#bestqualitycement

Poor construction methods and workmanship is responsible for the failure of buildings and structure. The poor construction methods and workmanship is caused due to negligence and inadequate quality control at construction site. The effects of some of the poor construction methods are as under :

(a) Incorrect Placement of Steel

Incorrect placement of steel can result in insufficient cover, leading to corrosion of the reinforcement. If the bars are placed grossly out of position or in the wrong position, collapse can occur when the element is fully loaded.

(b) Inadequate over to reinforcement

Inadequate cover to reinforcement permits ingress of moisture, gases and other substances and leads to corrosion of the reinforcement and cracking and spalling of the concrete.

(c) Incorrectly made Construction Joints

The main faults in construction joints are lack of preparation and poor compaction. The old concrete should be washed and a layer of rich concrete laid before pouring is continued. Poor joints allow ingress of moisture and staining of the concrete face.

(d) Grout Leakage

Grout leakage occurs where formwork joints do not fit together properly. The result is a porous area of concrete that has little or no cement and fine aggregate. All form work joints should be properly sealed.

(e) Poor Compaction

If concrete is not properly compacted by ramming or vibration the result is a portion of porous honeycomb concrete. This part must be hacked out and recast. If Complete compaction is essential to give a dense,impermeable concrete. Usage of good quality cement also plays a vital role in compaction

(f) Segregation

Segregation occurs when the mix ingredients become separated. It is the result of

Dropping the mix through too great a height in placing (chutes or pipes should be used in such cases)

Using a harsh mix with high coarse aggregate content

Large aggregate sinking due to over-vibration or use of too much plasticizer Segregation results in uneven concrete texture, or porous concrete in some cases.

(g) Poor Curing

A poor curing procedure can result in loss of water through evaporation. This can cause a reduction in strength if there is not sufficient water for complete hydration of the cement. Loss of water can cause shrinkage cracking. During curing the concrete should be kept damp and covered.

(h) Too High a Water Content