A study was made on the effect of the presence of rubble of building materials on the buffer capacity of loess soil (Typic Entrochrept acc. to FAO). Ground building materials: brick, concrete, foam concrete and mortar were added to the soil. Additionally, identical mixtures were prepared, with an addition of 6% of peat as reclamation material for the model mixtures. The prepared mixtures were subjected to thermal stress. They were frozen to –20°C, then the samples were transferred to a temperature of 30°C, all the time maintaining constant moisture at the level of 25% by weight, that is in the moisture range between the field water capacity and the wilting point for the loess soil. In the course of the study a significant impact of the building materials on the loess soil buffer capacity was observed. They varied with relation to the type of building material added, the time of thermal stress, and the additional presence of peat. It was found that the presence of building materials increased the buffering capacity of the soil in relation to substances of acidic nature. The presence of peat caused a reversal of this process. The ability of peat to remediate a soil degraded with building materials was also confirmed in the course of the study of the effect of thermal stress on the buffer capacity of the soil and its mixtures. With extension of the time of thermal stress, there was a decrease in the differences in buffer capacity between the particular mixtures and the soil.