We have investigated the effects of secondary raw materials content on the hydration of slag-cement mixtures. We focus on the important issue of studying cost-effective alkaline additives in binder mixtures based on phosphorus slag. We have analyzed the main phases in slag and ash and found that the most common phase was slag glass. This phase has considerable hydraulic properties due to high latent energy if we compare them to compare to those of the holocrystalline phase of the same compound. The process of adding small amounts of alkali and sulfates to vitreous slag activates its latent hydraulic properties. The effect of alkaline activators creates an alkaline environment required for the reactions between slag glass components. This article provides a way of determining the composition of raw mixtures and ensuring the possibility of correcting it, as well as a method for determining the proper (in terms of quality of concrete) pH value.
A new testing protocol, Alkali-Wrapped Concrete Prism Test (AW-CPT), is proposed to avoid alkali leaching and drying, which considerably influence expansion behavior of concrete affected by alkali-silica reaction (ASR). The approach used in this test is that a concrete specimen is wrapped by wet cloth containing alkali solution mimicking the alkalinity of the concrete pore solution. The proposed testing protocol was validated through laboratory and field-exposure measurements, with a focus on expansion, alkali mass balance, and mass change. The test results clearly showed that alkali leaching and drying were significantly reduced by using the AW-CPT method. AW-CPT gives a conservative threshold total alkali content, while conventional CPT overestimates it. The test results also highlighted that there may be an optimum condition of temperature and level of alkali boosting for each reactive aggregate.