Experimental Investigation on Ternary Blended Recycled Aggregate Concrete Using Glass Fibers
Department of Civil Engineering, Kumaraguru College of Technology, Coimbatore 641049, Tamil Nadu, India
*
Author to whom correspondence should be addressed.
Buildings 2023, 13(8), 1961; https://doi.org/10.3390/buildings13081961
Submission received: 29 June 2023
/
Revised: 19 July 2023
/
Accepted: 24 July 2023
/
Published: 1 August 2023
(This article belongs to the Section Building Materials, and Repair & Renovation)
Abstract
:The demand for sustainable construction materials has driven the exploration of various innovative approaches to enhance the properties of concrete for reducing its environmental impact. The present study examines the effects of incorporating recycled concrete aggregate (RCA), slag cement, alccofine, and glass fibers into concrete mixtures. In the present study, it has been observed that recycled concrete aggregate (RCA) exhibits inferior properties, including higher water absorption and poorer performance, when compared to natural coarse aggregate. Various replacement levels of RCA were utilized in this study to assess its impact on concrete performance. Alccofine, a supplementary cementitious material, is used to partially replace the binding material. Additionally, glass fibers were added to enhance the flexural and tensile behavior of the concrete. The concrete mixtures were designed to meet the required strength and durability specifications. A comprehensive testing program was conducted to evaluate the fresh and hardened properties of the concrete. A slump cone test was performed for assessing the workability of fresh concrete. For hardened concrete, compressive strength, flexural strength, and split tensile strength are evaluated. The results demonstrated that incorporating RCA, slag cement, alccofine, and glass fibers into the concrete mixtures improved mechanical properties. The use of RCA led to a reduction in natural resource consumption, namely natural coarse aggregate in concrete. On the other hand, the generated construction and demolition (C&D) waste is used effectively. Portland slag cement (PSC) and alccofine (A) improved the long-term strength of concrete. The addition of glass fibers significantly enhanced the tensile and flexural performance of the concrete, resulting in improved crack resistance and overall performance. This study introduces a novel concept by exploring the potential utilization of recycled concrete aggregate, slag cement, alccofine, and glass fibers in combination as sustainable and high-performance components in concrete mixtures. Previous research has not extensively studied this combination of materials, making it a unique and innovative approach. These findings contribute to the development of eco-friendly construction practices and provide insights for engineers, researchers, and practitioners aiming to incorporate recycled materials and supplementary cementitious materials into concrete construction.
1. Introduction
In recent decades, the construction industry significantly consumed natural resources and produced a substantial quantity of construction and demolition (C&D) waste. It uses available natural sand as a fine aggregate, limestone in cement manufacturing, and aggregates obtained by the quarrying of rocks are used as a coarse aggregate, which occupies a volume of 60–70% of the concrete. Developing nations like India are required to fulfill the needs of the increasing population in terms of infrastructure development and housing. Additionally, rapid industrialization and urbanization led to the consumption of the available natural resources, resulting in their depletion and causing scarcity for upcoming generations. Many researchers focus on minimizing the consumption of the available resources by using waste materials, which saves the economy and the environment. Whenever construction or demolition activities take place, it results in a generation of C&D waste, which is unavoidable. The stockpiling of C&D wastes in the landfill results in environmental degradation [1]. Moreover, construction waste management (CWM) has emerged as a significant environmental issue in numerous municipalities across India. The amount of construction waste generated in India stands at 150 million metric tons, representing approximately 35% to 40% of the global construction and demolition (C&D) waste produced each year [2]. Figure 1 illustrates the generation of construction and demolition (C&D) waste across different cities in India. Hence, the concept of recycling came into practice for using this waste, which results in sustainability and reduces the demand of landfill required for the disposal of C&D waste [2]. After enormous research, many countries have adopted the process of recycling C&D waste and published various codes regarding its use in construction activities. The concept of recycling and reusing helps in maintaining sustainability. This results in improving the economy and minimizes the consumption of the available natural aggregate. It reduces the reliance on natural aggregates. Generated C&D waste comprises concrete, bricks, tiles, glass, ceramics, wood, etc. [3]. Aggregates occupy a major share in the C&D waste of a concrete structure, and the aggregates obtained from the recycling plants after recycling C&D waste are termed recycled concrete aggregate [4].
Numerous studies have investigated the behavior of recycled aggregates in concrete’s mechanical and durability properties at various replacement percentages. From the literature review, it is evident that recycled concrete aggregate possesses inferior properties when compared to natural aggregates, such as higher water absorption [5], higher abrasion value [6], and higher crushing value [7], which is due to the pre-existence of old adhered mortar on recycled aggregates, which restricts its usage in construction activities and limits its usage as a granular base or sub-base for the construction of roads [2]. Moreover, it was observed that the water absorption of recycled concrete aggregates (RCA) tends to increase as the aggregate size increases [8]. Additionally, this relationship is observed to be independent of the grade of the parent concrete [9]. The aggregate crushing value is found to be higher than the conventional aggregate, and it is found to be 33% and 45% higher than the virgin aggregate for the 20–10 mm and 10–4.75 mm sized aggregates, respectively [10]. Table 1 shows the maximum permitted quantity of RCA to be used for different grades of the plain and reinforced concrete as per IS-383-2016 [11]. The higher water demand observed in recycled aggregates can be attributed to the presence of existing old, adhered mortar, unlike normal aggregates. The removal of adhered mortar on the surface of the aggregate depends on the method of crushing or the adopted treatment process. As the nominal size of the aggregate increases, there is a declining trend in the volume of adhered mortar content within the sample [9].
The quantity of adhered mortar removal on the aggregate depends on the method of crushing or the adopted treatment process. When the replacement percentage of RCA increases, it results in a decrease in the workability, hardened density, and mechanical properties of the recycled aggregate concrete (RAC) [2]. Earlier research findings indicate that the mechanical and durability properties of RAC are inferior to the NAC, and this disparity is predominantly attributed to the presence of adhered mortar on the surface of the recycled aggregates [12]. Therefore, there is a need to upgrade the quality of recycled aggregates before its utilization in concrete. The removal of the adhered mortar by mechanical action or soaking it in different acidic solutions, adopting different mixing techniques, strengthening the existing mortar on the aggregate like carbonation, or incorporating pozzolanic materials are some of the quality improvement techniques of RCA. Several studies have improved the behavior of recycled aggregate concrete by including supplementary cementitious materials (SCM), such as fly ash, ggbfs, silica fume, alccofine, etc., adding various types of fibers, and using different mixing approaches such as normal, two-stage, and three-stage mixing approaches. Alccofine is an environmentally friendly material that belongs to the new generation of SCMs. It is characterized by its high glass content and excellent reactivity. Alccofine consists of ultra-fine particles that, when incorporated into concrete, offer several benefits, including the reduction of cement consumption and CO2 emissions [13] Alccofine exhibits remarkable properties that contribute to enhancing the overall performance of concrete, both in its fresh and hardened states [14].
Concrete is an example of a brittle material and has poor performance in ductility. The strength and durability of the concrete is significantly influenced by properties of the fibers, including the fiber type, fiber length, aspect ratio, surface texture, and tensile strength. In general, conventional concrete has more resistance in compression and less resistance against tension, fatigue, and toughness. Concrete fibers are categorized into artificial and natural fibers. Examples of artificial fibers include steel, glass, polypropylene, and basalt fibers. Natural fibers, on the other hand, include palm fiber, jute fiber, coconut coir fiber, and so on. Fibers are used in enhancing the fatigue and toughness performance of the concrete.
GGBFS, a by-product of the iron-manufacturing process, exhibits cementitious properties. It can be utilized as a partial substitute for cement and acts as a SCM, which enhances the performance and durability of concrete when used [15]. Numerous researchers have investigated the properties of concrete through the utilization of GGBFS as a substitute for cement. As the replacement level of GGBFS increases, the performance of the concrete is observed to improve up to a certain threshold, beyond which it starts to decline [2]. Substituting a cement clinker with GGBFS often leads to reduced early strength, a gain of strength at later ages, prolonged setting times, and imposes limitations on the inclusion of high proportions of slag in Portland slag cement [15]. RCA, with its adhered mortar on its surface, has a porous nature and open cracks. When the GGBFS is added to the RCA, these cracks get filled up and enhance the performance of the RCA, which can be observed at later ages [2]. Due to the multiple advantages of slag in concrete, the slag is inter-ground with the clinker of OPC resulting in the formation of a Portland slag cement. It helps in reducing greenhouse gas emissions and conserving natural resources. Thus, the use of slag cement in concrete can be treated as ‘Green Concrete’ from the environmental point of view as it utilizes the waste by-product from iron-manufacturing industries [16]. PSC has better performance when compared to OPC, such as long-term strength development due to alkali-silica reactions, enhanced overall strength and durability, increased resistance to chemical attack, and improved resistance to sulfate and chloride ingress, and is environmentally friendly.
Figure 1.
C&D waste generation in various Indian cities [17].
Figure 1.
C&D waste generation in various Indian cities [17].
Based on the available literature, it is evident that the combination of slag cement, M sand, alccofine, recycled concrete aggregates from recycling plants, and glass fibers has not been widely investigated in concrete mixes. Moreover, there is limited research specifically addressing the use of recycled concrete aggregates with slag cement. In light of this, the present study introduces a novel concept by exploring the potential of incorporating a combination of recycled concrete aggregates, slag cement, alccofine, and glass fibers as sustainable and high-performance components in concrete mixtures. This research aims to investigate the behavior of these materials in different combinations and their practical application. The flow chart illustrating the research methodology is presented in Figure 2.
The current research seeks to offset the adverse impact of the RCA by employing the Portland slag cement that incorporates GGBFS as a raw material during its production, resulting in decreased environmental pollution caused by cement manufacturing. The present research evaluates the mechanical performance of the RAC without and with alccofine (10%, which is taken as optimum based on the results obtained in trial studies), in which the replacement level of RCA will be 0–100% with 25% intervals to the natural alkali resistant (AR) glass fibers of 12 mm, the size that is used in the present work. For this purpose, a total of 26 concrete mixes in five series were produced, and the properties, such as compressive strength, tensile splitting strength, and flexural strength after 7, 28, and 90 days of curing, were investigated on the concrete specimens.
2. Materials and Methods
Portland slag cement was used as a binder material, confirming IS:455-2015 [18]. In addition, Alccofine C-1203 (A 1203), procured from Counto Microfine Products Pvt Ltd., Goa, India, was used as a partial replacement to the binding material, having a specific gravity of 2.87 with a specific surface area of 1200 m2·kg−1, confirming ASTM C989-1999 [19]. The physical properties of PSC and OPC are presented in Table 2, and chemical properties of OPC and alccofine are mentioned in Table 3. Figure 3 and Figure 4 display microscopic images of alccofine and PSC. Manufactured sand was used as a fine aggregate (FA) and was obtained from the local industries, confirming IS-383-2016, falling under zone-2 whose specific gravity and water absorption were 2.47% and 2%, respectively. The crushed granite stone of 20 mm and 10 mm nominal size was obtained from the nearby locality. The recycled concrete coarse aggregate of 20 mm and 10 mm size was procured from the C&D waste recycling plant. To analyze the procured aggregates, sieve analysis was conducted according to the specifications outlined in IS-2386 Part-1. Figure 5 and Figure 6 represent the results of the grading analysis of fine and coarse aggregates, which indicate that the nominal size of the aggregates falls within the limit mentioned by IS: 383-2016. Table 4 presents the properties of coarse aggregates as per IS-2386 Part 3 and 4. From Table 4, it is evident that the RCA possesses inferior properties when compared with NCA. However, the RCA and NCA properties are within the specified limits of IS: 383-2016. In current research, an AR glass fiber of 12 mm length is used, and its properties are listed in Table 5. Conplast SP430, a super-plasticizer (SP) confirming to ASTM C494-2017 [20], was used in the present work and has a brown color appearance with a specific gravity of 1.18, in which the chloride content is 0 and the air entrainment is below 2%.
3. Mix Proportion and Designation
The mix design was carried out as per IS-10262-2019 [22] for M 40-grade of concrete (target strength is 48.25 MPa), and the details of mix notations and mix proportions are mentioned in Table 6 and Table 7, respectively. The combination of OPC (O) with natural coarse aggregates (N) is denoted as ON. Similarly, PSC (P) with natural coarse aggregates (N) is denoted as PN. Likewise, the other combinations are listed in Table 6. A total of 26 different mixes were prepared and tested in this study. Out of twenty-six different mix combinations, two of these mixes utilized natural coarse aggregates (NCA) and were prepared using both OPC and PSC. Additionally, four mixes were prepared with OPC, and four mixes were prepared with PSC using RCA. Another four mixes with the addition of 10% alccofine, along with PSC and RCA, were prepared. The dosage of alccofine was determined through trial studies, and RCA replacement levels were 25%, 50%, 75%, and 100%, respectively. A total of 12 mixes with glass fibers of 0.25%, 0.50%, and 0.75% proportions with 10% alccofine and with the RCA replacement of 25%, 50%, 75%, and 100% were casted.
4. Results and Discussion
4.1. Workability
In the present research, workability is expressed in terms of the slump. Many researchers concluded that the workability decreases with the increase of the replacement percentage of the recycled aggregates. By using a super-plasticizer Conplast SP430, the desired slump (50 ± 5 mm) is maintained uniformly for all the mixes. As per the research conducted by B. L. N. S. Srinath et al. [23], the addition of alccofine enhanced the workability by virtue of its fine particle size, smooth glossy surface, and increased the specific surface area, which also resulted in the reduction of SP dosage; the same is observed in the current research. The addition of AR glass fibers has a negative impact on the slump; this is because the fibers act as a physical barrier and hinder the flow of concrete. An increase in both fiber content and recycled concrete aggregate content leads to an observed increase in the dosage of superplasticizer (SP) required to maintain the desired slump in the concrete mixture.
4.2. Compressive Strength
The compression test is performed, as per IS-516-1959 [24], using a 150 mm size cube to mix all the proportions listed in Table 7 after 7, 28, and 90 days of curing. The results are plotted and presented in Figure 7 and Figure 8. From Figure 7, it can be seen that the compressive strength is found to decrease with the increase in the replacement content of RCA for both the OPC and PSC combinations. The increased water absorption of RCA, due to its porous nature, along with the increase in void ratio, adversely affects the compressive strength of RAC, which was concluded by M. H. El Ouni et al. [25] in their research. According to Ali and Qureshi et al. [26], the presence of a higher number of interfacial transition zones (ITZ) can be attributed to the lower strength in RAC compared to NAC. The compressive strength of the concrete mixtures OR25, OR50, OR75, and OR100 after 28 days of curing was reduced by 16–27%, respectively, compared to the strength of NAC made with OPC. The compressive strength of the RAC depends on the extent of RCA used. Furthermore, a study conducted by Li [27] demonstrated that the compressive strength of concrete exhibits an inverse correlation with the recycled concrete aggregate (RCA) content. The compressive strength of the concrete mixtures PR25, PR50, PR75, and PR100 after 28 days of curing was reduced by 12–23%, respectively, compared to the strength of the controlled specimen made with PSC. Based on these observations, it has been noted that the percentage decrease in the compressive strength of RAC is almost similar in strength after 7 days in both OPC and PSC combinations, but lesser in the case of the samples cast by using PSC after 28 days. The addition of PSC decreases the loss in compressive strength after 28 days of curing.
From Figure 7, it is observed that the RAC samples with PSC exhibited better strength—6–8% higher when compared with the OPC. This is due to the improved packing density, reduced heat of hydration, and the formation of additional hydration products, resulting in increased strength and durability. The inclusion of 10% alccofine as a replacement to the slag cement enhanced the compressive strength of RAC by 11%. This is due to the finer particle size and due to the formation of additional C–S–H gel, which is formed due to the reaction of Ca(OH)2 with alccofine, which was also concluded by S. C. Boobalan, et al. [28] in their study.
The incorporation of glass fibers improved the performance of the concrete. Glass fibers were added to the concrete with dosages of 0.25%, 0.50%, and 0.75%. From Figure 8, it is observed that relative optimum strength is achieved at the 0.50% dosage of glass fiber. An addition of fibers resulted in the gain of compressive strength by 4–15% after a 28 day period of curing. This may be attributed to the crack-arresting capability of fibers for enhancing the compressive strength of concrete. An overdosage of fiber can lead to the balling of fibers, and poor dispersion in the concrete results in a decrease of strength. From Figure 7, it is observed that the compressive strength after 90 days of curing is higher in the samples cast using PSC. This is due to the presence of GGBFS in PSC which is responsible for the development of the strength at the later ages [4]. From Figure 8, we can conclude that the RAC with 100% RCA with 10% alccofine and 0.50% glass fiber achieved the strength of 51.38 MPa, which is greater than the desired target strength.
4.3. Split Tensile Strength
The assessment of split tensile strength holds significant importance in concrete given its inherent weakness in tension due to its brittle characteristics. Therefore, evaluating the tensile strength of concrete is critical for ensuring structural integrity and performance. The test results of all the mixes after 7, 28, and 90 days of curing, which were evaluated per IS-5816-1999 on 150 mm diameter X 300 mm height cylindrical specimens, are presented in Figure 9 and Figure 10. B. Mas et al. [29] concluded, in their study, that the performance of RAC is consistently lower than NAC across all levels of RCA replacement, and the same is observed in the present study. At all replacement levels of RCA in RAC, it is found that the loss of compressive strength is greater than the loss of tensile strength, and the same was concluded by S. M. S. Kazmi et al. [30] in their study. The splitting tensile behavior of RAC has been found to depend on several factors, including the replacement of recycled aggregate (RA), water-binder ratio, mixing methods, type of cement used, curing age, and the quality of the recycled aggregate itself [7]. The split tensile strength of the concrete mixtures OR25, OR50, OR75, and OR100 after 28 days of curing was reduced by 11–20%, respectively, compared to the strength of NAC made with OPC. In comparison to the NAC made with PSC, the splitting tensile strength of the concrete mixtures PR25, PR50, PR75, and PR100 decreased by 7–18% after 28 days of curing. This may be due to the presence of old adhered mortar, more micro-cracks, and a weaker interfacial transition zone (ITZ), resulting in the negative performance of RAC. From Figure 9, it is concluded that the RAC of PSC samples exhibited better performance when compared to the RAC of OPC samples.
Observations have revealed that the utilization of slag cement improves the splitting tensile behavior of concrete. This is due to the phenomenon of the development of strength at later ages due to the GGBFS content in PSC. Ali and Qureshi [31] discovered that during the splitting tensile test, the failure plane, in the case of RAC, predominantly occurred within the coarse aggregates (i.e., RCA). On the other hand, in NAC, the failure plane passed through the ITZs between the NCA and the new cement paste, indicating a weaker bond. However, it is worth noting that the failure of ITZs in NAC may require a higher splitting tensile load compared to the failure of aggregates in RAC. As a result, NAC exhibited a higher tensile strength than RAC. Furthermore, the inclusion of alccofine enhanced the splitting tensile behavior of concrete at both early and later ages. This is due to the ultra-fine particle size of alccofine which reduces the heat of hydration and enhances the strength at early and later ages. Due to the inherent weakness of plain concrete in tension, incorporating glass fiber significantly improves the material’s ability to withstand cracking when subjected to tensile loads.
According to Ali and Qureshi et al. [26], glass fiber exhibits efficient resistance to tensile forces during both the primary and secondary stages of loading. Figure 10 shows that the 0.50% addition of glass fiber yielded the optimum strength when compared with the 0.25% and 0.75% dosages. Glass fibers act as reinforcement and are randomly distributed in concrete mixes, which provides additional strength and resistance to cracking. A lower dosage of fibers results in a uniform distribution of fibers in concrete mixes, which results in enhanced performance. The presence of glass fibers enhanced the performance of RAC by 13–24%. This agrees with the study conducted by Babar and Qureshi et al. [26]. Babar and Qureshi et al. concluded that an increment of split tensile strength by 16.67–24% with the 0.25–1.0% addition of GF was observed. Furthermore, the strength of RAC will be at the maximum for a fiber content between 0.50–0.75%. From our studies, it was also observed that the optimum dosage of glass fiber is 0.50%, which yielded the highest split tensile strength—4.95 MPa. The enhancements are attributed to the incorporation of fibers, which alter the stress distribution within the concrete and restrict the propagation of cracks, which was also observed by W. Alnahhal et al. [32] in their work. With the dosage of GF beyond 0.50%, the strength of RAC is found to be decreased, and this is due to the non-uniform distribution of the fibers, the entanglement of fibers which creates voids or weak points, and the formation of fiber balls which creates weak points leading to crack formations; a similar phenomenon is observed by Kou et al. [33]. From Figure 9 and Figure 10, it is observed that there is a strength gain after 90 days of curing in samples cast using PSC and alccofine when compared with the OPC samples. This is due to the pozzolanic reaction, which continues slowly over time and results in the formation of additional hydration products.
4.4. Correlation between Compressive Strength and Tensile Splitting Strength
The correlation co-efficient between the split tensile strength and compressive strength after 28 days of curing for the present study was found to be 0.89 for all the mixes and is illustrated in Figure 11. From Figure 12, the correlation co-efficient for RCA25, RCA50, RCA75, and RCA100 mixes after 28 days of curing is found to be 0.93, 0.942, 0.9368, and 0.9072, respectively, and the RCA50 series exhibited the highest correlation co-efficient. In an experimental study conducted by Cakır [34], the R50 series exhibited the highest correlation coefficient of 0.995. Similarly, in the study conducted by Duan and Poon [35], the correlation coefficient (R2) of 0.93 was attained for RAC mixes. In the experimental work by Kou and Poon [36], they observed a high correlation coefficient of 0.79 in RAC mixes.
4.5. Relationship between Split Tensile Strength and Compressive Strength
Well-developed analytical equations, which are mentioned in Table 8, are used for comparing the present investigation results. Table 9 displays the tensile splitting strength values derived by the equations mentioned in Table 8. Figure 13 depicts the relationship between the experimental values of compressive strength and split tensile strength after 28 days of curing, as well as the analytical equations. It has been observed that the experimental values of splitting tensile strength for plain concrete mixes align closely with the values obtained through the ACI method [37]. For those mixes with glass fiber, the experimental values are closer to the values obtained by the analytical equation proposed by Babar Ali, Qureshi et al. [38]. Moreover, the ratio of splitting strength to compressive strength is higher in the case of mixes with glass fibers when compared to the mixes without fiber. This confirms that the inclusion of fibers provides greater benefits to the tensile strength of concrete compared to its compressive strength, and the same was observed by B. González-Fonteboa et al. [39] in their study.
As the ratio of splitting tensile strength (fsp) to the compressive strength (fck) is different for the mixes with and without fiber, Equation (1) (see Figure 14) is used for all the mixes in which split tensile strength is expressed as a function of the glass fiber dosage. Moreover, the power equation (Equation (2) and Figure 15) is developed for predicting tensile strength for mixes with fibers without considering the fiber dosage. Both Equations (1) and (2) are developed considering the strength attained after the 28-day curing period. The integral absolute error (IAE) is also computed between the actual values and the predictions made by the analytical equations. IAE analysis indicates that the values predicted by Iravani [40] exhibit the highest IAE value, which is an indication of lower accuracy. The equation proposed by Babar Ali, Qureshi et al. [38] for GFRC shows IAE values slightly higher than that of proposed Equation (1) and (2). From IAE values, it is observed that the power relationship in Equation (2) showed a lesser IAE value when compared to Equation (1), which is an indication of higher accuracy.
fsp (MPa) = (−0.3159 × GF2 + 0.3396 × GF + 0.54) fck0.5
(28 days, for both plain and GFRC mixes,
for plain concrete, take Glass fiber, GF = 0)
(28 days, for both plain and GFRC mixes,
for plain concrete, take Glass fiber, GF = 0)
fsp (MPa) = 0.1237 × fck 0.9083 (28 days, for mixes with GF)
fsp = split tensile strength (MPa); fck = compressive strength (MPa)
Table 8.
Existing formulas to estimate split tensile strength (fsp) and flexural strength (fb) of concrete from its cubical compressive strength (fck).
Table 8.
Existing formulas to estimate split tensile strength (fsp) and flexural strength (fb) of concrete from its cubical compressive strength (fck).
| Type of Concrete | Split Tensile Strength (fsp) | Flexural Strength (fb) |
|---|---|---|
| Plain concrete | [37] | fb = 0.62 × (fc)0.5 [37] |
| fsp = 0.19 × fc0.75 [41] | fb = 0.81 × (fc)0.5 [42] | |
| fsp = 0.301 × (0.8fc)0.65 [40] | fb = 0.70 × (fc)0.5 [43] | |
| GFRC | fsp = 0.8fc/(0.1 × (0.8fc) + 7.11) [44] | - |
| fsp = 0.60 × (0.8fc)0.5 [45] | fb = 0.94 × (0.8fc)0.5 [46] | |
| fsp = 0.09 × fc + 0.025 [38] | fb = 0.11 × fc + 0.39 [38] |
Table 9.
Comparison of split tensile strength (fsp) between experimental values, suggested equations, published data, and codes of practice.
Table 9.
Comparison of split tensile strength (fsp) between experimental values, suggested equations, published data, and codes of practice.
| Experimental | Predicted fsp (MPa) | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| fc (MPa) | fsp (MPa) | Equation (1) | Equation (2) | ACI [37] | GB [41] | Iravani [40] | Choi and Yuan [45] | Ali and Qureshi [38] | Zain et al. [44] |
| 54.13 | 4.69 | 4.45 | 4.64 | 4.05 | 3.79 | 3.49 | 3.95 | 4.90 | 3.79 |
| 56.54 | 4.95 | 4.74 | 4.83 | 4.14 | 3.92 | 3.59 | 4.04 | 5.11 | 3.89 |
| 53.69 | 4.73 | 4.52 | 4.61 | 4.03 | 3.77 | 3.47 | 3.93 | 4.86 | 3.77 |
| 51.84 | 4.4 | 4.36 | 4.46 | 3.96 | 3.67 | 3.39 | 3.86 | 4.69 | 3.68 |
| 54.32 | 4.65 | 4.65 | 4.66 | 4.05 | 3.80 | 3.49 | 3.96 | 4.91 | 3.79 |
| 51.49 | 4.43 | 4.43 | 4.44 | 3.95 | 3.65 | 3.37 | 3.85 | 4.66 | 3.67 |
| 49.24 | 4.21 | 4.25 | 4.26 | 3.86 | 3.53 | 3.28 | 3.77 | 4.46 | 3.57 |
| 53.17 | 4.45 | 4.60 | 4.57 | 4.01 | 3.74 | 3.45 | 3.91 | 4.81 | 3.74 |
| 48.85 | 4.27 | 4.31 | 4.23 | 3.84 | 3.51 | 3.26 | 3.75 | 4.42 | 3.55 |
| 47.08 | 4.12 | 4.15 | 4.09 | 3.77 | 3.41 | 3.18 | 3.68 | 4.26 | 3.46 |
| 51.38 | 4.27 | 4.52 | 4.43 | 3.94 | 3.65 | 3.37 | 3.85 | 4.66 | 3.66 |
| 46.12 | 4.1 | 4.19 | 4.01 | 3.74 | 3.36 | 3.14 | 3.64 | 4.18 | 3.42 |
| IAE (%) | 2.44 | 1.61 | 11.14 | 17.75 | 24.01 | 13.29 | 4.97 | 17.44 | |
4.6. Flexural Strength
Flexural strength is another factor that impacts the structural performance of concrete. It serves as an indirect indicator of the tensile strength of concrete and is commonly referred to as the modulus of rupture. Prism samples of size 100 mm × 100 mm × 500 mm were cast and evaluated for their flexural behavior after 7, 28, and 90 days of curing, as per IS-516-1959. Figure 16 and Figure 17 show the test results of both NAC and RAC samples, and it is observed from the figures that the flexural strength of RAC is lower than the NAC, and the same was concluded by A. Kliszczewicz [47] in his research. It is concluded from Figure 16 that the flexural behavior of RAC is lowered by 16–26% and 12–23% at different levels of RCA in RAC in both the OPC and PSC samples after 28 days of curing. Panda et al. [7], in their work, reported that the flexural performance of concrete is reduced by 26% with 100% RCA in RAC. Bairagi et al. [48] reported that the flexural strength was reduced by 6–13% with 25% and 50% of RCA when compared with conventional concrete.
From the present study, it is observed that flexural performance is enhanced by 6–10% with the addition of alccofine. As per studies conducted by Babar Ali, fibers increase the rigidity of the cement matrix of concrete by virtue of their higher tensile strength and hence, resulted in higher flexural strength. According to Prasad and Kumar [49], the presence of glass fibers enhanced the flexural strength of recycled aggregate concrete. From Figure 17, the inclusion of GF increases the flexural performance of RAC by 19–36%. It is observed from Figure 17 that the flexural performance is optimum at the 0.5% dosage of GF, beyond which there is a negative effect. A higher dosage of fibers causes difficulty in dispersion and makes the fiber reinforcement ineffective with further enhancement of the flexural strength. Chakradhara R. Meesala [50], in his research, concluded that the strength of RAC with GF was enhanced by 19%. Flexural strength benefits more from adding GF than splitting tensile and compressive strength.
4.7. Relationship between Flexural Strength and Compressive Strength
Figure 18 illustrates the correlation between the experimental values of compressive strength (fck) and flexural strength (fb), providing a comparison with the existing formulations mentioned in Table 8. Based on the findings depicted in Figure 18, it can be concluded that the experimental values of plain concrete mixes align closely with the values obtained through the ACI formula. Experimental values of GFRC mixes are closer to those obtained by the CEB formula. As the ratio of flexural strength to compressive strength is different for plain and GFRC mixes, the relationship between these two properties is presented as a function of the GF dosage in Equation (3) (see Figure 19). Moreover, the power Equation (4) (see Figure 20) is developed for GFRC mixes without considering the dosage of GF.
Table 10 showcases the flexural strength values obtained from various equations mentioned in Table 8, as well as the corresponding experimental values. As per Table 10, it is concluded that the IAE values by the ACI equation have the highest value, which is an indication of least accuracy. It is also observed that the IAE values developed using Equations (3) and (4) are closer to the values developed using the CEB formula.
fb = (1.3922 × GF3 − 2.2962 × GF2 + 1.1253 × GF + 0.6488) × (fck)0.5
(28 days, for both plain and GFRC mixes,
for plain concrete, take Glass fiber, GF = 0)
(28 days, for both plain and GFRC mixes,
for plain concrete, take Glass fiber, GF = 0)
fb = 0.3313 × fck 0.7246 (28 days, for GFRC mixes)
fb = Flexural strength; fck = Compressive strength
5. Conclusions
The performance of recycled aggregate concrete is observed to be inferior compared to natural aggregate concrete.
The workability of concrete is found to be enhanced with the addition of alccofine due to its ultra-fine particle size, and it is found to be decreased with the addition of glass fibers as it hinders the flow of concrete.
Behavior of concrete mixes with Portland slag cement exhibited better performance than ordinary Portland cement at later ages, i.e., after 28 days of curing.
Slag cement can be considered an alternative to Portland cement and helps in reducing greenhouse gas emissions and in the preservation of natural resources to the fullest possible extent.
In general, the inclusion of alccofine resulted in the enhancement of the mechanical properties of concrete.
An addition of alccofine and glass fibers resulted in an increase in strength gain of 11% and 4–15%, respectively, under compression.
Recycled aggregate concrete with 100% recycled concrete aggregate with 10% alccofine and 0.50% glass fiber achieved the desired target strength.
The addition of glass fibers increased the split tensile performance of recycled aggregate concrete mixes by 13–24%. The highest strength was observed with a 0.5% dosage of glass fiber for all levels of recycled concrete aggregate replacement.
The presence of glass fiber significantly affects the ratio of tensile splitting strength to compressive strength. Equations (1) and (2) were developed to predict the split tensile strength of glass fiber-reinforced concrete mixes after 28 days of curing, and both equations demonstrated favorable results.
The mechanical properties of the material have shown that a glass fiber dosage of 0.50% resulted in the most favorable outcomes when compared to dosages of 0.25% and 0.75%.
After a 90-day curing period, it was observed that samples prepared with slag cement showed greater strength gain compared to those prepared with ordinary Portland cement (OPC).
The inclusion of glass fiber has a significant influence on the flexural behavior of concrete. Glass fiber augmentation enhances flexural strength by 19–36% in recycled aggregate concrete mixes.
The ratio of flexural strength to compressive strength is positively influenced by glass fiber inclusion. Equations (3) and (4) were formulated to predict the flexural behavior of concrete mixes incorporating glass fibers after a curing period of 28 days.
Scope of future work:
- Water absorption tests and durability studies, such as acid attack tests using different acids, can be conducted.
- Mechanical properties of concrete can be evaluated with different water-cement ratios, different binder content, and with different grades of concrete.
- Behavior of beams under static and dynamic loading can be evaluated.
- A layer of slab can be cast and evaluated for their temperature stress variation at different positions.
- Further research can be completed by evaluating their behavior in pre-cast concrete applications.
Author Contributions
Conceptualization, V.G. and G.C.; methodology, V.G.; software, G.C.; validation, G.C. and V.G.; formal analysis, G.C.; investigation, V.G.; resources, V.G.; data curation, G.C.; writing—original draft preparation, G.C.; writing—review and editing, V.G.; visualization, V.G.; supervision, V.G.; project administration, G.C. and V.G.; funding acquisition, G.C. and V.G. All authors have read and agreed to the published version of the manuscript.
Funding
This research received no external funding.
Data Availability Statement
The detailed data presented in this study are available on request from the corresponding author. The data are not publicly available due to ethical restrictions.
Acknowledgments
We gratefully acknowledge the contributions in terms of providing research materials from Indian industries for our research, including alccofine from Counto Microfine Products, Pvt Limited, Goa and C&D waste from recycling plant, Hyderabad.
Conflicts of Interest
The authors declare no conflict of interest.
References
- El-Hassan, H.; Kianmehr, P.; Zouaoui, S. Properties of pervious concrete incorporating recycled concrete aggregates and slag. Constr. Build. Mater. 2019, 212, 164–175. [Google Scholar] [CrossRef]
- Tüfekçi, M.M.; Çakır, Ö. An Investigation on Mechanical and Physical Properties of Recycled Coarse Aggregate (RCA) Concrete with GGBFS. Int. J. Civ. Eng. 2017, 15, 549–563. [Google Scholar] [CrossRef]
- Habibi, A.; Ramezanianpour, A.M.; Mahdikhani, M.; Bamshad, O. RSM-based evaluation of mechanical and durability properties of recycled aggregate concrete containing GGBFS and silica fume. Constr. Build. Mater. 2021, 270, 121431. [Google Scholar] [CrossRef]
- Majhi, R.; Nayak, A. Bond, durability and microstructural characteristics of ground granulated blast furnace slag based recycled aggregate concrete. Constr. Build. Mater. 2019, 212, 578–595. [Google Scholar] [CrossRef]
- Gómez-Soberón, J.M.V. Porosity of recycled concrete with substitution of recycled concrete aggregate: An experimental study. Cem. Concr. Res. 2002, 32, 1301–1311. [Google Scholar] [CrossRef] [Green Version]
- Yehia, S.; Helal, K.; Abusharkh, A.; Zaher, A.; Istaitiyeh, H. Strength and Durability Evaluation of Recycled Aggregate Concrete. Int. J. Concr. Struct. Mater. 2015, 9, 219–239. [Google Scholar] [CrossRef] [Green Version]
- Kisku, N.; Joshi, H.; Ansari, M.; Panda, S.; Nayak, S.; Dutta, S.C. A critical review and assessment for usage of recycled aggregate as sustainable construction material. Constr. Build. Mater. 2017, 131, 721–740. [Google Scholar] [CrossRef]
- Spanish Minister of Public Works. Instrucción de Hormigón Estructural EHE_08 (Spanish Structural Concrete Code); Spanish Minister of Public Works: Madrid, Spain, 2008; Volume Act 1247/2.
- Hansen, T.C. Recycled aggregates and recycled aggregate concrete second state-of-the-art report developments 1945–1985. Mater. Struct. 1986, 19, 201–246. [Google Scholar] [CrossRef]
- Matsagar, V. Advances in Structural Engineering. In Advances in Structural Engineering: Materials; Matsagar, V., Ed.; Springer: New Delhi, India, 2015; Volume 3, pp. 1619–2647. [Google Scholar] [CrossRef]
- IS-383-2016; Coarse and Fine Aggregate for Concrete-Specification. Bureau of Indian Standards: New Delhi, India, 2016.
- Martín-Morales, M.; Zamorano, M.; Ruiz-Moyano, A.; Valverde-Espinosa, I. Characterization of recycled aggregates construction and demolition waste for concrete production following the Spanish Structural Concrete Code EHE-08. Constr. Build. Mater. 2011, 25, 742–748. [Google Scholar] [CrossRef]
- Karthik, C.; Nagaraju, A. An Experimental Study on Recycled Aggregate Concrete with Partial Replacement of Cement with Flyash and Alccofine. IOP Conf. Ser. Earth Environ. Sci. 2023, 1130, 012012. [Google Scholar] [CrossRef]
- Kavyateja, B.V.; Jawahar, J.G.; Sashidhar, C. Effectiveness of alccofine and fly ash on mechanical properties of ternary blended self compacting concrete. Mater. Today Proc. 2020, 33, 73–79. [Google Scholar] [CrossRef]
- Kumar, S.; Kumar, R.; Bandopadhyay, A.; Alex, T.; Kumar, B.R.; Das, S.; Mehrotra, S. Mechanical activation of granulated blast furnace slag and its effect on the properties and structure of portland slag cement. Cem. Concr. Compos. 2008, 30, 679–685. [Google Scholar] [CrossRef]
- El Nouhy, H.A. Properties of paving units incorporating slag cement. HBRC J. 2013, 9, 41–48. [Google Scholar] [CrossRef] [Green Version]
- Swarna Swetha, K.; Tezeswi, T.P.; Siva Kumar, M.V.N. Implementing construction waste management in India: An extended theory of planned behaviour approach. Environ. Technol. Innov. 2022, 27, 1–16. [Google Scholar] [CrossRef]
- IS:455-2015; Portland Slag Cement-Specification. Bureau of Indian Standards: New Delhi, India, 2015.
- ASTM C989-1999; Standard Specification for Ground Granulated Blast-Furnace Slag for Use in Concrete and Mortars. American Society for Testing and Materials: West Conshohocken, PA, USA, 2006.
- ASTM C494/C949M-19; Standard Specification for Chemical Admixtures for Concrete. American Society for Testing and Materials: West Conshohocken, PA, USA, 2005.
- Sruthi, S.; Gayathri, V. Synthesis and Evaluation of Eco-Friendly, Ambient-Cured, Geopolymer-Based Bricks Using Industrial By-Products. Buildings 2023, 13, 510. [Google Scholar] [CrossRef]
- IS-10262-2019; Concrete Mix Proportioning-Guidelines. Bureau of Indian Standards: New Delhi, India, 2019.
- Srinath, B.S.; Patnaikuni, C.K.; Balaji, K.; Kumar, B.S.; Manjunatha, M. A prospective review of alccofine as supplementary cementitious material. Mater. Today Proc. 2021, 47, 3953–3959. [Google Scholar] [CrossRef]
- IS-516-1959; Method of Tests for Strength of Concrete. Bureau of Indian Standards: New Delhi, India, 1959.
- El Ouni, M.H.; Shah, S.H.A.; Ali, A.; Muhammad, S.; Mahmood, M.S.; Ali, B.; Marzouki, R.; Raza, A. Mechanical performance, water and chloride permeability of hybrid steel-polypropylene fiber-reinforced recycled aggregate concrete. Case Stud. Constr. Mater. 2022, 16, e00831. [Google Scholar] [CrossRef]
- Ali, B.; Qureshi, L.A.; Shah, S.H.A.; Rehman, S.U.; Hussain, I.; Iqbal, M. A step towards durable, ductile and sustainable concrete: Simultaneous incorporation of recycled aggregates, glass fiber and fly ash. Constr. Build. Mater. 2020, 251, 118980. [Google Scholar] [CrossRef]
- Li, X. Recycling and reuse of waste concrete in China. Part I. Material behaviour of recycled aggregate concrete. Resour. Conserv. Recycl. 2008, 53, 36–44. [Google Scholar] [CrossRef]
- Boobalan, S.; Srivatsav, V.A.; Nisath, A.M.T.; Babu, A.P.; Gayathri, V. A comprehensive review on strength properties for making Alccofine based high performance concrete. Mater. Today Proc. 2021, 45, 4810–4812. [Google Scholar] [CrossRef]
- Mas, B.; Cladera, A.; del Olmo, T.; Pitarch, F. Influence of the amount of mixed recycled aggregates on the properties of concrete for non-structural use. Constr. Build. Mater. 2012, 27, 612–622. [Google Scholar] [CrossRef]
- Kazmi, S.M.S.; Munir, M.J.; Wu, Y.-F.; Patnaikuni, I. Effect of macro-synthetic fibers on the fracture energy and mechanical behavior of recycled aggregate concrete. Constr. Build. Mater. 2018, 189, 857–868. [Google Scholar] [CrossRef]
- Ali, B.; Qureshi, L.A. Durability of recycled aggregate concrete modified with sugarcane molasses. Constr. Build. Mater. 2019, 229, 116913. [Google Scholar] [CrossRef]
- Alnahhal, W.; Aljidda, O. Flexural behavior of basalt fiber reinforced concrete beams with recycled concrete coarse aggregates. Constr. Build. Mater. 2018, 169, 165–178. [Google Scholar] [CrossRef]
- Xie, J.; Kou, S.-C.; Ma, H.; Long, W.-J.; Wang, Y.; Ye, T.-H. Advances on properties of fiber reinforced recycled aggregate concrete: Experiments and models. Constr. Build. Mater. 2021, 277, 122345. [Google Scholar] [CrossRef]
- Çakır, O. Experimental analysis of properties of recycled coarse aggregate (RCA) concrete with mineral additives. Constr. Build. Mater. 2014, 68, 17–25. [Google Scholar] [CrossRef]
- Duan, Z.; Poon, C.S. Properties of recycled aggregate concrete made with recycled aggregates with different amounts of old adhered mortars. Mater. Des. 2014, 58, 19–29. [Google Scholar] [CrossRef]
- Kou, S.-C.; Poon, C.S. Long-term mechanical and durability properties of recycled aggregate concrete prepared with the incorporation of fly ash. Cem. Concr. Compos. 2013, 37, 12–19. [Google Scholar] [CrossRef]
- ACI Committee; American Concrete Institute. Building Code Requirements for Structural Concrete (ACI 318-08) and Commentary; American Concrete Institute: Farmington Hills, MI, USA, 2007; Volume 2007. [Google Scholar]
- Ali, B.; Qureshi, L.A. Combined Effect of Fly Ash and Glass Fibers on Mechanical Performance of Concrete. NED Univ. J. Res. 2018, 15, 91–100. [Google Scholar]
- González-Fonteboa, B.; Martínez-Abella, F. Concretes with aggregates from demolition waste and silica fume. Materials and mechanical properties. Build. Environ. 2008, 43, 429–437. [Google Scholar] [CrossRef]
- Iravani, S. Mechanical Properties of High-Performance Concrete; American Concrete Institute/ACI Special Publication: Farmington Hills, MI, USA, 2010; Volume SP-128, pp. 416–426. [Google Scholar] [CrossRef]
- GB 50010-2010; Chinese Standard Code for Design of Concrete Structures. MOHURD: Beijing, China, 2015.
- Du Beton, C.E.-I. CEB-FIP Model Code 2010; CEB-FIP: Lausanne, Switzerland, 2012. [Google Scholar]
- IS 456; Plain Concrete and Reinforced. Bureau of Indian Standards: New Delhi, India, 2000.
- Zain, M.; Mahmud, H.; Ilham, A.; Faizal, M. Prediction of splitting tensile strength of high-performance concrete. Cem. Concr. Res. 2002, 32, 1251–1258. [Google Scholar] [CrossRef]
- Choi, Y.; Yuan, R.L. Experimental relationship between splitting tensile strength and compressive strength of GFRC and PFRC. Cem. Concr. Res. 2005, 35, 1587–1591. [Google Scholar] [CrossRef]
- Hilles, M.M.; Ziara, M.M. Mechanical behavior of high strength concrete reinforced with glass fiber. Eng. Sci. Technol. Int. J. 2019, 22, 920–928. [Google Scholar] [CrossRef]
- Ajdukiewicz, A.; Kliszczewicz, A. Influence of recycled aggregates on mechanical properties of HS/HPC. Cem. Concr. Compos. 2002, 24, 269–279. [Google Scholar] [CrossRef]
- Bairagi, N.; Ravande, K.; Pareek, V. Behaviour of concrete with different proportions of natural and recycled aggregates. Resour. Conserv. Recycl. 1993, 9, 109–126. [Google Scholar] [CrossRef]
- Prasad, M.L.; Rathish, K.P. Strength Studies on Glass Fiber Reinforced Recycled Aggregate Concrete. Asian J. Civ. Eng. Build. Hous. 2007, 8, 677–690. [Google Scholar]
- Meesala, C.R. Influence of different types of fiber on the properties of recycled aggregate concrete. Struct. Concr. 2019, 20, 1656–1669. [Google Scholar] [CrossRef]
Figure 2.
Flow chart for the present research work.
Figure 3.
(a) Field emission scanning electron microscope images of alccofine. (b) Energy dispersive X-ray analysis of alccofine.
Figure 3.
(a) Field emission scanning electron microscope images of alccofine. (b) Energy dispersive X-ray analysis of alccofine.
Figure 4.
(a) Field emission scanning electron microscope images of PSC. (b) Energy dispersive X-ray analysis of PSC.
Figure 4.
(a) Field emission scanning electron microscope images of PSC. (b) Energy dispersive X-ray analysis of PSC.
Figure 5.
Grading curve of fine aggregate.
Figure 6.
Grading curve of 20 mm NCA and RCA.
Figure 7.
Variation of compressive strength of concrete.
Figure 8.
Variation of compressive strength of concrete with GF.
Figure 9.
Variation of split tensile strength of concrete.
Figure 10.
Variation of split tensile strength of concrete with GF.
Figure 11.
Relation between split tensile strength and compressive strength of all concrete mixtures.
Figure 11.
Relation between split tensile strength and compressive strength of all concrete mixtures.
Figure 12.
Relation between split tensile strength and compressive strength of recycled aggregate concrete mixtures.
Figure 12.
Relation between split tensile strength and compressive strength of recycled aggregate concrete mixtures.
Figure 13.
Comparison of experimental values of split tensile strength with analytical values obtained from compressive strength using existing formulations.
Figure 13.
Comparison of experimental values of split tensile strength with analytical values obtained from compressive strength using existing formulations.
Figure 14.
Polynomial relationship between k = fsp/(fck)0.5 and GF (%).
Figure 15.
Power relationship between the split tensile strength and compressive strength of GFRC mixes.
Figure 15.
Power relationship between the split tensile strength and compressive strength of GFRC mixes.
Figure 16.
Variation of flexural strength of concrete.
Figure 17.
Variation of flexural strength of concrete with glass fiber.
Figure 18.
Comparison of experimental values of flexural strength with analytical values using existing formulations.
Figure 18.
Comparison of experimental values of flexural strength with analytical values using existing formulations.
Figure 19.
Polynomial relationship between k = fb/(fc)0.5 and GF (%).
Figure 20.
Power relationship between the flexural strength and compressive strength of GFRC mixes.
Table 1.
Maximum utilization of RCA in the plain and reinforced concrete.
| Type of Aggregate | Maximum Deployment | ||
|---|---|---|---|
| Plain Concrete (%) | Reinforced Concrete (%) (up to M 25 Grade Only) | Lean Concrete (%) (<M 15) | |
| Recycled concrete aggregate (RCA) | 25 | 20 | 100 |
Table 2.
Physical properties of the OPC and PSC.
| Property | Experimental Value of PSC | Requirement of IS 455- PSC | Experimental Value of OPC | Requirement of IS 12269-OPC 53 |
|---|---|---|---|---|
| Fineness (%) | 7 | <10 | 8 | <10 |
| Normal Consistency % | 32 | - | 31 | 30–35 |
| Specific Gravity | 3.01 | - | 3.14 | 3.10–3.15 |
| Soundness by Le-chatlier expansion in mm | 1 | ≤10 | 1 | ≤10 |
| Initial setting time (IST) in min | 170 | ≥30 | 35 | ≥30 |
| Final setting time (FST) in min | 215 | ≤600 | 178 | ≤600 |
| Compressive Strength in MPa | ||||
| 3 days (minimum) | 25.30 | 16 | 29.34 | 27 |
| 7 days (minimum) | 36.35 | 22 | 40.34 | 37 |
| 28 days (minimum) | 52.17 | 33 | 51.14 | 53 |
Table 3.
Chemical properties of OPC and Alccofine C-1203.
| Chemical Analysis | Cao | Al2O3 | SiO2 | MgO | Fe2O3 | SO3 |
|---|---|---|---|---|---|---|
| OPC | 64.63 | 5.60 | 21.29 | 2.06 | 3.35 | 2.15 |
| Alccofine-C-1203 [21] | 28.54 | 36.75 | 28.64 | - | 1.167 | 0.14 |
Table 4.
Mechanical properties of NCA and RCA.
| Characteristic | Referred to | NCA | RCA | IS: 383 Limit |
|---|---|---|---|---|
| Loose bulk density (kg·m−3) | IS: 2386 (part 3) | 1450 | 1310 | - |
| Compact bulk density (kg·m−3) | IS: 2386 (part 3) | 1565 | 1440 | - |
| Specific gravity—20 mm, 10 mm | IS: 2386 (part 3) | 2.68, 2.62 | 2.45, 2.24 | 2.4–2.9 |
| Water absorption (%)—20 mm, 10 mm | IS: 2386 (part 3) | 0.21, 0.14 | 3.40, 5.53 | Max 2% |
| Impact value (%) | IS: 2386 (part 4) | 13 | 25 | 45 |
| Abrasion value (%) | IS: 2386 (part 4) | 16 | 31.6 | 50 |
| Crushing value (%) | IS: 2386 (part 4) | 12 | 22 | 45 |
Table 5.
Properties of AR-GF.
| Parameter | Result |
|---|---|
| Length of fiber (mm) | 12 |
| Diameter (µ) | 14 |
| Density (g·cm−3) | 2.70 |
| Modulus of Elasticity (GPa) | 72 |
| Tensile Strength (MPa) | 1700 |
| Chemical Resistance | Very high |
| Thermal conductivity | Very low |
| Specific Gravity | 2.60 |
Table 6.
Nomenclature of mixes.
| Series | Notation | Expansion of Notation |
|---|---|---|
| N | ON | Concrete with OPC and NCA |
| PN | Concrete with PSC and NCA | |
| OR | OR25 | Concrete with OPC and RCA 25% |
| OR50 | Concrete with OPC and RCA 50% | |
| OR75 | Concrete with OPC and RCA 75% | |
| OR100 | Concrete with OPC and RCA 100% | |
| PR25 | PR25 | Concrete with PSC and RCA 25% |
| PR25A10 | Concrete with PSC and RCA 25% + Alccofine C-1203 10% | |
| PR25A10G0.25 | Concrete with PSC and RCA 25% + Alccofine C-1203 10% + Glass Fiber 0.25% | |
| PR25A10G0.50 | Concrete with PSC and RCA 25% + Alccofine C-1203 10% + Glass Fiber 0.50% | |
| PR25A10G0.75 | Concrete with PSC and RCA 25% + Alccofine C-1203 10% + Glass Fiber 0.75% | |
| PR50 | PR50 | Concrete with PSC and RCA 50% |
| PR50A10 | Concrete with PSC and RCA 50% + Alccofine C-1203 10% | |
| PR50A10G0.25 | Concrete with PSC and RCA 50% + Alccofine C-1203 10% + Glass Fiber 0.25% | |
| PR50A10G0.50 | Concrete with PSC and RCA 50% + Alccofine C-1203 10% + Glass Fiber 0.50% | |
| PR50A10G0.75 | Concrete with PSC and RCA 50% + Alccofine C-1203 10% + Glass Fiber 0.75% | |
| PR75 | PR75 | Concrete with PSC and RCA 75% |
| PR75A10 | Concrete with PSC and RCA 75% + Alccofine C-1203 10% | |
| PR75A10G0.25 | Concrete with PSC and RCA 75% + Alccofine C-1203 10% + Glass Fiber 0.25% | |
| PR75A10G0.50 | Concrete with PSC and RCA 75% + Alccofine C-1203 10% + Glass Fiber 0.50% | |
| PR75A10G0.75 | Concrete with PSC and RCA 75% + Alccofine C-1203 10% + Glass Fiber 0.75% | |
| PR100 | PR100 | Concrete with PSC and RCA 100% |
| PR100A10 | Concrete with PSC and RCA 100% + Alccofine C-1203 10% | |
| PR100A10G0.25 | Concrete with PSC and RCA 100% + Alccofine C-1203 10% +Glass Fiber 0.25% | |
| PR100A10G0.50 | Concrete with PSC and RCA 100% + Alccofine C-1203 10% +Glass Fiber 0.50% | |
| PR100A10G0.75 | Concrete with PSC and RCA 100% + Alccofine C-1203 10% +Glass Fiber 0.75% |
Table 7.
Mix proportion of concrete mixes for one cubic meter.
| Mix ID | Cement (kg) | Alcco-Fine C-1203 (kg) | FA (kg) | NCA 20 mm (kg) | NCA 10 mm (kg) | RCA 20 mm (kg) | RCA 10 mm (kg) | Water (kg) | Glass Fiber (%) |
|---|---|---|---|---|---|---|---|---|---|
| OPC + NCA | 390 | 0 | 698 | 867 | 283 | 0 | 0 | 157 | 0 |
| PSC + NCA | 390 | 0 | 698 | 867 | 283 | 0 | 0 | 157 | 0 |
| OR25 | 390 | 0 | 698 | 650.25 | 212.25 | 191.25 | 57 | 157 | 0 |
| OR50 | 390 | 0 | 698 | 433.5 | 141.5 | 382.5 | 114 | 157 | 0 |
| OR75 | 390 | 0 | 698 | 216.75 | 70.75 | 573.75 | 171 | 157 | 0 |
| OR100 | 390 | 0 | 698 | 0 | 0 | 765 | 228 | 157 | 0 |
| PR25 | 390 | 0 | 698 | 650.25 | 212.25 | 191.25 | 57 | 157 | 0 |
| PR50 | 390 | 0 | 698 | 433.5 | 141.5 | 382.5 | 114 | 157 | 0 |
| PR75 | 390 | 0 | 698 | 216.75 | 70.75 | 573.75 | 171 | 157 | 0 |
| PR100 | 390 | 0 | 698 | 0 | 0 | 765 | 228 | 157 | 0 |
| PR25A10 | 351 | 39 | 698 | 650.25 | 212.25 | 191.25 | 57 | 157 | 0 |
| PR50A10 | 351 | 39 | 698 | 433.5 | 141.5 | 382.5 | 114 | 157 | 0 |
| PR100A10 | 351 | 39 | 698 | 0 | 0 | 765 | 228 | 157 | 0 |
| PR25A10G0.25 | 351 | 39 | 698 | 650.25 | 212.25 | 191.25 | 57 | 157 | 0.25 |
| PR25A10G0.50 | 351 | 39 | 698 | 650.25 | 212.25 | 191.25 | 57 | 157 | 0.50 |
| PR25A10G0.75 | 351 | 39 | 698 | 650.25 | 212.25 | 191.25 | 57 | 157 | 0.75 |
| PR50A10G0.25 | 351 | 39 | 698 | 433.5 | 141.5 | 382.5 | 114 | 157 | 0.25 |
| PR50A10G0.50 | 351 | 39 | 698 | 433.5 | 141.5 | 382.5 | 114 | 157 | 0.50 |
| PR50A10G0.75 | 351 | 39 | 698 | 433.5 | 141.5 | 382.5 | 114 | 157 | 0.75 |
| PR75A10G0.25 | 351 | 39 | 698 | 216.75 | 70.75 | 573.75 | 171 | 157 | 0.25 |
| PR75A10G0.50 | 351 | 39 | 698 | 216.75 | 70.75 | 573.75 | 171 | 157 | 0.50 |
| PR75A10G0.75 | 351 | 39 | 698 | 216.75 | 70.75 | 573.75 | 171 | 157 | 0.75 |
| PR100A10G0.25 | 351 | 39 | 698 | 0 | 0 | 765 | 228 | 157 | 0.25 |
| PR100A10G0.50 | 351 | 39 | 698 | 0 | 0 | 765 | 228 | 157 | 0.50 |
| PR100A10G0.75 | 351 | 39 | 698 | 0 | 0 | 765 | 228 | 157 | 0.75 |
Table 10.
Comparison of flexural strength (fb) between experimental values, suggested equations, published data, and codes of practice.
Table 10.
Comparison of flexural strength (fb) between experimental values, suggested equations, published data, and codes of practice.
| Experimental | Predicted fsp (MPa) | |||||||
|---|---|---|---|---|---|---|---|---|
| fc (MPa) | fsp (MPa) | Equation (3) | Equation (4) | ACI [37] | CEB [42] | IS: 456 [43] | Hilles and Ziara [46] | Ali and Qureshi [38] |
| 54.13 | 6.03 | 5.95 | 5.97 | 4.56 | 5.96 | 5.15 | 6.19 | 6.34 |
| 56.54 | 6.25 | 6.11 | 6.17 | 4.66 | 6.09 | 5.26 | 6.32 | 6.61 |
| 53.69 | 5.92 | 5.80 | 5.94 | 4.54 | 5.94 | 5.13 | 6.16 | 6.30 |
| 51.84 | 5.78 | 5.82 | 5.79 | 4.46 | 5.83 | 5.04 | 6.05 | 6.09 |
| 54.32 | 5.89 | 5.99 | 5.99 | 4.57 | 5.97 | 5.16 | 6.20 | 6.37 |
| 51.49 | 5.68 | 5.68 | 5.76 | 4.45 | 5.81 | 5.02 | 6.03 | 6.05 |
| 49.24 | 5.67 | 5.67 | 5.58 | 4.35 | 5.68 | 4.91 | 5.90 | 5.81 |
| 53.17 | 5.96 | 5.92 | 5.90 | 4.52 | 5.91 | 5.10 | 6.13 | 6.24 |
| 48.85 | 5.39 | 5.53 | 5.55 | 4.33 | 5.66 | 4.89 | 5.88 | 5.76 |
| 47.08 | 5.51 | 5.55 | 5.40 | 4.25 | 5.56 | 4.80 | 5.77 | 5.57 |
| 51.38 | 5.72 | 5.82 | 5.75 | 4.44 | 5.81 | 5.02 | 6.03 | 6.04 |
| 46.12 | 5.32 | 5.37 | 5.32 | 4.21 | 5.50 | 4.75 | 5.71 | 5.46 |
| IAE (%) | 1.23 | 1.16 | 22.80 | 1.69 | 12.83 | 4.69 | 5.09 | |
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content. |
© 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
Share and Cite
MDPI and ACS Style
Govardhan, C.; Gayathri, V. Experimental Investigation on Ternary Blended Recycled Aggregate Concrete Using Glass Fibers. Buildings 2023, 13, 1961. https://doi.org/10.3390/buildings13081961
AMA Style
Govardhan C, Gayathri V. Experimental Investigation on Ternary Blended Recycled Aggregate Concrete Using Glass Fibers. Buildings. 2023; 13(8):1961. https://doi.org/10.3390/buildings13081961
Chicago/Turabian StyleGovardhan, Cheetirala, and Venkataraman Gayathri. 2023. "Experimental Investigation on Ternary Blended Recycled Aggregate Concrete Using Glass Fibers" Buildings 13, no. 8: 1961. https://doi.org/10.3390/buildings13081961
Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.
