Generally, 32 MPa is high strength concrete is used for the construction of structural elements or infrastructure such as bridges and roads.
It is also used for pre-cast elements (i.e., panels) to form building envelopes, such as exterior walls and house slabs, which are factory-fabricated in controlled environments, transported to the construction site and then lifted into place by a crane or other means of raising components into position.
This mix can be placed without too much difficulty due to its workability and self-consolidation characteristics even if not overstressed.
The 32 MPa concrete is only waterproof when it has been properly sealed after the curing process. If this is not done, water may penetrate the concrete surface from any water supply outlet which can cause damage to its internal structure.
It has a compressive strength range from 28 to 50 MPa. For precast elements such as floor slabs and wall panels, the targeted compressive strengths are usually at 37 and 42 MPa. This will be higher than that for structural elements such as bridge and elevated road construction which has a targeted compressive strength at 25 MPa.
MPa stands for Mega Pascal which is a unit of measurement used to measure the pressure that a substance exerts either due to its bulk or surface properties. The standard symbol used in engineering and material science is psi, psi being an abbreviation for pounds per square inch. Elevators also use MPa as a measurement to indicate how much weight it can hold before the door fails and the elevator falls to the ground floor.
No, 32 MPa concrete does not need vibration tools to set. The only time where vibrators are used is when the mix has been over-stressed or applied in tensioned or thin applications that would otherwise cause damage to its structure. Vibration tools include mechanical vibrators and pneumatic vibrators which work by transmitting the vibration energy through a kinetic source such as an electric motor or compressed air. Vibrating tools are used to enhance dispersion of the cement paste inside the mix, improve contact between aggregate particles, and reduce segregation.
No, 32 MPa concrete cannot be recycled since it would likely cause damage to its internal structure due to water infiltration. This is because water weakens the binder system of 32MPa concrete over time. Mixing recycled materials with worn-out asphalt pavements will not change its compressive strength nor make it harder to crush under pressure. Therefore, recycling these materials will only increase the stress on aggregates and reduce the durability of the mix.
It is used in applications where its high compressive strength overcomes any damage that might have otherwise been caused by subsurface conditions such as expansive soils or poor subbase conditions. Also, it can provide a finished floor with no major cracks nor defects which will not be harmful to pedestrians even if they experience greater loads placed on top. Moreover, 32 MPa concrete is also used in long-term structural elements because of its high resistance against freeze-thaw damage.
The compressive strength of 32MPa concrete is usually used when designing large-sized structural elements such as floor slabs and road panels. However, the compressive strength range for precast elements such as wall panels is only at 37 and 42 Mpa while bridge structures have a targeted compressive strength of 25Mpa. Depending on the desired serviceability requirements of your driveway, you will need a mix with a lower or higher compressive strength. For driveways where heavy trucks pass through them on a regular basis, it would be best to use a mix with an average compressive strength from 28 - 34 MPa.
It is not prone to cracking over time because its high compressive strength prevents cracks from forming even if there is uneven pressure on it. Cracks are more likely to form in applications where 32 MPa concrete is used for structural elements because of the deep-seated nature of stress on these types of mixes. Also, polished concrete that has a high water-to-cement ratio will most likely crack heavily since it cannot withstand coarse aggregates nor expansive soils underneath.
For driveways where heavy trucks with large weights pass through them, you will need to use deeper slab depths so that the compressive load over its surface area would be distributed equally throughout. This way, there won't be any major cracks nor defects which could pose harm to pedestrians. Slab depths for such applications can be around 200 to 250 mm thick.
For the next project, its best to hire a concreting expert or professional who is more capable and possesses more information which might require an upfront price but with the overall cost of the job being low. And any builder guys can produce and create the perfect footpaths or deliver other suitable labour services without much risk. For information on using precast concrete panels, take a look at the YourHome website.