International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395-0056
Volume: 12 Issue: 03 | Mar 2025
p-ISSN: 2395-0072
www.irjet.net
Effect of Rice Husk Ash and Silica Fume Dosage on Compressive Strength of Cement Mortar under Varying Curing Ages Shilong Wang1, Haoyi Ren2 1,2 School of Civil Engineering and Architecture, Anhui University of Science and Technology, Anhui, China
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Abstract - This study systematically investigates the
cross-scale correlation between microstructural optimization and macroscopic mechanical responses requires further exploration.
effects of rice husk ash (RHA, 0-10%) and silica fume (SF, 010%) dosages combined with curing ages (1/14/28 days) on the mechanical properties of cement mortar. Compressive strength tests were conducted using a WAW1000 computer-controlled electro-hydraulic servo universal testing machine, coupled with scanning electron microscopy (SEM) analysis to reveal the synergistic mechanisms between admixture proportions and curing duration. Results indicate that the 28-day compressive strength of specimens with 5% RHA and 5% SF reaches 48.7 MPa, demonstrating significant improvement compared to the control group. SEM observations confirm densified C-S-H gel formation and reduced porosity in the interfacial transition zone (ITZ) under this optimal mix proportion. The study concludes that cement mortar achieves peak mechanical performance when incorporating 5% RHA and 5% SF with 28-day curing. These findings provide theoretical insights for the mix design and age-dependent behavior prediction of agricultural waste-based green mortars.
The cement industry, contributing significantly to global carbon emissions, demands sustainable technologies for green transition. While silica fume (SF) has been widely adopted to enhance mechanical properties of cementitious materials due to its high pozzolanic activity, its high production costs and limited availability hinder large-scale applications. Conversely, rice husk ash (RHA), a silica-rich agricultural by-product, demonstrates promising substitution potential. This study designs experimental protocols to systematically investigate the effects of dual incorporation parameters of RHA and SF on the compressive strength of cement mortar under curing ages of 1/14/28 days. The findings aim to provide practical methodologies for agricultural waste valorisation and cementitious material design, thereby advancing the circular economy in the construction sector.
Key Words: Dosage, Age, Rice husk ash, Cement mortar, Compressive strength.
2. Experimental Design
1. INTRODUCTION
The materials used in this study included rice husk ash (RHA) calcined at 600°C, 42.5-grade ordinary Portland cement, sand with a fineness modulus of 1.69, and silica fume (SF) containing 96% SiO₂. Tap water was employed for both mixing and curing processes. The RHA preparation began with soaking raw rice husks in a hydrochloric acid solution under continuous stirring for 1 hour. After acid treatment, the husks were thoroughly rinsed with distilled water to achieve a neutral pH. The cleaned husks were then dried in an oven and subsequently calcined in a muffle furnace at 600°C for 3 hours. Following calcination, the RHA was rapidly quenched in an ice-water mixture (0°C), dried again, and ground into a fine powder passing through a 180-mesh sieve.
As the world's largest rice producer, China generates over 40 million tons of rice husk waste annually. The improper disposal methods such as open-air burning and random stockpiling have led to severe environmental challenges, including particulate pollution and greenhouse gas emissions. Since the 1980s, Chinese researchers have systematically explored the resource utilization of rice husk ash (RHA), achieving groundbreaking progress: A Tsinghua University research team first validated the feasibility of RHA as a siliceous admixture (1985), the China Building Materials Academy developed a calcination activation process for RHA that was granted a national patent (1992), and engineering applications in modified high-iron Sulphoaluminate cement have been realized over the past decade. However, critical limitations persist in current studies: [1] RHA applications remain predominantly confined to single-sector construction materials, with insufficient investigation into its synergistic effects with industrial by-products like silica fume (SF); [2] The coupling mechanisms between dosage and curing age variables lack clarity, constrained by inadequate long-term performance evolution data; [3] The
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The mix proportions were designed based on previous research [4-6], with a cement: sand: water ratio of 330:1210:160 kg/m³. Six distinct mix groups (labelled G1 to G6) were prepared by replacing SF with RHA at substitution rates of 0%, 10%, 30%, 50%, 70%, and 90%, respectively. All specimens were fabricated and cured in compliance with the Standard for Test Methods of
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