This is a KEY assignment within the overall SMARTnet project, where all disciplines come together. Open for students and professionals of Architecture and Material Science, as well as for Mechanical and Product Engineering, as well as for Structural and Earthquake Engineering. For more info please contact Martijn Schildkamp at info@smartshelterresearch.com or see our website www.smartshelterresearch.com
The knowledge of how conventional techniques behave in earthquakes is quite high and such techniques have been tested thoroughly. Brick masonry walls and concrete structures can be calculated, because the material properties are well known. We can even make quite elaborate computer models of such engineered structures.
This is not the case for most traditional, natural and alternative materials. It is very difficult to model or calculate techniques like stone masonry or earthen structures, due to a high ratio of uncertainties and variables such as material inconsistency and local workmanship. Somehow, these variables must be taken into account.
Our focus is on rubble stone masonry as it is still widely used in the Himalayan areas, which consists of field stones and mortar, which (in the case of cement mortar) is a combination of cement, sand and water. If we incorporate reinforced concrete bands into the walls, we must also add aggregates and reinforcement steel to the list of materials.
This particular research is focusing on each of these materials separately and aims to gain better understanding of the material properties of stones, cement, sand, water, aggregates and steel bars, by investigating the effects of this particular element within their combined actions into mortars, concretes or masonry.
Firstly, we want to have a better understanding of the material properties of traditional techniques, which are often built with natural materials; such as wood, earth, stone and bamboo. These techniques generally include uncertainties and variables such as material inconsistency and workmanship, which we somehow must take into account.
The water that is used for construction purposes in developing countrie, generally comes from local water bodies such as rivers, streams or lakes, or from water wells that tap into the ground water. Especially after the monsoon period there is plenty of water available in the Himalayan areas, whereas during the dry season it may be difficult to transport the water to the building site. Sometimes pipes are available and gravity does its work, but often the water needs to be transported in buckets and jars on the backs of people. Although the water in the mountains is regarded as relatively clean, the first question is: how clean?
Secondly, we need to know much more about the characteristics of alternative techniques and unconventional solutions. Recycling of materials is very popular now, for example building with plastic bottles, compressed blocks of plastics, car tires and earth bags. But how can we determine the compression of a bottle, or the flexibility of a straw bale?
After arrival of the water on the building site, it can be utilized for preparing mixtures for mortars and concretes. As a second question, we are interested to find out if the constant movement of the water from the original source to numerous handlings into buckets, containers and barrels, has any effect on the water quality and thus on the quality of the mortars and concretes. Does the water somehow get influenced along the way, so that it may have an impact on the construction quality?
Water bodies close to heavy industries may be polluted with chemicals or heavy metals. Another serious contamination is arsenic in the ground water, which is known to impose a big health problem in the Terai region of Nepal, as well as in many other Asian regions. Sometimes water is brackish, muddy or includes organic matter. Sometimes water is sourced nearby a sewer, toilet or septic tank. We need to know more about the extent of such elements in the water on the construction quality, which can either be negative, or which may possibly have positive side-effects. Note: The research excludes the use of sea water, which is not likely to be used in these regions.
For testing of materials, including water properties, standard test procedures exist such as ASTM, RILEM or Indian Standards. Part of the literature review is to create an overview of suitable tests, and key to this research assignment is to describe in detail which steps must be undertaken to create consistent test outputs. During the actual testing of samples and specimens, all parameters must remain constant, with the only variable being the water. That is, the quality of the water, not the amount of water in the various mixes.
Furtherly, this research assignment aims to develop field tests that can simulate the highly controlled lab testing. The challenge is to develop low-tech test procedures and methodologies by using low-cost testing equipment, that are locally applicable in the field, but with reliable test outcomes. This will enable the researchers to conduct simple tests in the field, and it helps the home owners and masons to buy high quality products and to use the correct materials.
