STUDY ON INFLUENCE OF MOISTURE CONTENT ON STRENGTH DEVELOPMENT OF HIGH-STRENGTH CONCRETE

混凝土的强度发展受养护过程中的温度和湿度条件的影响。高强混凝土由于其单位含水率低，从一开始就几乎不含足够的水。本研究通过试验研究了湿养护条件对不同强度混凝土的影响，以阐明和定量评价湿养护条件对高强混凝土强度发展的影响。此外，我们还利用热敏元件和陶瓷传感器检测了结构混凝土中的水分行为。(2)湿养护条件对高强混凝土含水率的影响不大。(3)提出了用混凝土含水率、未水化水泥掺量和水化水泥浆体掺量来表示水泥浆体形成速率的强度发展计算公式。根据该强度发展计算公式，强度较高的混凝土水化倾向于停滞，而未水化水泥含量和含水率保持较高。(4)干燥条件下结构混凝土表层的含水率低于内部，随着水灰比的增大，这一现象变得更加明显。(5)结构混凝土高温养护引起内部水分向表层的迁移，受水蒸气分压的影响。通过高温固化使内部快速水化，使水分向内部移动表层。这些行为是复杂的，内部部分与表层之间的抗压强度差异在长期内变得更加紧密，并随着强度的提高而变得明显。

Strength development of concrete is affected by the temperature and moisture conditions during curing. High-strength concrete contains barely sufficient water from the beginning due to its low unit water content.In this study, the authors experimentally examined the effects of moist curing conditions on concretes having different strengths to elucidate and quantitatively evaluate the effect of moist curing conditions on the strength development of high-strength concrete.In addition we examined behavior of water content in structural concrete by using thermo-elements and ceramic sensor.The results are summarized as follows ;(1) The curing with lower relative humidity leads to lower long-term strength development.(2) The effect of moist curing conditions on the water content of high-strength concrete is marginal.(3) The equation for calculating the strength development, in which the rate of cement paste formation is expressed by the water content of concrete, unhydrated cement content, and content of hydrated cement paste formed is proposed. According to this equation for calculating strength development, hydration in concrete with a higher strength tends to stagnate while unhydrated cement content and water content remain higher.(4) The surface layer of concrete in structure has less water content than the internal parts when drying condition, and it became conspicuous when the water-cement ratio became higher.(5) High temperature curing of concrete in structural causes water movement internal parts to surface layer affected by partial pressure of water vapor. And rapid hydration at internal parts by high temperature curing causes water movement surface layer to internal parts. These behaviors were complicated and different of compressive strength between internal parts and surface layer became closer in long term, and it became conspicuous when the strength became higher.