Cement stabilized rammed earth (CRSE) is a sustainable, low energy consuming construction technique which utilizes inorganic soil, usually taken directly from the construction site, with a small addition of Portland cement as a building material. This technology is gaining popularity in various regions of the world, however, there are no uniform standards for designing the composition of the CSRE mixture. The main goal of this article is to propose a complete algorithm for designing CSRE with the use of subsoil obtained from the construction site. The article’s authors propose the use of artificial neural networks (ANN) to determine the proper proportions of soil, cement, and water in a CSRE mixture that provides sufficient compressive strength. The secondary purpose of the paper (supporting the main goal) is to prove that artificial neural networks are suitable for designing CSRE mixtures. For this purpose, compressive strength was tested on several hundred CSRE samples, with different particle sizes, cement content and water additions. The input database was large enough to enable the artificial neural network to produce predictions of high accuracy. The developed algorithm allows us to determine, using relatively simple soil tests, the composition of the mixture ensuring compressive strength at a level that allows the use of this material in construction.
Cemented stabilized rammed earth (CSRE) is a building material used to build load bearing walls from locally available soil. The article analyzes the influence of soil mineral composition on CSRE compressive strength. Compression tests of CSRE samples of various mineral compositions, but the same particle size distribution, water content, and cement content were conducted. Based on the compression strength results and analyzed SEM images, it was observed that even small changes in the mineral composition significantly affected the CSRE compressive strength. From the comparison of CSRE compressive strength result sets, one can draw general qualitative conclusions that montmorillonite lowered the compressive strength the most; beidellite also lowered it, but to a lesser extent. Kaolinite lightly increased the compressive strength.
Predicting the compressive strength of cement-stabilized rammed earth (CSRE) using current testing machines is time-consuming and costly and may harm the environment due to the samples’ waste. This paper presents an automatic method using computer vision and deep learning to solve the problem. For this purpose, a deep convolutional neural network (DCNN) model is proposed, which was evaluated on a new in-house scanning electron microscope (SEM) image database containing 4284 images of materials with different compressive strengths. The experimental results show reasonable prediction results compared to other traditional methods, achieving 84% prediction accuracy and a small (1.5) oot Mean Square Error (RMSE). This indicates that the proposed method (with some enhancements) can be used in practice for predicting the compressive strength of CSRE samples.
Cement-stabilized rammed earth (CSRE) is a sustainable construction material. The use of it allows for economizing on the cost of a structure. These two properties of CSRE are based on the fact that the soil used for the rammed mixture is usually dug close to the construction site, so it has random characteristics. That is the reason for the lack of widely accepted prescriptions for CSRE mixture, which could ascertain high enough compressive strength. Therefore, assessing which components of CSRE have the highest impact on its compressive strength becomes an important issue. There are three machine learning regression tools, i.e., artificial neural networks, decision tree, and random forest, used for predicting the compressive strength based on the relative content of CSRE composites (clay, silt, sand, gravel, cement, and water content). The database consisted of 434 samples of CSRE, which were prepared and crushed for testing purposes. Relatively low prediction errors of aforementioned models allowed for the use of explainable artificial intelligence tools (drop-out loss, mean squared error reduction, accumulated local effect) to rank the influence of the ingredients on the dependent variable—the compressive strength. Consistent results from all above-mentioned methods are discussed and compared to some statistical analysis of selected features. This innovative approach, helpful in designing the construction material is a solid base for reliable conclusions.
The article compared the test results of a number of features determining the durability of rammed earth durability in a humid continental climate. The results of wet to dry compressive strength ratio, frost resistance, linear shrinkage, resistance to erosion under the influence of a stream of pressurized water, and resistance to erosion under the influence of cyclic wetting and drying were presented. All of the tests were done on the same soil-cement mixture. On this basis, it was determined which of the methods of durability assessment is more and which is less restrictive. A new method for assessing the durability of CSRE in a humid continental climate has been proposed, which is the frost resistance test. This test is determined by the method that is described in the national annex of the European concrete standard of one of the temperate climate countries. The article also shows that a minimum of 9% of the cement additive and a soil mixture containing a gravel fraction are required, in order to ensure adequate rammed earth durability in a humid continental climate (i.e., frost resistance).Buildings 2020, 10, 26 2 of 20 size of the obtained soil, modifies the soil mixture. The need for cement stabilization is determined, among other things, by the exposure conditions of the rammed earth building and the requirements in terms of mechanical properties [3]. The ingredients are mixed together in an air-dry state and water is then added to ensure that the mixture is sufficiently moist, and therefore able to obtain sufficient workability for compaction by ramming. The layers of the moist, loose mixture are laid in formwork and then compacted with a traditional or mechanized rammer. Once the layer has been properly compacted, further layers are successively added until the planned height of the element is reached. The formwork is then removed. The compaction of layers is intended to reduce the porosity of the material, which involves an increase in its bulk density.Buildings 2019, 9, x FOR PEER REVIEW 2 of 20 the grain size of the obtained soil, modifies the soil mixture. The need for cement stabilization is determined, among other things, by the exposure conditions of the rammed earth building and the requirements in terms of mechanical properties [3]. The ingredients are mixed together in an air-dry state and water is then added to ensure that the mixture is sufficiently moist, and therefore able to obtain sufficient workability for compaction by ramming. The layers of the moist, loose mixture are laid in formwork and then compacted with a traditional or mechanized rammer. Once the layer has been properly compacted, further layers are successively added until the planned height of the element is reached. The formwork is then removed. The compaction of layers is intended to reduce the porosity of the material, which involves an increase in its bulk density.
One of the main threats to constructions made from rammed earth is destruction due to exposure to water.The way to limit this dangerous phenomenon is to supplement the local soil mixtures with stabilizing agents.The main component used is Portland cement. This article analyses the results of research which focused on the resistance of rammed earth to water erosion. Because of the lack of national standards regarding the method of examining the durability of rammed earth, the research was based on the New Zealand standard NZS 4298: 1998. The results confirm the possibility of using rammed earth stabilized by cement in a temperate climate.
Currently, a worldwide dynamic rise of interest in using soil as a construction material can be observed.This trend is evident in the rapid rise of the amount of standards that deal with soil techniques.In 2012 the number of standards was larger by one third than five years prior. To create a full standardization of the rammed earth technique it is necessary to take into account the diversity of used soil and stabilizing additives. The proportion of the components, the process of element production and the research methods must also be made uniform. The article describes the results of research on the compressive strength of rammed earth samples that differed from each other with regards to the type of loam used for the mixture and the amount of the stabilizer. The stabilizer used was Portland cement CEM I 42.5R. The research and the analysis of the results were based on foreign publications, the New Zealand standard NZS 4298:1998, the American Standard NMAC14.7.4 and archival Polish Standards from the 1960's that dealt with earth material.
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