DESIGNING AND CONSTRUCTION OF ROADS, SUBWAYS, AIRFIELDS, BRIDGES AND TRANSPORT TUNNELS

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1 Russian Journal of Building Construction and Architecture DESIGNING AND CONSTRUCTION OF ROADS, SUBWAYS, AIRFIELDS, BRIDGES AND TRANSPORT TUNNELS UDC 625 Dr. Shashi Kant Sharma 1, Aniruddha D. Chopadekar 2, Samarth Y. Bhatia 3 IMPROVEMENT IN PAVEMENT QUALITY CONCRETE BY USING POZZOLONIC MATERIALS WITH POLYPROPYLENE FIBER Himachal Pradesh India, NIT Hamirpur, Hamirpur, tel.: , shashi.pec@gmail.com 1 Assistant professor, Department of Civil Engineering 2 Student of M. Tech Civil engineering, Department of Civil Engineering 3 Student of M. Tech Civil engineering, Department of Civil Engineering Statement of the problem. Pozzolans like Fly ash and silica fume are extensively used in concrete to replace cement without affecting its strength. Micro fibers helps in controlling the cracking caused due to shrinkage of concrete, which is essential parameter to be studied in regards with pavement quality concrete (PQC). Results. Thus the present study aims at determining combined effect of polypropylene fibers with pozzolonic materials on PQC. Fly ash, Silica fume and Polypropylene fibers in different proportion were used. The specimens were tested for compressive & flexural strength after 7, 28, 60 and 90 days. Also shrinkage test was performed after 28 days. Conclusions. The results showed that, polypropylene fiber works well with pozzolonic materials. It was found that shrinkage reduced upto 0.6 % fiber volume with a total of 35% pozzolans. The maximum 90 day compressive and flexural strength obtained were Mpa and 9.81 Mpa respectively and minimum 28 day shrinkage strain value of 339 was observed. Thus, combination helped in increasing the strength parameter while reducing shrinkage. Keywords: Pozzolans, Fly ash, Silica fume, Pavement quality concrete, Polypropylene fiber. Introduction Pavement is a layered structure which supports the wheel loads and transfers the load stresses through a wider area on the soil sub grade beneath. The surface of the roadway should be stable and non-yielding to allow the heavy wheel loads of road traffic to move with least possible rolling resistance. Rigid pavement structure is widely used nowadays because of its dura- Dr. Shashi Kant Sharma, Aniruddha D. Chopadekar, Samarth Y. Bhatia,

2 Issue 4 (36), 2017 ISSN bility and high flexural strength. A cement concrete pavement slab of specified strength characteristics are laid with or without steel reinforcement at the joints. Generally, the material used for the construction of rigid pavements is high quality plain cement concrete meant for the pavement generally called Pavement Quality Concrete (PQC). PQC is firstly designed for the flexural and later for compressive strength. Maintaining the quality of the concrete is one of the primary objectives of Pavement Quality Control program. The tensile stresses are developed in the rigid slab due to the heavy wheel load movement. Pozzolonic materials can be used in construction of rigid pavements. Fly ash and Silica fume are the most common pozzolans used in construction. Fly ash is the waste product produced in the thermal power plants while generating the electricity using coal. The presence of fly ash in concrete makes it more flexible and the pavement constructed by using it possess higher flexural strength, there by this pavement can be classified as a semi-rigid pavement. According to the literature available on utilization of fly ash in the construction of rigid pavement, good quality fly ash can be used to replace cement by 10 to 30 percent. In this study, cement is replaced with fly ash by 10, 20 and 30 percent by weight of cement. The use of fly ash in pavement construction saves the resources which helps in achieving economy in pavement construction without compromising quality and also gives a way for disposal of fly ash. Silica fume is used in high strength and high performance concrete. It is found to be very useful material in the concrete construction. It is very fine and highly reactive industrial byproduct obtained during the production of metallic silicon or ferrosilicon alloys. Silica fume can be obtained by the process of reduction of high purity quartz with coal in an electric arc furnace. It is composed of submicron particles of silicon dioxides. The first utilization of silica fume in concrete was reported in 1952 by a Norwegian researcher. Effect of silica fume as a cementitious material on compressive strength and workability has been studied in various studies that silica fumes increases the compressive strength while decreasing the workability. The primary role of fiber in a cementitious composite is to control cracks, increase the tensile strength and to improve deformation characteristics of the composite. There are various types of fibers available in the market like steel fiber, polypropylene fiber, carbon fiber, glass fiber etc. Steel fiber and Polypropylene (PP) fibers are most widely used in concrete mix. In this study, PP fibers were used; it has been used in cement concrete since 1960s. PP fibers are thermoplastic polymers which can be produced from the waste plastics by their recycling. PP fibers are added to concrete as secondary reinforcement to control shrinkage. It mitigates plastic and early drying shrinkage by increasing the tensile strength of concrete and bridging the 117

3 Russian Journal of Building Construction and Architecture forming cracks. The effect of PP fibers on the properties of harden concrete varies depending on the type, length and volume fraction of PP fiber. In this study PP fiber of length 6.00 mm and aspect ratio of 90 was used. The most crucial problem associated with concrete pavements is that of cracking. Once these cracks are produced, they act as conduits for ingress of gases and water. This type of degradation of concrete results in reduction of strength and service life of pavement. The development of cracks severely affects durability property of pavements. One of the major causes of pavements cracking is plastic and drying shrinkage. Thus to check the durability performance of pavement, shrinkage test is performed in the present study. The effect of PP fiber and Pozzolans individually with PQC has been researched upon to a large extent by many researchers previously. However the combined effect of PP fibers and pozzolans has not been studied much. Thus the purpose of this research is to study how PP fibers and pozzolans behave together to affect strength parameters and shrinkage. Material used The materials used in this study include cementitious material (Cement, Fly ash and Silica fume), Aggregate, PP fiber and water. To maintain the qualities of study, materials selected were tested according to the quality parameters given in the respective IS codes. Cemetitious materials act as a binder in concrete matrix. Cement, Fly ash and Silica fume were used in this study. Pozzolona Portland Cement of 43 Grade (PPC 43), fineness 2 %, Specific Gravity 3.10, Standard Consistency 35 %, IST and FST 45 and 190 minutes respectively were used. The fly ash used in this study was brought from Ropar Thermal Power Plant, Punjab, India, having a specific gravity, maximum dry density and optimum moisture content of 1.784, KN/cu.m and 26 % respectively. These properties of fly ash were evaluated by referring to IS :2003. Silica fume of specific gravity 2.2 gm/cc was used. The PP fiber used was procured from industrial area Ludhiana, Punjab. Properties of PP fiber as specified by supplier are; Length, Aspect ratio, specific gravity, modulus of elasticity and melting point are 6mm, 90, 0.91, 3500 to 3900 N/Sq.mm and C respectively. The crushed aggregate of size 10 to 20 mm and fine aggregates of zone II of size range between 4.75 mm to mm were taken, conforming to IS 383:1970. Locally available potable water of suitable ph range, fulfilling the requirement of IS 456:2000 was used for preparing cement concrete mix. Mix proportion and Mix design In this study project, ten mixtures were prepared for studying the behavior of concrete with pozzolans and PP fiber. The replacement level of fly ash with cement is 10, 20 and 30 percent and fraction of polypropylene fiber is 0.20, 0.40 and 0.60 percent of volume of specimen. A 118

4 Issue 4 (36), 2017 ISSN constant amount of silica fume i.e. 5 percent was added into all mixture excluding the control mixture. Table 1 show the mixture proportion used in this study. A concrete of M40 grade (control mix) was designed according to the guidelines given in the IRC: 44 (1976). The mix was designed in such a way that focus is given on achieving design flexural strength of 4.5 Mpa rather than compressive strength. Initial water-binder ratio of 0.43 was selected for control mix. The water-binder ratio varied according to the mix proportion selected. The specimens were cast and tested after 7, 28, 60 and 90 days of curing for Compression strength as well as flexural strength. Shrinkage strain test specimens were tested after 28 days of curing. Experimental Test on material used To maintain the quality of concrete mix it is required to perform quality checking tests on the material. The quality of cement is checked as per the tests given in the IS 1489: The effect of replacing the cement by fly ash and silica fume on the properties of cement were tested in this study. For this Standard consistency test and Setting time test was performed for various mixes as given above. Similarly, the quality of Fly ash and Silica fume were checked according to the quality standards given in IS 3812 (2): 2003 and IS 15388: 2003 respectively. Mix Proportion Table 1 Material Water/ Fly Mix Fiber Fiber SF SF Fly Ash Cement FA CA Proportion Binder Ash Code % (gm/m 3 ) % (kg/m 3 ) (kg/m 3 ) (kg/m 3 ) (kg/m 3 ) (kg/m 3 ) (C:FA:CA) ratio % C 1:1.63: CP1F1S 1:1.88: CP1F2S 1:2.04: CP1F3S 1:2.21: CP2F1S 1:1.94: CP2F2S 1:2.09: CP2F3S 1:2.27: CP3F1S 1:2.01: CP3F2S 1:2.17: CP3F3S 1:2.36: SF: Silica Fume, FA: Fine Aggregate, CA: Coarse Aggregate. Test on fresh concrete To evaluate the workability of concrete mix, Slump cone test was performed on the fresh mix according to the guidelines and procedure given in IS 1199:

5 Russian Journal of Building Construction and Architecture Compressive strength test and Flexural strength test Compressive strength test was performed on the concrete specimen. For this, the specimens of size mm were cast and tested after 7, 28, 60 and 90days of curing under the standard laboratory conditions and according to the guidelines given in IS 516:1959. Similarly, the specimens of size mm were cast and tested after same duration. The average of three specimens was taken as the compressive strength and flexural strength result; total 120 specimens of standard size for each test were cast and tested. Shrinkage test In this study drying shrinkage strain have been determined after 28 days of curing of cement composites. The drying shrinkage test was performed as per guidelines given in IS 4031 (Part 1): The specimens of size mm were cast. The specimen was measured for first length reading and then the specimen were stored in lime saturated water or in a moisture room with temperature maintained at 23±2 º C. This first length reading is for information only, not to be use in drying shrinkage calculations. After 7 days of curing, specimen shall be removed and initial length reading shall be taken. This reading shall be used as the initial reading for calculation of linear dry shrinkage. After the initial reading, specimens were placed in a drying room until the age of 35 day i.e. 28 days more after initial reading. The humidity of drying room shall be monitored with the beaker method according to ASTM C 157/C157 M-04. Final reading is taken after 35 days. Then the shrinkage strain is calculated according to equation (a). Linear Shrinkage Strain = [(L-l))/L] 100, Where, L = Original length of specimen; l = Length of specimen after 28 days. The average of three specimens is taken as the Shrinkage strain; total 30 specimens of standard size as mentioned above were cast and tested. Results and discussion As per IRC58: 2011, concrete design is based on 28 day strength. But in case of concrete pavement, 90 days strength can be permitted in view of the fact that during initial period of 90 days, the number of repetitions of load is very small and has negligible effect on cumulative fatigue damage of concrete. Hence in this study a comparison is made between the strength parameter at 90 days. The test results are given in Table 2. Standard Consistency and Setting time of cement paste The effect of replacement of cement by fly ash and silica fume on consistency of cement paste is represented in table 2. It can be observed from the results that normal consistency of control 120

6 Issue 4 (36), 2017 ISSN mix obtained is 32 %. On addition of fly ash and silica fume the normal consistency of cement paste increases. The outer surface of fly ash particles increases with increase in fly ash content, the amount of absorbed calcium ion increases. This inhibits calcium ion concentration built up in fresh paste during early hydration resulting setting time is prolonged and thus the heat of hydration decreases causing consistency to increase. Also the results show that both Initial setting time and final setting time of mix increase as replacement level of fly ash increases. There is lesser effect on final setting time as compared with initial setting time at same replacement level of fly ash. Table 2 Results Setting Time Normal Compressive strength (Mpa) Flexural strength (Mpa) Mix (min) Shrinkage Consistency Code Strain (%) Initial Final Day Day Day Day Day Day Day Day C CP1F1S CP1F2S CP1F3S CP2F1S CP2F2S CP2F3S CP3F1S CP3F2S CP3F3S Workability The slump cone value for each mix type obtained is given in table 2. It was observed that with the addition of fibers, the entrapped air voids increases and hence the increased air content reduces the workability. Due to reduction in workability, compaction of fresh concrete becomes difficult. As observed from the slump cone values, it can be seen that the workability of fresh concrete decreases with increase in polypropylene fiber volume but this can be overcome by adding Water reducing admixture. There is reduction in workability with increase in fiber content. Up to the fiber content of 0.40 percent there is not much reduction in workability, it was within the permissible requirement but, for 0.60 percent fiber content a suitable dose of 1.5 percent of super plasticizer was added to achieve desired slump value. 121

7 Russian Journal of Building Construction and Architecture Compressive strength The compressive strength test results are presented in fig 1. The maximum compressive strength is observed to be Mpa for mix 10 (containing 0.60 % PP fibers with 30 % fly ash and 5 % silica fume replacement). For a same fly as replacement level, as fiber volume increases there is an increase in compressive strength. However it can be observed that increase in compressive strength in not significant. 70 Compressive strength (Mpa) C CP1F1SCP1F2SCP1F3SCP2F1SCP2F2SCP2F3SCP3F1SCP3F2SCP3F3S 7 Day 28 Day 60 Day 90 day Mix type Fig. 1. Compressive strength result Flexural strength The flexural strength test results are presented in fig 2. The maximum flexural strength is observed to be 9.81 Mpa for mix 9 (containing 0.60 % PP fibers with 20 % fly ash and 5 % silica fume replacement). The results show that pozolons replacement and PP fiber volume greatly affects flexural strength. As fly ash replacement level increases flexural strength increases. Also direct relation is observed between fiber volume and flexural strength. Flexural strength (Mpa) Day 28 Day 60 Day 90 Day Mix type Fig. 2. Flexural strength result 122

8 Issue 4 (36), 2017 ISSN Shrinkage strain The results obtained from shrinkage test are presented in fig 3. From the results it is observed that the PP fiber with pozzolons is very effective in controlling shrinkage of concrete. The minimum shrinkage observed at mix 10 (Containing 0.60 % PP fiber with 30% fly ash replacement and 5 % silica fume) as C CP1F1S CP1F2S CP1F3S CP2F1S CP2F2S CP2F3S CP3F1S CP3F2S CP3F3S 28 Day Mix type Fig 3. Shrinkage strain resul Conclusion PP fiber tends to behave well with pozzolans. There is not much significance of polypropylene fibers addition on compressive strength but it improves the behavior under flexural loading. Also it mitigates shrinkage by increasing the tensile strength of concrete and bridging the forming cracks. In this study, it was found that the strength parameters increase with an increase in polypropylene fibers volume. For same replacement of fly ash as the fiber volume is increased from 0.20 % to 0.40 % a maximum increase of 16 % in flexural strength is observed. Further increase in fiber volume does not yield a significant increase in flexural strength. Most of the developed as well as developing countries are having huge resource of waste materials such as fly ash and silica fume. These waste materials if not disposed of properly can cause severe environmental degradation. The results of present study shows that these materials tend to perform well with PQC thereby providing a means for their effective disposal. The results show that the gain in compressive and flexural strength is less at early age of 7 days, but gain in later age strength is more due to pozzolonic reactions which sets in late. The durability in terms of shrinkage strength decreases with the use of pozzolans which is an additional benefit. 123

9 Russian Journal of Building Construction and Architecture It can be inferred from the result that, the optimum PP fiber content and replacement level of fly ash varies with the parameter under consideration. The maximum 90 day compressive strength and Flexural strength is obtained as Mpa and 9.81 Mpa for mix CP3F2S (0.60 % PP fiber volume, 20 % fly ash and 5% silica fume replacement), whereas minimum 28 day shrinkage strain of 339 is obtained for CP3F3S (0.60 % PP fiber volume, 30 % Fly ash and 5 % Silica fume replacement). Thus in general CP3F2S can be considered as best mix. The construction of rigid pavement with polypropylene fiber may increases the cost of construction which can be counter balanced by reduction in the maintenance and rehabilitation operation cost. Also, the replacement of cement with pozzolans further helps in cost reduction. Acknowledgements The author would like to acknowledge Ropar Thermal Power plant, Punjab India for providing us Fly ash. The contribution of materials from Transportation engineering Laboratory, NIT Hamirpur is greatly appreciated. References 1. Hussam A. Toutanji. Properties of polypropylene fiber reinforced silica fume expansive-cement concrete. Construction and Building materials, Elsevier, 1999, vol. 13, pp Madhkhan M., R. Azizkhani and M. E. Torki Harchegani. Effects of pozzolans together with steel and polypropylene fibers on mechanical properties of RCC pavements. Construction and Building materials, 2011, vol. 26, pp Kolluru V. Subramaniam, Roman Gromotka, Surendra P. Shah, Karthik Obla and Russell Hill. Influence of Ultrafine Fly Ash on the Early Age Response and the Shrinkage Cracking Potential of Concrete. Journal of materials in civil engineering, ASCE, 2005, vol. 17 (1), pp Alaa M. Rashad, Hosam El-Din H. Seleem and Amr F. Shaneen. Effect of Silica Fume and Slag on Compressive strength and Abrasion Resistance of HVFA Concrete. International journal of Concrete Structures and Materials, 2014, vol. 8, pp Shiping Zhang and Binghua Zhao. Influence of polypropylene fibre on the mechanical performance and durability of concrete materials. European Journal of Environmental and Civil Engineering, Taylor and Francis, 2012, vol. 16 (10). 6. Osman Gencel, Cengiz Ozel and Witold Brostow. Mechanical properties of self-compacting concrte reinforced with polypropylene fibres. Material research innovations, Research Gate, 2011, vol Zhen Mei and D. D. L. Chung. Improving the flexural Modulus and Thermal Stability of Pitch by the Addition of Silica Fume, Journal of Reinforced plastics and Composites, 2000, vol. 21 (1). 8. IS : 2003, Specification for pulverized fly ash for use as an admixture in mortar or concrete. 9. IS 383: 1970, Specifications for coarse and fine aggregates from natural sources for concrete. 10. IS 456: 2000, Plain and Reinforced Concrete - Code of Practice. 124

10 Issue 4 (36), 2017 ISSN IRC 44: 1976, Tentative guidelines for cement concrete mix design for pavements. 12. IS 1489 (1):1991, Specifications for Portland pozzolona cement. 13. IS 15388: 2003, Silica fume specifications. 14. IS 1199: 1959, Methods for sampling and analysis of concrete [CED 2: cement and concrete]. 15. IS 516: 1959, Method of tests for strength of concrete. 16. IS 4031 (1): 1996, Methods of physical tests for hydraulic cement. 17. ASTM C 157/ C157 M-04, Guidelines for shrinkage test of cement mortar. 18. IRC 58: 2011, Guidelines for plain jointed rigid pavements for highways. 125