The mixing water used for cement concrete has a significant effect on the physical properties of the material after hardening; however, other than the upper limit for the mixed impurities, not enough consideration has been given to the functions and characteristics of water at the molecular level. In this study, we investigated the effect of four different types of water (two spring-, mineral waters, tap water and distilled water) on the drying shrinkage of the hardened cement by comparing the material properties of the concrete specimens and analyzing the molecular structure of the water and cement mortar using aquaphotomics. The near infrared (NIR) spectra of waters used for mixing were acquired in the transmittance mode using a high-precision, high-accuracy benchtop spectrometer in the range of 400–2500 nm, with the 0.5 nm step. The NIR spectra of cement paste and mortar were measured in 6.2 nm increments in the wavelength range of 950 nm to 1650 nm using a portable spectrometer. The measurements of cement paste and mortar were performed on Day 0 (immediately after mixing, cement paste), 1 day, 3 days, 7 days, and 28 days after mixing (cement mortar). The spectral data were analyzed according to the aquaphotomics’ multivariate analysis protocol, which involved exploration of raw and preprocessed spectra, exploratory analysis, discriminating analysis and aquagrams. The results of the aquaphotomics’ analysis were interpreted together with the results of thermal and drying shrinkage measurements. Together, the findings clearly demonstrated that the thermal and drying shrinkage properties of the hardened cement material differed depending on the water used. Better mechanical properties were found to be a result of using mineral waters for cement mixing despite minute differences in the chemical content. In addition, the aquaphotomic characterization of the molecular structure of waters and cement mortar during the initial hydration reaction demonstrated the possibility to predict the characteristics of hardened cement at a very early stage. This provided the rationale to propose a novel evaluation method based on aquaphotomics for non-invasive evaluation and monitoring of cement mortar.

Polycarboxylic acid-based superplasticizers are being used for various fields of concrete work, however little has reported on changing basic performance by thermal fluctuation. In this study, heating superplasticizers itself is hereinafter as referred to as “thermal stimulation”, the effect of thermal stimulation and heat retention of superplasticizer on the fresh mortar, moreover the influence of molecular structural changed of superplasticizer by thermal stimulation were investigated. As the result, it was confirmed that improving fluidity of the mortar flow on this condition the highly heat temperature and heat over a long time by thermal stimulation of superplasticizer. In addition, it turned out that this phenomenon was caused molecular structural changed by thermal stimulation, and the result was revealed that the effect of thermal stimulation varies according to the type of polymer.

It is widely known that basic performance of superplasticizer can be fluctuated by change of ambient temperature. However, it is not known that fluidity of concrete can be improved by thermal stimulation to superplasticizer. It was confirmed that fluidity of the mortar has been improved by heating superplasticizer in the previous study, therefore in this study, Examination of thermal stimulation effect on the molecular weight distribution of superplasticizer, the study of retention effect of fluidity after thermal stimulation of superplasticizer, and its sustainability were examined. As a result, it was confirmed that thermal stimulation doesn't negatively affect the molecular weight distribution and affects only the three-dimensional structure of the polymer molecule. Moreover, it was confirmed that the thermal stimulation effect not only sustained the improvement of the initial dispersion performance well but also did not lower the slump keeping performance thereafter. In addition to it was confirmed that the thermal stimulation effect lasted for about 7 days, and the residual characteristics differed depending on the superplasticizer.

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In recent years, concrete structures have tended to be taller and larger than before. With that trend, concrete as a material has diversified, and various kinds have been developed to meet differing quality requirements. In particular, the need for high-strength concrete is increasing. In general, high-strength concrete has a low water-binder ratio, so its workability is inferior to general concrete. Including admixtures such as silica fume is one way to remedy this problem. Previous studies have discussed the quality and hardening characteristics achievable using silica fume. Nevertheless, expected increasing demand for high-strength concrete dictates the need to understand not only its properties when fresh, but also to have an accurate picture of its vibration compaction properties on construction sites. In this study, the effect of adding silica fume on the workability of mortar was investigated by evaluating its fresh properties, plastic viscosity, and vibration propagation characteristics. Changes to mortar’s fresh properties due to pressure were also investigated to clarify its behavior in pumping environments. The study confirmed that the addition of silica fume decreases plastic viscosity and increases vibration propagation characteristics, and that increased plastic viscosity due to pressurization can be reduced.