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用于就地强度测量的成熟度方法

在本文中,我们将调查使用成熟度方法进行真正的强度测量。我们将审查成熟技术背后的概念,以及最常见的做法。后来,我们将描述这种方法的充分强度预测方法的益处和局限性。在本文的最后一部分中,我们将审查和检查一些现有技术,以使用成熟技术。

混凝土强度

混凝土(压缩)强度是迄今为止混凝土最重要的财产。它代表混凝土的机械性能;例如,混凝土汽缸的28天压缩强度用作设计目的的规定抗压强度(ACI 318.-14年,CSA A23.3-14)。强度也被认为是(至少在旧学校)的关键因素持久性能。

The most common method for the evaluation of concrete compressive strength is the breaking cylindrical concrete samples in a compressive-testing machine. The force associated with the breaking point is divided by area to get the compressive strength. In a standard practice (i.e.ASTM C 39), concrete samples should be cured for 28 days in water tank, or in moist room condition.

为什么放置混凝土强度?

实力测量有几个好处。以下描述了就地强度测量的优点:

1-确定结构是否能够投入服务
2 - 结构固化和混凝土保护的充分性
3- Form or shoring removal time requirements
4- Termination of cold weather protection
5- Post-tensioning of tendons
6-开放通往交通的道路

成熟方法 - 模板拆除

ASTM C 31specifies the standard test procedure for in-place measurement of concrete strength using concrete cylinders. The use of Cast-in-Place-Punch-Out-Cylncore, known as (CIPPOC) is another method used in construction practice these days.

There are certain challenges with these practices. Generally, test samples do not reflect the influence of several factors on strength, including, Temperature fluctuations within mass of concrete, Weather conditions, critical curing conditions. In addition, the improper sample preparation and testing can make interpretation of the results even more difficult. Selecting the location to take these samples can be very subjective.

cippoc

成熟方法

“成熟方法是一种考虑时间和温度对混凝土强度发展的综合影响的技术。”(Carino and Lew, 2001)。成熟度方法提供了一种简单的方法,用于实时评估水泥基材料的强度,即在施工期间。

The two common procedures for using the maturity technique are standardized in the ASTM C 1074. These are:

方法1– Time-Temperature Factor
方法2.– The Equivalent-Age Factor

The following video describes the concept behind the method, and how to implement it in field practice.

成熟方法的益处和应用

1-该方法提供了一个简单的现场实现
2-现场实时和连续强度预测。在这种情况下,测试可以被认为是非破坏性的。
3- Maturity method offers a cheap, yet reliable alternative to conventional method of CIPPOC’s.
在此方法中选择诸如关节的关键位置,或者是可能的。
5-测试结果不受气缸或CIPPOC样品制备,处理和测试的影响。

这些益处使成熟方法是实时保证/控制的可靠替代品。减少了LAB的压缩强度结果的等待时间,并且可以在快速调度是一个问题时使用。该测试还提供了一种可靠的方法,用于选择终止寒冷天气保护的最佳时间。

成熟度法的局限性

Maturity method provides a simple and effective approach for evaluating in-place strength of concrete. However, the application of this method has some limitations. ASTM C 1074 summarizes some of the limitations as:

1-混凝土必须保持在允许水泥水合的条件下;
2-成熟法没有考虑到早期混凝土温度对长期强度的影响;
3- The method needs to be supplemented by other indications of the potential strength of the concrete mixture.

除了标准中提到的局限性之外,工程师和现场技术人员报告了以下挑战:

4-高强度混凝土成熟度法的应用进一步调查。
5-校准每个组合的强度 - 成熟度关系是具有挑战性的。
6-选择适当的基准温度或激活能量可能是主观的。最近的研究昌亨李和肯尼斯C.徘徊investigates the significance of these initial values on the strength prediction.

作者

Hamed LayssiPouyaPourbeik

HAMES-LAYSSI.

Pouya-pourbeik

7关于“真实力量测量成熟方法”的思考

  1. Very good technique. I believe that normally curing of concrete in field is much less than curing in lab for 28 days and thus determination of lab concrete strength is not a correct way; rather in place as explained herein is more reliable.

  2. Dr. Basim Abbas

    成熟不仅取决于温度,还取决于混凝土中的“水分”。这在早期混凝土年龄的暴露表面上是特别重要的。如果相对湿度下降下降(约70%),混凝土可能会停止增强。
    However for the normal conditions with continuous water curing the effective factor is temperature.
    如果需要,我可以在成熟概念上提供更多信息和数学模拟。

  3. Interesante los comentarios sobre todo con el tema del proceso de madurez, personalmente por experiencia se que los procedimientos de curado en obra no han sido los mas adecuados actualmente me inclino por el uso de curadores que impermeabilizan la estructura evitando la evaporación del agua de la mezcla de concreto; lo que conlleva a mejorar la resistencia del concreto.

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