Jul 2018 STOPPING CRACKS ON A CONCRETE PATH
Avoiding cracks on a concrete path may seem like a near impossible task but Sephaku Cement has a few solutions on how to avoid these nasty imperfections. Having followed all the steps to installing a picturesque path in your garden, with fingers crossed and baited breath you watch and hope for the best. Considered to be one of the most widely used products in building and construction given its durability, serviceability and strength, why does concrete almost always seem to crack?
There are 3 main reasons why concrete tends to crack namely:
- Excess Water Added to the Cement MixThe wetter the cement the easier it is to install however, when excess water is added to the cement mix resulting in a soupy consistency it impedes the strength and durability of the final product. Further to this, as concrete hardens it shrinks as the water used to mix the cement dries. The more water there is to evaporate, the greater the propensity for shrinkage, this excessive shrinking is considered to be one of the main causes for cracks in concrete pathways.
- Too Dry Too QuicklyIn converse to a cement mix that is too wet (soggy), the chemical reaction that takes place in concrete referred to as Hydration, can take place for up to, and sometimes over a week after pouring the concrete. In order to change from a plastic state to a solid state while gaining strength, curing cement requires the assistance of water. If the curing concrete is lacking in the hydration process with too little water to support the chemical reaction, the end result will be brittle and weak concrete that is prone to cracks and fissures.Make sure that curing concrete remains moist in aid of the hydration process by covering the pathway with a polythene (plastic) sheet over it for as long as possible or spray with a mist water onto concrete for at least seven days or longer if possible. Ensuring that the curing concrete does not dry too quickly, the concrete is able to gain strength and can therefore withstand more shrinkage as well as extreme temperature changes (expansion and contraction) without cracking.
- Neglecting to Use Control JointsAs the name suggests, control joints create “planned cracks” in cured concrete that caters to the expansion and contraction of the finished product. As a guide it is recommended not to lay concrete without joints in slabs exceeding in length and breadth the following size 32 X the thickness of your slab. E.g. if the concrete slab is 120mm thick the length and breadth must not exceed approximately 3.5 meters. Control Joints also support dry shrinkage during curing and extreme weather conditions where temperatures move from very cold to excessively hot. Where weather conditions can be extreme between seasons and no control joints are fitted, the consistent expansion and contraction of the cured concrete (as a result of the concretes porous molecular makeup) eventually diminishes durability, weakening the concrete and causing unsightly cracks.
In understanding what causes cracks in concrete, contractors and DIY enthusiasts are better equipped at ensuring that the concrete mix is prepared correctly, expertly placed and is allowed to cure under the most optimal conditions, by adhering to these basic guidelines as well as following a regular maintenance, upkeep, cleaning and intermittent sealing regiment, most concrete pathways should remain crack free throughout the duration of their lifetime.