STUDY ON DURABILITY PROPERTIES OF PERLITE INCORPORATED CONCRETE

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1 International Journal of Civil Engineering and Technology (IJCIET) Volume 9, Issue 10, October 2018, pp , Article ID: IJCIET_09_10_154 Available online at ISSN Print: and ISSN Online: IAEME Publication Scopus Indexed STUDY ON DURABILITY PROPERTIES OF PERLITE INCORPORATED CONCRETE Prekshi Khanna B.Tech, School of Civil and Chemical Engineering, Vellore Institute of Technology (VIT), Vellore, Tamil Nadu, India Archana Manoj Mukulam B.Tech, School of Civil and Chemical Engineering, Vellore Institute of Technology (VIT), Vellore, Tamil Nadu, India K. Varun Teja Research Scholar, School of Civil Engineering, Vellore Institute of Technology (VIT), Vellore, Tamil Nadu, India Prof. T. Meena Associate Professor, School of Civil Engineering, Vellore Institute of Technology (VIT), Vellore, Tamil Nadu, India ABSTRACT Perlite Powder is one of the light weight material mostly used for agriculture purpose. But it is an unknown fact that perlite is also having pozzolanic properties which can be used in concrete as additive or replacement of cement and fine aggregate. Most of the research has been done by using perlite as the fine aggregate replacement. In this study, concrete utilized Perlite powder (PP) has been used as the replacement of cement. Perlite Powder is varied with 0%, 1%, 3%, 5% and 7% by weight of cement. The research is done on the durability properties of the Perlite Concrete. The tests such as water absorption, sorptivity, shrinkage and acid attack tests were carried out, so as to check the durability of Perlite concrete. The results show that the perlite addition can improve the durability of concrete to a large extent. Key words: Perlite powder, Durability properties, Water absorption test, Sorptivity, Shrinkage, Acid attack Test. Cite this Article: Prekshi Khanna, Archana Manoj Mukulam, K. Varun Teja, T. Meena, Study on Durability Properties of Perlite Incorporated Concrete, International Journal of Civil Engineering and Technology (IJCIET) 9(10), 2018, pp editor@iaeme.com

2 Study on Durability Properties of Perlite Incorporated Concrete 1. INTRODUCTION Perlite is an amorphous, white volcanic rock having a glassy appearance. It has a composition of 70-75% Silicon Dioxide (SiO 2 ) and 12-18% Aluminum Oxide (Al 2 O 3 ) approximately and it contains 2-6% of chemically combined water which causes it to expand, resulting in a cellular material of immensely low bulk density when heat is applied at the temperature of approximately 900 C [1]. The applications of Expanded Perlite are diverse such as construction, gardening and industrial. Few of the applications of perlite powder are : as a replacement of fine aggregate for building construction, an additive in bleach for textile industry and an absorbent in chemical industry [2]. Perlite is a pozzolanic material owing to its glassy structure and high SiO 2 Al 2 O 3 content. Even though such pozzolanic characteristics have been explored by few researches [6-9], no studies have been conducted on the usage of perlite in manufacturing cements. As of now, perlite powder has always been used as a replacement of aggregate in concrete all over the world. Some of the studies which have been conducted include thermal conductivity [3], durability [4] and its application in self compacting concrete [5]. There have been numerous studies regarding perlite powder as a replacement of cement. In these studies, tests such as, normal consistency, setting time, soundness and compressive strength have been conducted. Erdem et al. (2007) experimented with Perlite by replacing OPC and concluded that it leads to increase in water/ binder ratio which in turn results in an increase of initial and final setting time. Previously, by studying the compressive strength of concrete, Yu et al. (2003) studied the effects of pozzolanic reaction of perlite powder [10]. Due to the arising need of sustainable development, It has become essential that additional cementing materials be used as a replacement of cement [11]. Replacing cement with perlite powder can be advantageous as it reduces the quantity of cement used. It therefore reduces the cost as well as CO 2 emissions. Perlite also provides the advantages of other admixtures and so the researchers have aimed to investigate the durability of concrete [1]. The serviceability of a structure crucially depends on the durability of the concrete. Hydration and drying of the cement results in the reduction in volume which results in shrinkage of the cement paste. Some of the important factors that influence shrinkage are capillary tension in the pores, instance of disjoining pressure and tension variations of solid gel molecules [13]. Water absorption gives the capacity of concrete to take in water by capillary suction method which is widely used to quantify the durability of concrete. Sorptivity is a measure of absorption or desorption of moisture into unsaturated samples, and it is also an important indication of concrete durability [14]. The attack of sulphuric acid in concrete results in formation of gypsum and ettringite due to the ingress of sulphate ions, in the areas near the surface which leads to spalling making the inner fresh surface vulnerable to attack. Acid attack on concrete depends on properties such as temperature, associated cat ion and sulphate concentration. The overall objective of this study is to check the durability of concrete when cement is replaced by perlite powder at 0%, 1%, 3%, 5% and 7% by weight which is named as PP0, PP1, PP3, PP5, PP7 respectively. The durability tests include shrinkage, sorptivity, water absorption and acid attack. 2. MATERIALS USED 2.1. Cement 53 Grade Ordinary Portland cement (OPC) was used in this experimental study. To save the cement from environmental factors like humidity, utmost care was taken in order to store the editor@iaeme.com

3 Prekshi Khanna, Archana Manoj Mukulam, K. Varun Teja, T. Meena cement in sacks. The chemical and physical compositions are summarized in Table 1 and Table 2 respectively. Table 1 Cement Properties S.No. Tests Conducted Value 1. Specific gravity Normal Consistency (%) Setting Time Initial 36 min Final 396 min 4. Fineness (%) Soundness mm 2.2. Aggregates According to Indian Standard Specifications IS , pulverized rock which is locally available was used as coarse aggregate (Sieved through 20mm sieve). Aggregates were taken after washing with water to remove dirt and girt, they were dried under dry shell conditions. According to Indian Standard Specifications IS for fine aggregates, Zone II River sand was used. They are made sure to be free of dirt, chemically inactive and free from other impurities. Table 2 Properties of Fine and Coarse aggregates S. No. Properties Fine Aggregate Coarse Aggregate 1 Maximum aggregate size (mm) Bulk specific capacity Absorption capacity (%) Fineness modulus Perlite Powder Perlite powder (PP) was used as a mineral admixture by replacing 1%, 3%, 5% and 7% of cement by weight. It was purchased from Astra Chemicals, Chennai, India. One of the striking properties of perlite powder is that it is a lightweight material, therefore it can be used as a lightweight aggregate. Table 4 Chemical Composition of Perlite powder S. No Chemical composition Percentage 1. SiO Al 2 O Fe 2 O MgO CaO Na 2 O K 2 O H 2 O 0.5(maximum) An important property of Perlite is that when it is subjected to elevated temperatures of 900 C C it increases its volume by approximately 4 to 20 times its original volume. This happens because the bound water present in perlite expands during heating similar to the popcorn effect and assumes the form of a porous swollen material editor@iaeme.com

4 Study on Durability Properties of Perlite Incorporated Concrete Table 5 Perlite powder Properties S No. Physical Properties Value 1. Apparent density kg/m 3 2. Hardness index 5.5 mohs 3. Specific gravity ph Water absorption (%) EXPERIMENTAL PROCESS In our study, cement was replaced with Perlite powder at various percentages. A total of 5 substitution levels of binary concrete were casted after making the mix proportion appropriately. Out of these 5 samples, one is normal concrete and the rest with Perlite powder at 1%, 3%, 5% and 7% substitution levels. Tests such as Water absorption, Sorptivity, Acid attack and shrinkage test were done. For water absorption and acid attack tests cubes of dimensions 100 mm x 100 mm x 100mm were casted for each percentage separately for each test. After 24hours the specimens were demoulded and kept in water for 7, 28 and 56 Days. For Sorptivity test, cylinders are casted for each percentage of Perlite and immersed in water for 28 and 56 days. For the Shrinkage test 3 specimens of 300mm x 15mm x 15mm were casted. After casting the specimens were demoulded after 24hours and immersed in water for 7days later they are kept out for drying Sorptivity Test After curing the specimen (cylinder of 100 mm diameter and 50 mm height) for 28 days in water bath, the specimen is oven dried at 110 C and left it for room temperature. Later the specimens are covered with the tape by leaving the lower surface open. Then the specimens were immersed in a water tub with a maximum water level of 5 mm from the base of the specimen. The quantity of water absorbed in time period of 30 minutes was measured by weighing the specimen on a top pan balance weighing upto 0.1 mg. Figure 1 Sorptivity specimens immersed in water 3.2. Water Absorption Test After taking out the specimens from curing tank after 28 and 56 days, they were weighed and were heated in the oven at 110 C for 24 hours. Later, it was weighed again and the sample is kept in water for 48 hours and then weighed again editor@iaeme.com

5 Prekshi Khanna, Archana Manoj Mukulam, K. Varun Teja, T. Meena A) Specimens kept for oven drying B) Specimens kept at curing for 48hrs Figure 2 Specimens of Water absorption Test 3.3. Shrinkage Test The specimens of dimensions 300mm x 15mm x 15mm were casted and kept in water bath for curing for 7 days. After the period of 7 days, the samples were kept for open drying. From this point, shrinkage values for 7 days, 28 days and 56 days were measured. Figure 3 Shrinkage Test Apparatus 3.4. Acid Attack Test After curing for 28 days, the specimens were again immersed in water which is diluted with 3% H 2 SO 4. These specimens were then tested for the loss in the weight due to acid attack. Therefore, weight of the samples was measured for 28 days and 56 days editor@iaeme.com

6 Sorptivity Study on Durability Properties of Perlite Incorporated Concrete A) Specimens kept at H2SO4 Solution B) Surface layer after 28days acid Curing Figure 4 Acid Attack Test 4. RESULTS AND DISCUSSION 4.1. Sorptivity Results are taken after specimens were immersed in water for 30min and the results figured out in fig 5 Sorptivity PP0 PP1 PP3 PP5 PP7 Perlite % 28 Days 56 Days Figure 5 Sorptivity test of perlite concrete From Fig 5 and Fig 6, we can see that the sorptivity of the concrete reduces with the increase in the percentage of Perlite powder. It has the water absorption properties which are the reason for lower sorptivity as the proportion of Perlite increases. When water is added, the pores get filled with Perlite powder so this reduces the capacity of water to get transported due to lesser availability of free water, thus results in lower sorptivity. We can see, as the age of concrete increases, sorptivity decreases editor@iaeme.com

7 Weight Loss % Water Absorption % Prekshi Khanna, Archana Manoj Mukulam, K. Varun Teja, T. Meena 4.2. Water Absorption Water Absorption PP0 PP1 PP3 PP5 PP7 Perlite % Figure 6 Water Absorption Test As Fig 7 suggests, water absorption increases with an increase in the percentage of Perlite powder. Perlite is a highly water absorptive material and thus with the increase in the proportion of Perlite quantities there is an increase of water absorption. The rate of increase in water absorption increases with age of concrete as the slope of the curve for 7 days is more than that in 28 and 56 days Acid Attack Acid Attack PP0 PP1 PP3 PP5 PP7 Perlite % 28 DAYS 56 DAYS Figure 7 Weight Loss due to acid attack By Fig 8, we can see that as the percentage of Perlite powder increases, the loss in weight decreases. This means that the effect of acids on perlite concrete is comparatively less than normal concrete. This implies that Perlite usage is beneficial in the presence of acids. Therefore, we can say that perlite protects the concrete from acids editor@iaeme.com

8 Study on Durability Properties of Perlite Incorporated Concrete 4.4. Shrinkage Shrinkage Strain Initial 7 Days 28 Days 56 Days PP0 PP1 PP3 PP5 PP7 Age of concrete Figure 8 Strain Vs age of concrete Perlite powder has the property to absorb water, so as the percentage of perlite increases, the amount of water absorbed will be more. In this research, by increasing the percentage of perlite powder, the shrinkage will be reduced. As the age of concrete increases, the strain also increases. This is due to the holding of water by Perlite particles. 5. CONCLUSIONS Perlite traps the water inside the particle more, so the water absorption capacity of perlite is more. In present research by increasing the perlite percentage water absorption is more and by increasing the age the absorption level become decreased. Increase in Perlite percentage decreases the sorptivity value to 0.4 and 0.32 mm/min 0.5 at 28 and 56 days of curing. It shows that increasing the perlite powder will fill the voids in the structure and will not allow the water to flow. Increasing the age of concrete decreases the sorptivity value. Perlite concrete at replacement of PP5 shows enhanced performance at all the ages in terms of the shrinkage strain effect. Concrete immersed in H 2 SO 4 shows less weight loss by increasing the percentage of Perlite compared to normal concrete which shows that Perlite concrete can withstand with its strength. Form the investigation 5PP perlite concrete shows good durability properties. REFERENCES [1] Erdem, T. K., Meral, C., Tokyay, M., & Erdoğan, T. Y. (2007). Use of perlite as a pozzolanic addition in producing blended cements. Cement and Concrete Composites, 29(1), [2] Vosoughi, V., Crin, S. M. M., & Eisapour, S. (2015). Evaluation of perlite powder Performance in concrete to replace part of the cement. Cumhuriyet Science Journal, 36(4), [3] Demirboǧa, R., & Gül, R. (2003). Thermal conductivity and compressive strength of expanded perlite aggregate concrete with mineral admixtures. Energy and Buildings, 35(11), editor@iaeme.com

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