Using rammed earth mixed with recycled aggregate as a construction material

Abstract

The importance and recognition of sustainability is growing within the construction industry. Traditional rammed earth has many benefits in terms of sustainability. For this reason, this ancient building method is regaining popularity. Also, the conservation of natural resources as well as the reduction of waste generation is an important aspect of sustainability. Thus, incorporating recycled aggregates (RA) into rammed earth would greatly contribute sustainable practices in the construction industry and promote the wider use of this building technology. The overall target of this study is to improve the knowledge of rammed earth structures that incorporate RA and to further the development of future sustainable construction. For this purpose, we used artificial soil with different Recycled Aggregates replacement percentages endeavors, to examine the effect of varying different size of RA particles on the unconfined compressive strength (UCS) of rammed earth and also compare the linear shrinkage between the mixes with natural aggregates (NA) and with RA. The use of appropriate soil is the key to the success of rammed earth. Therefore the characteristics of the soil are considered important. In the state of the art, we focus on the test methods and explain typical physical properties of rammed earth, production process, compaction of the rammed earth and methods used for construction.Initially the grading and the particles fractions for our artificial soil from natural aggregate was chosen and then after finding the optimum moisture content for rammed earth with natural aggregate we start replacing RA in different percentage instead of bigger particles (gravel and sand) in our samples .Some samples were tested for unconfined compressive strength after 7days and the other after 28 days. The results of unconfined compressive tests in this experiment indicate that rammed earth mixes with RA have acceptable strength and their compressive strength were fairly lower than natural aggregates. All batches have strengths exceeding 2 MPa and thus can be used in rammed earth construction. The addition of RA in this study does not lead into a decrease in characteristic UCS, and in general, especially when the coarser natural aggregate (gravel) replaced by coarse recycled aggregates. Finally in this study, the results of linear shrinkage test were approving the recommendations and were acceptable. In regards to rammed earth incorporating RA, this study focused in most part on the effect that RA has on the compressive strength and shrinkage of rammed earth. The effect of RA on other properties of rammed earth should also be examined. Other properties such as durability, erosion resistance and thermal conductivity may be affected by the addition of RA and should be study in future.