Study On The Strength And Expansion Of Composite Cementitious System Under Different Curing Conditions

Based on the ternary system composed by Ordinary Portland cement, aluminate cement and calcium sulphate can achieve fast setting, rapid hardening, high early strength and little expansion, which may have potential applications, not only in the rapid repair of airfield runways, bridges and highways, but also can be used for large area of beam slab or roof concrete construction. Therefore, widespread attention and research of cementitious system received in recent years. In this paper, we study the strength and expansion of the ternary binder under different curing conditions. The strength development of the quaternary system at low temperature was studied by adding lime into the ternary binder, which can provide a theoretical basis of this kind of cementitious materials for engineering applications.In this paper, naphthalene-based superplasticizer(BNS) and Polycarboxylate superplasticizer(PC) were mixed to choose the appropriate matching of ternary binder and quaternary system, then tested the fluidity, setting time, compressive strength, flexural strength and expansion of the systems under different curing conditions. The evolution of phases present was also studied from X-ray diffraction(XRD) spectra. According to the result of thermogravimetry(TG) and scanning electron microscope(SEM), the evaluation of the hydration products from different age was discussed then.The result show that:(1) the suitable matching of ternary binder is 82%:10%:8%; due to the hydration of C3 S, which the strength is ensured at later stage under 80oC; due to the decomposition of ettringite under high temperature, which is not conducive to long-term construction, so select 60 oC curing as the best conservation system.(2) the basal matching of quaternary system is 76%:16%:8% without calcium oxide; with the increasing of the content of calcium oxide, the initial setting time and the final setting time of the system is shortened and the limited expansion is increased, although the strength be lower at early age, be higher at later age due to the delay action of calcium oxide; no matter which temperature, the strength are the highest when the amount of calcium oxide is 2%, so 2% is intended to be the most appropriate amount of this system, the suitable matching of quaternary system is 74%:16%:8%:2%.