Modified mortar pad behavior in the transfer of compressive stresses

J D Ditz,G H Siqueira,M K El Debs

doi:10.1590/s1983-41952016000300006

J D Ditz, G H Siqueira + Show 1 more

Open Access

https://doi.org/10.1590/s1983-41952016000300006

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Abstract

ABSTRACT This research aims to analyze the compressive stress transfer between precast concrete elements using cement mortar pads modified with polypropylene fibers, styrene-butadiene latex and heat-expanded vermiculite. The stress transfer analyses are performed interleaving a cementbearing pad between two concrete blocks, subjecting the entire specimen to different compressive load tests. The parameters analyzed in the tests are: surface roughness (using bosses on the bonded phase of different thicknesses), compressive strength with monotonic and cyclic loadings. The main results obtained in this study are: a) the presence of pad increased the strength in 24% for thicknesses of imperfections of 0.5 mm and approximately 12% for smooth faces blocks; b) gain of effectiveness of the bearing pad when the concrete strength was reduced; c) for cyclic loading, the bearing pad increased in 48% the connections strength.

Highlights

The connections between precast concrete elements are very important in the design of this type of structural solution [1,2]
One can observe that there are some differences between the results presented by SIQUEIRA & EL DEBS [4], where the presence of modified mortar pad (MMP) did not result in significant differences for the compressive strength, and the results presented in this study where a gain of compres
From experimental and statistical analysis of connections between concrete blocks, some inferences about their overall behavior with and without the use of MMP are presented below: a) In tests to evaluate the effectiveness of the MMP on connections submitted to monotonic compressive loadings, it is observed that the efficiency of MMP is optimal to intermediate levels of surface roughness

Summary

Introduction

The connections between precast concrete elements are very important in the design of this type of structural solution [1,2]. The MMP is produced introducing in the Portland cement-based mortar a styrene-butadiene latex, polypropylene fibers and heat-expanded vermiculite The use of these additions results in a material with greater deformability and higher toughness, compared to an ordinary cement mortar, being able to transfer the compressive stresses in an appropriate manner. After some tests varying the number of cycles and the level of compressive load applied, the experimental results demonstrated that the stiffness for the MMP did not suffered significant change when compared to samples loaded monotonically. These results confirmed the resilient capacity of the pad. It was observed that with an increase in the amount of vermiculite in the mixture, there was a significant

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