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Rank: Member Joined: 5/9/2011 Posts: 786 Location: Mashinani
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Kwa watu waliojenga Which is recommended. Concrete mix for upper floor (slab) of a residential house? Im getting all sorts of ratios. Want to be armed with knowledge for my koroga kesho Peace in our Homeland.
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Rank: Veteran Joined: 11/11/2006 Posts: 971 Location: Home
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kamundu wrote:Kwa watu waliojenga
Which is recommended. Concrete mix for upper floor (slab) of a residential house? Im getting all sorts of ratios. Want to be armed with knowledge for my koroga kesho This is not under stocks Concrete class 20, recommended for most light structural works. 1:2:4 class. 1:cement 2:Sand/Fine aggregate 4:Coarse aggregate/ballast(aggregate should not exceed 20mm) Water cement ratio is 0.5. The fundis can sometimes skip a component in the batch. Hope you had someone check your reinforcement if they were properly placed. Good luck.
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Rank: Member Joined: 5/9/2011 Posts: 786 Location: Mashinani
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holycow wrote:kamundu wrote:Kwa watu waliojenga
Which is recommended. Concrete mix for upper floor (slab) of a residential house? Im getting all sorts of ratios. Want to be armed with knowledge for my koroga kesho This is not under stocks Concrete class 20, recommended for most light structural works. 1:2:4 class. 1:cement 2:Sand/Fine aggregate 4:Coarse aggregate/ballast(aggregate should not exceed 20mm) Water cement ratio is 0.5. The fundis can sometimes skip a component in the batch. Hope you had someone check your reinforcement if they were properly placed. Good luck. Thanks! Yes someone checked my reinforcement today. How do you physically apportion water to cement using that ratio? Peace in our Homeland.
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Rank: Veteran Joined: 11/11/2006 Posts: 971 Location: Home
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The water cement ratio is a guide, depending on the casting conditions. Google hydration of cement. Its not strictly 0.5, the method of batching might necessitate more water than that. Its more of a text book thing/ideal condition. Make sure the water is not too much but enough to let the concrete be moved(workability)
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Rank: Member Joined: 5/9/2011 Posts: 786 Location: Mashinani
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Thanks. What about a 1:3:4 ratio which is commonly used? Peace in our Homeland.
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Rank: Veteran Joined: 11/17/2012 Posts: 1,461 Location: Ngong Forest
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You mean u are doing it yourself? No senior fundi, approved arch & structural maps?
Since they contain all this info.
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Rank: Member Joined: 5/9/2011 Posts: 786 Location: Mashinani
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Ngong wrote:You mean u are doing it yourself? No senior fundi, approved arch & structural maps?
Since they contain all this info. Actually, i have all those, infact my engineer was on site today. I am just getting confused na hizo ratios, fundi anasema tufanye 1:3:4, engineer anasema 1:1.5:3 Peace in our Homeland.
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Rank: Veteran Joined: 11/11/2006 Posts: 971 Location: Home
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kamundu wrote:Ngong wrote:You mean u are doing it yourself? No senior fundi, approved arch & structural maps?
Since they contain all this info. Actually, i have all those, infact my engineer was on site today. I am just getting confused na hizo ratios, fundi anasema tufanye 1:3:4, engineer anasema 1:1.5:3 Class 15 the 1:3:6 is for blinding, the concrete that is first laid on the ground/soil. Acts like a protection. 1:1.5:3 is for class 25. Ask him what class he used in his design, if he used class 25 then kindly follow his instructions. I find class 25 to be on the high side for a residential building unless you plan on doing some light industrial work on the suspended floor.
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Rank: Member Joined: 5/9/2011 Posts: 786 Location: Mashinani
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holycow wrote:kamundu wrote:Ngong wrote:You mean u are doing it yourself? No senior fundi, approved arch & structural maps?
Since they contain all this info. Actually, i have all those, infact my engineer was on site today. I am just getting confused na hizo ratios, fundi anasema tufanye 1:3:4, engineer anasema 1:1.5:3 Class 15 the 1:3:6 is for blinding, the concrete that is first laid on the ground/soil. Acts like a protection. 1:1.5:3 is for class 25. Ask him what class he used in his design, if he used class 25 then kindly follow his instructions. I find class 25 to be on the high side for a residential building unless you plan on doing some light industrial work on the suspended floor. 1:3:4 nayo? Some site says its just like 1:2:4 Peace in our Homeland.
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Rank: Elder Joined: 6/2/2011 Posts: 4,818 Location: -1.2107, 36.8831
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kamundu wrote:Ngong wrote:You mean u are doing it yourself? No senior fundi, approved arch & structural maps?
Since they contain all this info. Actually, i have all those, infact my engineer was on site today. I am just getting confused na hizo ratios, fundi anasema tufanye 1:3:4, engineer anasema 1:1.5:3 Just do what the engineer is telling you, especially if he is the one who did the the structural design. The one he is Class 25 (i.e 1:1.5:3). NOTE: These ratio are in terms of weight and not volume, so, the one of fundi sounds 'funny' to me, but i assumed his is volume based. If nothing was specified in the approved design/construction drawings or the BoQ specific item, then call the design engineer and confirm. Receive with simplicity everything that happens to you.” ― Rashi
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Rank: Member Joined: 5/9/2011 Posts: 786 Location: Mashinani
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dunkang wrote:kamundu wrote:Ngong wrote:You mean u are doing it yourself? No senior fundi, approved arch & structural maps?
Since they contain all this info. Actually, i have all those, infact my engineer was on site today. I am just getting confused na hizo ratios, fundi anasema tufanye 1:3:4, engineer anasema 1:1.5:3 Just do what the engineer is telling you, especially if he is the one who did the the structural design. The one he is Class 25 (i.e 1:1.5:3). NOTE: These ratio are in terms of weight and not volume, so, the one of fundi sounds 'funny' to me, but i assumed his is volume based. If nothing was specified in the approved design/construction drawings or the BoQ specific item, then call the design engineer and confirm. The fundis do 1:3:4 by volume not weight Peace in our Homeland.
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Rank: Member Joined: 5/9/2011 Posts: 786 Location: Mashinani
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@holycow ahsante. We decided tufanye 1:2:3 after consultations na engineer Peace in our Homeland.
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Rank: Member Joined: 8/4/2009 Posts: 136
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Ratios are always by volume not weight.
class 20 1.2.4 is most suitable for residential structures where the loading is minimal.
wats the rationale given by your engineer on settling for a mix of 1.2.3?
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Rank: Member Joined: 8/4/2009 Posts: 136
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Next time consider using waffles for your slab and slash costs..
It's too late for tomorrow's concreting but next slab holla and we compare solid slab vs waffle slab.
There are precast staircases in the market now as well.
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Rank: Veteran Joined: 11/17/2012 Posts: 1,461 Location: Ngong Forest
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wangu.n wrote:Next time consider using waffles for your slab and slash costs..
It's too late for tomorrow's concreting but next slab holla and we compare solid slab vs waffle slab.
There are precast staircases in the market now as well. Any photos sir?
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Rank: Member Joined: 8/4/2009 Posts: 136
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I will post here pics in the course of the day.
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Rank: Veteran Joined: 11/1/2008 Posts: 834
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 If you are going to be thinking only one thing, you might as well be thinking big. -Donald J . Trump
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Rank: Veteran Joined: 11/1/2008 Posts: 834
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If you are going to be thinking only one thing, you might as well be thinking big. -Donald J . Trump
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Rank: Veteran Joined: 11/17/2012 Posts: 1,461 Location: Ngong Forest
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Hi @livie, is this the waffle slab someone has mentioned above?
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Rank: Member Joined: 6/17/2010 Posts: 572
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Ngong wrote:Hi @livie, is this the waffle slab someone has mentioned above? you can check out the kcb hq under construction in upperhill before they do the cladding, think they used waffle slabbing to put up the structure 'One headache for famous medieval holy people was that someone might murder you to acquire your body parts for the relics trade'
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