Abstract
In this paper, the use of natural pozzolan as a partial cement substitute in concrete materials is investigated. By means of a test series, four mixes using three types of natural pozzolan, as well as a Class F fly ash, are evaluated. The effectiveness of each pozzolan in controlling alkali-silica reactions has been studied. Correlations have been revealed between the mechanical properties of the proposed mixes and a Portland cement control mix. The results are also compared with industry standards for mortars made with fly ash and silica fume. The paper's findings indicate that one type of pozzolan may be used as a substitute for fly ash, but not for silica fume.
Highlights
Under the strong contemporary demand for modern and environmentally friendly materials, natural pozzolan can be proved to be such a material and several researchers have focused their research efforts in using it as a partial substitute in the manufacture of concrete and mortar [1,2,3,4,5,6,7,8,9,10].Pozzolans are divided into two categories, namely the natural and the artificial, as metakaoline and silica fume (SF)
A 14-day expansion greater than 0.20% indicates a potentially reactive aggregate in the field, while a 14 day expansion smaller than 0.10% indicates a non-reactive aggregate. (Fig. 8 – Fig. 10) show the expansion test results. These results show that, fly ash is slightly more effective than the natural pozzolans, both pozzolans significantly reduce the 14-day expansions and control alkalisilica reaction (ASR)
While the natural pozzolan met the silica fume requirements for Blaine fineness and the percentage remaining on the 45 micron sieve, it is significant that it did not meet the 7-day strength activity index of 85%
Summary
Under the strong contemporary demand for modern and environmentally friendly materials, natural pozzolan can be proved to be such a material and several researchers have focused their research efforts in using it as a partial substitute in the manufacture of concrete and mortar [1,2,3,4,5,6,7,8,9,10]. This paper investigates the feasibility and effectiveness of using naturally occurring pozzolan materials as an additive or substitute for cement in concrete mixtures. This investigation has been carried out through a series of experiments using a Class F fly ash and three types of natural pozzolans under the following laboratory tests: chemical composition, moisture content, loss on ignition, compressive strength, strength activity index, expansion from alkali-silica reaction (ASR), heat of hydration, slump, drying shrinkage, and autoclave expansion
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