The vibration process applied to fresh concrete is an important link in the construction process, but the lack of effective monitoring and evaluation methods results in the quality of the vibration process being difficult to control and, therefore, the structural quality of the resulting concrete structures difficult to guarantee. In this paper, according to the sensitivity of internal vibrators to vibration acceleration changes under different vibration media, the vibration signals of vibrators in air, concrete mixtures, and reinforced concrete mixtures were collected experimentally. Based on a deep learning algorithm for load recognition of rotating machinery, a multi-scale convolution neural network combined with a self-attention feature fusion mechanism (SE-MCNN) was proposed for medium attribute recognition of concrete vibrators. The model can accurately classify and identify vibrator vibration signals under different working conditions with a recognition accuracy of up to 97%. According to the classification results of the model, the continuous working times of vibrators in different media can be further statistically divided, which provides a new method for accurate quantitative evaluation of the quality of the concrete vibration process.

In this paper, the effects of dry density, w/c ratio, and municipal solid waste incineration (MSWI) powder on the multi-scale properties and internal pore structure of foamed concrete were studied by using a single-factor controlled experiment. It was found that an increase in the dry density of foamed concrete could effectively reduce the porosity, leading to the improvement of compressive strength and impermeability and to the reduction of water absorption. The compressive strength, water absorption, and impermeability were mainly affected by the porosity when the w/c ratio changed. With the increase in porosity, the water absorption rate increased, and the compressive strength and impermeability decreased. The addition of MSWI powder caused no obvious change in the overall pore size distribution of the foamed concrete, and there was no significant change in the water absorption and impermeability of the structure. However, because the hydration activity of MSWI powder was lower than that of ordinary Portland cement, the compressive strength of foamed concrete decreased with the increase in MSWI powder.

In the process of construction, pouring and vibrating concrete on existing reinforced structures is a necessary process. This paper presents an automatic vibration position detecting method based on the feature extraction of 3D lidar point clouds. Compared with the image-based method, this method has better anti-interference performance to light with reduced computational consumption. First, lidar scans are used to capture multiple frames of local steel bar point clouds. Then, the clouds are stitched by Normal Distribution Transform (NDT) for preliminary matching and Iterative Closest Point (ICP) for fine-matching. The Graph-Based Optimization (g2o) method further refines the precision of the 3D registration. Afterwards, the 3D point clouds are projected into a 2D image. Finally, the locations of concrete vibration points and concrete casting points are discerned through point cloud and image processing technologies. Experiments demonstrate that the proposed automatic method outperforms ICP and NDT algorithms, reducing the mean square error (MSE) by 11.5% and 11.37%, respectively. The maximum discrepancies in identifying concrete vibration points and concrete casting points are 0.059 ± 0.031 m and 0.089 ± 0.0493 m, respectively, fulfilling the requirement for concrete vibration detection.

In this paper, the strength characteristics and erosion resistance of solid waste incineration (MSWI) powder were studied. Firstly, the optimum process for the preparation of regenerated powder from MSWI bottom slag by ball milling was determined as follows: rotational speed 350 r/min, time 45 min. The strength activity index of regenerated powder reached the maximum when the substitute content of powder was 30%. Secondly, the semi-erosion method was used to study the strength variation rule of mortar with different content of MSWI powder in semi-immersion of salt solution. It was found that the higher the content of MSWI powder, the greater the anti-erosion coefficient of mortar specimen. Finally, the capillary rise test, crystallization test and capillary pore water absorption test were used to study the total porosity, coarse capillary-pore porosity and fine-capillary pore porosity of concrete containing MSWI powder. The results showed that, with the increase in MSWI powder content, the above pore structure properties were improved. The results revealed the transport and crystallization process of salt solution in concrete mixed with MSWI powder and the mechanism of corrosion resistance.