Portland cement, as one of the environmentally polluting materials, improves durability in most damaging environments and increases the useful life of concrete structures. Therefore, conducting research on cement substitutes with desirable properties and the possibility of their industrial production in the country is inevitable. Natural pozzolans, iron and copper slags, fly ash, silica fume, rice husk ash, and calcined clay are among the cement substitutes that have been studied so far. Also, the use of some nanomaterials, including nanosilica and nanoclay, as composites with cement has been considered in recent years. Layered Double Hydroxides (LDH) are two-dimensional materials that are also called anionic clays. There are reports of the use of LDHs as cement substitutes, but so far there is no comprehensive study to investigate the effect on the properties of different cement systems. In this study, the effect of replacing part of the cement with calcined and uncalcined Mg-Al-CO3 LDH at a concentration of 2% by mass of cement on the rate of hydration reaction and some properties of cement mortar, including water absorption, compressive strength, and flexural strength, was investigated, and the results obtained were compared with reference samples. X-ray fluorescence spectroscopy (XRF), X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA) were used to determine the characteristics and properties of the studied LDH.