Abstract The effects of varying concentrations of pectin (0.1–1 wt% of cement) on the properties of ordinary portland cement (PC) and cement containing colemanite ore waste (CW) were investigated. Variation in setting time, compressive strength, and volume expansion of hydrated specimens were determined. It was found that pectin acts as an accelerator for PC cement and as a retarder for CW cement at a level below 0.1%. The inclusion of pectin in PC resulted in a reduction in the early strength of the mortar. However, pectin had positive contribution to the early compressive strength of the CW mortar. The hydration products were also identified by means of X-ray diffraction (XRD) and their microstructure by scanning electron microscopy (SEM). Although the observed hydration products were mostly as expected, due to presence of pectin in the cement paste, the degree to which these phase was present was unusual. In particular, the relative intensity of calcium hydroxide peaks decreased with the increasing pectin content at 2 days curing age.