Author: Mezie Ethelbert

Reading Time: 3 minutes The shear strength and stiffness modulus are accepted indicators of the susceptibility of the soil to permanent deformation. A soil with high values of both of these characteristics will be less susceptible to permanent deformation. Both are usually reduced by increases in moisture content. Knowledge of them is essential with the pavement design process in order to determine the required thickness of the pavement. It is not usually always feasible to establish these two parameters for a soil. So, the CBR test is often used as an index test (in place of them). The CBR test acts as an attempt…

Reading Time: 3 minutes Soil blending is one of the popular means of soil modification. Fuller’s method appears to be the most popular method while other methods such as the Triangular chart method and Rothfuch’s Graphical method are often commonly used too. Well-graded soils are often the most desirable type of soils for engineering construction works especially where high shear strength is required. This is because well-graded soils have the capacity to achieve high shear strength under compaction due to the fact that the fine particles of the soil adequately fill the voids created by the interlocking of the coarse particles, thus, giving little…

Reading Time: 3 minutes When a soil mass is loaded, it undergoes compression/consolidation which is due to the stress from the load it is subjected to. The higher the load, the bigger the stress. If in the course of time, the load causing the compression is reduced by action of man or through natural actions such as erosion, the soil now experiences stress that is less than the initial stress it experienced in the past and the curve of void ratio against the pressure adjusts its shape as shown below (Figure 1). Such soil is said to be overconsolidated. Before the removal of the…

Reading Time: 3 minutes There are varieties of painting materials and decorative finish available in the market. Each type of paint and decorative finish has its covering capacity in m2. This covering capacity varies between surfaces to be treated. Table 1 below shows the covering capacity of various paints per 100 m2 of wall in litres (1 litre = 0.264 gallons). The choice of the type of type of paint for buildings or other works depends on many factors some of which can be found HERE. Table 1; Paint covering capacity Covering capacity per 100 m2 (1 coat only)Volume (litres)Alkaline resisting primer to lime…

Reading Time: 4 minutes In this article, I would show two methods of finding stresses on a plane in a soil element under stress. These two methods are: The Mohr circle method, andThe pole method A. The Mohr Circle method Figure 1 (a & b) show a soil element in which it is required to determine the stresses on the plane EF of the soil. The stresses can be determined from the equilibrium of forces acting on the wedge on Figure 1(b). From geometry, EB = EF cos θ and FB = EF sin θ From Figure 1b, resolving the forces in the x-direction…

Reading Time: 6 minutes Introduction A vertical sand drain is a boring through clay or silty soil that is filled with sand or gravel to facilitate drainage of a liquid from the soil. The use of sand drains is a necessity in construction work in places where drainage is poor due to very fine soils such as clay or silty soil. In most cases, they are used to pre-load the soil and hence pre-consolidate the soils before construction begins. The aim is to ensure that all settlement occurs before/during and not after construction. Vertical sand drains are usually employed in the construction of highway…

Reading Time: 3 minutes Serviceability limit state (SLS) governs the functional and operational use of structural elements. These limit states include: crack due to fatigue, repairable damage, corrosion, fire, deflections/deformation and vibration in structure. Deflection control aims at not avoiding deflection completely because every loaded member must deflect but avoiding visible deflection which in other words is called excessive deflection. This implies that when deflection becomes visible in a house and makes the user uncomfortable, it is excessive. Checking for deflection ensures that the structure does not deflect excessively in a manner that would impair the appearance of the structure, cause cracking to partitions…

Reading Time: 2 minutes Erosion control in Anambra state have been on the high point over the last 10 years courtesy of the NEWMAP. Many research findings have enumerated the causes of gully erosion but one of the most authentic sources would be from the construction experts in the field who have had direct encounter and challenge in managing the problem. The Nigeria Erosion and Watershed Management Project (NEWMAP) is an eight year innovative and multi-sectoral project initiated by the Federal Government of Nigeria and some select states of which Anambra state is among and financed by the World Bank to address and resolve…