Water absorption and water/fertilizer retention performance of vermiculite modified sulphoaluminate cementitious materials

• Published in: Construction & building materials 2017-04, Vol.137, p.224-233
• Main Authors: Li, Laibo, Zhou, Xiangming, Li, Yanlin, Gong, Chenchen, Lu, Lingchao, Fu, Xinghua, Tao, Wenhong
• Format: Article
• Language: English
• Subjects: Analysis; Cements (Building materials); Mechanical properties; Planting concrete; Porosity; Sulphoaluminate cementitious materials; Vermiculite; Water; Water absorption; Water/fertilizer retention
• ISSN: 0950-0618; 1879-0526
• DOI: 10.1016/j.conbuildmat.2017.01.061

•Vermiculite was introduced to modify sulphoaluminate cementitious materials.•Water absorption capacity increased with the increase of vermiculite dosage.•Water/fertilizer property was greatly enhanced by 20wt% vermiculite. This paper investigated the effects of vermiculite on water absorption, water/fertilizer retention and basic physicochemical properties of sulphoaluminate cementitious materials for plant growing applications. Vermiculite was utilised to partially replace sulphoaluminate cement (SAC) for the preparation of a cementitious material with enhanced water absorption capacities and water/fertilizer retention properties which are essential for plant growing in a cement-based environment. Mercury intrusion porosimetry (MIP) and thermal analysis (TG-DSC) were employed to characterize the effects of vermiculite on the porosity and hydration products of hardened SAC-based pastes for plant growing. Hydration heat-evolution was introduced for the hydration process of SAC-based materials. Experimental results showed that SAC based materials delivered the best performance at a 20wt% vermiculite content. At this SAC replacement level, the water absorption rate of hardened SAC-based paste increased by 95.3% while the water retention capacity of the SAC-based hardened paste increased 13% at 120h. In addition, other property enhancements were measured including reduction of the fertilizer pervasion rate by up to 15.3wt%, a 0.45 drop in the pore fluid alkalinity and the early-age compressive strength of up to 35.1MPa.