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Showing posts from November, 2017

On High Water Table

When preparing the foundation of a building at a place near water bodies or in a location simply with more water, there are cases where we encounter a high water table. The water table is the level below ground at which the ground is saturated with water. When dug to this point, ground water will appear around the soil and is not a desirable condition for keeping foundations stable. When building close to a water body, the water table will also change with the time of the day. At high tide, the water table will be higher than at lower tide. Sometimes, this is useful when planning the construction work load in order to avoid digging too much when the water table is high. Additionally, a pump is necessary to pump out the extra water so excavation works can continue in a safe manner. For architects, this high water table is a concern when building underground basements as well as any sort of semi-sub subterranean structures such as lift and escalator pits. Proper waterproofing material...

On Lighting Colour Temperature

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The colour of light can have a very profound effect on how Architecture looks like during the night, and sometimes even in the day. With the advent of LED technology, there has been an ongoing refurbishment works across the globe to change many street lights from the warm yellow hue to cold bluish tones. But what is colour temperature? As shown by this chart from  https://www.downlights.co.uk/faq-which-colour-temperature-.html , light can have a variety of "temperature" which corresponds to its colour. Temperature is measured in Kelvin and the higher the value, the more bluish it becomes. 2700K - Extra warm white LED: Appears warmer 3000K - Warm white LED: Slightly white but not too cold 4000K - Cool white: Slightly bluish When choosing lighting, it is recommended to get a warmer hue when used in areas intending for relaxation, while choosing a colder tone when it is important to be alert and see all details. As such, a bedroom may be using 2700K while a clinic may...

On "Cold Joint"

Cold joint is a specific word used to describe a process in concrete casting. In standard conditions, a piece of concrete needs to be cast in one shot in order to ensure its cohesive strength, however, when it is cast in a few batches where the time between each batch is too long, it will cause "cold joint", which is a phenomenon in which the two separate batches do not join together well and result in a "layered" look between the two pieces. This affects the strength of the casted concrete and is to be avoided whenever possible. Nevertheless, different storeys and sections of a building are usually "cold joined". In these cases, various measures needs to be taken to ensure the integrity of the joint pieces. For example, ribars are to connect between the joints, edges are to be roughened to improve connectivity and bonding agents are used.

On Pipes that Mechanical Engineers Deal With

There was a time when it was pretty confusing to understand all the different types of pipes that are involved with a Mechanical Engineer's works, so here's a simple breakdown of some involving liquid elements: Plumbing Pipes Deals with fresh water supplied to the development Supplies to water points such as taps, shower heads, WC, etc. Could be running two separate lines because of different types of water used, for example: In Singapore: Between fresh water pipes and NEWater pipes; NEWater is used for non-potable uses such as AC system and toilet flushing (to score on Green Mark points, it is recommended to use NEWater for non-potable sources if it is available for your development) In Hong Kong: Between fresh water pipes and sea water pipes. Similarly, sea water is used for non potable uses such as toilet flushing For small developments, pipes are connected directly from the main public water line, this is for low rise buildings where the water pressure from PUB i...

On Spun Pile and Bored Pile

There are many types of piles used by the Civil engineer when preparing the foundation of a building. Here's a look at 2 common kinds: Spun Pile Precast concrete pile - stable conditions, uniform strength Of fixed length Tends to be cheaper (at least in Singapore) Could be (and is usually) hollow inside the pile Cast using a machine that pushes the pile into the ground, could be damaged during driving Needs excavation to cast, and may push unstable soil around Cannot be driven in very large diameters Could be used quickly after piling Could carry less weight per pile and is usually used for low to medium height buildings Bored Pile Cast in place concrete pile - depends on weather, not so uniform strength Could be extended to desired length Tends to be more expensive (in Singapore) Is solid inside the pile Cast using a bored piling machine that drills into the ground to remove soil, and is thus more stable to surrounding conditions Could be cast without excava...

On S Trap and P Trap

S trap and P trap are Mechanical terms that relate to sanitary plumbings. Both types of pipes are used at the discharge point of grey water and black water. To be put simply, both are bent pipe systems. The bends are to ensure that the grey/ black water do not back flow, and ensure that the stack it discharges to does not allow rats, insects and bacteria to travel back into the WC/ tap point. In addition, they help to trap objects not intended to flow down the pipes at the curve. S trap Pipe is in the shape of a S (Sometimes considered) an older design In Singapore, used more for WCs, but may also be applied to sinks and floor traps Require more space for the S bend P trap Pipe is in the shape of a P (Sometimes considered) a newer design In Singapore, used more for sinks and floor traps Require less space for the P bend For both cases, because the bends tend to collect objects and sediments, maintenance on the bent portions are necessary in order to ensure a well fun...