GB 50496-2018 (English Version)

Standard No.: GB 50496-2018
Language: Chinese, Available in English version
Release Date: 2018
Published By: Ministry of Housing and Urban-Rural Development of the People's Replublic of China
Latest: GB 50496-2018

Scope: The "Construction Standards for Mass Concrete" is now approved as a national standard, numbered GB50496-2018, which will come into effect on December 1, 2018. Among them, Articles 4.2.2 and 5.3.1 are mandatory provisions and must be strictly implemented. The original national standard "Code for Mass Concrete Construction" GB50496-2009 will be abolished at the same time. This standard is published on the website of the Ministry of Housing and Urban-Rural Development (www.mohurd.gov.cn), and is published by China Architecture and Construction Press organized by the Institute of Standards and Quotas of the Ministry of Housing and Urban-Rural Development. Ministry of Housing and Urban-Rural Development of the People's Republic of China April 25, 2018

Introduction

Analysis of the core content of the standard

Key indicators	2009 edition	2018 edition	Technical improvement
Heat of cement hydration	3d≤240kJ/kg	3d≤250kJ/kg	Adapt to the application of high-strength cement
Temperature difference between inside and outside	≤25℃	≤25℃ (excluding shrinkage equivalent)	More precise control
Curing time	≥14d	≥14d (clear moisture requirements)	Emphasis on humidity control

Key technical points

1. Material control

Mandatory clause 4.2.2 requires that key indicators such as hydration heat must be tested when cement is delivered to the site. The hydration heat of 52.5 grade cement should be <300kJ/kg at 7 days. The mud content of coarse aggregate should be ≤1%, and medium sand (fineness modulus> 2.3) should be used as fine aggregate.

2. Innovation in mix ratio

60d/90d strength can be used as the basis for acceptance
Dual-mixing technology: fly ash ≤50%+slag powder ≤40% (total ≤50%)
Water-cement ratio ≤0.45, sand rate 38%-45%

Breakthrough in construction technology

Case of skip-bin construction

The foundation raft of a super-high-rise building in Shanghai adopted a skip-bin spacing of 40m and was cast at intervals of 7d. Steel plate waterstop + expansive concrete were set at the joints, successfully controlling the cracks to <0.2mm.

Three elements of temperature control

Mold temperature 5-30℃
Cooling rate ≤2.0℃/d
Surface and ambient temperature difference ≤20℃

Temperature monitoring specifications

Monitoring point layout requirements: 3 layers for thickness ≤2.5m, 5 layers for 2.5-5m, 1 layer for every additional 1m for thickness >5m. When using electronic thermometer, the accuracy must reach ±0.3℃.

GB 50496-2018 history

2018 GB 50496-2018 Mass Concrete Construction Standards
2009 GB 50496-2009 Code for construction of mass concrete