Self Compacting
Concrete Using Recycled Aggregate and
Polypropylene Fiber
Self compacting concrete (SCC) was first developed in 1988 in Japan to achieve durable concrete structures. As SCC has various advantage over normal concrete, it also posses a major disadvantage i.e it is uneconomical. Therefore, in this dissertation work emphasis has been laid to reduce the cost of the SCC without reducing the strength of the SCC, hence by-product which are available cheaply and easily i.e recycled aggregate (demolish concrete and fly ash) has been used to reduce the manufacturing cost without reducing the strength of SCC. Hence in this work demolished concrete in various % (I.e 5%, 10%, 15%&20% of T.C.A) has been used as partial replacement of coarse aggregate and fly ash with 45% replacement of cement has been used. To enhance the property of SCC made with the use of demolish concrete and fly ash, polypropylene fiber has been added to the mix. Polypropylene fiber in various % (i.e 0.1%, 0.15%&0.20% of Wt. of cement) has been added in the mix which contain demolish concrete and gave highest strength i.e (10% demolish concrete). Keywords: SCC, recycled aggregate, polypropylene fiber, Total coarse aggregate (T.C.A). 1. INTRODUCTION Self-compacting concrete as the name suggest it get compacted by itself i.e it does not require any vibration for compaction. The SCC came into existence in the year 1988 in Japan where the inventers fell the need of faster construction rate. A SCC must possess three properties such as: 1) Have fluidity that allows self compaction without external energy, 2) Remain homogeneous in a form during and after the placing process and 3)Flow easily through reinforcement. A SCC has many advantages over conventional concrete: 1) Eliminating the need for vibration,2) Decreasing the construction time and labor cost,3) Reducing the noise pollution ,4) Improving the interfacial transitional zone between cement paste and aggregate or reinforcement, 5) Decreasing the permeability and improving durability of concrete,6) Facilitating constructability and ensuring good structural performance and 7) Provide freedom in design. SCC while possessing several advantages also have a disadvantage i.e it is uneconomical. The high cost of SCC is due to the fact that the materials used in making of SCC are costly such as Admixture (mineral and chemical) and cement. In this dissertation emphasis has been laid on reducing the cost of SCC and making it cost effective without reducing the strength (compressing and flexural). Therefore 50% cement has been replaced by fly ash and the coarse aggregate partially in various percentages (5%, 10%, 15% and 20%) has been replaced by demolish concrete. Both materials used I.e fly ash and demolish concrete are by-product and waste respectively and are cheaply and easily available. Whereas the demolished concrete used also has a disadvantage that it has low compressive strength. 2. MATERIALS USED AND PROCEDURE The sieve analysis of the coarse aggregate and fine aggregate are given in Table 1. In the dissertation demolished concrete has been used of size between 10mm and 12mm. The water absorption of the demolish concrete was found to be 4%. The ISSN 2393-8471 International Journal of Recent Research in Civil and Mechanical Engineering (IJRRCME) Vol. 2, Issue 1, pp: (173-177), Month: April 2015 – September 2015, Available at: www.paperpublications.org Page | 174 Paper Publications specific gravity of fine and coarse aggregate was 2.62. A polypropylene fiber (Recron 3s) has been used in the project to enhance the properties of SCC made with demolish concrete and fly ash. Ordinary Portland Cement of 43 grade was used in all mixes with a specific gravity of 3.15. 50% fly ash by mass of cementitious material as cement replacement was used. A poly- carboxylic-ether (PCE) super plasticizer was added in all mix, the PCE used was in the liquid form with specific gravity of 1.20. To enhance the stability of SCC a viscosity modifying agent (VMA) has been used. Demolish concrete with different percentage say (5%, 10%, 15% and 20%) was used as partial replacement of coarse aggregate in the work. Aggregate, demolish concrete, sand, cement and fly ash were mixed first for 1min, and then super plasticizer, VMA & polypropylene fiber that was mixed in water was added. Then all materials were mixed for 2 to 4 min. Several design procedure based on scientific theories or empirical experience have been proposed for the normal S.C.C. in general these procedures fall into the following three categories: 1) combination of super plasticizer and high content of mineral powders.2) combination of super-plasticizer and VMA with or without deforming agent, and 3) a combination of super plasticizer, mineral power and VMA. Here to achieve the SCC mix design, among the three mentioned basic criteria suggested to produce normal SCC, a combination of super plasticizer and VMA type was chosen and it was found that it is working well for a concrete to be self compacting. Figure 1 shows mixing and testing procedure. The main requirement of fresh SCC is a high rate of workability caused by high flow and mobility with sufficient cohesion and resistance to segregation during transportation and placement. The significant requirement is also resistance to blocking during concrete work of densely reinforced components and prolonged time of workability. Concrete design to fulfill such requirement completely fill the forms and moulds of complex, densely reinforced component by its own weight and at the same time, compact it self uniformly within as much as 90 min after mixing. The benefit of this technology is certainly also the fact that the SCC technologies considerably utilize waste materials, e.g fly ash, blast furnace slags, demolish concrete (as in this case). 3. PROPERTIES AND DISCUSSIONS OF FRESH SCC A concrete mix can only be classified as self-complication if it has the following characteristics. Filling ability Passing ability Segregation resistance Immediately after the mixing, the value of J-ring, V-funnel and V-funnel at T5min test were determine for finding out passing ability, filling ability and Segregation resistance respectively, for SCC by the following method. J-ring test: The J-ring test is used to determine the passing ability of the SCC. The equipment consists of a rectangular section (30mm*25mm), open steel ring, drilled vertically with holes to accept threaded section of reinforcement bar. These section of bar can be of different diameter spaced at different interval, in accordance with normal reinforcement consideration. The diameter of the ring of vertical bars is 300mm, and the height 100mm. After the test, the difference in ISSN 2393-8471 International Journal of Recent Research in Civil and Mechanical Engineering (IJRRCME) Vol. 2, Issue 1, pp: (173-177), Month: April 2015 – September 2015, Available at: www.paperpublications.org Page | 175 Paper Publications height between the concrete inside and the just outside the j-ring is measured. This is an indication of passing ability, or the degree to which the passage of concrete through the bars is restricted. Figure 2 J-Ring Test V-funnel and V-funnel at T5min Test V-funnel test: The v-funnel test is used to determine the deformability through restricted area. The version selected for evaluation in this study had a rectangular crossing tapering to a bottom opening of 65mm*75mm. The funnel was fitted with a trap door. The test result is given as a flow time. The v-funnel selected can deal with mixes containing aggregate of size not exceeding 20mm. A sample of fresh concrete of between 12 to 15 liter in volume is required. Acceptable value range from 8-12 sec. The test was carried out for SCC. V-funnel test at T 5min.: In this test the funnel can be filled with concrete and left for 5 minutes to settle. If concrete shows segregation then the flow time will increase significantly. For V- funnel flow time at T 5 min. + 3 second is allowed. Table 2=Result of properties of fresh SCC S.NO Type Of Mix J-Ring V-Funnel V-Funnel-T5min 1 Type 1 3mm 9 sec 11 sec 2 Type 2(10%)D.C 4.5mm 9.5 sec 11.70 sec 3 Type 3 (0.1%)P.F 5mm 10.8 sec 13.5 sec 4 0.15% P.F 6.7mm 11.40sec 14.20sec 5 0.20% P.F 7.3mm 12.70sec 15.64sec 4. EXPERIMENTAL TEST AND DISCUSSION OF HARDENED SCC Casting and curing of test specimen After casting, the molded specimens were left on the casting room at room temperature for 48h. They were than demolded and cured in water for 28 days. The specimens of dimension (15*15*15cm) were used for compressive strength (cube) and specimen of dimension (10*10*50cm) were used for flexural strength (beam). In this dissertation work 3 type of casting has been done to study the properties of SCC. Type 1-Nominal casting for SCC of M25 grade. Type 2-Casting of SCC with the partial replacement of coarse aggregate with demolish concrete in various percentage say (5%, 10%, 15% & 20%) in the nominal mix. Type 3- Casting of SCC with the addition of polypropylene fiber in various percentage say (0.1%, 0.15% & 0.20% by wt of cement) to the mix which gave highest strength while using demolish concrete. Compressive Strength Test and Results: For three type of studied, the total number of 24 concrete cube specimens of (15*15*15cm) was caste and tested at 28 days. The result for average value of three specimens, were calculated and is shown in the table below. ISSN 2393-8471 International Journal of Recent Research in Civil and Mechanical Engineering (IJRRCME) Vol. 2, Issue 1, pp: (173-177), Month: April 2015 – September 2015, Available at: www.paperpublications.org Page | 176 Paper Publications Table:3. Compressive strength for type 1 mix S.NO Compressive Strength(MPa) 1 34.22 Table: 4. compressive strength for type 2 mix S.NO Demolished concrete% Compressive Strength(MPa) 1 5% 26.17 2 10% 29.37 3 15% 24.32 4 20% 23.85 Table: 5. compressive strength for type 3 mix S.NO % of Polypropylene Fiber Compressive Strength(MPa) 1 0.1 28.31 2 0.15 29.07 3 0.20 28.05 Flexural Strength Test and Results: For three type of studied, the total number of 24 concrete beam specimens of (10*10*50cm) was casted and tested at 28 days. The result for average value of three specimens, were calculated and is shown in the table below. Table: 6. Flexural strength for type 1 S.NO Flexural Strength(MPa) 1 8.47 Table: 7. Flexural strength for type 2 S.NO Demolished concrete% Flexural Strength(MPa) 1 5% 5.98 2 10% 6.20 3 15% 4.12 4 20% 1.98 Table: 8. Flexural strength for type 3 S.NO % of Polypropylene Fiber Flexural Strength(MPa 1 0.1 6.34 2 0.15 7.15 3 0.20 5.08 ISSN 2393-8471 International Journal of Recent Research in Civil and Mechanical Engineering (IJRRCME) Vol. 2, Issue 1, pp: (173-177), Month: April 2015 – September 2015, Available at: www.paperpublications.org Page | 177 Paper Publications 5. CONCLUSION The following important result can be summarized by the investigation carried out on the different mix of SCC tests: 1. The SCC made with 45% of fly ash as the cement replacement gave satisfactory result after the 28 days of testing. Compressive strength for M25 grade of SCC was found to be 34.22MPa and modulus of rapture as 8.47. 2.On the base of above result, on the same mix T.C.A was partially replaced by demolish concrete in different percentages (5%,10%,15% &20%) it was found that best result for compressive strength and modulus of rupture was for 10% demolish concrete i.e 29.37 MPa and 6.20 repectively. 3. On the above mix polypropylene fiber was added in various percentages to enhance the properties of SCC and it was found that no considerable change in compressive strength was found but the modulus of rupture was found to increase for 0.15%. But with further increase in the % of polypropylene modulus of rupture was found to decrease. Hence 0.15% of wt of cement of polypropylene fiber should be added for best result for SCC.
Self compacting concrete (SCC) was first developed in 1988 in Japan to achieve durable concrete structures. As SCC has various advantage over normal concrete, it also posses a major disadvantage i.e it is uneconomical. Therefore, in this dissertation work emphasis has been laid to reduce the cost of the SCC without reducing the strength of the SCC, hence by-product which are available cheaply and easily i.e recycled aggregate (demolish concrete and fly ash) has been used to reduce the manufacturing cost without reducing the strength of SCC. Hence in this work demolished concrete in various % (I.e 5%, 10%, 15%&20% of T.C.A) has been used as partial replacement of coarse aggregate and fly ash with 45% replacement of cement has been used. To enhance the property of SCC made with the use of demolish concrete and fly ash, polypropylene fiber has been added to the mix. Polypropylene fiber in various % (i.e 0.1%, 0.15%&0.20% of Wt. of cement) has been added in the mix which contain demolish concrete and gave highest strength i.e (10% demolish concrete). Keywords: SCC, recycled aggregate, polypropylene fiber, Total coarse aggregate (T.C.A). 1. INTRODUCTION Self-compacting concrete as the name suggest it get compacted by itself i.e it does not require any vibration for compaction. The SCC came into existence in the year 1988 in Japan where the inventers fell the need of faster construction rate. A SCC must possess three properties such as: 1) Have fluidity that allows self compaction without external energy, 2) Remain homogeneous in a form during and after the placing process and 3)Flow easily through reinforcement. A SCC has many advantages over conventional concrete: 1) Eliminating the need for vibration,2) Decreasing the construction time and labor cost,3) Reducing the noise pollution ,4) Improving the interfacial transitional zone between cement paste and aggregate or reinforcement, 5) Decreasing the permeability and improving durability of concrete,6) Facilitating constructability and ensuring good structural performance and 7) Provide freedom in design. SCC while possessing several advantages also have a disadvantage i.e it is uneconomical. The high cost of SCC is due to the fact that the materials used in making of SCC are costly such as Admixture (mineral and chemical) and cement. In this dissertation emphasis has been laid on reducing the cost of SCC and making it cost effective without reducing the strength (compressing and flexural). Therefore 50% cement has been replaced by fly ash and the coarse aggregate partially in various percentages (5%, 10%, 15% and 20%) has been replaced by demolish concrete. Both materials used I.e fly ash and demolish concrete are by-product and waste respectively and are cheaply and easily available. Whereas the demolished concrete used also has a disadvantage that it has low compressive strength. 2. MATERIALS USED AND PROCEDURE The sieve analysis of the coarse aggregate and fine aggregate are given in Table 1. In the dissertation demolished concrete has been used of size between 10mm and 12mm. The water absorption of the demolish concrete was found to be 4%. The ISSN 2393-8471 International Journal of Recent Research in Civil and Mechanical Engineering (IJRRCME) Vol. 2, Issue 1, pp: (173-177), Month: April 2015 – September 2015, Available at: www.paperpublications.org Page | 174 Paper Publications specific gravity of fine and coarse aggregate was 2.62. A polypropylene fiber (Recron 3s) has been used in the project to enhance the properties of SCC made with demolish concrete and fly ash. Ordinary Portland Cement of 43 grade was used in all mixes with a specific gravity of 3.15. 50% fly ash by mass of cementitious material as cement replacement was used. A poly- carboxylic-ether (PCE) super plasticizer was added in all mix, the PCE used was in the liquid form with specific gravity of 1.20. To enhance the stability of SCC a viscosity modifying agent (VMA) has been used. Demolish concrete with different percentage say (5%, 10%, 15% and 20%) was used as partial replacement of coarse aggregate in the work. Aggregate, demolish concrete, sand, cement and fly ash were mixed first for 1min, and then super plasticizer, VMA & polypropylene fiber that was mixed in water was added. Then all materials were mixed for 2 to 4 min. Several design procedure based on scientific theories or empirical experience have been proposed for the normal S.C.C. in general these procedures fall into the following three categories: 1) combination of super plasticizer and high content of mineral powders.2) combination of super-plasticizer and VMA with or without deforming agent, and 3) a combination of super plasticizer, mineral power and VMA. Here to achieve the SCC mix design, among the three mentioned basic criteria suggested to produce normal SCC, a combination of super plasticizer and VMA type was chosen and it was found that it is working well for a concrete to be self compacting. Figure 1 shows mixing and testing procedure. The main requirement of fresh SCC is a high rate of workability caused by high flow and mobility with sufficient cohesion and resistance to segregation during transportation and placement. The significant requirement is also resistance to blocking during concrete work of densely reinforced components and prolonged time of workability. Concrete design to fulfill such requirement completely fill the forms and moulds of complex, densely reinforced component by its own weight and at the same time, compact it self uniformly within as much as 90 min after mixing. The benefit of this technology is certainly also the fact that the SCC technologies considerably utilize waste materials, e.g fly ash, blast furnace slags, demolish concrete (as in this case). 3. PROPERTIES AND DISCUSSIONS OF FRESH SCC A concrete mix can only be classified as self-complication if it has the following characteristics. Filling ability Passing ability Segregation resistance Immediately after the mixing, the value of J-ring, V-funnel and V-funnel at T5min test were determine for finding out passing ability, filling ability and Segregation resistance respectively, for SCC by the following method. J-ring test: The J-ring test is used to determine the passing ability of the SCC. The equipment consists of a rectangular section (30mm*25mm), open steel ring, drilled vertically with holes to accept threaded section of reinforcement bar. These section of bar can be of different diameter spaced at different interval, in accordance with normal reinforcement consideration. The diameter of the ring of vertical bars is 300mm, and the height 100mm. After the test, the difference in ISSN 2393-8471 International Journal of Recent Research in Civil and Mechanical Engineering (IJRRCME) Vol. 2, Issue 1, pp: (173-177), Month: April 2015 – September 2015, Available at: www.paperpublications.org Page | 175 Paper Publications height between the concrete inside and the just outside the j-ring is measured. This is an indication of passing ability, or the degree to which the passage of concrete through the bars is restricted. Figure 2 J-Ring Test V-funnel and V-funnel at T5min Test V-funnel test: The v-funnel test is used to determine the deformability through restricted area. The version selected for evaluation in this study had a rectangular crossing tapering to a bottom opening of 65mm*75mm. The funnel was fitted with a trap door. The test result is given as a flow time. The v-funnel selected can deal with mixes containing aggregate of size not exceeding 20mm. A sample of fresh concrete of between 12 to 15 liter in volume is required. Acceptable value range from 8-12 sec. The test was carried out for SCC. V-funnel test at T 5min.: In this test the funnel can be filled with concrete and left for 5 minutes to settle. If concrete shows segregation then the flow time will increase significantly. For V- funnel flow time at T 5 min. + 3 second is allowed. Table 2=Result of properties of fresh SCC S.NO Type Of Mix J-Ring V-Funnel V-Funnel-T5min 1 Type 1 3mm 9 sec 11 sec 2 Type 2(10%)D.C 4.5mm 9.5 sec 11.70 sec 3 Type 3 (0.1%)P.F 5mm 10.8 sec 13.5 sec 4 0.15% P.F 6.7mm 11.40sec 14.20sec 5 0.20% P.F 7.3mm 12.70sec 15.64sec 4. EXPERIMENTAL TEST AND DISCUSSION OF HARDENED SCC Casting and curing of test specimen After casting, the molded specimens were left on the casting room at room temperature for 48h. They were than demolded and cured in water for 28 days. The specimens of dimension (15*15*15cm) were used for compressive strength (cube) and specimen of dimension (10*10*50cm) were used for flexural strength (beam). In this dissertation work 3 type of casting has been done to study the properties of SCC. Type 1-Nominal casting for SCC of M25 grade. Type 2-Casting of SCC with the partial replacement of coarse aggregate with demolish concrete in various percentage say (5%, 10%, 15% & 20%) in the nominal mix. Type 3- Casting of SCC with the addition of polypropylene fiber in various percentage say (0.1%, 0.15% & 0.20% by wt of cement) to the mix which gave highest strength while using demolish concrete. Compressive Strength Test and Results: For three type of studied, the total number of 24 concrete cube specimens of (15*15*15cm) was caste and tested at 28 days. The result for average value of three specimens, were calculated and is shown in the table below. ISSN 2393-8471 International Journal of Recent Research in Civil and Mechanical Engineering (IJRRCME) Vol. 2, Issue 1, pp: (173-177), Month: April 2015 – September 2015, Available at: www.paperpublications.org Page | 176 Paper Publications Table:3. Compressive strength for type 1 mix S.NO Compressive Strength(MPa) 1 34.22 Table: 4. compressive strength for type 2 mix S.NO Demolished concrete% Compressive Strength(MPa) 1 5% 26.17 2 10% 29.37 3 15% 24.32 4 20% 23.85 Table: 5. compressive strength for type 3 mix S.NO % of Polypropylene Fiber Compressive Strength(MPa) 1 0.1 28.31 2 0.15 29.07 3 0.20 28.05 Flexural Strength Test and Results: For three type of studied, the total number of 24 concrete beam specimens of (10*10*50cm) was casted and tested at 28 days. The result for average value of three specimens, were calculated and is shown in the table below. Table: 6. Flexural strength for type 1 S.NO Flexural Strength(MPa) 1 8.47 Table: 7. Flexural strength for type 2 S.NO Demolished concrete% Flexural Strength(MPa) 1 5% 5.98 2 10% 6.20 3 15% 4.12 4 20% 1.98 Table: 8. Flexural strength for type 3 S.NO % of Polypropylene Fiber Flexural Strength(MPa 1 0.1 6.34 2 0.15 7.15 3 0.20 5.08 ISSN 2393-8471 International Journal of Recent Research in Civil and Mechanical Engineering (IJRRCME) Vol. 2, Issue 1, pp: (173-177), Month: April 2015 – September 2015, Available at: www.paperpublications.org Page | 177 Paper Publications 5. CONCLUSION The following important result can be summarized by the investigation carried out on the different mix of SCC tests: 1. The SCC made with 45% of fly ash as the cement replacement gave satisfactory result after the 28 days of testing. Compressive strength for M25 grade of SCC was found to be 34.22MPa and modulus of rapture as 8.47. 2.On the base of above result, on the same mix T.C.A was partially replaced by demolish concrete in different percentages (5%,10%,15% &20%) it was found that best result for compressive strength and modulus of rupture was for 10% demolish concrete i.e 29.37 MPa and 6.20 repectively. 3. On the above mix polypropylene fiber was added in various percentages to enhance the properties of SCC and it was found that no considerable change in compressive strength was found but the modulus of rupture was found to increase for 0.15%. But with further increase in the % of polypropylene modulus of rupture was found to decrease. Hence 0.15% of wt of cement of polypropylene fiber should be added for best result for SCC.
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