Performance of cement mortar containing cellulosic nanocrystals from palm oil waste

Abstract

A study on the utilization of cellulose nanocrystals (CNCs) as a natural-base additive in cement mortar as a strengthening agent had been conducted. Since cementbased materials such as concrete and mortar are known as the most utilized materials on earth after water, various studies on the cement mortar have been done to improve its properties to make more compatible with the current demand. Nowadays, the development of construction industries is going towards producing cement mortar that high in strength and environmentally friendly. However, to develop a cement mortar that as strong as concrete is challenging due to no coarse aggregate is used in the mortar mix. Thus, the development of new technologies and materials that can improve the strength of mortar without the usage of coarse aggregates was studied. These days, additive to strengthen the cement mortar by using natural resources had gained interest among researchers. Still, limited study had been conducted to study the outcome of natural-based additive in cement mortar as a strengthening agent. Thus, this research aims to investigate the changes in cement mortar properties and behavior after it is affected by a natural-based additive known as cellulose nanocrystals (CNCs). CNCs, known as advanced materials produced by using current advanced nanotechnologies and bring out the strongest part of the cellulose which is stronger than a strength of steel in tensile. The CNCs was used in cement mortar to study deeply on its characteristic and improvement contributed by CNCs. In this study, the mortar specimens were prepared with a mass ratio of 1: 2.75 (cement: fine aggregates), the water-cement ratio of 0.47 and 0.2 to 0.8% of CNCs addition by weight of cement content. Three types of curing regimes were executed known as a wrap, lime and water curing in order to find the most compatible curing method with CNCs mortar. The wrap curing method was found to produce better strength performance with the addition of CNCs compared to lime and water curing during the pilot study. Therefore, wrap curing was used throughout the study. The normal mortar was prepared as a control sample. Three important phases of tests were carried out in this study starting from chemical and physical tests characterization of the CNCs. This was followed by the performance of fresh and hardened properties of cement composites after incorporating the CNCs and ended with thermal performance tests of the CNCs mortar. The experimental results showed that the optimum percentage of CNCs used in the mix was 0.4% as it resulted in higher compressive, flexural and tensile strength. The cement mortar containing CNCs was found to perform effectively in improving the strength properties up to 43.6 %, 20 % and 147 % for compressive, flexural and tensile strength, respectively, as well as alter the thermal conductivity for 0.1% and 0.2% for the thermal resistance of cement mortar. All tests were carried out by following the American Standard Testing Method (ASTM), British Standards (BS) and Japanese International Standards (JIS) standards. Overall, test results including microstructure studies showed that CNCs can be used as an additive in cement mortar to strengthen the cement properties.