I will pass on the silica sand item and the strength increases. Try the portland cement association site.
As for durability, the most success I know of has been the use of air entraining agents in concrete. My experience is in roads and bridges. A 6% air entrainment (one was called Darex) dramatically improves the ability of concrete to withstand freeze-thaw cycles. Test specimens that I saw had been put through thousands of cycles. The non-air sample was pitted, spalled, pockmarked while the air mix looked pristine. The amont of air entraining agent is critical because it reduces the strength of the mixture (solid sand,and stone particles have been replaced by microscopic air voids).
There are hundreds of ways to improve strength and early development of strength. The biggest effect is overuse of the chemical h2o. Also, in the long run air entrainment maintains strength longer because of the durability increase.
Either (or both) an increase in the reactants or temperature will increase the rate of a chemical reaction.
Increasing the temperature of the reactants can increase the rate of the chemical reaction.
The rate of chemical reaction increase as the concentration of the chemicals increase. The reason is obvious. There is more opportunity for the atoms to come in contact with each other. This facilitates rate of chemical reaction.
Many things lead to an increase in the rate of chemical reactions. These factors include: - Addition of Catalysts - Light (only in some reactions) - Increase in temperature - Increase in Pressure - Increase in amount of reactants
methamphetimeins
Consider what marble powder is. It is basically calcite, which is an already common component of concrete. Adding more would be to increase the ratio of calcium carbonate to other plasticizing materials. In effect, it would make the concrete more stony and brittle.
aggregates are used to concrete for following purposes: 1.if totally binding materials like cement is used in concrete, the cost of concrete will be high which is uneconomical. 2.to prevent high shrinkage of concrete mix fine aggregates are used. 3.to increase the volume of concrete mix aggregates are used.
Mineral admixture are those which are mixed with concrete ingredients and spread through out the body of concrete to favourably modify the properties of concrete . the commonly used mineral admixture are1. Fly ash2. Silica fume3. Rice Husk ash4. matakaoline
It is economical. Full cross-section of member is utilized. Increases durability. Reduces corrosion of steel. Increase in shear capacity. Larger spans can be constructed. It allows rapid construction.
If you are using a traditional concrete mix you can increase the slump by increasing the water you add.
they go between the truck and the bearing wheel to increase durability
As pozzolan greatly improves the strength and durability of concrete, the use of ash is a key factor in their preservation and add to the concrete's final strength and increase its chemical resistance and durability.It can also increase workability of cement while reducing water demand. The replacement of Portland cement with fly ash also reduces the greenhouse gas foot print of concrete, as the production of one ton of Portland cement produces approximately one ton of CO2. Since the worldwide production of Portland cement is expected to reach nearly 2 billion tons by 2010, replacement of 30% of this amount by fly ash could dramatically reduce global carbon emissions.
No, they Increase the speed of chemical reactions
Micro structure of concrete with nano materials gets changed like anything and is resulting tremendous increase in compressive strength apart from increase in specific surface area.
Either (or both) an increase in the reactants or temperature will increase the rate of a chemical reaction.
There are a number of factors that improve flotation for concrete vessels:Large ratio of empty hull space compared to concrete hull and wallsAs above, wider beam (width) to increase volume of submerged airspace for the given overall weightLower weight of concrete, using lighter aggregate (*this can decrease the strength and durability)Thinner reinforcing bars and wireHoneycombs or airspaces within walls (rather than solid beams)Minimum mass in superstructure and in keel
The chemical reactivity of alkali metals increase when the atomic number increase.