General concrete knowledge:   HE stands for High Early Strength Cement.  Select all of the correct statements regarding HE cement.  Marks are awarded for each correct selection, but are deducted for incorrect selections.  Total marks awarded for this question will not be less than zero. a. Strength achieved at 7 days by concrete using HE cement is lower than the strength achieved at 7 days when using GP cement. b. Concrete made with HE cement is suitable for use in situations where it is beneficial to strip formwork early. c. Concrete made with HE cement produces greater heat of hydration than GP cement. d. Concrete made with HE cement produces less heat of hydration than GP cement. e. Concrete made with HE cement is suitable for use in thick concrete elements. f. Concrete made with HE cement is suitable for use in situations where there are low ambient temperatures (eg:  colder climates, early morning pours etc.) g. Strength achieved at 7 days by concrete using HE cement is higher than the strength achieved at 7 days when using GP cement.

The correct statements regarding High Early Strength Cement (HE cement) are:

b. Concrete made with HE cement is suitable for use in situations where it is beneficial to strip formwork early. This is because HE cement gains strength faster than General Purpose (GP) cement, allowing for the formwork to be removed sooner.

c. Concrete made with HE cement produces greater heat of hydration than GP cement. The heat of hydration is the heat produced when water and cement react. High early strength cement produces more heat faster than GP cement because it reacts faster.

f. Concrete made with HE cement is suitable for use in situations where there are low ambient temperatures (eg: colder climates, early morning pours etc.) The faster reaction time of HE cement can help counteract the slower curing times in cold weather.

g. Strength achieved at 7 days by concrete using HE cement is higher than the strength achieved at 7 days when using GP cement. This is the defining characteristic of HE cement - it gains strength faster than GP cement.

The incorrect statements are:

a. Strength achieved at 7 days by concrete using HE cement is lower than the strength achieved at 7 days when using GP cement. This is incorrect because HE cement is specifically designed to gain strength faster than GP cement.

d. Concrete made with HE cement produces less heat of hydration than GP cement. This is incorrect because the faster reaction of HE cement actually produces more heat.

e. Concrete made with HE cement is suitable for use in thick concrete elements. This is incorrect because the greater heat of hydration produced by HE cement can lead to thermal cracking in thick elements.