Inspecting Hill Slopes

Currently it is rainy season here which is normal every year end. However for those involve in construction line especially those working at hillside areas, they can’t sleep easy. This is because in this time landslide always happens.

Recently, there were two big disasters on landslide happened in Malaysia. One was in Ulu Yam killing 2 siblings and another one just recently happened last week at Bukit Antarabangsa in Selangor. This time 4 were killed and one is still missing.

My current project is not exceptional also, there is a big hill cut here. Previously this area was a toe of hill, but later it was cut to allow for the construction of a 6 storey block which is still under construction. The slopes is almost complete except lower part which is yet to cut. Technically we apply slope cutting 1:1.5 gradient to these slopes, provide proper drainage, plant turf on the slopes and soon will install horizontal drains.

Hill cut at my project

However for further precaution, a few days ago together with contractor we did joint inspection at this cut hill to make sure there is no clogging at drainage system as well as checking if there are signs of movements and etc. Any wild plants covering and disturbing the function of hill drains have been removed. We pray that this big cut safe and brings no harm to those reside nearby.

Earthworks, slope erosion and mud flood

Recently, I was not happy with the contractor. I had numerously highlighted to the project manager long-long time ago from the beginning of earthworks to monitor the slopes and take appropriate rectification actions if the slopes found to be not in order.

While doing regular inspection at site, I found one slope was in bad condition. The slope erodes and brings mud flood to nearby operating facilities. You can see in the photo below.

This should not happen if the contractor provides temporary drainage at the top and bottom of the slopes plus with temporary slope protection such as planting close turf on the slopes. If not repaired, this will destabilize the slope structure and will affect road works nearby. The drawings and specifications have details on these but it seems the contractor fails to follow.

Brick Work

Basic general requirement for brick work:

-external wall - common clay brick is used due to weather exposure
-Mesh (Exmet) - every 4th course
-bonding ties - 6mm mild steel rod at 500mm c/c
-damp proof course - above ground floor level to prevent water seepage
-joint between course - sufficiently filled with mortar at 13mm
-reinforced concrete stiffener - middle of wide wall (4m x 4m). For half brick wall only
-verticality - within tolerance of 4mm per 1.2m height

Concrete Curing & Curing Compound

Curing for concrete works is very important particularly in hot climate countries such as Malaysia. The temperature at daytime can go as high as 36-37 deg Celsius in fine unclouded weather. My experiences show that, if curing not properly carried out, concrete cracks tend to occur in form of hairline cracks. For example in my recent project of five storey building, the contractor failed to carry out proper curing (for the first few days after concreting) for wide-area slab (for floor) and therefore concrete cracks have occurred.


Hairline cracks about to form just about an hour after concrete casting in hot weather (when concrete surface about to dry and lose its moisture).

Concrete cracks observed in the concrete surface due to poorly carried-out curing. It is observed that some cracks had openings of about 2mm-3mm widths and depths of 30mm-35mm (measuring by penetrating wire that used in re-bars tying works into the cracks; this is rough estimates and therefore not accurate due to nature of wire itself which is quite rigid and its bigger size to enter finer cracks).

concrete cracks observed on the concrete surface

Contractor for this project has failed to carry out proper curing as required in specifications. The contractor failed to commit their promise to use gunnysacks with frequent water spraying on it as a method chosen for concrete curing.

During recent site inspection, the client has not satisfied with this condition. Finally the contractor has opted to use curing compound for concrete curing.

The contractor has chosen curing compound ‘Fosroc Concure’. For comparison, I have carried out simple experiment and marked the areas of slab to be implemented both with curing compound and without curing compound (side by side). Concrete works then carried out in the morning (around 9.30am) with fine unclouded weather. The following is the results you can see:

Concrete surface after curing compound applied-less cracks observed; very fine and negligible (at left side, however the application of curing compound causing the concrete surface relatively a bit darker compared to non-applied-curing -compound area at right side). At right side where concrete surface is without curing compound; concrete cracks occurred; visible, larger than hairline cracks occured at the curing compound area and so glaring that can be seen from quite a distance. This photo taken at 3^rd day after concrete casting for floor slab.

However, a fine tune still needs to be carried out in order to set a proper timing to apply curing compound so that its intended use can be optimally used as per its manual. This is because it is observed that few concrete cracks still happened there (only minor negligible hairline cracks). It is believed that this occurred due to delay in applying the curing compound material.