Effect of Using Dry Sludge (DS) of Water Purification in Combination with Treated Wastewater (TWW) on Concrete Strength

The construction industries utilize large amount of fresh water. Water used in the construction industry is not for only mixing concrete; it is also used for equipment cleaning, washing aggregate, and curing concrete. The social and economic cost of the scarce source of water in many parts of the world makes it significant to look for lower quality water to be used in concrete production. The water must meet certain quality requirements to be suitable for concrete mixing and curing. It has been found that certain water that does not meet high quality can be used in making concrete of acceptable quality. The short and long effects of using low quality water on concrete mechanical properties have been investigated in different parts of the world. Combining the use of recycled materials and low quality water in concrete mix could increase the deterioration of mechanical properties of hardened concrete. In this paper, the effect on compressive strength of hardened concrete using treated wastewater (TWW) and dry sludge (DS) produced by water purification facilities in concrete mixes to substitute potable water (PW) and fine aggregate. The TWW is used to substitute PW in ratios between 30 and 100% while DS is used in ratios of 10 to 30% of fine aggregate. Different design mixes are prepared and standard concrete samples are cast and tested to report the changes in compressive strength due to alteration of the standard concrete mix. Results show that using TWW only reduced the compressive strength of concrete by about 11 % while using DS in combination with TWW reduced the compressive strength by a percentage reached 26%. The use of recycled materials will affect the concrete quality with acceptable values. Utilizing these recycled materials on concrete mix will save environment and release part of the pressure on scarce sources such as water in semi-arid regions.