Structural
Everything you own and love is surrounded by concrete and mortar in some form or another. Both concrete and mortar are composed of an aggregate material bound together by the addition of water to cement. Put another way, everything of value to you is surrounded by sand chemically bonded together by the addition of water to cement.
Cement is manufactured by heating a blend of naturally occurring materials to produce metal oxides of Calcium, Silica, Aluminium and Iron. When water is added to cement a chemical reaction occurs and the oxides hydrate; bonding the other components together and eventually creating a stone-like material.
To meet it's design criteria and to produce structures that will stand the test of time, it is important to get the cement-aggregate ratio, of the concrete, correct at the time of placement. Once placed and hardened the concrete is subjected to the normal environmental conditions of use; obvious defects such as ‘cracking’ and ‘creep’ can be easily monitored, more damaging is the chemical attack of the cement causing a loss in concrete strength. Of particular importance are Carbonation and Chloride & Sulphate attack.
Chemical Damage
1. Carbonation
Carbon Dioxide from air can react with the calcium hydroxide in concrete to form calcium carbonate. This process is called carbonation, which is essentially the reversal of the chemical process of calcination of lime taking place in a cement kiln. Carbonation of concrete is a slow and continuous process progressing from the outer surface inward. Carbonation has two effects: it increases mechanical strength of concrete, but it also decreases alkalinity, which is essential for corrosion prevention of the reinforcement steel. For this reason, carbonation is an unwanted process in concrete chemistry.
2. Chlorides & Sulphides
Chlorides & Sulphates in solution in contact with concrete can cause chemical changes to the cement, which can cause significant microstructural effects leading to a weakening of the cement binder as well as attacking the steel reinforcement present in most concrete.
Understanding the chemical nature of cements provides a unique perspective on the state of health of a building. At Waterfall & O’Brien we test and measure the concrete and mortar to ensure the building stands the test of time.
Purchase a Test
Select the test you require below. A self testing kit will be despatched to you along with a pre-paid enevelope to return it for analysis. Delivery costs £5 per order.
"We test and measure the concrete and mortar to ensure your buildings stand the test of time."
