Effects of Used Engine Oil as an Admixture in Concrete Durability

Excellent flowability is one of the important characteristics of concrete for easier handling and placing and it facilitates the removal of undesirable air voids by introducing superplasticizer (SP). But due to environmental issue related to the waste during SP production, alternatives being initiate to incorporate used engine oil (UEO) that has the same function as SP. It was reported that UEO resulted in improving some concrete properties therefore can lead to counter problems of higher SP cost and UEO disposal. The principal aim of this research mainly to identify the effectiveness of UEO in durability improvement of concrete. Investigation of porosity, chloride penetration and high elevated temperature exposure was conducted. From the result obtained, UEO decrease the concrete porosity and comparable with SP. The result of chloride penetration showed that incorporation of 0.5% of UEO did not cause any adverse effect as compared to the control mix, which meant that UEO could improve the concrete durability. Elevated temperature exposure test was conducted and the percentage strength loss of concrete with UEO was almost similar to the mix with SP. It can be stated that UEO performed very good in durability improvement and comparable with SP. Original Research Article Beddu et al.; BJAST, 15(6): 1-10, 2016; Article no.BJAST.20738 2


INTRODUCTION
Recently, the interest on utilization of greener technology is on the rise. A lot of wastes are being utilized to replace the commercially available materials. While the previous researchers have discussed the powerful superplasticizer function, however the alternative admixture to replace it is something new to be explored. With the increase usage of concrete, new type of admixtures that are cost effective may have many economic and technical impacts on the Malaysian construction industry as well as worldwide concrete usage. This research was carried out extensively along with the increasing concern about environmental issues from superplasticizer (SP) production and used engine oil (UEO) disposal.
SP is functioning in providing excellent workability to the concrete. However, production of SP is commonly associated with the water pollution. Liquid and solid waste produced due to the manufacturing process discharged into public sewerage network was found violating the environmental regulations. The chemicals used during the manufacturing processes are also hazardous and have severe impact on the environment [1].
In the meantime, the number of vehicles is increasing all over the world therefore this leads to the increase production of UEO. According to the Annual Report of the Road Transport Department of Malaysia, the number of registered road vehicles had increased from more than 6.8 million in 1995 to more than 12.2 million in March 2003 [2]. It is estimated 380 million gallons of UEO are recycled each year [3]. It was reported that worldwide 45% of UEO is being collected while remaining 55% is thrown away the end used in the environment [4]. Besides that, 40% of the total re-used oil is improperly disposed.
The potential of UEO as concrete admixture were found by Mindess and Young [5]. They were reported that the leakage of oil into the cement in older grinding units result in concrete with greater resistance to freezing and thawing. This implies that adding UEO to the fresh concrete mix could be similar to adding an airentraining chemical admixture, thus enhancing some durability properties of concrete while serving as another technique of disposing the oil waste. It was also discussed by Chin [6] that UEO has similar SP properties because of the SO 3 content.
Oil is a common and highly visible form of pollution. Oil and water are immiscible and even a small spillage can cause significant pollution. Studies have shown that 5 litres of it can cover a small lake [7].
Bilal et al. [8] have studied the effects of UEO on fresh and hardened properties and also structural performance of concrete and it gave the positive effects comparable with the available commercially air entraining agent. UEO also suggested by Aravind and Das [9] to be used in highway construction but requires well organized oil collection system. The further research is noteworthy to produce the good quality and performance of concrete.
The study of the effect of UEO on properties of concrete has been carried out by Bilal et al. [10]. Mixes was contained with 0.075, 0.15 and 0.30% of UEO by weight of cement. Result shows that UEO acted as a chemical plasticizer improving the fluidity and almost double slump of the concrete mix and supported by Chin et al. [9]. Beddu et al. [11] stated that UEO did not adversely affect the strength development process of concrete with silica fume, 28 days strength was achieved as 76MPa with 4% UEO. It was also stated that UEO act positively towards the concrete performance. Concrete mixes containing high percentage of fly ash (40% and 50%) followed the same trend [12].
The research of UEO effects in concrete were then publish by Kamal et al. in 2014 [13] that stated the inclusion of 0.5% UEO gave the highest compressive strength and comparable with SP. Assaad [14] concluded that an optimum UEO dosage of 0.3% of cement mass was found, beyond which detrimental effects on initial slump, setting time, and compressive strength can be encountered.
The research of UEO also being explored by some researcher. Salmia et al. [15,16] concluded that used cooking oil can contribute to the improvement of slump, mechanical properties and microstructure with the optimum dosage of 1.5 of cement content.
The main objective of this research is to identify the effects of used engine oil with respect to durability, important consideration in the design and construction of new structures and also when assessing the condition of existing structures.

Design Mix
In order to achieve reliable results, practicing of strict measures of quality control is the most important criterion for the experimental investigation as part of any research program. Therefore, the spurious results and false trend can be avoided by applying the prevailing code of standards and specifications for the selection of concrete making materials and mix proportions. The mix proportions of concrete for casting of specimens are presented in Table 1. Eleven mixes were cast with water binder ratios (w/b) of 0.55. Water and admixture were measured in percentage by weight proportion of cement used.

Materials
The Ordinary Portland Cement (OPC) Type 1 was used in this research, that complied to the requirements of BS 12 (1996) [18] and MS 522 (1989) [17]. OPC Type 1 was preferred because the observation on concrete properties can be done in normal hydration process. OPC was supplied by Tasek Corporation Sdn. Bhd., located in Ipoh, Perak.
Superplasticizers (SP) are used in fresh concrete to enhance its workability and allow to reduce the water content, so the high strength concrete could be produced. In this study, SP call Sikamen-N1 supplied by SIKA-Kimia, Malaysia was used. This SP is Sulfonated Naphtalene Formaldehyed (SNF) condensate type.
Used engine oil (UEO) was collected from service-stations around Tronoh and Seri Iskandar, Perak. It was collected randomly at the service-stations that have no proper disposal. Samples of UEO and superplasticizer were analyzed using X-ray fluorescence (XRF) technique to determine their chemical composition in percent, which is given in Table 2.

Porosity test
The porosity of concrete was carried out by coring three 50 mm diameter from concrete planks. Total porosity was determined by vacuum saturation method developed by RILEM CP 113 [19] and the porosity calculated as: Where P = total porosity in percentage Ws = mass of saturated samples measured in the air, g Wd = mass of oven dried samples measured in the air, g Ww = mass of saturated samples measured in the water, g

Chloride penetration test
Rapid migration test according to AASHTO T277 [20] was carried out to determine the depth of chloride penetration into the mortar cube. The

High elevated temperature exposure test
Elevated temperature test of concrete is important to evaluate the effect of high temperature exposure especially during fire. Hence, a series of fire endurance temperature tests on various types of concrete were conducted to measure their fire endurance temperatures and then compared to control mix. This method of testing was adopted from Mundhada et al. [21] that that concluded quality of concrete suffers slightly & strength too comes down, therefore the method is appropriate.
The mixes containing 0.5% chemical admixtures (UEO and SP) in OPC concrete was chosen since it gave the optimum performance. Concrete cubes of 100 mm size were cast, for testing at age 28 days, 3 cubes were tested at every testing. After de-moulding, the specimens were then dried at 110°C to remove the water and moisture from the specimens. Then, all of the specimens were simultaneously placed inside a furnace at the Material Laboratory of Universiti Teknologi PETRONAS. The temperature of the furnace was increase up to 500°C. After the temperature reached 500°C, the furnace was turned off for the specimens to cool off for a day.
Then, the specimens were tested for compressive strength at the Concrete Laboratory of Universiti Teknologi PETRONAS. The average value of compressive strength for each type of concrete were recorded and compared to each other and with the normal concrete. From the results, the residual compressive strength and the actual strength were compared and presented as percentage strength lost due to exposure to extreme fire and heat. Fig. 1 shows the effects of SP and UEO on slump value of OPC concrete. In this series of mixes, all ingredients were kept constant except the dosage of SP and UEO, which was varied from 0 to 1% by weight of cement content.

Effect of UEO and SP on the Concrete Workability
As shown in the figure, slump value increased from 20 mm to 48 mm when dosage of SP was increase by 0.15%. A steady increase in the slump value was observed when the SP dosage was increased to 0.3% and 0.5%, which was measured as 60 mm and 80 mm. There was a sudden jump in the slump value to 200 mm when the SP dosage was increased to 0.8%. However at 1% SP dosage, the rate of increment was lower and it reached to 220 mm. To study the effects of UEO on 100% OPC concrete, it can be concluded that up to dosage of 0.5%, the slump value obtained was similar to that obtained with SNF superplasticizer. Beyond 0.5% dosage of UEO, it still acted as plasticizer in concrete, however its effectiveness was inferior to that of SP.

Fig. 1. Effect of SP and UEO dosage on workability of OPC concrete
The trend of workability improvement of OPC concrete containing SP and UEO did not show much significant difference since the differences in the value of exponential equation are very small. It can be stated that UEO can possibly act as water reducer and lubricant that improve concrete workability. The result obtained shows that UEO acted as chemical plasticizer by improving the fluidity of fresh concrete mix. Thus, there are similarities between UEO and SP in improving the fluidity of fresh concrete.  Fig. 3 shows the total porosity of OPC concrete containing different dosages of UEO in comparison with the control mix. Concrete with 0.15% and 0.3% UEO showed lower porosity at all ages, whereas concrete with 0.5% and 0.8% dosage showed almost the same porosity result at the age of 28 days and beyond. At the age of 28 days, 0.15% UEO concrete showed a porosity result of 7.6% which was lower than the porosity of 0.15% SP concrete that showed a result of 8.0% with 0.3% dosage of UEO, the porosity results at ages were obtained similar to that of 0.3% SP concrete results. Fig. 4 shows the total porosity of concrete containing different dosages of SP, which compared with the total porosity of control mix. For control mix, total porosity at age of 3 and 7 days was obtained as 11.6% and 11.0% respectively, which was substantially reduced at the age of 28 days that was obtained as 8.4%. Beyond 28 days the porosity was reduced up to 8%, which was not an appreciable reduction in porosity.

Fig. 4. Total porosity of concrete containing various dosages of SP
At the ages of 3, 7, and 28 days, porosity of concrete with 0.15%, 0.3% and 0.5% SP was almost similar. At 3 days it was about 8.5%, which was reduced to 8.4% at 7 days, whereas at 28 days it was obtained between 7.95% and 8%. Similarly as obtained in the control mix, porosity of concrete with different SP dosage did not reduced much after 28 days. In general, porosity of SP mixes was obtained lower than the control mixes, it was due to the SP caused the flocculation effects that reduced the cement absorbed water with the solid particles, so the size of pores would be of smaller sizes than the control mix. It can be stated that, the incorporation of UEO contributed towards the reduction of porosity and comparable with SP. It can be explained that the capillary porosity formed from residual spaces occupied by original mix water increases with high water/cement ratio within Portland cement paste. Adding superplasticizer or used engine oil could increase the free water in the mix therefore caused very high workability, increased capillary porosity, lower strength and potential decrease in durability of the concrete. For this experiment, at 0.55 w/c, the incorporation of superplasticizer or used engine oil beyond 0.3% could increase the total porosity of concrete. Besides that, used engine oil contains heavy metal and high air content that also contribute to the higher porosity. The chloride penetration result showed that 0.5% used engine oil did not give very high air entraining potential to concrete and the result were found similar to SP concrete at the same dosage. It can be stated that SO 3 function in workability improvement and also contributed towards the proper concrete matrices therefore decrease chloride penetration rate in concrete.

Effects of Concrete Containing UEO on Elevated Temperature Exposure
Compressive strength of OPC control mix, OPC with SP and OPC with UEO before exposed to the heat are 42, 35 and 32 MPa respectively while the compressive strength after exposed heat are 39, 31 and 29 MPa.
The percentage of strength loss after burned is 8%, 11% and 10% respectively as illustrated in Fig. 7. The compressive strength of OPC was slightly higher as compared to OPC with SP and OPC with UEO for both before and after exposed to fire and heat. It is also noted that the percentage of strength loss after burn at 500°C for the concrete with chemical admixture which are SP and UEO is slightly higher than the ordinary concrete. Thus, it shows that the performance of UEO in terms of compressive strength is comparable with SP.

CONCLUSION
The following conclusions could be made from the studies: 1. UEO can act as a chemical plasticizer similar to superplasticizer to improve workability, air content and strength of OPC concrete. The slump value of OPC concrete containing UEO and superplasticizer was 3.9 time and 4.4 times as OPC control mix. 2. Incorporation of UEO and SP similarly decrease the compressive streng about 10% and 12% respectively. It may due to the optimum or enough water content for hydration process in concrete. As a comparison between UEO and SP, the incorporation below 1% dosage give almost similar strength. Therefore, it can be concluded that UEO has potential to improve concrete strength as water reducing admixture same as SP. 3. UEO contributed to lower the porosity for all type of concrete and was comparable with SP. Therefore, during investigating the effects of used engine oil on porosity of concrete, up to 1% dosage did not cause any adverse as compared to the control mix, which means used engine oil can improve the durability. 4. The result of chloride penetration showed that incorporation of 0.5% of UEO did not cause any adverse effect as compared to the control mix, which meant that UEO could improve the durability. Therefore, when mortar samples were immersed in sodium chloride solution, used engine oil and superplasticizer caused 3% lower penetration as compared to control mix. 5. In order to determine the effects of used engine oil on fire resistivity of concrete, cubes were placed in oven at 500°C for one whole day. Results showed a reduction in strength of about 11% or below, which is supposed to be very minimal, hence, UEO did not add combustibility to concrete.