Frictional behaviour of segmental retaining wall units infilled with recycled concrete aggregate
The use of segmental retaining wall units as the facing column for mechanically stabilized earth (MSE) retaining walls has increased noticeably all over the world. Hollow and solid, both types of modular block units are used in dry-stacked facing columns. Nowadays, Hollow concrete units are being implicated frequently because of its cost-effectiveness and other technical advantages. The cavities of hollow concrete units are filled with natural (fresh) aggregates for better shear resistance. The use of fresh aggregates as in-fillers in retaining wall constructions is expensive and unsustainable (annihilation of natural resources). This study mainly focuses on frictional behavior of newly designed and manufactured precast “I” blocks infilled with fresh and recycled aggregates. A series of tests were performed using a specially designed & fabricated direct shear apparatus to assess the frictional behavior of infilled blocks under different normal loading conditions. The tests were executed based on the exiting ASTM and National Concrete Masonry Association (NCMA) test protocols. Test results were outlined in the form of shear stress-displacement relationship to compare the effect of recycled aggregate against the fresh aggregate. Shear capacity envelopes were also plotted using Mohr-Coulomb failure criteria to find out the angle of friction for each case. Test results revealed that the angle of friction of the blocks infilled with the recycled aggregate is almost equal to those with the fresh aggregate.
Application of recycled concrete aggregates as alternative granular infills in hollow segmental block systems
Abstract Geosynthetic Reinforced Segmental Retaining Walls (GR-SRWs) are developing as well recognized earth retaining structures for their manifold economic and technical advantages. It is a matter of great concern that still now a huge volume of natural coarse aggregate is used as filler in GR-SRWs, thus depleting natural resources and presenting a challenge for sustainable development. The main objective of this study is to examine the effect of recycled coarse aggregates (RCAs) used as alternative granular infills in hollow facing column. As granular infills, two types of recycled aggregates were used along with natural coarse aggregates (NCAs). Recycled aggregates were primarily selected based on the grading of the source waste concretes to investigate its effect on the frictional behavior of recycled aggregates used as infillers. Purely frictional capacity of I-Block infilled with recycled aggregates was compared to those infilled by fresh aggregates. To eliminate the effect of shear pins on interface shear capacity of I-Block system infilled with gravels, none were used in purely frictional shear. A series of direct shear tests was performed using a specially designed and fabricated direct shear apparatus to assess the frictional behavior of infilled blocks under different normal loading conditions. The tests were conducted following the exiting ASTM and National Concrete Masonry Association (NCMA) test protocols. The test results were outlined in the form of shear stress–displacement relationship to compare the effect of recycled aggregate against the fresh aggregate. Shear capacity envelopes were also plotted using Mohr–Coulomb failure criterion to find out the angle of friction for each case. Test results reveal that the angle of friction of the blocks infilled with the recycled aggregate is almost equal to those with the fresh aggregate. The results also show that compressive strength of the source waste concretes has a little or no effect on the frictional performance of recycled concrete aggregates used in facing units.
The Hollywood War Machine: U.S. Militarism and Popular Culture
CONTENTS Preface Chapter One: Media Culture in the Imperial System Chapter Two: Militarism in American Popular Culture Chapter Three: War and Cinema: The Historical Legacy Chapter Four: The Vietnam Syndrome: Politics and Cinema Chapter Five: Recycling the Good War Chapter Six: Cinematic Warfare in the New World Order Chapter Seven: Hollywood After 9/11