Impact Of Sewage Sludge Ash Underdifferent Incineration Temperatures On Cement Mortar

As the byproduct of waste water treatment plants, sewage sludge not only takes up land, also caused serious damage to the ecosystem. Disposal of sewage sludge from waste water plants is a serious environmental problem of increasing magnitude for many cities. Currently, main disposal solutions remain landfill and soil amendment, which consumes enormous space and contaminates surrounding environment. Though incineration leads to an important reduction in volume, there are still 30% solids remain as ash. Besides the problem of heavy metal leaching remains unsolved. The subjective of this present study is to determine the feasibility of sewage sludge ash(SSA) being used as a substitution to cement in construction materials.After the process of drying, grinding and calcination, it’s physical properties, and chemical composition was studied by means of XRD, XRF, laser granulometry and so on.Results show that SSA is composed of coarse and irregular grains,which are high in silicon, calcium and aluminum. It can be observed that density and total loss of mass of SSA increase with calcination temperature.The impact of SSA under different incineration temperatures on cement hydrating process is studied by XRD, TGA and electrical resistivities. Resistivity changes in cement paste containing SSA was observed. Results show that incorporation of SSA leads to increase in electrical resistivity and delay in cement solvation. It can also be observed that effect of delay lightens when incineration temperature goes higher. Hydration product of cement containing SSA is also presented in this paper. Compared with control sample, higher content of Si O2 and Ca O·Si O3 is observed, while Ca(OH)2 diminished. On one hand, mixing of SSA reduces short delays of cement hydration, which is due to it’s dilution effect. On the other hand, pozzolanic activity of SSA has a long term positive effect on cement paste.pozzolanic activity of SSA and workability, pore structure, freezing resistance, shrinkage and mechanic performance of mortar containing SSA is also presented in this paper. Results show that:(1) SSA demonstrates highest pozzolanic activity when incinerated under 700℃;(2) SSA under different incineration temperatures shows no difference in reducing mortar workability;(3) in corporation of SSA leads to an increase in porosity,average pore size and irregular pore structure;(4) SSA processed under temper range from 500℃~800℃ improves freezing resistance of mortar in vary degrees. Mortars prepared by replacing 10% Portland cement with SSA incinerated under 700℃ shows 2.5% less mass loss rate than control group after 100 times of freezing-thawing.(5) blending of SSA has greatly increased shrinkage of mortar, while SSA incinerated under 700℃ demonstrates lightest influence.(6)SSA incinerated under 700℃donesn’t have a significant effect on mortars’ flextural strength, however their compressive strength decreases linearly with replacing percentage goes up. When replacing rate is less than 20 percent, the compressive strength is higher than 42.5MPa after curing for 56 days.