Causes, Prevention and Repair of Cracks in Buildings: (A Case Study of Chinua Achebe Lecture Theatre in Michael Okpara University of Agriculture, Umudike)
Abstract
This study was carried out by employing several observatory and
analytical techniques to observe and understand the types and nature
of cracks associated with building, the causes of such cracks, what
could have been done to prevent these cracks as well as reparative
measures that could be employed to remedy the cracks.
Reconnaissance study was carried out on the structure to discover the
nature and extent of cracks with the aid of traditional laboratory tools
that can measures and monitor the cracks. From the overall properties
and behaviours of the cracks, their possible causes and reparative
measures could be established. The compressive structural strength of
the key members of the building (slabs, columns and beams) was
determined using the non-destructive Schmidt Hammer test. The
minimum required compressive strength of 28day old concrete is 25
N/mm2, this is supposed to have attained a strength of 31 N/mm2 after
1year of the concrete life, and the strength is supposed to marginally
increase with time. The shear strength of the foundation soil was
determined through the shear box test which yielded the soil cohesion
to be, c = 0.0355 kN/m² and angle of internal friction, ???? = 25.34° =
25°. The ultimate bearing capacity of the foundation soil which is
409.86Kpa is satisfactory and was calculated using the Terzaghi’s
formula, Qu = cNc+γzNq+0.5BNγ. The majority of the cracks
observed in the building are non-structural cracks. The main
structural cracks observed in the building were caused by differential
settlement of soil, faulty design and poor workmanship. Some of these
are still actively cracking and hence pose a real threat of future
collapse. Hence, they require urgent professional repairs. The
appropriate remedy to cracks should be such that its nature and
causes should be properly investigated and established before repair.
Otherwise, wrongly treated cracks would reappear after some time
