ESTIMATION METHOD OF NON-HYDRATED CEMENT ON CEMENT RECYCLING SYSTEM USING SODIUM GLUCONATE

ATARASHI Daiki, KAMIO Tetsuji, AIKAWA Yutaka, SAKAI Etsuo

doi:10.14250/cement.67.46

Most ready-mixed concrete plants have a large problem of construction waste sludge, which causes environmental pollution and economic loss. Therefore, the cement sludge recycling system is highly requested.<br/>Japanese Industrial Standard（JIS）A 5308 permits the addition of 3％ sludge（as solid state）to cement in concrete. However, it is pointed out that the reduction of fluidity and increase of water demand was occurred upon utilization of sludge. To achieve more widespread recycling of sludge by using set-retarders, we have to establish the evaluation method of residual cement content of sludge.<br/>The rate of heat liberation of residual ordinary Portland cement in sludge water was measured by using conduction calorimeter. And the residual amount of sodium gluconate in sludge water was measured by Total Organic Carbon Analyzer（TOC）.<br/>The amount of residual cement in sludge water by XRD quantitative method was related to the heat liberation of residual cement in sludge water. It is concluded that the residual amount of cement in sludge water can be estimated by using conductive type calorimeter. When the Mg（NO₃）₂・6H₂O was added, the retardation of cement hydration by sodium gluconate was decreased. It is considered that the acceleration mechanism of Mg（NO₃）₂・6H₂O is the decrease of sodium gluconate concentration in liquid phase. The amount of residual cement with sodium gluconate in sludge water can be evaluated by using conductive type calorimeter and Mg（NO₃）₂・6H₂O. Furthermore, swift evaluation method of residual cement amount in sludge water is established by using the simulation of heat liberation curve.

ESTIMATION METHOD OF NON-HYDRATED CEMENT ON CEMENT RECYCLING SYSTEM USING SODIUM GLUCONATE

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