, S_GP2_0%, S_GP3_0%)

As shown in Fig. 2, the L-D curves of the R-C-B are presented. As pointed out in Fig. 2, for the SS elected as 160 mm (S-GP3), the maximum load level was obtained as 55.16 kN, and the maximum displacement was measured as 10.22 mm. When the SS was selected as 200 mm (S-GP2), these values were found to be 48.16 kN and 8.89 mm. When the SS was increased to 270 mm (S-GP1), it was observed that these values reduced to 41.70 kN and 6.93 mm. Compared to S-GP3, S-GP1 and S-GP2 carried 24.4% and 12.7% less load, respectively23. This proves that the load-carrying capacity will decrease as the SS increases. When the damage analyses were examined, it was observed that the fracture occurred as shear compression failure since the SS was large in SGP-1. In addition, diagonal tension failure was observed in S-GP2 and S-GP3.

Fig. 2
figure 2

Comparison of failure patterns and L-D for 0% WGP with different SS23.

Full size image

Situation 2: fracture and L-D behavior of R-C-B (S_GP4_10%, S_GP5_10%, S_GP6_10%)

In this part of the investigation, WGP, including 10%, was chosen as a replacement for cement to examine the influence of WGP with SS on shear productivity. In Fig. 3, the L-D curves of the R-C-B tests are shown, and the R-C-B’s fracture and collapse forms are noticed. Depending on these curves, for the SS selected as 160 mm (S-GP6), the maximum load level was noted as 49.41 kN, and the maximum displacement was found to be 12.77 mm. When the SS was selected as 200 mm (S-GP5), these values reached 46.27 kN and 9.23 mm. When the SS was enhanced to 270 mm (S-GP4), it was observed that these values reduced to 38.68 kN and 8.14 mm. In other words, compared to S-GP4, S-GP5 and S-GP6 carried 19.6% and 27.7% more load, respectively. When compared with the above condition (Situation 1), it can be concluded that as the percentage of the WGP was enhanced from 0 to 10%, the load-bearing capacity from S-GP1 to S-GP4 (7.2%), S-GP2 to S-GP5 (3.9%) and S-GP3 to S-GP6 (10.4%) decreased. When the influence of stirrup placing on the L-D abilities of R-C-Bs is estimated, it is observed that as the SS reduces, the L-D abilities of the R-C-Bs gradually increase. It was concluded that these implications were parallel to the above situation 1. When the fracture modes of the specimens were examined, diagonal tension failure was first observed in S-GP4, and then shear tension failure emerged as a result of the leverage effect as the load increased, and the experiment was terminated. While diagonal tension is observed in S-GP5, failure occurred as a result of diagonal tension damage due to crushing as a result of stress concentration in S-GP6. In other words, while shear compression damage was observed in SGP-1, the damage was shear tension with 10% WGP contribution. Diagonal tension damage in S-GP2 and S-GP3 was also observed in S-GP5 and S-GP6. This indicates that a 10% WGP contribution changed the fracture mode of S-GP4, S-GP5 and S-GP6.

Fig. 3
figure 3

Comparison of failure patterns and L-D for 10% WGP with different SS.

Full size image

Situation 3: fracture and L-D behavior of R-C-B (S_GP7_20%, S_GP8_20%, S_GP9_20%)

In this part, 20% WPG was used as a replacement for cement to observe the influence of WGP with SS on shear productivity. In Fig. 4, the L-D curves of the R-C-B tests are shown in the experimental results. According to these curves, for the SS selected as 160 mm (S-GP9), the maximum load level was obtained as 47.29 kN and the maximum displacement was noted as 12.08 mm. While the SS was selected as 200 mm (S-GP8), these values reached 39.70 kN and 12.35 mm. While the SS enhanced to 270 mm (S-GP7), it was concluded that these values reduced to 36.58 kN and 8.03 mm. Compared to the previous conditions (Situation 1 and Situation 2), it can be observed that the load-carrying capacity of S-GP7 decreased by 12.3% and 5.4%, respectively, when the WGP increased to 20%. The load-carrying capacity of S-GP8 is 17.6% less than S-GP2 and 14.2% less than S-GP5. Finally, S-GP9 carried 14.3% and 4.3% less load than S-GP3 and S-GP6, respectively. At the end of the experiment, all beams collapsed as a result of shear damage. However, when the fracture modes were examined in detail, it was observed that shear tension in S-GP7, shear compression in S-GP8, and diagonal tension in S-GP9 were the causes of failure. These implications were understood to be parallel to the above in Situation 1 and Situation 2.

Fig. 4
figure 4

Comparison of failure patterns and L-D for 20% WGP with different SS.

Full size image

Situation 4: fracture and L-D behavior of R-C-B (S_GP10_30%, S_GP11_30%, S_GP12_30%)

In this section, the 30% contribution of WGP to cement is examined. As indicated in Fig. 5, the L-D curves of the R-C-B experiments are examined. Based on these curves, for the stirrup arrangement chosen as 160 mm (S-GP12), the maximum load level was found as 41.84 kN and the maximum displacement was detected as 13.47 mm. When the stirrup arrangement was selected as 200 mm (S-GP11), these values were obtained as 37.68 kN and 11.87 mm. When the SS was increased to 270 mm (S-GP10), it was observed that these values reduced to 35.80 kN and 8.02 mm. As related to the above condition (Situation 1, Situation 2, and Situation 3), it may be observed that as the percentage of the WGP was enhanced to 30%, the L-D abilities of the R-C-Bs increasingly reduced as a consequence of the future existence of shear fractures in the R-C-Bs. In other words, the load-carrying capacity of S-GP12 is 24.1% less than S-GP3, 15.3% less than S-GP6, and 11.5% less than S-GP9. The decrease in load-carrying capacity for S-GP11 was 21.8% for (S-GP2), 18.6% for (S-GP5), and 5.1% for (S-GP8). For S-GP10, the decrease in load-carrying capacity was 14.1% for (S-GP1), 7.4% for (S-GP4) and 2.1% for (S-GP7), respectively. When the damage modes of the specimens were examined at the end of the test, the S-GP10, S-GP11 and S-GP12 specimens were found subjected to diagonal tension damage. It was considered that these implications were parallel to those in Situation 1, Situation 2, and Situation 3.

Fig. 5
figure 5

Comparison of failure patterns and L-D for 30% WGP with different SS.

Full size image

As can be noticed from Figs. 2, 3, 4 and 5, the reference R-C-Bs have got the maximum load capacity in all SS. Nonetheless, the bending productivity of R-C-Bs reduced as the consumption of WGP enhanced, just parallel to the CS of concrete. In R-C-B specimens with SS values of 160 mm, 200 mm and 270 mm, 0%, 10%, 20%, and 30% WGP additives decreased the loading capacity of the R-C-Bs compared to the reference specimens. This decreased ratio is found to be 10.42(S-GP6)−14.26(S-GP9)−24.15%(S-GP12);3.92(S-GP5)−17.56(S-GP8)−21.77%(S-GP11) and 7.24(S-GP4)−12.26(S-GP7)−14.14%(S-GP10), respectively. Additionally, although this decrease in the loading capacity of the R-C-Bs is associated with the quantity of WGP, it is not linear. It may be concluded from this information, that the quantity of decrease in the loading forces changed depending on the stirrup gaps. As the arrangement of the stirrups in the R-C-B decreased (270 mm > 200 mm > 160 mm), the WGP also had a negative effect on the bearing ability of the R-C-B at increasing WGP values (10%<20%<30%). The reason for this might be that the share of shear stresses covered by the stirrup is higher due to the reduction of the SS. Furthermore, as mentioned above, while the effect of stirrup position on the load-bearing capabilities of R-C-Bs is clear, as the stirrup positioning reduces, the load-bearing capacities of the R-C-Bs gradually increase as a consequence of the later existence of shear fractures in the R-C-Bs.

Influence of different percentages of WGP on reinforcement

In the section, to examine the influence of changed WGP percentages on reinforcement, R-C-Bs were subjected to testing with changed WGP percentages. For this purpose, the weight percentages of 0%, 10%, 20% and 30% WGP were selected and verified. Details are given in the following sections.

Situation 1: fracture and L-D behavior of percentage of WGP for stirrup arrangement of 160 mm

The quantities of WGP are designated as 0%, 10%, 20% and 30% and stirrup arrangement in the R-C-B is selected uniformly as 160 mm. As a result of the investigational examination for 0%, 10%, 20% and 30%, it is observed that there were significant bending fractures in the R-C-B based on the vertical load as presented in Fig. 6. Concerning Fig. 6, for the WGP percentage chosen as 0%, the maximum load level was obtained as 55.16 kN (S-GP3) and the maximum displacement was found to be 10.22 mm. When the WGP percentage was chosen as 10%, these values were found to be 49.41 kN (S-GP6) and 12.77 mm. When the WGP percentage was increased to 20%, it was observed that these values reduced to 47.29 kN (S-GP9) and 12.08 mm. At that point, when the WGP percentage was increased to 30%, it was observed that these values reduced to 41.84 kN (S-GP12) and 13.47 mm. Finally, the load-carrying capacity of S-GP12 is 24.1% less than S-GP3, 15.3% less than S-GP6, and 11.5% less than S-GP9. S-GP3, S-GP6, S-GP9 and S-GP12 were observed to have collapsed as a result of diagonal tension failure.

Fig. 6
figure 6

Evaluation of L-D of R-C-Bs with stirrup arrangement 160 mm for different quantity of WGP.

Full size image

Situation 2: fracture and L-D behavior of percentage of WGP for stirrup arrangement of 200 mm

In this section, the quantities of WGP are selected as 0%, 10%, 20% and 30% while the stirrup arrangement in the R-C-B is taken to be constant at 200 mm. As a result of examination for 0%, 10%, 20% and 30%, it was measured that there were significant bending fractures in the R-C-B subject to the vertical load as given in Fig. 7. With regard to Fig. 7, for the WGP percentage designated as 0%, the maximum load level was found to be 48.16 kN (S-GP2) and maximum displacement was detected as 8.89 mm. When the WGP percentage was designated as 10%, these values were 46.27 kN (S-GP5) and 9.23 mm. When the WGP percentage was increased to 20%, it was observed that these values reduced to 39.70 kN (S-GP8) and 12.35 mm. As the WGP percentage was increased to 30%, it was established that these values reduced to 37.68 kN (S-GP11) and 11.87 mm. In other words, the decrease in load-carrying capacity for S-GP11 was 21.8% (S-GP2), 18.6% (S-GP5), 5.1% (S-GP8). S-GP2, S-GP5 and S-GP11 collapsed as a result of diagonal tension, while shear compression damage occurred in S-GP8.

Fig. 7
figure 7

Evaluation of L-D of R-C-Bs with stirrup arrangement 200 mm for different quantity of WGP.

Full size image

Situation 3: fracture and L-D behavior of percentage of WGP for stirrup arrangement of 270 mm

To examine the influence of changed WGP percentages on stirrup arrangement, the quantities of WGP are selected as 0%, 10%, 20% and 30% while the stirrup arrangement in the R-C-B is chosen constant as 270 mm. As a result of investigational examination implications for 0%, 10%, 20% and 30%, it is observed that there were significant bending fractures in the R-C-B based on the vertical load, as given in Fig. 8. According to Fig. 8, for the WGP percentages designated as 0%, the max. load level was found to be 41.70 kN (S-GP1) and the maximum displacement was 6.93 mm. When the WGP percentage was designated as 10%, these values were 38.68 kN (S-GP4) and 8.14 mm. As the WGP percentages were increased to 20%, it was observed that these values reduced to 36.58 kN (S-GP7) and 8.03 mm. Next, when the WGP percentages were increased to 30%, it was observed that these values reduced to 35.80 kN (S-GP10) and 8.02 mm. For S-GP10, the decrease in load-carrying capacity was 14.1% (S-GP1), 7.4% (S-GP4) and 2.1% (S-GP7), respectively. Significant changes in damage modes were observed in specimens with a SS of 270 mm. In other words, the increase in the WGP ratio in beams with a large SS had an effect on the damage modes. Shear compression in S-GP1, diagonal tension first and later shear tension in S-GP4, shear tension in S-GP7 and diagonal tension in S-GP10 were observed.

Fig. 8
figure 8

Evaluation of L-D of R-C-Bs with stirrup arrangement 270 mm for different quantity of WGP.

Full size image

As a result, as might be noted from Figs. 6, 7 and 8 given above, it is observed that the load capacity of the R-C-Bs gets reduced as the WGP percentages in the concrete combination are increased from 0 to 30%. From the L-D curve it was noticed that the deformation decreased linearly with increasing loading. A significant reduction was noticed as the WGP percentage adding level became greater than 10%. The R-C-Bs with 10% WGP exhibited further brittle failure, with extensive fracture compared to the reference R-C-B.

Influence of changed percentages on the energy dissipation of WGP

Energy distribution is known as a limitation that contributes to the deformation progression of structural components. Concrete CS, reinforcement ratio, cross-section dimensions, and loading history might be counted among the factors affecting the value of energy distribution. Energy dissipation is obtained as a result of computing the area under the load-deflection curve from the experimental tests. Energy dissipation is the capability of a structural member to transfer energy from side to side in the process of yielding the reinforcement, thus it defines the destruction mechanism of structures. Normally, the destruction mechanism is exposed as structural fractures or yielding of reinforcement. Thus, large dissipation energy is the best characteristic for structural components. When the energy dissipation is huge, plastic distortion might be achieved earlier than failure occurrence. Park et al.24 indicated that energy dissipation is closely associated with ductility. A structural component with a high ductility might resist more loads as a result of large inelastic bending before reaching failure. Table 3 shows the ductility ratio (µ) of the R-C-B. To determine the value, the formula µ = δu/δy was utilized. In this equation, δu represents the observed displacement value at peak failure load, and δy indicates the experimental deflection under yielding conditions. Furthermore, it was necessary to determine the entire amount of energy that was necessary to generate deformation to evaluate the strength of the R-C-B. This was accomplished by measuring the area under the load-deflection curve up until the point of failure. Information on four distinct categories of energy absorption values—EPmax, Ey, Ep, and ET—is provided in Table 4. The four energy components give the energy dissipated up to the ultimate load (Pmax), 85% of the ultimate load (yielding load, Py), the plastic region, and the ultimate deflection (δmax). An evaluation of all experiment samples is given in Tables 3 and 4. According to these Tables, if the energy dissipation is investigated according to the changed stirrup arrangement, the percentage of total energy dissipation of S_GP3_0% increased by 95% when compared to S_GP1_0%. Compared to S_GP1_0%, the percentage of total energy dissipation that was achieved by S_GP4_10% increased by 26%. In comparison to S_GP2_0%, the percentage of total energy dissipation for S_GP5_10% dropped by 3.10% as the WGP amount in the concrete combination increased from 0 to 10%. When compared to S_GP1_0%, S_GP7_20% obtained a 18.71% higher percentage of total energy dissipation. As the WGP quantity in the concrete combination grew from 0 to 20%, the percentage of total energy dissipation for S_GP8_20% increased by 24.49% compared to S_GP2_0%. With the increase in WGP quantity in the concrete combination from 0 to 20%, the percentage of total energy dissipation for S_GP9_20% rose by 13.67% compared to S_GP3_0%. S_GP10_30% was able to accomplish a higher percentage of total energy dissipation than S_GP1_0%, which resulted in a 3.03% increase in the attained percentage. In comparison to S_GP2_0%, the percentage of total energy dissipation for S_GP11_30% increased by 20.84% as the WGP amount in the concrete combination changed from 0 to 30%. As a result of the increase in the amount of WGP in the concrete mixture from 0 to 30%, the percentage of total energy dissipation for S_GP12_30% increased by 14.26% in comparison to S_GP3_0%.

These values ​​are significant in terms of demonstrating the variations in the energy dissipation percentages for different stirrup intervals. For the same stirrup ratio, the increase in SGP-6, S-GP9, and S-GP12 compared to S-GP3 was 17.13%, 13.67% and 14.26%, respectively. Similarly, SGP-5 decreased compared to S-GP2 (3.10%), while S-GP8 increased compared to S-GP11 by 24.49% and 20.84%, respectively. Finally, the increase in SGP-4, S-GP7, S-GP10 compared to S-GP1 was 26.05%, 18.71% and 3.03%, respectively.

In accordance with results and conclusions available in the literature, it was recognized that the main factor affecting energy dissipation is the presence or production of ductility24.

Table 3 Experimental results for load and disp. Values.
Full size table

[Edit]

Table 4 Experimental test results for energy dissipation ability.
Full size table

Evaluation of shear test results with eurocode 2 and ACI 318 − 19

In this section, the experimental shear strengths of beams obtained as a result of four-point bending tests are compared with the so-called shear abilities estimated using Eurocode 225and ACI 318 − 1926 regulations. Safety coefficients given in the regulations were not used in the comparisons.

Eurocode 2 proposes equations in which the concrete contribution to shear strength (Vc) and the contribution of the stirrups to shear strength (Vs) are considered separately. In this context, in the calculation of the shear abilities of beams with Eurocode 2, it was used in calculations greater than Vc or Vs. Since the shear arm length of the beam is (a = 350 mm), the angle between the compression strut and the beam axis (θ) has been accepted as the angle between the beam axis and the line drawn from the support to the point of loading (θ = 18.48o). However, since Eurocode 2 limits this angle to 21.8 degrees, a value of 21.8 degrees is used in the calculations.

$$\:{V}_{c}=0.18k\sqrt[3]{100{\rho\:}_{sl}{f}_{c}^{{\prime\:}}}{b}_{w}d$$
(1)
$$\:{V}_{c,min}=0.035{k}^{\frac{3}{2}}\:\sqrt{{f}_{c}^{{\prime\:}}}{b}_{w}d$$
(2)
$$\:k=1+\sqrt{\frac{200}{d}}\le\:2$$
(3)
$$\:{\rho\:}_{sl}=\frac{{A}_{sl}}{{b}_{w}d}\le\:0.02$$
(4)
$$\:{V}_{s,max}=\frac{{\alpha\:}_{cw}{b}_{w}z\:{\nu\:}_{1}{f}_{c}^{{\prime\:}}}{cot\theta\:+tan\theta\:}$$
(5)
$$\:{\nu\:}_{1}=0.6\left[1-\frac{{f}_{c}^{{\prime\:}}}{250}\right]$$
(6)
$$\:{V}_{s}=\frac{{A}_{sw}}{s}z{f}_{ywk}cot\theta\:\le\:{V}_{Rd,max}$$
(7)
$$z = 0.9d$$
(8)
$$\:{\rho\:}_{w}=\frac{{A}_{sw}}{s\bullet\:{b}_{w}}$$
(9)
$$\:{\rho\:}_{w,min}=0.08\frac{\sqrt{{f}_{c}^{{\prime\:}}}}{{f}_{y}}$$
(10)

where, Asl is the tensile reinforcement area (mm2), ρsl is the tensile reinforcement ratio (mm2/mm2), αcw is the compression chord coefficient (1 for non-prestressed), ν1 is a factor of strength reduction for concrete ruptured in shear, z is the moment arm (mm), Asw is the stirrup area (mm2), ρw is the stirrup ratio (mm2/mm2), fy is the yield strength of steel reinforcement (MPa), and s is the SS (mm).

In contrast to Eurocode 2, the ACI 318 − 19 regulation proposes an equation in which the contribution of concrete to shear strength (Vc) and the contribution of stirrups to shear strength (Vs) are considered together to calculate the so-called shear capacity of the beam (Vn=Vc+Vs).

$$\:{V}_{c}=0.66\lambda\:\sqrt[3]{{\rho\:}_{sl}}\sqrt{{f}_{c}^{{\prime\:}}}{b}_{w}d\le\:{V}_{c,max}$$
(11)
$$\:{V}_{c,max}=0.42\lambda\:\sqrt{{f}_{c}^{{\prime\:}}}{b}_{w}d$$
(12)
$$\:{{A}_{sw}\ge\:A}_{sw,min}=0.35\frac{{b}_{w}}{{f}_{y}}s$$
(13)
$$\:{V}_{s}=\frac{{A}_{sw}{f}_{y}}{s}d\le\:{V}_{s,max}$$
(14)
$$\:{V}_{s,max}=0.66\sqrt{{f}_{c}^{{\prime\:}}}{b}_{w}d$$
(15)
$$\:{V}_{n}={V}_{c}+{V}_{s}$$
(16)

where λ is the modification weight factor for concrete (where the value of 1 can be taken for normal weight concrete).

Shear strengths calculated with regulation formulas and shear strengths obtained as a result of the beam tests are given in Table 5. In addition, the results obtained are shown graphically in Fig.  9 to make comparisons easier.

Table 5 Comparison of experimental shear force with ACI 318 − 19 and Eurocode 2.
Full size table
Fig. 9
figure 9

Comparison of experimental shear force with ACI 318-19 and Eurocode 2.

Full size image

When the shear capacity (Vc) of beams without stirrups is compared for the two regulations, the shear capacities calculated with ACI318-19 (welding) are much lower than the values calculated with EC2 (welding). The beam shear capacity estimated by ACI 318 − 19 for all beams is between 0.56 and 0.62 times EC2. However, when only the contribution of stirrups to shear capacity (Vs) is compared in beams, it is seen that EC2 results in a much higher contribution. When the results are compared to each other (Vs, EC2/ Vs, ACI), it is seen that EC2 estimates the stirrup contribution to shear capacity to be 125% higher than ACI. This is due to the shortness of the beam and the small compression strut angle (θ = 21.8o). Since ACI318-19 (welding) is based on the classical truss method, the angle of the compression struts with the beam axis is 45 degrees. Since the compression strut angle is included in the Eq. 8 (cot21.8o = 2.5) proposed by EC2, and the useful height is multiplied by 0.9, the contribution of stirrups is approximately 125% larger. However, EC2 limits the shear contribution of the concrete or stirrups to Eq. 5 so that the compression bars can carry them without being crushed. In this case, the stirrup contribution is between 0.90 times and 2.25 times of ACI 318 − 19.

Final shear capacities estimated by the regulation formulas are compared with the experimental results in Fig. 10. The shear capacities of the beams with EC2 varied between 0.95 times and 1.72 times the experimental results. The main reason for this big difference is that the compression strut angle is added to the equation as mentioned before. It is seen that the estimation performance of EC2 increases as the SS decreases in beams or, in other words, as the stirrup ratio increases. It is seen that the estimation performance of EC2 increases slightly as the compressive strength of concrete decreases.

It can also be observed from Fig. 10 that, unlike EC2, ACI318-19 predicts the shear capacities of beams as closer to the experimental results. Estimates ranged from 1.15 times to 1.51 times compared to the experimental values. Interestingly, as the spacing of the stirrups decreases in the beams, the percentage of deviation of the estimates from the experimental results increases. A similar situation arises as the CS of concrete decreases. This is most likely due to the fact that the concretes used in the tests have a lower shear strength than expected, depending on the CS of 15 MPa or less (fcylinder=0.8fcube). According to ACI 318 − 19, the lowest cylinder concrete CS to be used is 17 MPa.

Fig. 10
figure 10

Ratios of shear abilities estimated by regulations to experimental results.

Full size image

Strain and deflection estimate using DIC

In the study, the strain and displacement values of the beams under load were measured by the DIC and compared with the test results. The image processing process and measurement details have been explained in detail and Fig. 1123.

This investigation supports to the deformation of the real R-C-B example while it is under loading as given in Fig. 11. Reference points chosen on the R-C-B for imaging are given in Fig. 11. As the loading reaches the failure load, a distinct shear fracture is visible at the bottom of the displacement pattern. Additionally, as shown in Fig. 11 the digital image of R-C-B displays the presence of minor fractures on the R-C-B surface depending on the strain values. Additionally, the pictures also reveal crack propagation in the R-C-B test specimens. As the R-C-B is put to failure loading, it is fractured as given in Fig. 12. As load is increasingly enhanced, the strain amount demonstrates minor strain occurred at the R-C-B bottom in the y direction. When increasing the loading, it has been appointed that fractures that might not be detected with the naked eye occur and are noticeable in the figure. The strains on R-C-B exhibit a 45-degree route for all strain capacities, which is comparable to the digital depiction shown in Fig. 12. This, in turn, has an impact on the specimen fracture to shear, as indicated by the strain diagram. At the end of the image processing, as given in Fig. 13, the assessment of the displacement values obtained from investigational tests and image processing are given. To carry out a comparison between the real data collected from the Digital Image Correlation (DIC) system and the findings produced from the beam, it is necessary to convert the displacement values to a coordinate system that is appropriate27. Therefore, changes were made and compared according to the displacement results obtained according to reference points. Alterations in load are not taken into consideration. As observed in Fig. 13, closer agreement between the values obtained from experimental tests and image processing is observed. It is clear from a comparison of the findings presented in Fig. 13 that the displacement and strain measurements in structures can be determined in a manner that is nearly cost-effective by employing a technology that does not involve destruction. After determining structure deformations, damage can be prevented or repaired within a particular period. The DIC also shows the deteriorating movement of uncertain locations due to loads.

Fig. 11
figure 11

Comparison of the cracking development in image processing.

Full size image
Fig. 12
figure 12

Comparison of the experimental and image processing cracking observation.

Full size image
Fig. 13
figure 13

Comparison of the displacement values attained from experimental tests and image processing.

Full size image

Conclusions

This research investigated the flexural behavior of R-C-Bs containing varying quantities of WGP based on their Wf percentages: 10%, 20%, and 30% respectively, and also on changed SS (270 mm, 200 mm and 160 mm). The conclusions in brief are as follows:

  • As the quantity of WGP replacing the cement in the concrete was increased up to 30%, there was a noteworthy decrease in CS compared to the reference concrete. This decrease in strength is proportionally in the order of 3.65%, 9.42%, and 43.52%. Furthermore, an important reduction on the L-D curve was observed as the WGP percentage adding level was more than 10%. The R-C-Bs with 10% WGP demonstrated further brittle failure, with more extensive fractures than that of the reference R-C-B.

  • In R-C-B specimens with a SS of 160 mm, 200 mm, and 270 mm, 0%, 10%, 20%, and 30% WGP additives decreased the loading capacity of the R-C-Bs compared to the reference specimens. The S-GP12 has a load carrying capacity that is 24.15% lower than that of the S-GP3, while the S-GP6 and S-GP9 have load carrying capacities that are 10.42% and 14.26% lower than the S-GP3, respectively.

  • When the total energy dissipation capacities are compared, the highest increase of 17.1% was observed in S-GP6 for 160 mm stirrup spacing. For 200 mm stirrup spacing, the highest increase was observed in S-GP8 with an increase of 24.5%, and the highest increase of (26.1%) was observed in S-GP4 for 270 mm stirrup spacing. In other words, as the WGP ratio increases, the energy dissipation capacity tends to decrease.

  • When the shear capacity (Vc) of longitudinally reinforced beams without stirrups was compared for different regulations, it was observed that the shear capacities calculated with ACI318-19 are much lower than the values ​​calculated with EC2. The beam shear capacity estimated as a result of ACI 318 − 19 for all R-C-Bs is between 0.56 and 0.62 times that given by EC2. However, when only the contribution of stirrups to the shearing capacity (Vs) is compared in beams, the contribution of stirrups calculated with EC2 is between 0.77 times and 2.26 times the value calculated with ACI 318 − 19.

  • The so-called shear strengths of beams calculated with ACI 318 − 19 varied between 1.15 times and 1.51 times the experimental results, while the strengths calculated with EC2 varied between 0.95 times and 1.72 times the experimental results.

  • As opposed to EC2, it can be observed that ACI318-19 predicts the shear abilities of R-C-Bs which are higher than the experimental results. It was observed that the estimated values were 15–51% higher than the experimental results. Remarkably, as the spacing of the stirrups decreased in the R-C-Bs, the percentage of deviation of the estimates from the experimental results also increased. It was noted that a similar situation arises as the CS of concrete decreased. This was most likely due to the fact that the concretes used in the tests had less shear strength than expected, depending on the CS of 15 MPa or less (fcylinder=0.8fcube). According to ACI 318 − 19, the lowest cylinder concrete CS to be used is 17 MPa.

  • In this investigation, the results attained from the experimental investigations were compared with the Image Processing Technique. As a result of the tests, it has been noted that the results of the Image Processing Technique are very close to the experimental results.

Future Studies.

It is considered that the optimum consumption percentages determined by the results of the present work will provide a guide for future research. Additionally, the usage of concrete inclusive WGP in columns and R-C-Bs may be studied for structural weight, structural rigidity, the fundamental period of the construction, and the earthquake structural response. It has been found that the image processing technique used in this study can be a supportive tool for destructive and non-destructive testing methods in future investigations.