Fine Aggregate Gradation Research Articles

Development of a cementless mortar using hwangtoh binder

This paper presents the properties of a cementless mortar developed to produce eco-friendly building material without carbon dioxide emissions and with various beneficial effects. The binder, hwangtoh binder (HB), used in this mortar was developed by reaction of a very small amount of inorganic minerals and activated hwangtoh, which is rich in silica, SiO 2, and alumina, Al 2O 3. To investigate the compressive strength and shrinkage deformation of the cementless mortar using HB, HB mortar, water–HB ratio, fine aggregate–HB ratio, and the maximum size and grading of fine aggregate were selected as the main variables of test specimens classified into three groups. The test results presenting the effect of various parameters on the properties of HB mortar confirmed that the developed HB has a highly effective performance as a binder. The equations using nonlinear multiple regression analysis based on the test results are represented to assess the flow and 28-day compressive strength of HB mortar. Comparisons between predicted and measured flow and 28-day compressive strength show good agreement.

Effects of Proposed Well-Graded Aggregate Gradations on Frost Durability of Concrete

Abstract More stringent gradation requirements than found in ASTM C 33 are sometimes specified to provide a more well-graded particle size distribution, presumably reducing voids, improving workability, thereby reducing water demand, and requiring less cement. Little information is available regarding the effects of gradation on frost durability. A two-phase study examined the effects of selected aggregate gradations on water demand, selected mechanical properties, and deicer salt scaling resistance. In the first phase, the effects of the “8-to-18” combined aggregate gradation, using crushed stone and natural sand, were examined. In the second phase, the effects of fine aggregate gradation were examined for manufactured sands with different angularities. This study found that water demand and deicer salt scaling were both compromised using the “8-to-18” approach. Little, if any, real difference in water demand and scaling resistance between well-graded and uniformly graded manufactured sands was found, however, angularity did have a significant effect.

フレッシュモルタルの流動特性に及ぼす細骨材の量および粒度の影響を表すパラメータ

This paper describes the validity of a new parameter for the content and grading of fine aggregate used in the quantitative rheological formula of fresh mortar when the mortar is assumed as a Bingham body. The rheological constants of fresh mortar, i.e. the yield value and the plastic viscosity were measured at 20±2°C with a parallel-plate plastometer using the mortar specimens of 30cm in diameter and about 3cm in height. All the measurements of these rheological constants were carried out by the same procedure within six minutes after mixing. The consistency of each mortar mix ranged from 110 to 250 in terms of JIS flow value.The rheological constants of fresh mortar using coarser fine aggregate were found to be smaller than those of mortar using finer one at the same mix proportion. By assuming that the particle of fine aggregate is a sphere, the effective volume fraction was obtained from the fine aggregate volume fraction of mortar and the thin paste (10μm) adhered over the surface of the particles. A good correlation was obtained between the fine aggregate effective volume fraction and the yield value or the plastic viscosity. So this parameter is considered suitable for the evaluation of the effects of grading and content of fine aggregate on the rheological constants of fresh mortar.

Ideal and Quasi-Ideal Grading of Coarse and Fine Aggregates for Mass Concrete

Abstract In an earlier publication the author presented a set of tables for proportioning continuously and gap-graded concrete of 38-mm (1.5-in.) maximum size, on the basis of Weymouth's theory of particle interference. In this paper, Weymouth's theory has been restated in algebraic form, thus making applications to mix proportioning less difficult. Moreover, tables for optimum grading of 76-mm (3-in.) maximum size coarse aggregate as well as tables for optimum grading of fine aggregate are included.