Abstract
Nowadays, global warming and the ensuing climate change are one of the biggest problems for humanity, but environmental pollution and the low ratio of waste management and recycling are not negligible issues, either. By producing alkali-activated cements (AACs), it is possible to find an alternative way to handle the above-mentioned environmental problems. First, with a view to optimizing experimental parameters, metakaolin-based AACs were prepared, and in it, waste tire rubber was used as sand replacement (5–45 wt %). Insufficient wetting between the rubber particles and the matrix was corrected through different surface treatments of the rubber. For improving the mechanical/strength properties of the specimens, fibrous waste kaolin wool (0.5–1.5 wt %) was added to the AAC matrix. Considering the results of model experiments with metakaolin, blast-furnace-slag-based AAC composites were developed. The effects of storage conditions, specimen size and cyclic loading on the compressive strength were investigated, and the resulting figures were compared with the relevant values of classic binders. The strength (44.0 MPa) of the waste-based AAC composite significantly exceeds the required value (32.5 MPa) of clinker saving slag cement. Furthermore, following cyclic compressive loading, the residual strength of the waste-based AAC composite shows a slight increase rather than a decrease.
Highlights
Today, concrete is the most widely used material system in the world
It is expected that these non-cement-based binders will not completely replace conventional binders (e.g., ordinary Portland cement (OPC)) but may be good alternatives
The great advantage of activated cements (AACs) production is that waste materials can be used as raw materials
Summary
The basic element of this is ordinary Portland cement (OPC), which has an annual global production volume of nearly 4 billion tons [1]. This amount is generating increasing environmental problems: suffice it to mention CO2 emission and the destruction of landscapes. For this reason, research for new types of binders is incessantly ongoing, and in the scope of such research alkali-activated cements (AACs), termed geopolymers, play a leading role. It is important to continuously develop AACs, one possible way of which is to produce AAC-based composite material systems
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