Experimental Study on Feasibility of Non Potable Water with Lime on Properties of Ppc

This research aimed to investigate feasibility of outlet water of water treatment plant and limewater on properties of Portland pozzolana cement (PPC). Twenty water treatment plants were found out in the Bhimavaram municipality region in West Godavari district, Andhra Pradesh, India. Approximately, each plant supplying potable water about 4000 to 5000 L/day. All plants are extracting ground water and treating through Reverse Osmosis (RO) process. At outlet, huge quantity of wasted water is being discharged into side drains in Bhimavaram municipality. One typical treatment plant was selected, and water at outlet was collected and Physical and chemical analysis was carried out as per producer described in APHA. The effect of plant outlet water(POW), lime water(LM), and plant outlet water with lime (POWL) on physical properties i.e., setting times, compressive strength, and flexural strength of Portland pozzolana Cement (PPC) were studied in laboratory and compared same with reference specimens i.e., made with Distilled Water (DW) as mixing water. No significant change was observed in initial and finial setting time in POW, LW, and (POWL) as compared with reference specimens made with distilled water (DW). Compressive strength was significantly increased with LW and (POWL) specimens compared to that of reference specimens. XRD technique was employed to study the mineralogical analysis.


INTRODUCTION
Ever since concrete began to be used as a construction material, potable water has been using as the mixing water in concrete due to the chemical composition is well known. The literature search indicates that, not much research work has carried out on the quality of mixing water in concrete and there are no detailed guide lines [1 -3] for the use of water in concrete. The building code requirements of different countries generally contain broad guidelines on mixing and curing water. Most of the codes consider potable water to be satisfactory for both mixing and curing of concrete and stipulate permissible limits for solids and aggressive chemicals. .However, In recent years, attention has been focused on the potential for various aspects of wastewater reuse, although previous research has been performed on the use of wastewater that are producing from the water treatment plants and industries for making concrete and reported that no adverse effects on concrete properties in fresh and hardened state [6][7][8][9][10][11][12][13][14][15][16]. Also [1,17] stated that the compressive strength of the cubes made of water with unknown chemical composition not to be less than 90% of cubes made with potable water. There is a note in BS 3148 -1980which states that non potable water that results in a strength reduction of up to 20% can be acceptable compared to that of cubes made with potable water, with appropriately mix proportions. However, limit of a chemical in mixing water of concrete given by various codes is tabulated in table .1 Therefore, throughout Andhra Pradesh 71 municipalities and 13 municipal corporations were existed. From these municipalities, small to large scale water treatment plants might have been setup. As a result of water treatment plants, huge volume of ground water is wasted as wastewater. Hence, present work is taken up on the effect of plant outlet water with lime on properties of PPC.

Cement
Portland Pozzolana cement was used. The physical properties of cement are given in Table: 2.

Sand
The ennor sand was used. Table 3 gives its physical properties. The cement to fine aggregate ratio was maintained at 1:3 by weight in the mortar mixes.

Water
Distilled water was used in reference specimens and plant outlet water, Limewater (300mg/L), plant outlet water with lime(300 mg/L) were used in test specimens. The physical and chemical properties of DW, POW, POWL, and LW are given in Table: 4.  Table:1 Tolerable limits of impurities in mixing water of concrete ( all values in mg/L, except pH)   initial and final setting time using Vicat's apparatus. Sixty mortar cubes with 50 cm2cross sectional area and same number of square prisms of 160X40X40 mm were cast for compressive and flexural strengths. Tests were performed at 3 days, 7 days, 28 days and 90 days for compressive and flexural strengths. The compacted specimens in moulds were maintained at a controlled temperature of 270±20 and at 90 percent relative humidity for 24 hours by keeping the moulds under gunny bags wetted by the same mixing waters of the specimens. After 24 hours, all specimens were subjected to immerse curing for rest of 27 days.

Powdered X-Ray Diffraction (XRD)
Powdered XRD analyses were conducted to investigate the mineralogical composition of cement paste on 28 days of hydration [37]. The reference and test specimen (POWL) were grinded to a fine powder and a flat specimen was prepared on a glass surface using an adhesive for XRD measurement. The diffracted intensities were recorded using monochromatic Copper Kα radiation. Influence of DW, POW, POWL and LW on flexural strength of PPC is shown in Fig.3. . For 7 days flexural strength of DW, POW, POWL and LW are 4.9, 5.0, 5.7 and 5.8 N/mm 2 , flexural strength of POWL and LW is 16.32%, 18.36% higher than that of DW. For 28 days flexural strength of DW, POW, POWL and LW are 6.2, 5.9, 6.7 and 6.8N/mm 2 , increase in flexural strength of POWL and LW is 8.06%, 9.67% higher than that of DW. For 90 days flexural strength of DW, POW, POWL and LW are 6.5, 6.4, 6.8 and 7.0 N/mm2 respectively, increase in compressive strength of POWL and LW is 7.14%, 10.76% higher than that of DW. However, flexural strength of POW at 3, 7, 28, and 90 days is with a little variation same as that of DW.

RESULTS AND DISCUISSION
XRD of DW and test sample POLW cured for 28 days is shown in Fig. 4. It can be seen that both reference and test samples XRD patterns are almost same. The compounds identified in reference sample (DW) and test sample (POLW) are C3S, C2S, CSH, and CH. No new compounds are formed, due to lime water, extra C-S-H gel produced, hence, strength is increased.

CONCLUSION
The following conclusions are drawn on the basis of the results obtained in this paper • Setting times of POW, POWL and LW is almost same as that of DW.
• Compressive and flexural strengths of POL and DW is almost same • Compressive and flexural strengths of POWL and LW are significantly higher than that of DW, • In the XRD analysis, regular compounds C3S, C2S, CSH, and CH are appeared.
• Water treatment plants outlet waters may be recommended to use in cement mortar.