*2.1. Materials and Methods*

Waste and natural raw materials were used for the partial replacement of CEM I 42.5 R cement. The first of these was limestone powder from the production facilities in Bukowa. The specific surface area of the limestone powder according to Blaine method was approximately 5650 cm2/g. Table 2. shows the chemical composition of this additive. The microstructure of the material is shown in Figure 2a.

**Table 2.** Chemical composition of the limestone powder used in the tests [% by weight].


(**a**) (**b**) (**c**)

**Figure 2.** SEM photo of (**a**) limestone powder, (**b**) silica fly ash, (**c**) silica granulated ground blast furnace slag.

The silica fly ash used in the study was recovered from the combustion of hard coal in Opole. It conforms to the requirements of the standard [7]: owing to its roasting loss, it is classified in class A, whereas owing to its fineness, it is classified in category N. The specific surface area of the ash according to the Blaine method was approximately 4150 cm2/g. The chemical composition of this material is shown in Table 3. The microstructure of the material is shown in Figure 2b.

**Table 3.** Chemical composition of the silica fly ash used in the tests [% by weight].


The granulated ground blast furnace slag used in the study came from the Katowice Steelworks. The specific surface area of the slag according to the Blaine method was approximately 3700 cm2/g and was similar to the specific surface area of the cement used. Table 4 shows the results of the chemical composition analysis of this additive. The microstructure of the material is shown in Figure 2c.

**Table 4.** Chemical composition of the granulated ground blast furnace slag used in the study [% by weight].


*2.2. Formulations of the Test Samples*

To compare the properties of cement mortars without additives and mortars containing waste products and lime meal in their composition, four types of mortar were prepared:



**Table 5.** Composition of samples modified with limestone powder.

**Table 6.** Composition of samples modified with silica fly ash.


**Table 7.** Composition of samples modified with ground granulated blast furnace slag.


In the samples, 2 per cent, 4 per cent, 6 per cent, 8 per cent and 10 per cent by weight of cement were replaced with additives of fly ash, limestone mortar and ground granulated blast furnace slag. In Tables 5–7, the proportion of additives is given in relation to the total weight of the dry ingredients, whereas the proportion of superplasticiser is given in relation to the weight of cement.
