Use of Alum and Polyelectrolyte Coagulants in Mixing Water in Concrete Bunkers Building or Construction

Abstract

This paper examines the possibility of using water treatment plant’s sludge [WTP] in mixing water in preparing high strength concrete bunkers. The two main chemical coagulants used in Dokan WTP 70 km southwest of Sulaimani city in Iraq, are alum and polyelectrolyte and they produce a coagulant’s sludge which settled at the end of sedimentation process on the bottom of the clarifier tanks. In this study, the two chemical coagulants alum and polyelectrolyte used as a concrete additives. Samples of the raw water taken from the inlets and have been tested continuously for a time period of 12 months during summer and winter seasons especially at the beginning of the stratification periods of Dokan Lake (source of the treatment plant). The tests included jar tests and turbidity of the samples, then determining the optimum quantity of each of alum and polyelectrolytes. So the maximum amount of the alum was 15mg/L while for polyelectrolyte was 10mg/L. Those two maximum high values of rates of alum and polyelectrolytes and their hybrid mixing rates have been used in preparation 7 concrete prototype bunkers with dimensions of 80cm x 80cm x 15cm with an admixture rates of 15mg/L alum, 15mg/L polyelectrolyte, 10mg/L alum, 10mg/L polyelectrolyte , 10mg/L alum with 5 mg/L polyelectrolyte, 5 mg/L alum with 5 mg/L polyelectrolyte and zero mg/L for both of them (blank). Two different types of tests have been performed for the prepared concrete bunkers; the in-lab compression tests for the cube samples of the prototypes concrete and the outdoor field shouting test for the prepared concrete bunker prototypes using 12.7 mm gun fire bullets and a shooting 100m from the target. Concrete compression laboratory tests have been conducted for 7,21and 28days aged concrete prototype bunkers while the depth, length and the diameter of the cracks and punching of the bullet hitting locations on the targeted prototype concrete bunker were measured. The results of this research reveals that adding alum along either in 15mg/l or 10 mg/ l doses in the three aged concrete 7,21,and 28 days will affect inversly on the concrete compaction strength by a (1 – 8)% while adding the other mensioned doses (polyelectrolyte along with different doses 10mg/l or 15 mg/l and a hybird doses of alum 10mg/l mixed with polyelectrolite 10mg/l ,will help in increasing the concrete compression strength of the concrete by 3.5% to 12%. Through out the tests its clearly appeared that the optimum coagulant in increasing the capacity of the concrete is polyelectrolyte and with a dosage of 15mg/l and it helps to increase the capacity of the concrete to 9% at 7days , 11.5 % at 21days and 13% at 28days from the age of the concrete .The results showed that the penetration depth for all the seven concrete bunker prototypes, evaluates each prototype performance via their penetration depths, because the penetration depth of the bullet is the most important variable in selecting the best performance concrete bunker prototype among all of them. The results also showed that the minimum penetration was 1.7 cm of polyelectrolyte used coagulant prototype of 15mg/L, and the maximum ratio about 2.2cm for the concrete banker prototype containing 15 mg/L of polyelectrolyte coagulant in mixing water of the concrete mixture used in it. Also the smallest diameter as a result of shooting test was 10 cm for this prototype while the largest diameter was 20 cm for the bunker prototype containing 10 mg/L of polyelectrolyte coagulant in mixing water of the mixture used in it.