Utilization of Colemanite waste in Concrete Design

Waste material is formed in enormous quantities during the beneficiation of raw ore. These wastes can cause both economic loss and environmental pollution. Thus, in this study, the effect of CW obtained from Eti Mine Establishments Kütahya-Emet Boron Plants on the compressive strength and cylinder splitting tensile strength of concrete and its USAbility as a concrete admixture is investigated. The results found show that utilization of Colemanite Waste is possible when it is used as additive in concrete.


I. INTRODUCTION
Turkey has 72% of the world's total boron reserves and produces 1.72 million tons per annum [1]. There are three important boron mineral in Turkey which are ulexite, tinkle and colemanite. Waste material is formed in enormous quantities during the beneficiation of raw ore. These wastes can cause both economic loss and environmental pollution. The use of these wastes as additives in the production of concrete will contribute to both economic and environmental protection. Some waste materials, which are very similar to Portland cement and have pozzolanic properties in terms of their basic composition, can be used as building materials. Although the mineral additives used in concrete have similar physical properties and mineralogical and chemical compositions to Portland cement. Due to pozzolanic activity of these substances they have a role in formation of hydration products due to pozzolanic activities. Thus, while the various properties of the concrete are improved, mineral additives with high pozzolanic activity can improve the void structure, resulting in a denser structure, increasing the adherence between the aggregate and matrix interface, and achieve high strengths [2]. Colemanite and Tinkal Concentrator consist of eight oxides (Al2O3, SiO2, MgO, Fe2O3, CaO, SO3, Na2O, K2O) forms cement's chemical composition of the wastes and other additives used in cement production [3].These materials has been the subject of many researchers to develop new materials [4][5][6][7][8][9]. In another study, mechanical properties of colemanite-added concretes were investigated. Colemanite was added at different ratios as cement admixture and it has been reported that the colemanite admixture has no significant effect on workability and the strength values do not show any significant change compared to the control concrete when the amount of added colemanite does not exceed 10% by weight [10]. CW is used as an aggregate, the physical and mechanical properties of the concrete produced were investigated. Properties such as air content, compressive and tensile strength, Schmidt test, modulus of elasticity, freeze-thaw resistance, unit weight were investigated. As the colemanite ratio increases, the engineering properties of concrete are improved [11]. To determine the effect of Kütahya-Emet colemanite on the splitting tensile strength and shrinkage properties of mortar, samples were tested at 7, 28, 56 and 90 days. It has been stated that concrete mixtures containing 3% and 5% CW have higher strength compared to the control concrete and that the shrinkage of the mortar compared to the control sample is reduced by 37%. Based on these results, it was CW could be used as an effective anti-shrink agent in terms of cost [12]. Studies on the use of colemanite waste (CW) as a mineral additive in concrete and mortars instead of a part of cement are limited in the literature. In this study, the effect of CW obtained from Eti Mine Establishments Kütahya-Emet Boron Plants on the compressive strength and cylinder splitting tensile strength of concrete and its usability as a concrete admixture is investigated.

II. MATERIAL AND METHOD 2.1. Materials
The cement used in this study is normal (CEM I 42.5 R) Portland cement in accordance with TS EN 197-1: 2002, manufactured by Adana Cement Industry. The cement has a specific gravity 3.15 g/cm 3  saturated specific gravity of the fine and coarse aggregate were 2.60 and 2.75 gr / cm 3 , respectively. Iskenderun city water was used as a mixture water.

Experimental Method
In this research, two sets of experiments with two different water-binding ratios (0.50 and 0.60) and a 350 kg/m 3 binder were designed. Totally 10 different concrete mix design were studied with CW replacement with CEM I 42.5 R by weight of 0%, 3%, 5%, 10% and 15%. The properties of the mixtures are given in Table 2.

Slump Test
The slump test was carried out to determine the collapse class from the fresh concrete properties. The bottom diameter of cone is 200 mm in diameter and 100 mm in the upper diameter and 300 mm in height. The concrete mixture prepared in accordance with the principles stated in the design was filled in three stages on a flat ground. The slump is raised slowly upwards and fresh concrete will weigh with its own weight. The distance from the top of the concrete to the bottom of the bar is measured and this length is called slump value of fresh concrete.

Compressive Strength
Maximum stress in the concrete under impact of axial pressure loading in this study were determined according to ASTM C 39 [13] standard. In the experimental design, the compressive strengths of concrete specimens were determined with cube samples of dimensions 150x150x150 mm at the ages of 7, 28, 90 and 180 days.

Splitting Tensile Strength
The splitting tensile strength test was executed accordance with the principles specified in the ASTM C 496 [14] standard on 28 and 180 days with 150 x 150 x 150 mm cube samples. The partition jointa are placed on the bottom and top surfaces of the cube samples and the axial load applied by pressing is transformed into linear. Tensile stresses resulting from tensile forces in the perpendicular direction to the loading direction cause fracture of the specimen. The splitting tensile strength of the sample was calculated with the equation (1).
"e" , "P" and "a" refer splitting tensile strength, failure load and length of cube specimen, respectively.

Ultrasonic Pulse Velocity Test (UPV)
Ultrasonic pulse velocity test was carried out according to ASTM C 597-02 [15] for 28 and 180 days of concrete samples. The passing time of the ultrasonic pulse from one surface to other of concrete sample was measured.

Schmidt Test
The test specimens were tested on the concrete samples at 7, 28, 90 and 180 days. The restitution coefficient of Schmidt test hammer was recorded.

Hardened Concrete Properties 3.2.1. Compressive Strength Test
The compressive strengths obtained from concrete samples containing colemanite are presented in Table 4.
The tests were formed by compressing concrete having 15x15x15 cm 3 dimensions. Figures 1 and 2 show the compressive strength results of each mixture graphically.

Splitting Tensile Strength Test
Splitting tensile strength resistance is determined by cylinder splitting test. Tests were carried out on the specimens kept in the curing pool for 28 and 180 days. Table 5 presents the results of cylinder splitting tensile strength resistance of the test samples. Figures 3 and 4 show graphical representation of the strength results for each mixture. ://dx.doi.org/10.22161/ijaers.4.12.25  ISSN: 2349-6495(P) | 2456-1908(O) www.ijaers.com Page | 173 When the results of the splitting tensile strength are examined, it is seen that the samples containing 3% and 5% CW in all mixture groups (B and D) have higher strength than the control sample at both ages. It is seen that these results are compatible with the results of 28 days of tensile strength determined by [16]. The samples with 10% CW reached almost the same splitting tensile strength with the control sample at the end of 180 days in all groups. On the other hand, the samples with 15% CW also give a value of splitting tensile strength slightly lower than the control sample at all ages in all mixture groups.

Ultrasonic Pulse Velocity Test
Ultrasonic pulse velocity tests were carried out on cube specimens of 15X15X15 cm in size.   Table 9, these results are evaluated accord6 given by Whitehurst, 1951. When Table 7  When the results of the cylinder splitting tensile strength are examined, it is seen that the samples containing 3% and 5% CW in all mixture groups improved the cylinder splitting tensile strength higher than the control sample at both ages. The samples with 10% CW reached almost the same cylinder splitting strength with the control sample at the end of 180 days in all groups. When examining the test results of mixtures with 350 Dose 0.6 W/B ratios, it is seen that all CW -added mixtures have developed compressive strengths close to the control sample at almost all ages. The ultrasonic pulse velocity results of group B mixtures (350 doses, 0.6 W/B ratio) show that mixtures with 3%, 5% and 10% CW contribution reach higher pulse transmission rates which are close to the control sample at all ages. On the other hand, mixtures with a contribution of 15% CW were found to have a velocity transit speed very close to the control sample on the 180th day. When the ultrasonic pulse velocity results of the D group mixtures (350 doses, 0.5 W/B ratio) are examined, it appears that all mixtures containing CW have higher pulse transmission rates than the control sample at all ages. It has been found that there is a strong relationship between the compressive strengths of the test hammer and the concrete test press.