Investigation of pozolanic properties of some industrial waste materials in hydraulic lime-based restoration mortars

Natural hydraulic lime (NHL)-based mortars are preferred in restoration projects due to their ability to support long-term durability in historic buildings without compromising the structural integrity and heritage value. In this thesis, NHL-based mortars containing waste marble dust, ceramic dust, and stone wool dust (at 5wt%, 10wt%, and 15wt%) were produced, and their performance was investigated. Mechanical (compressive and flexural strength), flow, and capillary water absorption tests were conducted to evaluate the performance of the produced mortars. Grain size distribution and density analyses were conducted to examine the physical properties of the mortars. Additionally, XRD (X-ray diffraction) analyses were performed on NHL mortars containing 15% of the additive. Mechanical tests showed that the compressive and flexural strengths of the marble dust and ceramic dust-added mortars were lower than those of the reference samples. However, significant improvements were observed in both compressive and flexural strengths of the NHL-based mortars with stone wool additives, particularly under water-curing conditions, in samples aged 7 to 28 days. The highest compressive and flexural strengths of 2.91 MPa and 1.15 MPa, respectively, were obtained in 28-day water-cured mortars containing 15% by weight stone wool powder. The results of the conducted XRD analyses enabled the identification of the mineral phases present in the mortars, thereby providing consistent support for the observed mechanical strength outcomes. Mechanical test results were supported by XRD analysis results. Spreading (flow) tests showed that increasing the additive powder ratio in the mortar from 5% to 15% resulted in a significant increase in spreading diameter. While the spreading diameter in the mortars containing 15% by weight marble and ceramic dust was 165 mm and 170 mm, respectively, it reached 200 mm in the sample containing 15% by weight stone wool powder. This indicates that the fluidity is improved due to the porous and fibrous structure of the stone wool powder material. Water absorption tests showed that all mortars produced exhibited higher short-term absorption, but similar saturation levels were reached after 24 hours. The addition of stone wool powder accelerated early water absorption more than the addition of marble and ceramic powder, but also contributed to a reduction in long-term permeability. The results indicated that adding ceramic and stone wool powder to NHL-based mortar generally improved the sample's mechanical performance, workability, and long-term moisture resistance, increasing its potential for use in restoration and construction applications, while marble powder should be limited to non-structural applications.