Research On The Control Of Thermal Crack Of Mass Concrete Raft-Foundation

In recent years, as the high-rise building is constantly emerging, mass concreteraft-foundation of the structure has been applied to the engineering practice. The mass concreteraft-foundation are often cracked by temperature stress in practice, therefore, research of themass concrete raft-foundation will become more and more attention.More cracks in mass concrete comes form the surface of the concrete, and when the cracksformed, the erosion things can be easily flow into the concrete structure and lead to the corrosionof the steels in reinforced concrete. The corrosion can lead to damage of the concrete surface andreducing the strength of the concrete and affecting the durability of concrete. To this end, theconstruction of mass concrete crack control must be considered.In this paper, the control of thermal crack about mass concrete raft-foundation issystematically studied. The work of this paper includes the following respects:1. On the basis of consulting a large number of references, the mechanism of productionand influencing factors of the cracks of mass concrete are introduced. The feasibility andnecessity of the control of the cracks are proofed. The material control, the design measure andthe construction measure are elaborated in this paper.2. In this paper, measures which are to avoid thermal crack of raft-foundation are identifiedthrough model text. The model test result shows that the development of temperature field ofmass concrete can be approximately divided into three phases as “warming fast”,“coolingfast” and “cooling steadily”. Insulating material should be coated in different ways to adapt tothe development of temperature field. Protruding part of raft-foundation will lead to the increaseof the cooling speed of the protruding part and the thermal spike of mass concrete. Protrudingpart will bring the negative impact on the control of temperature field, and trigger thermal crackof mass concrete easily. The results of the model test provide data to the simulation analysis andthe control of temperature field.3. In this paper, the scale model of mass concrete raft-foundation is studied by the methodof simulation analysis. Through contrast of scale model test and simulation analysis, the scalemodel test which is used in the study of mass concrete is feasible. The preferences of simulationanalysis is reasonable. Reliable material parameters that will be used in the optimization ofconstruction is provided.4. Through the simulation analysis of mass concrete, warming law, the distribution ofsection of raft-foundation and the influence of the new pouring concrete is studied. A reasonableblue print of pouring put forward in this paper.5. Through a successful cracks controlling example of a high-rise residential which has amass concrete raft-foundation in Shenyang, the simulation analysis and optimization design ofthe mass concrete raft-foundation are used in this paper. This has Designed a set of measureswhich include the two aspects of material and construction to control the thermal crack. Throughchoosing proper concrete material, the hydration heat of concrete and the temperature difference between concrete block can be prevented. This paper gives a complete set of methods whichfrom the mixing of concrete and transported to the pouring of concrete and vibration andmaintenance to prevent cracks in concrete. The Paper shows that the measures of temperatureControl are reasonable and effective.All in all, the temperature control measures and monitoring results not only provides aconvenient for the similar construction projects, but also provides reference data foe furthertheoretical research.