Abstract:
In concrete material, using two materials with Portland cement relies on the potential and function of each material. In case of fly ash (FA), the potential for pozzolan reaction was good in the later stage but not good in the beginning. Limestone powder (LP), which is an inert material, can help fill the gaps well, so the initial strength can be improved. The mechanism of filling LP depends essentially on particle size.
This research aimed to study the effect of the fineness of LP on the properties of concrete mixed with FA and LP. LP with fineness of 2, 8, and 15 micrometers was replaced in ordinary Portland cement (OPC) of 0 Percent, 5 Percent, 10 Percent, and 20 Percent by weight mixed with the FA replacement ratios of 30 Percent, 25 Percent, 20 Percent, and 10 Percent.
Results showed that the early compressive strengths concrete mixed with LP had higher tendency than those of OPC concrete. In addition, long-term compressive strength of the concrete mixed with FA and LP was also higher than that of the OPC concrete. Further splitting tensile strength and the modulus of elasticity of concrete mixed with FA and concrete mixed FA-LP had a similar tendency to their compressive strength. Likewise, the chloride penetration resistance of concrete mixed with FA and LP was better; quite clear when compared to OPC concrete. The expansion in sodium sulfate solution of mortar mixed with FA and the LP-FA mortar was less, while the expansion in sodium sulfate solution of mortar with LP was not different when compared with those of OPC mortar. In summary, the fineness of LP directly affected the concrete properties. The finer LP is, the better concrete properties are.