The objective of this research is to investigate the influence of aggregate properties (material, shape, and surface texture) on the mechanical properties of concrete (compressive strength) and the interfaces between cement and aggregates. Different types of aggregates were used in concrete production, sourced from various geological regions within the province of Tehran. Selected samples include marl limestone, dolomite, tuff, and quartzite. The initial properties of the selected aggregates were studied, followed by crushing the rock specimens using the Los Angeles apparatus. The characteristics of aggregates, such as surface texture, shape, petrography, and particle size distribution, were determined. Concrete mixtures were prepared with a constant ratio of water to cement (0.55) for each type of angular and rounded aggregates to study the microscopic and compressive strength properties of concrete samples at ages of 28, 14, 7, and 90 days. Microscopic examinations revealed the presence of a transition zone in the matrix, demonstrating a uniform thickness in concrete samples with limestone aggregates compared to variable thickness in the case of tuff aggregates. The results also indicate that limestone aggregates, with suitable porosity and establishing a reaction with cement, create a stronger bond compared to other aggregates. The comparison of compressive strength results shows that concrete made with angular aggregates generally exhibits higher resistance compared to crushed aggregates of the same type. In general, aggregates suitable for use in concrete, including lightweight aggregates with low water absorption capabilities and angular shapes, tend to have higher short-term strength.
Type of Study:
Review Article |
Subject:
Engineering Geology Received: 2023/05/17 | Accepted: 2024/04/30 | Published: 2024/05/20