$4($a$)$ List any FIVE $(5)$ factors affecting the compressive strength of concrete.

$(5$ marks$)$

$($b$)$ The rate of deterioration of concrete structures was increasingly concerned. Almost all forms of deterioration are the result of water ingress. The action of water may be twofold namely physical attack and chemical damage. Elaborate the twofold actions.

$(6$ marks$)$

$($c$)$ Describe any ONE main type of concrete deterioration and suggest one method for each type of concrete deterioration to reduce its effect on concrete.

$(4$ marks$)$

$($d$)$ Schmidt rebound hammer test is used for measuring the hardness of hardened concrete, state any TWO advantages and any TWO limitations of using the test. $(4$ marks$)$

$5.$ You are an Engineer of a consulting firm and responsible for the supervision of building construction works. During the site inspection, you observe some clay brickwork has been attacked by sulphate. You are required to find out the possible causes for this attack and suggest measures to avoid reoccurrence.

$(6$ marks$)$