Shear behavior of cement stabilized rammed earth assemblages

Abstract

Adoption of rammed earth technology in building construction has witnessed a surge during the recent times and hence it is essential to understand the mechanical behavior of rammed earth under various loading conditions. In this study, in-plane shear behavior of cement stabilized rammed earth (CSRE) is assessed by conducting two types of tests namely (i) Direct shear test of CSRE causing shearing along two adjacent rammed earth layers similar to triplet shear test of masonry bed joints which is henceforth called as triplet test and (ii) Diagonal tension (shear) test of CSRE panels. Three types of bonding techniques between the rammed layers of CSRE are explored in this study, namely, (i) making conical dents which act as shear connectors between rammed earth layers, (ii) applying a coat of fresh cement slurry along the interfaces of rammed layers and (iii) combination of dents and fresh cement slurry and their influence in enhancing the interface shear strength of CSRE is assessed. The bonding techniques are adopted for both, triplet specimens and diagonal panels. Further, the effect of compressive stress normal to the rammed earth layers on the interface shear behavior of triplet specimens is examined. The different levels of normal pre-compression considered are 0.05 MPa, 0.3 MPa and 0.9 MPa. The triplet and diagonal tension (shear) tests on CSRE assemblages are conducted under both, dry and wet conditions. Shear behavior is assessed in terms of shear strength, shear modulus, strain at peak stress, post-peak behavior and failure patterns. Among the different bonding techniques assessed in this study, CSRE specimens with a coat of fresh cement slurry exhibited higher shear strength in comparison to specimens with other types of bonding techniques or no bonding technique. Further, CSRE triplet specimens exhibited steady increase in interface shear strength with increase in normal pre-compression, both in dry and wet conditions. Also, shear strength of CSRE was found to be lower in wet condition, in comparison to shear strength in dry condition, for all the bonding techniques. A Mohr-Coulomb failure envelope was developed for CSRE under wet and dry conditions based on the results of triplet tests conducted in this study. Overall, the study aims to understand the efficacy of the proposed bonding techniques in enhancing the shear strength of CSRE and the influence of normal precompression and moisture content on shear behavior of CSRE.

Bond strength of substrate with repair material for masonry structures

“…The second theory takes into account the chemical bonds on the interface. The contact at phases determines bond strength [39]. The transition theory elucidates the formation of the surface at repair material and substrate contact.…”

Mechanical characterization and elastic stiffness degradation of unstabilized rammed earth

“…In the traditional rammed earth construction (called unstabilized rammed earth), the only binder is clay. In the case of stabilized rammed earth, other binders such as cement, lime or coal ash are added in order to increase its durability and mechanical properties [11][12][13]. However, the use of these binders increases the construction cost and its environmental impact.…”

Seismic performance test of rammed earth wall with different structural columns

“…At present, many scholars have studied RE. In this study, triplet shear test and diagonal tensile test were used to study the shear characteristics of cement stabilized RE (Pavan et al, 2020). Lepakshi and Venkatarama Reddy (2020) determined the shear strength parameters, cohesion, and internal friction angle of cement stabilized RE under dry and wet conditions through triaxial compression test.…”