SMDStructural Floor and Roof Solutions

1 of 2SMD.DAT.220.V4Concrete Department

SMD aim to provide the best possible surface finish to a slab on all projects. To enable SMD to provide an acceptable surface finish, it is advisable for concrete pours to be carried out in an enclosed environment to provide adequate protection of the works against inclement weather. Whilst SMD appreciate that it is not always feasible for the client to provide a weather proof envelope due to site programme, it should be understood that this may have a detrimental effect on the final surface finish (depending on the severity of the conditions).

As part of our aim, we will always review the latest weather forecast information on The Met Office website 24 hours before a scheduled pour date. The forecast for the project location will be displayed similarly to the view illustrated in Fig.1.

Should the forecast appear unfavourable, this will be highlighted to the client’s on site management team for their review accordingly. The ultimate decision as to whether to proceed with a concrete pour will always be that of SMD’s client. Should the decision to cancel and rearrange the pour be taken, this must be established by 12:00pm the day prior to the programmed pour date to avoid cancellation charges from the pump supplier, concrete plant and labour operatives.

SMD cannot be held responsible for weather damage incurred to concrete slabs where pours are carried out against the advice of the SMD project management team upon review of the most up to date weather forecast. In the event of cancellation, SMD will aim to reprogramme the pour at the earliest opportunity. It is unlikely (in most cases) to be rearranged for the following day as due notice of up to 1 week needs to be given in order to rearrange labour, plant and materials.

Cold weather has the potential to effect concrete operations on steel decking as steel decking is a poor insulator. Precautions to prevent the concrete at the steel interface falling below 5°C should be provided (by others) until the concrete has achieved a strength of at least 5N/mm². Additional preventative measures should also be considered (by others) for protection of newly laid concrete surfaces against the effects of frost.

Fig.1 - Typical detailed weather forecast

Best Practice Data Sheet DATA/15

Concrete weather review and potential effects of pouring concrete in an exposed environment

2 of 2SMD.XXX.000.V1Department Name 2 of 2Concrete Department

SMD.DAT.220.V4

www.smdltd.co.ukSMD Limited Unit C The Outlook Tower Park Poole Dorset BH12 4PYTel: +44 (0) 1202 718 898 Email: contactus@smdltd.co.uk

SMDStructural Floor and Roof Solutions

Fig. 2 Fig. 3 Fig. 4

Fig. 5 Fig. 6 Fig. 7

Rain damage can have a varying impact on a slab (Fig.2-7), from light cosmetic “pitting” on the surface to washing away some of the cement from the concrete and exposing the aggregate.

High/cross winds or sunlight may cause premature drying of the concrete surface leading to surface delamination (Fig.8-10) and/or premature plastic shrinkage cracks occuring (Fig.11-13). High winds will also impact the safe operation of the concrete pump, particularly on pours at height.

Fig. 8 Fig. 9 Fig. 10

Fig. 11 Fig. 12 Fig. 13