Sub: Proposal for using Load Bearing Hollow Clay Brick in Place Hollow sandcrete Block for construction of 132/33Kv Control Room Building at 132/33KV ikorodu substation under NGPT1 LOT2 Project.

Dear Sir,

With reference to your letter SB/ZS/2475.720 dt 17/03/14 as a response to our proposal of using filled hollow block with mixture of Stone dust/sand / cement, in place of hollow block for construction of control room building to achieve strength required by TCN civil regulation, through which some query has been raised and we were asked to provide the code of practice and explanation for using the filled blocks.In the meantime when we are preparing a solutions to the query raised and exploring on possible solution for hollow block , we came to know about M/S CLAY INDUSTRY NIGERIA LIMITED who are producing BURNT CLAY LOAD BEARING BRICKS used for wall of building. We have visited the Factory and have seen various range of Clay bricks available in their list. Hence we propose to use below Load Bearing Brick against Hollow sandcrete Block.1. LOAD BEARING HOLLOW CLAY BRICK (225mm) at all exterior wall of control Room Building in place of 225mm Hollow sandcrete Block.2. LOAD BEARING HOLLOW CLAY BRICK (150mm) at all interior wall of control Room Building in place of 150 mm Hollow sandcrete Block. Advantage of BURNT CLAY LOAD BEARING BRICKS over Normal Sandcrete Hollow block is as below1. Burnt clay Brick are lighter than as sandcrete block, thus imposed weight on foundation is considerably reduced.2. The thermal insulation is greater superior than normal sandcrete block.3. The conduit for electrical wiring and fittings can be easily laid in place with adequate cover by opening a grove in the side of brick.4. Non Absorbent and safe in swamp.5. Maintain ambient temperature/heat resistance.6. Stronger than sandcrete block.7. Retains beauty for long time without painting.8. Brick building dose not burn nor disintegrate under fire.9. This clay brick are lighter in weight but has higher compressive strength as compared to Hollow sancrete block. Load bearing Hollow Clay brick 225mm will give a compressive crushing strength of 14.84N/mm2. Load bearing Hollow Clay brick 150 mm will give a compressive crushing strength of 21.86N/mm2.As per civil spec of TCN the average strength required is 6N/mm2 but clay brick provide much better strength to the building walls. In Lagos Most of the high rise building are constructed using Clay brick. Cataloque for CLAY INDUSTRY LIMITED , LAGOS is attached for your crosschecking purpose. We have tried 4 times with various mixes for hollow sandcrete block, but we are not able to get value required as per civil specification of TCN of average strength of 6N/mm2 as crushing strength. We were also blamed that we are trying to delay the job, which is not correct, we are trying to find a solution but the issue was each time we mould a block we need to wait for at least 28days before we can know the result. We would like to inform that we have constructed many control room building all over Nigeria for PMU, TCN and NIPP and everywhere same problem was faced but client has accept block with strength of 3N/mm2, due to which we are able to complete control buildings in all those project.

Although the above proposed solution of using clay brick is an expensive solution but looking to the delay in construction of control room building and for the sake of project completion on time, we will do same without additional cost implication. Hence we request you to kindly approve our proposal of using Load bearing clay brick in place of hollow sandcrete Block for construction of control room building.Above brick will be directly procure from factory hence after receiving approval on above proposal construction work for control room building can proceed in full swing.