Physical and Mechanical Properties of a Bulk Lightweight Concrete with Expanded Polystyrene (EPS) Beads and Soft Marine Clay

Abstract

The variation of physical and mechanical properties of the lightweight bulk filling material with cement and expanded polystyrene (EPS) beads contents under different confining pressures is important to construction and geotechnical applications. In this study, a lightweight bulk filling material was firstly fabricated with Singapore marine clay, ordinary Portland cement and EPS. Then, the influences of EPS beads content, cement content, curing time and confining pressure on the mass density, stress–strain behavior and compressive strength of this lightweight bulk filling material were investigated by unconsolidated and undrained (UU) triaxial tests. In these tests, the mass ratios of EPS beads to dry clay (E/S) were 0%, 0.5%, 1%, 2%, and 4% and the mass ratios of cement to dry clay (C/S) were 10% and 15%. Thirdly, a series of UU triaxial tests were performed at a confining pressure of 0 kPa, 50 kPa, 100 kPa, and 150 kPa after three curing days, seven curing days, and 28 curing days. The results show that the mass density of this lightweight bulk filling material was mainly controlled by the E/S ratio. Its mass density decreased by 55.6% for the C/S ratio 10% and 54.9% for the C/S ratio 15% when the E/S ratio increased from 0% to 4% after three curing days. Shear failure more easily occurred in the specimens with higher cement content and lower confining pressure. The relationships between compressive strength and mass density or failure strain could be quantified by the power function. Increasing cement content and reducing EPS beads content will increase mass density and compressive strength of this lightweight bulk filling material. The compressive strength with curing time can be expressed by a logarithmic function with fitting correlation coefficient ranging from 0.83 to 0.97 for five confining pressures. These empirical formulae will be useful for the estimation of physical and mechanical properties of lightweight concretes in engineering application.

An Estimation Approach for the Effective Elastic Modulus of Lightweight Bulk Filling Material with Compressible Inclusions and Imperfect Interfaces

“…The effects of curing time, confining pressure and imperfect interface parameters are then investigated. For the lightweight clay [11], the basic parameters are listed in Table 2.…”

“…Four estimation models are compared with the experimental effective elastic moduli of lightweight clay at the curing time of 3 days, 7 days and 28 days [11]. The first estimation model is the series model, where the effective elastic modulus of the composite material is calculated by the weighted average of the elastic moduli of matrix and inclusions.…”

“…However, an approach is still unavailable to estimate the mechanical properties of lightweight bulk filling material. The lightweight bulk filling materials (a) lightweight clay [11]; (b) lightweight concrete [12].…”

“…This interaction among inclusions and the imperfect interface Figure 1. The lightweight bulk filling materials (a) lightweight clay [11]; (b) lightweight concrete [12].…”

Improved Packing Model for Functionally Graded Sand-Fines Mixtures—Incorporation of Fines Cohesive Packing Behavior

“…Many physical properties of granular materials such as permeability, shear strength, elastic modulus, thermal conductivity and electrical resistivity depend on the packing state (or porosity) of the materials [1][2][3][4][5][6][7][8]. Therefore, preparation of mixed soil specimens at a target porosity (or void ratio) or predicting the porosity of such mixtures can be of great significance for several applications in earth and environmental sciences [8][9][10], as well as civil engineering [11][12][13][14][15]. Due to their abundance in nature and their desirable low porosity and permeability, mixtures composed of coarse sand or aggregates mixed with very fine particles such as clay or fine silt (less than 0.100 mm in size), has received increasing attention [8,[15][16][17][18][19][20].…”