Rammed Earth Is a technique for building walls using raw materials of earth and other martials such like clay. It is an ancient building method that has seen a revival in recent years as people seek more sustainable building materials and natural building methods.
The main goal of this project is to check whether the soil available in this country can be used in rammed earth technique or not. In addition to that the project found out the optimum percentages of clay cement mixture that will give the most appropriate properties of soil to be used as rammed earth
Rammed earth technology has been around for thousands of years, Real life examples are shown in the following Figures.
Church of the Holy Cross (Episcopal) Stateburg (or Holy Cross Episcopal Church), built of rammed earth in 1850–1852.
Borough House Plantation (Stateburg, South Carolina).
Today more than 30 percent of the world's population uses earth as a building material, Rammed earth has been used around the world in a wide range of climatic conditions, from wet Northern Europe to dry regions in Africa. The images below show some modern buildings using rammed earth technique.
1)Rammed earth is a simple construction technique. 2)cement has been the stabilizer of choice for modern times to be nixed with earth. 3)After compressing the earth the wall frames can be immediately removed and require an extent of warm dry days after construction to dry and harden. 4)The structure can take up to two years to completely cure.
1)It is widely available. 1)It has a low cost. 2)It is sustainable resource. 1)The construction using earth has a minimal environmental impact.
It viable and suitable for low income builders. Unskilled labor can do most of the necessary work in construction. Rammed earth has a high thermal mass; it can absorb heat during the day and release it at night. This moderates daily temperature variations and reduces the need for air conditioning and heating.
Thermal mass Noise reduction Low Maintenance Fire Proof Rapid Construction Healthy and Environmentally Friendly Cost Effective
The tests conducted in the lab were Atterbeg’s limits, which are liquid limit and plastic limit;. unconfined compression test was another important test conducted.
Three sites were suggested to collect clay soil that will be checked it is suitability to be used as rammed earth. Clay soil was mixed with percentages of water and cement, to reach the proper mix that ensures the suitable properties.
The first sample was taken from Qarwa Bani Hassan town- Salfeet area from a place there called " Jabal Alimrd", Picture below shows "Jabal Alimard" and the sampling process.
The second sample was taken from Beit Wazan town – Nablus area, the soil was found not suitable. The third sample was taken from down town of Nablus city, from an area called "Albasateen" the soil was found to be “clayey with boulders". Picture below shows the place where the third sample was taken from.
The Atterberg’s limits are a basic measure of the nature of a fine-grained soil. Depending on the water content of the soil, it may appear in four states: solid, semi-solid, plastic and liquid. In each state the consistency and behavior of a soil is different and thus so are its engineering properties
The liquid limit (LL) is the water content at which a soil changes from plastic to liquid behavior
The importance of the liquid limit test is to classify soils. Different soils have varying liquid limits. Also to find the plasticity index of a soil you need to know the liquid limit and the plastic limit.
The plastic limit is determined by rolling out a thread of the fine portion of a soil on a flat, non- porous surface.
For 0 % cement. LL = 44.6 PL = 28.6 PI = LL - PL =16.1
For 2 % cement. LL =44.6 PL =35.9 PI = LL - PL =8.7
For 6 % cement. LL =44.6 PL =36.1 PI = LL - PL =8.5
For 12 % cement. LL =44.6 PL =34.4 PI = LL - PL =10.2
Percent of cement to the total Wight 12 % cement 6% cement 2% cement 0% cement 44.6 Liquid Limit 34.436.135.928.6 Plastic Limit 10.28.58.716.1Plasticity Index
Percent of cement to the total Wight 12 % cement 6% cement 2% cement 0% cement 2week strength (kN/m2) 1week strength (kN/m2) 2week strength (kN/m2) 1week strength (kN/m2) 2week strength (kN/m2) 1week strength (kN/m2) strength (kN/m2) Cube Number 40302900310025503420245011801 37502700355026003260235012302 3890280033252575334024001205Average
It can be concluded that the site Jabal Al-Imrad, presented at good source of clay soil to be used as Rammed Earth. (Tests) was carried out to figure the most suitable % of cement to be added to the silty clay to produce good rammed earth. It was found that the most appropriate % of cement is in range of 2%. Summary of laboratory tests are as follows:
– Plasticity index decreases with cement added to the clay soil. However, 2% of cement is enough for reducing plasticity index. – Plastic limit increases as cement is added to the clay, but the value does not change with changing % of cement. – Liquid was found to be unaffected with quantity of cement. – Regarding compressive strength it is noted that as the amount of cement increase the strength does not increase predominantly. It seems that 2% of cement by weight would produce good strength rammed earth. – In addition to that as time increases rammed earth gain more strength.
Construction of sample elements form rammed earth such as blocks or walls. Testing their strength as whole unit, such as wall, columns or beams Inspect their insulation to temperature and acoustics. More places must be checked out locally to make sure that rammed earth is feasible at our country. That is to determine the quantity of clay available.