Performance of hydrocarbon particles on the drying shrinkage of cement mortar

The inherent volume reduction normally witnessed in hydraulic cement mixes is probably one of the most important threats to its durability as this is often accompanied by deleterious cracks. This paper presents experimental findings on the drying shrinkage of poly(1,4-isoprene) modified-hydraulic cement mortar. Based on mechanical and durability requirements 0–20% (vol.) isoprene/water ratio was employed. Normal and modified mortar specimens were prepared, cured and tested for drying shrinkage. Microstructural details of both normal and modified phases were examined through scanning electron microscopy (SEM). In addition, compressive strengths of the hardened mixes and thermogravimetry analysis (TGA) of the poly(1,4-isoprene) were noted. Results have indicated a continuous decrease in the drying shrinkage of mortar with a corresponding increase in poly(1,4-isoprene) up to 10% (vol.) isoprene/water ratio, beyond which the shrinkage increases with increase in the isoprene content. Thus, inclusion of optimum content of poly(1,4-isoprene) into the normal hydraulic cement mortar minimizes its drying shrinkage, principally due to blocking effects of the isoprene particles against the inter-particle attraction of the mixed-conglomerate during the volume reduction. Indeed, this could inhibit formation and propagation of harmful cracks.