Geopolymer cement (GPC) is a promising oil and gas well cementing alternative to Ordinary Portland Cement (OPC). OPC forms ettringite, causing water absorption and shrinkage. GPC, with lower calcium content, is expected to have lower shrinkage. This study assesses GPC's performance with elastomeric expandable additive (R-additive), up to 25 wt.. The mixing, rheological test, free water, compressive strength, and linear expansion test were done in accordance with American Petroleum Institute Recommended Practice 10. Results demonstrated that increasing R-additive concentration reduced slurry density. Additionally, rheological properties improved, with plastic viscosity increasing from 48 to 104 cP and the yield point from 3.8 to 12.3 N/m2. The optimal R-additive concentration for ideal rheology was 20 wt.. All formulations showed zero free water, while compressive strength and linear expansion (l/l0) varied with curing time. The study also confirmed self-healing in geopolymer cement, preventing flow through the cement sheath at varying temperatures. A 25 wt. R-additive concentration allowed successful pumping at 4.8 barrels per minute with 100 psi pumping pressure. In a nutshell, the inclusion of R-additive between 10 to 25 wt into geopolymer cement meets the standards of the oil and gas industry and becomes the potential replacement for OPC. © 2024 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.