Sunday, August 14, 2011

Fish Pond Apron

This  is a nice looking Balinese design Koi fish pond, with a  pebble apron. And this picture will be good for only about six months. 


Thereafter, the grass and weeds will invade the apron and the side of the pond.
This Koi fish pond was designed and built by an Indonesia Koi pond expert. Everything was in a perfect condition,  until the weeds and grass appeared among the pebbles. My initial solution was just regular weeding. The grass and weed were too pervasive and invaded the gaps between the tiles of the pond. They were perpetual  nuisance.  A permanent solution is required.  
I decided to build a concrete slab apron, with pebbles spread on top of it, in order to retain the feature.  A contractor’s quote for the job is RM2,000.00 (USD666.00) with material and labour supplied.  I pondered over the quotation for a couple of weeks, before deciding to go DIY.


It will be a tough job to complete the apron at one go and single-handedly. This will take at the least three  full day of 8 manhours per day.


 I wanted to do this at my own leisure time and enjoy the DIY.      




 I did  not set a target completion date and without a fixed work schedule. If the weather is kind to me, I will work on that day and not more than 3 manhours per day so as not to exhaust myself.
I decided to partition the apron into six blocks and make one block at a time.
Material required are sand, cement, thick cardboard, 1"X2” wood and steel bar. The steel bars are used to re-enforce the concrete slabs and prevent  cracks. The thick cardboard and wood are for formwork.

Tools required are wheel barrow, spade,  cement trowel and a large picnic umbrella for shade. 

One and a half bag of cement (75kg) and one excavator bucket load of sand (local hardware shop sell sand by excavator  bucket load) is required. Total cost is RM135.00(USD45.00), excluding the tools.

The first task is to remove all the pebbles. Then, remove the invasive roots of the grass thriving underneath the pebbles. This is followed by the removal of top soil.
Once the ground preparation is completed, lay the formwork for the concrete slab.

Prepare the cement mix with 1:1 cement/ sand ratio and mix with water thoroughly. The amount of water will depends on the condition of the sand (dry or wet) and the required viscosity of the mix. There is no formula for the amount water.

The cement mix is pour into the formwork with two parallel steel bars place in the centre between the bottom and top surface of the slab. Vibrate and level  the cement mix with a cement trowel. Vibration is to compact the cement mix and prevent honey comb formation  inside  the concrete slab.
Let the cement mix to cure for at least 8 hours before stepping on it. If the weather is too hot, sprinkle some water on the semi-hardened surface. Heat is generated during curing process.  This is to cool down and slow the expansion of the slab, in order to prevent cracks.  Do not use the jet or direct tap water. The water pressure may damage the surface.