The Combined effect of wood ash and nanosilica on the mechanical properties of blended mortar

Abstract

• The revision of the original manuscript covering the abstract, introduction, materials, methods, and tests. • Evidence of the photos of the materials used. • Photos showing specimens during mixing, casting, curing, and testing. • Evidence of pozzolanic reaction of the investigated composite materials, among others. One of the primary construction materials with many cost benefits is cement. However, its production contributes to global warming by releasing greenhouse gases into the atmosphere. To reduce the negative impact of this greenhouse gas emission, a concentration of approximately 0.265 mol per litre of nanosilica solution as a percentage of mixing water was used. This study investigates the combined effect of woodash (WA) and nanosilica solution (NSS) as a sustainable solution to cement production problems. The investigation focuses on the mechanical properties (compressive and flexural strength) of wood ash mortar (WAM) containing NSS. Firstly, WA was characterized, and WAM was produced using Ordinary Portland Cement. A total of 21 mixtures were prepared with standard sand, and the water/binder ratio ranges from 0.5 to 0.67. The hardened mortar specimens were tested for compressive and flexural strength, conforming to SANS 5864. The results showed that the combined effect of 5 % of wood ash and 1.1 % NSS produced a compressive strength of 59.5 MPa compared to the reference mix of 51.2 MPa at 28 days. Similarly, the flexural strength of 5 % of wood ash and 1.7 % NSS produced the highest flexural strength of 7.8, 8.4, and 9.9 MPa for 7, 28, and 90 days respectively, in comparison to the control sample which has a flexural strength of 7, 7.1 and 8.6 MPa for 7, 28, and 90 days curing period respectively. As a result of this investigation, the inclusion of WA at 5 % and NSS at 1.7 % resulted in the optimum mechanical strength, which suggests its use in high-performance concrete, while also being cost-effective, suggesting its potential application for green concrete in the future.