Will Cement Grade Restrictions Be Enough?

The Standards Organisation of Nigeria (SON) recently put a regulation in place to list and restrict the areas of use of various cement grades for construction processes.

But the appropriateness of the directive in stemming the ugly trend of building collapse has sparked more debates amongst concerned professionals in the construction, engineering and cement manufacturing industry.

The directive states that 52.5 grade cement must be used for bridges, 42.5 grade cement can be used for casting of columns, beams, slabs and for moulding blocks, while 32.5 grade cement can only be used for plastering.

The erroneous belief by members of the public that the quality and grade of cement being used in the country is mainly responsible for building collapses led to SON initiating deliberations with stakeholders in the construction industry and manufacturing sector.

It must be pointed out however that the new directive by SON seems to be a unilateral solution that will not only leave a large part of the problem (building collapse) unsolved, it might also spring up new problems.
In the Nigerian market, there are three main grades of Portland cement that find regular use in the construction industry namely; the 32.5, 42.5, 52.5 cement grades.

Each of these cement grades derives it grading from the minimum compressive strength they gain after pouring their cement-sand mortar mixture after 28 days. The 32.5 grade will have a minimum compressive strength of 32.5 Kg/cm2 after 28 days with the 42.5 and 52.5 grades developing minimum compressive strengths of 42.5Kg/cm2 and 52.5Kg/cm2 respectively.

The three common Portland cement grades and their areas of application in construction is shown in the table below;
Cement Grade                                                                                    Areas of Application in Construction

32.5                                              General paving, mass concreting, plastering/rendering, block moulding/setting, light concrete                                                                            works, small-scale consumers.

42.5                                                Residential, commercial and industrial structures, heavy concrete works such as: heavy                                                                                         retaining walls, large piers and abutments, flyovers, dams/marine constructions

52.5                                                Construction of skyscrapers, bridges and other heavy load bearing structures

 

It can therefore be seen that despite the fact that each of the cement grades has its own areas of application, areas of overlap exist between the functionality of the different cement grades particularly between the 32.5 grade and the 42.5 grade.

The directive of the SON restricting the use of 32.5 grade cement to only rendering/plastering leaves out more areas of application that the 32.5 grade can be used for such as block moulding/setting, small scale buildings and light concrete works.

A structural and engineering explanation of the cement grades’ respective compressive strengths means that the ability to bear loads under certain loading ranges and environmental conditions is what gives them their grades.

Therefore, not permitting the use of certain grades of cement in areas where they can be correctly used becomes a misplacement of priority which can also increase the cost of building/constructing structures.
According to Engr. Olorunfemi, President of the Nifgerian Society of Engineers (NSE), “inappropriate application of cement in the production of concrete and not the choice of cement grade has been pointed out as the cause of most building collapses.”

He added that it was misleading to assert that cement grade was a prime cause of building collapse in Nigeria adding that building collapse is also caused by design flaws, ageing, extreme operational and environmental conditions, accidents, terrorist attacks and natural hazards.

Engr. Salihu Lawal, National Chairman of the Nigerian Institution of Civil Engineers in a press release puts it that Design flaws, Ageing, Materials’ fatigue, Extreme Operational and Environmental conditions, Accidents and some other factors other than the grade of cement used are key factors responsible for building collapses.
Other factors considered key in the durability of a building apart from the cement grade are type of cement, design of concrete mix, placing compaction/curing of concrete and subsequent maintenance/repairs.

From all of the above said, it is expedient that the Standards Organisation of Nigeria gears itself as well as other concerned regulatory and professional bodies in the construction industry to rise up to the task at hand.

The Standards Organisation of Nigeria should concern itself more on curtailing the activities of cement adulterators and educating the public more on quality and adulteration indicators that cement users should watch out for.

Some of these features that could help end users of cement identify adulterated products include; packaging markings, physical identify features, packaging styles, etc.

Concerned regulatory bodies should also monitor the activities of building/construction practitioners in the industry and also put in place punitive measures to correct erring members and discourage quackery.
The professional bodies should put in place training and sensitisation programmes for members and the general public to raise the awareness level of the prevailing issues in the building sector and means of addressing them.

They also need to encourage their members to co-opt the services of ancillary professionals who will be able to offer professional advice in areas of work overlap when the need arises.

The general public too must be educated on the need to engage the services off qualified professionals within the construction industry to handle projects.

This article was first published by Nigeria’s Engineering Network.