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In this work, we propose the use of steel slag instead of slag powder, in addition to fly ash and silica fume, to obtain high-performance sulphoaluminate cement-based materials. According to the closest-packing theory and on the basis of the minimum water requirement test, the influence of mineral admixtures on the minimum water requirement was evaluated for sulphoaluminate composite system paste. The optimal composition of the cementitious materials was thus determined. Orthogonal tests were used to assess the validity of this ratio. The correlation between minimum water requirement and the standard consistence was not only analyzed in the system of the minimum water requirement method decided but also in the complicate system of the orthogonal tests determined. Experimental results show that the influence of steel slag on the minimum water requirement is the largest in composite cement paste; minimum water requirement and standard consistency have a good correlation; the cement paste designed with the optimum composite had the highest strength of all the tested materials, but minimum water requirement and strength have a poor correlation in the orthogonal tests. We demonstrate that standard consistency evaluation can replace the minimum water requirement method to determine the optimum ratio of cement mineral admixtures. The proposed method not only simplifies the process but also makes the method more scientific.

In current projects, many garages were built after the main structure finished. However, the excavation of garage foundation not only changed the bearing capacity modification by depth, but also makes the soil pressure along the two sides become different. And thus the stress condition of the main building foundations is changed. The change of stress condition affects the stability of main structure directly. Based on the stress condition of high buildings foundation after one side excavation, the change of settlement under the eccentric action was studied. The change of settlement makes the tilt turning appear and thus makes the overturning resistance moment change. The dynamic principle of stability safety factors were also investigated in this paper. The effect of settlement affected by the change of stress condition was considered in the stability analysis of high building. This new method can better and truly evaluate the effect of excavation of foundation on the stability of overturning resistance than the traditional method considering only the static load-carrying capability. The operation of the new method is stronger in the project application for its clear mechanism.