Formulation and Physico-mechanical Characterization of an Eco-mortar Composite Based on Bottom Ash and Magnetized Water

Objectives: To study the influence of electromagnetic fields on the physico-mechanical properties of the mortar (resistance to compression and bending). Methods/analysis: In the current research, the influence of the electromagnetic field in the mortar was studied experimentally by replacing the cement with 10% bottom ash provided from a thermal power plant and formulates a mortar with high resistance to compression and bending. Scanning electron microscopy (SEM)/X-ray diffraction (XRD) analyses were further performed to confirm the obtained results. Findings: Based on the above results, it was found that the use of magnetized water offered better microstructure and mechanical resistance to compression and bending, for both normal mortar and mortar containing 10% of bottom ash from thermal power plants. The majority of previous publications were produced on normal mortars based on cement and ordinary water, while this study was carried out on mortars with magnetized water and bottom ash. Novelty /improvement: A new method was proposed for the formulation of an eco-mortar based on bottom ash obtained from thermal power plant and magnetized water. Water mortar magnetizes with bottom ash to provide several Article Type: Article Article Citation: Redouane Mghaiouini, AbderrazzakGraich, Anis Elaoud, Toufik Garmim, M.E. Belghiti, Nisrine Benzbiria, Mahmoud Hozayn, Mohamade Monkade, Abdeslam El Bouari. Formulation and physicomechanical characterization of an ecomortar composite based on bottom ash and magnetized water. Indian Journal of Science and Technology. 2020; 13(10), 1172-1187. DOI: 10.17485/ijst/2020/ v013i10/149889 Received date: January 18, 2020 Accepted date: February 18, 2020 *Author for correspondence: Redouane Mghaiouini @ filagri1. maroc@gmail.com Department of Chemistry, Physical Chemistry Laboratory Applied Materials, Faculty of Sciences-Ben M’sik, Hassan II University, Casablanca, Morocco


Introduction
The hydration of the cement is done in a faster and active way because the magnetic field decreases the size of the clusters of water molecules which gives water this capacity to penetrate easily inside the particles of cement [1], which improves the resistance of concrete. The storage of magnetized water in a basin can probably last up to 12 hours. However, over this space of time, the magnetization can be weakened or canceled [2][3]. The study by Ref. [4] showed that when mortar is kneaded with magnetic water, the characteristics of the mortar and cement paste are enhanced. The magnetic field improves the compressive strength of concrete and also the distribution of pore size [1]. In Refs. [5][6][7][8], authors analyzed the workability and the compressive strength of the mortar and concrete prepared with granulated blast furnace slag and magnetized water. Results showed that the compressive strength of mortars formulated with magnetic water was improved by 9% to 19% more than those prepared with tap water. The compressive strength of concrete formulated with magnetic water was improved by 10-23% more than that of mortars with tap water. It was also found that the magnetic water improved the flow of the mortar and the hydration of the concrete. [7,[9][10][11]. The literature review showed that the potential use of cement is mainly determined by its physical characteristics such as particle size, coloring potential, etc. Indeed, the coarse and glassy structure of the bottom ash makes it a perfect substitute for natural materials [12]. It is still used as an economical substitute for more expensive sand in concrete manufacturing. Furthermore, bottom ash is also introduced as a basic constituent in road construction [13]. Earlier researches showed that bottom ash was also used in ceramic [14] and bricks manufacturing [15][16]. It was shown that coal cement used as a partial substitute for cement with a 10% substitution rate increased the compressive strength compared to ordinary cement at all ages. In the present study, a drop in resistance was observed with a rate higher than 10%; however, the resistance became again superior to ordinary cement only up to 56 days of cure. In Ref. [17], Monse also showed that ground clinker can effectively substitute up to 20% of a cement, without reducing the strength class of that cement.

Mortar Preparation
Mortar is a composite material, essentially made up of a mixture of three ingredients: sand, hydraulic binder (cement or lime), and water, which is generally tap water. In this study, the bottom ash (BA) is introduced into the formulation of the cement mortar by replacing it with different percentages of BA with BA/cement mass ratios equal to: 10%. To determine the mechanical properties, the mortars were prepared according to the European standard NF EN 196-1 which requires the normal mortar to be composed in mass, of a portion of cement (450 g), three portions of sand (1350 g) and half a portion of water (225 g), i.e. with a water/cement ratio W⁄C equal to 0.5. The ingredients were mixed in accordance with the requirements of the standard for 4 min in a 5 L mixer at temperature ambient and at a relative humidity higher than 50% [18]. Before starting the mechanical study; the mortars were prepared in the form of prismatic test pieces with the dimensions 4*4*16 cm 3 as shown in Figure 1. The samples thus formed were stored in open air. Then, these test pieces were tested after 28 days by mechanical resistance to bending and compression. Table 1 shows the complete formulation of the mortars. M0 mortar is the normal mortar that we take as a reference. The M10 mortar was obtained by replacing part of the cement with bottom ash quantities of 10% by mass.

Cement
The cement used in the formulation of mortars is CEM II (CPJ 45) defined in the Moroccan standard NM 10.1.004. It is a Portland cement made up of 81.5% clinker, 12% limestone; the rest is gypsum which regulates the setting.
The chemical composition of CPJ 45 cement is presented in Table 2 below:

Sand
The sand used in the mixtures was taken from the coast (Oualidia). Its particle size analysis was carried out according to standard NF P18-560 with an electric sieve shaker. The results obtained are summarized in Figure 2.
According to the grain size curve, the corresponding uniformity coefficient Cu is 1.7 and the predominant grain size ranges from 0.2 mm to 0.315 mm. The sand used is therefore uniform and composed mainly of fine grains. The apparent density of the sand used was determined, considering a proportion of pores (voids) of 41.5%. The results obtained are summarized in table3: The actual density obtained of 2.77 g/cm 3 corresponds well to the specific weight of sand.

Coal Bottom Ash
The results of analysis of the chemical composition of the JLEC bottom ash are given in Table 4.
It is noted that more than 80% of the chemical constitutions of the ashes were composed of the constants SiO 2 , Al 2 O 3 , and Fe 2 O 3 , with regard to lime the mineralogical   composition of the bottom ash contains 2% maximum of this element as indicated by the X-ray diffraction technique. This study reveals the existence of two peaks. The first is attributed to the quartz (SiO 2 ) and the second corresponds to the mullite ( Figure 3). This result can be explained by the mineralogy of the coal used, which generally consists of crystalline silica in the form of quartz and phyllitheous minerals from the group of clays (schists) [19].
The study of the morphology of bottom ash was carried out using Philips XL 30 ESEM scanning electron microscope (SEM). Figure 4 illustrates the morphological structure of the crude bottom ash obtained before filtration: they are in the form of spherical particles of irregular sizes. This result is similar to the one reported by Wei-ling Sun et al. [20] , who showed by SEM micrographs that the observed irregularity reveals the presence of porosity. The authors also showed  that most of the cement grains were in the form of hollow spheres or spheres filled with smaller spheres. Micro crystals are also observed at the surface of the particles, which may indicate the presence of mullite and quartz. The elements Si, Al, Ca, Na, and small amounts of Fe are contained in the pledospheres. This is consistent with our mineralogical spectrum depicted in Figure 3 which chemical composition is illustrated in Table 2. It can also be pointed out that the specific surface area measured for these crude bottom ash (400 m 2 /kg) remains low compared with that of fly ash.

Study of Mechanical Resistance to Bending
The experimental determination of the mechanical flexural strength of mortars was carried out on a material characterization machine provided with a three-point bending device as shown in Figure 5 [21]. The experimental conditions used are described by standard EN 196-1.
The test piece is placed symmetrically on the terminals of the support so that the path of the force is perpendicular to the longitudinal axis of the test piece. A preload was applied to avoid any specimen play and to balance the displacement measurement device. In order to obtain the breaking load, the increasing force F is applied to the upper face of our specimen at a constant speed of 1 mm/min until the prism breaks. We then deduce the mechanical resistance to bending given by:

Mechanical Resistance to Compression
After flexural, we re-use each half-prism to measure the mechanical resistance to compression ( Figure 6) [21].
A progressive force was applied on the transverse section (4 × 4 cm 2 ) of the test piece with the same speed until the breaking load from which the mechanical resistance to compression was calculated in mega-Pascal using the following formula: Afterwards, the specimens were also analyzed a diffract meter of flat technical form at the university of Chouaib Doukkali El Jadida Morocco, using a copper anticathode (Cu-Kα) with wavelength λ equal to 1. 5406 A. The specimens after crushing were analyzed by a IRTF type Thermo.

Experimental Variables
Tap water is treated through a kind electromagnetic field by the System Aqua 4D. Figure 7 shows the electromagnetic field generator machine developed for this research. The length of this machine is 804 mm and its weight is about 2 kg. The diameter of the drain hose is 112 mm. The water flow can be adjusted using a proportional integral differential regulator (PID). The system is a set composed of the following modules: • The F Pro command that brains the system. It generates processing signals and continuously checks the proper functioning of the system. • The processing units (TU) which diffuse the signals generated by the F Pro control into the water.
When tap water passes through this electromagnetic field, it turns into EMFTW as shown in Figure 7.
The water to cement ratio (W/CM) of the mortar samples is 0.5. For mortar specimen, the percentage of cement substituted by bottom ash is equal to 10%.  containing 10% of BA mixed with tap water (TW) and magnetized water (MW). Although prepared with varying percentages of bottom ash substitution of cement, all of the mortar specimens show a similar evolution, indicating that the effect of EMFTW magnetic field strength on resistance to the compression of different mortar specimens is almost identical. As it can be seen, if bottom ash is used instead of cement and regardless of the bottom ash content, flexural and compression strength of the mortar mixed with EMFTW is greater than those of the control (the tap water being represented by 0 T). In other words, EMFTW is more effective than tap water during the hydration process. In addition, the effect of EMFTW on compressive strength varies with the percentage of bottom ash. The greatest growth is noticed when working with 10% bottom ash. Inside the electromagnetic field generated by AQUA 4 D, the magnetic force can fragment small clusters of water into clusters. As a result, the efficiency of water increases [20]. As does the hydration of the cement grains, the speed of distribution and penetration  of EMFTW through the almost impermeable layer of the cement paste is greater than that of tap water. As a result, the hydration is improved, which increases the strength of the mortar. Furthermore, during the hydration the clusters of magnetized water become smaller. This induces their dispersion and facilitates their penetration through the particles of cement which improves the reaction of water with the cement and increases the interface water magnetized with particles of sand and bottom ash [7,[22][23]. It is also interesting to mention that the mortar manufactured by EMFTW contains fewer micro pores as it is denser and therefore less permeability of water through the mortar is expected [24].

Characterization of Mortars by X-ray Spectroscopy
From the X-ray diffraction pattern presented in Figure 12,

Interpretation of IR results
From Figures 14 and 15, a band around 525.53 cm −1 (Si-O-Si) is observed which corresponds respectively to the valence vibration and deformation modes of the Si-O (silica phase) layer C3S and C2S. Moreover, an intense peak around 976, 73 cm −1 shows a very precise percentage of cement. A bung towards 875 cm −1 is also revealed, followed by a changeable peak towards 872, 83 cm −1 followed in turn by a peak which changes around 1409, 87 cm −1 , characteristic of the modes of vibration of elongation of the C-O. These   Furthermore, the peaks revealing water (H 2 O) appear above 3000 cm −1 (around 3386 cm −1 ) alongside a peak relative to an elongation vibration mode of the OH layer. In Figure  15, hearth ash (pozzolan) present in small quantity in the composite to analyze is not detected. This component is generally determined by a wide and intense vibration of the Si-O silica layer at 1030 cm −1 . In fact, hearth ash is completely camouflaged by the clinker, which makes it very difficult to detect this phase by IR technique [25].

Conclusion
This research was to develop the bottom ash which is a waste of thermal centrals in the field of materials construction. This research focused on replacing a part of cement with this waste harmful to the environment. In the course of this study, several conclusions were made: In an experimental way, it was shown that the use of magnetized water improved the mechanical properties of normal bottom ash mortars compared to that with 0% of magnetized water. Mortar mixed with magnetized water was improved by 12.56% compared to the one mixed with tap water. In the case of the asserted mortar with 10% bottom ash and magnetized water, flexural strength was improved by 12.67% compared to mortar mixed with 10% bottom ash and tap water.
The compressive strength of normal mortar formulated with magnetized water was enhanced by 5.91% compared to mortar mixed with tap water.
For the asserted mortar with 10% bottom ash and magnetized water, compressive strength increased by 6.42% if compared to mortar mixed with 10% bottom ash and tap water.
Adding bottom ash in the formulation of an eco-mortar seems to be a solution that takes into account both environmental, economic and growing global demand for building materials.