In some cases one may encounter weak stratum this prompts need for improving the ground if a structure is to be constructed, to make sure that safety of the structure and the stability of adjacent buildings. Improvement of ground can be done using several techniques, in particular granular soils like sandy soil can be improved using different techniques such as; Grouting, Vibro-compaction, Thermal treatment, Pre-compressing, Ground freezing, Soil nailing, Micro- piles and stone columns.
During selection of the most appropriate method to be used depend on several of factors, these are: type of soil and its condition, available technology, the structure being constructed, equipment and materials available, time allocated to complete the project, degree of compaction required and unique features of a site.
Sand a commonly available granular material, formed through mechanical breakdown and weathering of rocks like granite, limestone, shale and quartz. Sand tend not retain water which results into shifting of a structure supported above it as water drains. Over a long time, sand particles tend to lose their cohesion and friction washed resulting into this particles being washed away, leading to formation of gaps beneath a foundation. Saturated loose sandy soil may also result in liquefaction in case of seismic actions. A soil is classified as a sandy soil if 85% or more of its particles are sand-sized by mass; particles are bigger than 2mm in diameter.
Bearing capacity is maximum load that can be applied into a soil or rock per unit area without resulting into yielding or excessive displacement. The bearing capacity of a soil or rock depend on several factors such as internal angle of friction of the soil, its water content, bulk density and manner of application of the load.
Grouting on the other hand is a process of injecting or pumping a fluid under pressure into asubsurface soil or rock to fill voids, cracks and fissures for purpose of achieving a decrease in permeability and compressibility, to improve it strength or to decrease it seepage flow. The treatment can be used before construction or as a rehabilitative treatment for structuressuffering from post-construction distress due to poor soil condition.